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Jahan M, Amir A, Das A, Kihlström J, Nag S. Automated radiosynthesis of mGluR5 PET tracer [ 18F]FPEB from aryl-chloro precursor and validation for clinical application. J Labelled Comp Radiopharm 2024; 67:155-164. [PMID: 38369901 DOI: 10.1002/jlcr.4088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/11/2023] [Accepted: 01/29/2024] [Indexed: 02/20/2024]
Abstract
The radioligand [18F]FPEB, used for PET imaging of the brain's metabotropic glutamate receptor subtype 5 (mGluR5), undergoes a thorough validation process to ensure its safety, efficacy, and quality for clinical use. The process starts by optimizing the synthesis of [18F]FPEB to achieve high radiochemical yield and purity. This study focuses on optimizing the radiolabeling process using an aryl-chloro precursor and validating the GMP production for clinical applications. Fully automated radiolabeling was achieved via one-step nucleophilic substitution reaction. [18F]FPEB was produced and isolated in high radioactivity and radiochemical purity. Throughout the validation process, thorough quality control measures are implemented. Radiopharmaceutical batch release criteria are established, including testing for physical appearance, filter integrity, pH, radiochemical purity, molar activity, radiochemical identity, chemical impurity, structural identity, stability, residual solvent, sterility, and endotoxin levels. In conclusion, the validation of [18F]FPEB involved a comprehensive process of synthesis optimization, quality control, which ensure the safety, efficacy, and quality of [18F]FPEB, enabling its reliable use in clinical PET. Here, we successfully radiolabeled and validated [18F]FPEB using aryl-chloro precursor according to GMP production for clinical application.
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Affiliation(s)
- Mahabuba Jahan
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Arsalan Amir
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Arindam Das
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Jacob Kihlström
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
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2
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Haveman LYF, Vugts DJ, Windhorst AD. State of the art procedures towards reactive [ 18F]fluoride in PET tracer synthesis. EJNMMI Radiopharm Chem 2023; 8:28. [PMID: 37824021 PMCID: PMC10570257 DOI: 10.1186/s41181-023-00203-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 08/03/2023] [Indexed: 10/13/2023] Open
Abstract
BACKGROUND Positron emission tomography (PET) is a powerful, non-invasive preclinical and clinical nuclear imaging technique used in disease diagnosis and therapy assessment. Fluorine-18 is the predominant radionuclide used for PET tracer synthesis. An impressive variety of new 'late-stage' radiolabeling methodologies for the preparation of 18F-labeled tracers has appeared in order to improve the efficiency of the labeling reaction. MAIN BODY Despite these developments, one outstanding challenge into the early key steps of the process remains: the preparation of reactive [18F]fluoride from oxygen-18 enriched water ([18O]H2O). In the last decade, significant changes into the trapping, elution and drying stages have been introduced. This review provides an overview of the strategies and recent developments in the production of reactive [18F]fluoride and its use for radiolabeling. CONCLUSION Improved, modified or even completely new fluorine-18 work-up procedures have been developed in the last decade with widespread use in base-sensitive nucleophilic 18F-fluorination reactions. The many promising developments may lead to a few standardized drying methodologies for the routine production of a broad scale of PET tracers.
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Affiliation(s)
- Lizeth Y F Haveman
- Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
- Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam, The Netherlands
| | - Danielle J Vugts
- Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands
- Cancer Center Amsterdam (CCA), Amsterdam, The Netherlands
| | - Albert D Windhorst
- Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, The Netherlands.
- Neuroscience Amsterdam, Amsterdam, The Netherlands.
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3
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Lopresti BJ, Royse SK, Mathis CA, Tollefson SA, Narendran R. Beyond monoamines: I. Novel targets and radiotracers for Positron emission tomography imaging in psychiatric disorders. J Neurochem 2023; 164:364-400. [PMID: 35536762 DOI: 10.1111/jnc.15615] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 10/18/2022]
Abstract
With the emergence of positron emission tomography (PET) in the late 1970s, psychiatry had access to a tool capable of non-invasive assessment of human brain function. Early applications in psychiatry focused on identifying characteristic brain blood flow and metabolic derangements using radiotracers such as [15 O]H2 O and [18 F]FDG. Despite the success of these techniques, it became apparent that more specific probes were needed to understand the neurochemical bases of psychiatric disorders. The first neurochemical PET imaging probes targeted sites of action of neuroleptic (dopamine D2 receptors) and psychoactive (serotonin receptors) drugs. Based on the centrality of monoamine dysfunction in psychiatric disorders and the measured success of monoamine-enhancing drugs in treating them, the next 30 years witnessed the development of an armamentarium of PET radiopharmaceuticals and imaging methodologies for studying monoamines. Continued development of monoamine-enhancing drugs over this time however was less successful, realizing only modest gains in efficacy and tolerability. As patent protection for many widely prescribed and profitable psychiatric drugs lapsed, drug development pipelines shifted away from monoamines in search of novel targets with the promises of improved efficacy, or abandoned altogether. Over this period, PET radiopharmaceutical development activities closely paralleled drug development priorities resulting in the development of new PET imaging agents for non-monoamine targets. Part one of this review will briefly survey novel PET imaging targets with relevance to the field of psychiatry, which include the metabotropic glutamate receptor type 5 (mGluR5), purinergic P2 X7 receptor, type 1 cannabinoid receptor (CB1 ), phosphodiesterase 10A (PDE10A), and describe radiotracers developed for these and other targets that have matured to human subject investigations. Current limitations of the targets and techniques will also be discussed.
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Affiliation(s)
- Brian J Lopresti
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sarah K Royse
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Chester A Mathis
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Savannah A Tollefson
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rajesh Narendran
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,Departments of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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4
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Krzyczmonik A, Grafinger KE, Keller T, Pfeifer L, Forsback S, Haaparanta-Solin M, Gouverneur V, López-Picón F, Solin O. Evaluation of [ 18F]FMTEB in Sprague Dawley rats as a PET tracer for metabotropic glutamate receptor 5. Nucl Med Biol 2023; 116-117:108309. [PMID: 36521341 DOI: 10.1016/j.nucmedbio.2022.108309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 10/31/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
INTRODUCTION [18F]FMTEB, along with other tracers, was developed as a promising PET radioligand for imaging metabotropic glutamate receptor subtype 5 (mGluR5). Despite favorable preliminary results, it has not been used further for studies of mGluR5. This paper presents an in-depth preclinical evaluation of [18F]FMTEB in healthy Sprague Dawley rats. METHODS [18F]FMTEB was synthesized from a boronic ester precursor using copper-mediated fluorination. In vivo PET imaging was performed on six rats, of which three were pre-treated with a high affinity mGluR5 receptor antagonist. An additional 18 rats were used for ex vivo experiments for metabolite analyses in plasma, brain and urine, and for biodistribution and ex vivo brain autoradiography at different time points. RESULTS [18F]FMTEB was synthesized in adequate radiochemical yield and a molar activity of 154 ± 64 GBq/μmol. Both in vivo imaging and ex vivo brain autoradiography showed high specificity for mGluR5, and the blocking experiments showed a clear decrease in radioactivity in mGluR5-rich brain areas. Metabolite analyses confirmed fast metabolism of the tracer in plasma. The percentage of parent compound in brain tissue exceeded 90 % up to 90 min after injection. CONCLUSION [18F]FMTEB produced via copper-mediated 18F-fluorination fulfilled the requirements for preclinical evaluation in rats. The absence of specific uptake in cerebellum and absence of defluorination of the tracer allowed cerebellum to be used as a reference tissue. Due to the fast kinetics in rats, the region-to-cerebellum ratios equilibrated within 30 min. These results prove [18F]FMTEB to be a good candidate for mapping mGluR5 in rat brain and a suitable alternative to [18F]FPEB.
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Affiliation(s)
- Anna Krzyczmonik
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - Katharina E Grafinger
- Turku PET Centre, Preclinical Imaging, University of Turku, Turku, Finland; MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Thomas Keller
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - Lukas Pfeifer
- University of Oxford, Chemistry Research Laboratory, Oxford, United Kingdom
| | - Sarita Forsback
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland; Department of Chemistry, University of Turku, Turku, Finland
| | - Merja Haaparanta-Solin
- Turku PET Centre, Preclinical Imaging, University of Turku, Turku, Finland; MediCity Research Laboratory, University of Turku, Turku, Finland
| | | | - Francisco López-Picón
- Turku PET Centre, Preclinical Imaging, University of Turku, Turku, Finland; MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Olof Solin
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland; Department of Chemistry, University of Turku, Turku, Finland; Turku PET Centre, Accelerator Laboratory, Åbo Akademi University, Turku, Finland.
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5
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Asch RH, Fowles K, Pietrzak RH, Taylor JR, Esterlis I. Examining mGlu5 Receptor Availability as a Predictor of Vulnerability to PTSD: An [ 18F]FPEB and PET Study in Male and Female Rats. CHRONIC STRESS (THOUSAND OAKS, CALIF.) 2023; 7:24705470231215001. [PMID: 38024327 PMCID: PMC10666551 DOI: 10.1177/24705470231215001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 11/02/2023] [Indexed: 12/01/2023]
Abstract
Background Females are twice as likely to experience post-traumatic stress disorder (PTSD) than males, yet specific factors contributing to this greater risk are not fully understood. Our clinical and recent preclinical findings suggest a role for the metabotropic glutamate receptor 5 (mGlu5) in PTSD and differential involvement between males and females. Methods Here, we further investigate whether mGlu5 receptor availability may contribute to individual and sex differences in PTSD susceptibility by quantifying receptor availability using the mGlu5 receptor-specific radiotracer, [18F]FPEB, and positron emission tomography in male (n = 16) and female (n = 16) rats before and after traumatic footshock exposure (FE) and assessment of stress-enhanced fear learning (SEFL) susceptibility, as compared with no-shock controls (CON; n = 7 male; n = 8 female). Results Overall, FE rats displayed greater fear generalization as compared with CON (p < .001). Further, greater mGlu5 receptor availability at baseline (p = .003) and post-test (p = .005) was significantly associated with expression of the SEFL phenotype. Notably, FE female rats displayed a shift to more passive coping (ie, freezing), and displayed greater SEFL susceptibility (p = .01), and had lower baseline mGlu5 availability (p = .03) relative to their FE male rat counterparts. Conclusion Results are consistent with clinical findings of higher mGlu5 receptor availability in PTSD, and add to growing evidence implicating these receptors in the pathophysiology of PTSD and sex-differences in susceptibility for this disorder.
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Affiliation(s)
- Ruth H. Asch
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Krista Fowles
- Department of Radiology & Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Robert H. Pietrzak
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- US Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, VA Connecticut Healthcare System, West Haven, CT, USA
| | - Jane R. Taylor
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- Department of Psychology, Yale University, New Haven, CT, USA
- Department of Neuroscience, Yale University, New Haven, CT, USA
| | - Irina Esterlis
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
- Department of Radiology & Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
- US Department of Veterans Affairs National Center for Posttraumatic Stress Disorder, VA Connecticut Healthcare System, West Haven, CT, USA
- Department of Psychology, Yale University, New Haven, CT, USA
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6
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Glorie D, Verhaeghe J, Miranda A, De Lombaerde S, Stroobants S, Staelens S. Quantification of Metabotropic Glutamate Receptor 5 Availability With Both [ 11C]ABP688 and [ 18F]FPEB Positron Emission Tomography in the Sapap3 Knockout Mouse Model for Obsessive-Compulsive-like Behavior. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2022; 7:607-615. [PMID: 34856382 DOI: 10.1016/j.bpsc.2021.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/17/2021] [Accepted: 11/20/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND This study provides a first direct comparison between positron emission tomography radioligands targeting the allosteric site of the metabotropic glutamate receptor 5 (mGluR5): [11C]ABP688 and [18F]FPEB. A blocking paradigm was set up to substantiate the common binding site of both radioligands. Second, both radioligands were applied in Sapap3 knockout (KO) mice showing compulsive-like behavior characterized by a lower in vivo mGluR5 availability. METHODS First, wild-type mice (n = 7) received four position emission tomography/computed tomography scans: a [11C]ABP688 scan, a [18F]FPEB scan, and two blocking scans using cold FPEB and cold ABP688, respectively. A second experiment compared both radioligands in wild-type (n = 7) and KO (n = 10) mice. The simplified reference tissue model was used to calculate the nondisplaceable binding potential representing the in vivo availability of mGluR5 in the brain. RESULTS Using cold FPEB as a blocking compound for [11C]ABP688 micro-positron emission tomography and vice versa, we observed averaged global reductions in mGluR5 availability of circa 98% for [11C]ABP688 and 82%-96% for [18F]FPEB. For KOs, the [11C]ABP688 nondisplaceable binding potential was on average 25% lower compared with wild-type control mice (p < .0001-.001), while this was about 17% for [18F]FPEB (p < .05). CONCLUSIONS The current findings substantiate a common binding site and suggest a strong relationship between mGluR5 availability levels measured with both radioligands. In Sapap3 KO mice, a reduced mGluR5 availability could therefore be demonstrated with both radioligands. With [11C]ABP688, higher significance levels were achieved in more brain regions. These findings suggest [11C]ABP688 as a preferable radiotracer to quantify mGluR5 availability, as exemplified here in a model for compulsive-like behavior.
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Affiliation(s)
- Dorien Glorie
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium
| | - Alan Miranda
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium
| | - Stef De Lombaerde
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium; Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium; Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Wilrijk, Belgium.
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7
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Rokka J, Nordeman P, Roslin S, Eriksson J. A comparative study on Suzuki-type 11 C-methylation of aromatic organoboranes performed in two reaction media. J Labelled Comp Radiopharm 2021; 64:447-455. [PMID: 34250640 DOI: 10.1002/jlcr.3932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/13/2021] [Accepted: 07/05/2021] [Indexed: 11/07/2022]
Abstract
The Suzuki-type cross coupling reaction is a palladium-mediated multistep reaction that has been used to synthesize several 11 C-labeled tracers for PET. However, the impact of the selected organoborane reagent and reaction medium on the radiochemical yield (RCY) has not been thoroughly investigated. To bridge this gap, we studied the synthesis of 1-[11 C]methylnaphthalene using four different organoborane precursors in reactions performed in DMF/water and THF/water. In the synthesis of 1-[11 C]methylnaphthalene, the best radiochemical yields (RCYs), approximately 50%, were obtained with boronic acid and pinacol ester precursors, whereas less than 4% RCY was obtained when performing the reaction with the N-methylimidodiacetic acid boronic ester (MIDA ester) precursor. 1-[11 C]methylnaphthalene was obtained in higher yields in almost all syntheses performed in THF/water as compared to DMF/water. This observation was in line with previously reported results for [11 C]UCB-J, a tracer for the synaptic vesicle glycoprotein 2A (SV2A) receptor, that also was obtained in higher RCY when synthesized in THF/water. The same trend was observed with [11 C]cetrozole, where the RCY was more than doubled in THF/water compared to the previously published synthesis performed in DMF. These results suggest that THF/water could be the preferred reaction medium when producing PET tracers via the Suzuki-type coupling reaction.
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Affiliation(s)
- Johanna Rokka
- Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala, Sweden
| | - Patric Nordeman
- Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University Hospital, Uppsala, Sweden
| | - Sara Roslin
- Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University Hospital, Uppsala, Sweden
| | - Jonas Eriksson
- Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University Hospital, Uppsala, Sweden
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8
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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9
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Bennett KA, Sergeev E, MacSweeney CP, Bakker G, Cooper AE. Understanding Exposure-Receptor Occupancy Relationships for Metabotropic Glutamate Receptor 5 Negative Allosteric Modulators across a Range of Preclinical and Clinical Studies. J Pharmacol Exp Ther 2021; 377:157-168. [PMID: 33541889 DOI: 10.1124/jpet.120.000371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/26/2021] [Indexed: 01/17/2023] Open
Abstract
The metabotropic glutamate receptor 5 (mGlu5) is a recognized central nervous system therapeutic target for which several negative allosteric modulator (NAM) drug candidates have or are continuing to be investigated for various disease indications in clinical development. Direct measurement of target receptor occupancy (RO) is extremely useful to help design and interpret efficacy and safety in nonclinical and clinical studies. In the mGlu5 field, this has been successfully achieved by monitoring displacement of radiolabeled ligands, specifically binding to the mGlu5 receptor, in the presence of an mGlu5 NAM using in vivo and ex vivo binding in rodents and positron emission tomography imaging in cynomolgus monkeys and humans. The aim of this study was to measure the RO of the mGlu5 NAM HTL0014242 in rodents and cynomolgus monkeys and to compare its plasma and brain exposure-RO relationships with those of clinically tested mGlu5 NAMs dipraglurant, mavoglurant, and basimglurant. Potential sources of variability that may contribute to these relationships were explored. Distinct plasma exposure-response relationships were found for each mGlu5 NAM, with >100-fold difference in plasma exposure for a given level of RO. However, a unified exposure-response relationship was observed when both unbound brain concentration and mGlu5 affinity were considered. This relationship showed <10-fold overall difference, was fitted with a Hill slope that was not significantly different from 1, and appeared consistent with a simple Emax model. This is the first time this type of comparison has been conducted, demonstrating a unified brain exposure-RO relationship across several species and mGlu5 NAMs with diverse properties. SIGNIFICANCE STATEMENT: Despite the long history of mGlu5 as a therapeutic target and progression of multiple compounds to the clinic, no formal comparison of exposure-receptor occupancy relationships has been conducted. The data from this study indicate for the first time that a consistent, unified relationship can be observed between exposure and mGlu5 receptor occupancy when unbound brain concentration and receptor affinity are taken into account across a range of species for a diverse set of mGlu5 negative allosteric modulators, including a new drug candidate, HTL0014242.
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Affiliation(s)
| | | | | | - Geor Bakker
- Sosei Heptares, Cambridge, CB21 6DG, United Kingdom
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10
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Petropoulou PI, Mosialou I, Shikhel S, Hao L, Panitsas K, Bisikirska B, Luo N, Bahna F, Kim J, Carberry P, Zanderigo F, Simpson N, Bakalian M, Kassir S, Shapiro L, Underwood MD, May CM, Soligapuram Sai KK, Jorgensen MJ, Confavreux CB, Shapses S, Laferrère B, Mintz A, Mann JJ, Rubin M, Kousteni S. Lipocalin-2 is an anorexigenic signal in primates. eLife 2020; 9:58949. [PMID: 33231171 PMCID: PMC7685704 DOI: 10.7554/elife.58949] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 10/23/2020] [Indexed: 12/12/2022] Open
Abstract
In the mouse, the osteoblast-derived hormone Lipocalin-2 (LCN2) suppresses food intake and acts as a satiety signal. We show here that meal challenges increase serum LCN2 levels in persons with normal or overweight, but not in individuals with obesity. Postprandial LCN2 serum levels correlate inversely with hunger sensation in challenged subjects. We further show through brain PET scans of monkeys injected with radiolabeled recombinant human LCN2 (rh-LCN2) and autoradiography in baboon, macaque, and human brain sections, that LCN2 crosses the blood-brain barrier and localizes to the hypothalamus in primates. In addition, daily treatment of lean monkeys with rh-LCN2 decreases food intake by 21%, without overt side effects. These studies demonstrate the biology of LCN2 as a satiety factor and indicator and anorexigenic signal in primates. Failure to stimulate postprandial LCN2 in individuals with obesity may contribute to metabolic dysregulation, suggesting that LCN2 may be a novel target for obesity treatment.
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Affiliation(s)
| | - Ioanna Mosialou
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Steven Shikhel
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Lihong Hao
- Department of Nutritional Sciences, Rutgers University, New Brunswick, United States
| | - Konstantinos Panitsas
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Brygida Bisikirska
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Na Luo
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
| | - Fabiana Bahna
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Jongho Kim
- Department of Radiology, Columbia University Medical Center, New York, United States
| | - Patrick Carberry
- Department of Radiology, Columbia University Medical Center, New York, United States
| | - Francesca Zanderigo
- Department of Psychiatry, Columbia University Medical Center, New York, United States.,Molecular Imaging and Neuropathology Area, New York State Psychiatric Institute, New York, United States
| | - Norman Simpson
- Department of Psychiatry, Columbia University Medical Center, New York, United States
| | - Mihran Bakalian
- Department of Psychiatry, Columbia University Medical Center, New York, United States
| | - Suham Kassir
- Department of Psychiatry, Columbia University Medical Center, New York, United States.,Molecular Imaging and Neuropathology Area, New York State Psychiatric Institute, New York, United States
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Mark D Underwood
- Department of Psychiatry, Columbia University Medical Center, New York, United States.,Molecular Imaging and Neuropathology Area, New York State Psychiatric Institute, New York, United States
| | - Christina M May
- Department of Pathology, Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, United States
| | | | - Matthew J Jorgensen
- Department of Pathology, Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, United States
| | | | - Sue Shapses
- Department of Nutritional Sciences, Rutgers University, New Brunswick, United States.,Department of Medicine, Rutgers - RWJ Medical School, Rutgers University, New Brunswick, United States
| | - Blandine Laferrère
- New York Obesity Nutrition Research Center, Columbia University, New York, United States.,Department of Medicine, Division of Endocrinology, Columbia University Irving Medical Center, New York, United States
| | - Akiva Mintz
- Department of Radiology, Columbia University Medical Center, New York, United States
| | - J John Mann
- Department of Radiology, Columbia University Medical Center, New York, United States.,Department of Psychiatry, Columbia University Medical Center, New York, United States.,Molecular Imaging and Neuropathology Area, New York State Psychiatric Institute, New York, United States
| | - Mishaela Rubin
- New York Obesity Nutrition Research Center, Columbia University, New York, United States
| | - Stavroula Kousteni
- Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, United States
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11
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Nag S, Varnäs K, Arakawa R, Jahan M, Schou M, Farde L, Halldin C. Synthesis, Biodistribution, and Radiation Dosimetry of a Novel mGluR5 Radioligand: 18F-AZD9272. ACS Chem Neurosci 2020; 11:1048-1057. [PMID: 32167745 PMCID: PMC7309225 DOI: 10.1021/acschemneuro.9b00680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
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The metabotropic
glutamate receptor subtype mGluR5 has been proposed
as a potential drug target for CNS disorders such as anxiety, depression,
Parkinson’s disease, and epilepsy. The AstraZeneca compound
AZD9272 has previously been labeled with carbon-11 and used as a PET
radioligand for mGluR5 receptor binding. The molecular structure of
AZD9272 allows one to label the molecule with fluorine-18 without
altering the structure. The aim of this study was to develop a fluorine-18
analogue of AZD9272 and to examine its binding distribution in the
nonhuman primate brain in vivo as well as to obtain
whole body radiation dosimetry. 18F-AZD9272 was successfully
synthesized from a nitro precursor. The radioligand was stable, with
a radiochemical purity of >99% at 2 h after formulation in a sterile
phosphate buffered solution (pH = 7.4). After injection of 18F-AZD9272 in two cynomolgus monkeys, the maximum whole brain radioactivity
concentration was 4.9–6.7% of the injected dose (n = 2) and PET images showed a pattern of regional radioactivity consistent
with that previously obtained for 11C-AZD9272. The percentage
of parent radioligand in plasma was 59 and 64% (n = 2) at 120 min after injection of 18F-AZD9272, consistent
with high metabolic stability. Two whole body PET scans were performed
in nonhuman primates for a total of 231 min after injection of 18F-AZD9272. Highest uptakes were seen in liver and small intestine,
followed by brain and kidney. The estimated effective dose was around
0.017 mSv/MBq. 18F-AZD9272 shows suitable properties as
a PET radioligand for in vivo imaging of binding
in the primate brain. 18F-labeled AZD9272 offers advantages
over 11C-AZD9272 in terms of higher image resolution, combined
with a longer half-life. Moreover, based on the distribution and the
estimated radiation burden, imaging of 18F-AZD9272 could
be used as an improved tool for quantitative assessment and characterization
of AZD9272 binding sites in the human brain by using PET.
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Affiliation(s)
- Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Katarina Varnäs
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Mahabuba Jahan
- Department of Medicinal Chemistry, Uppsala University, Uppsala 751 05, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
- PET Science Centre, Precision Medicine, Oncology R&D, AstraZeneca, Stockholm 17176, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm 17176, Sweden
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 639798
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12
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Varlow C, Murrell E, Holland JP, Kassenbrock A, Shannon W, Liang SH, Vasdev N, Stephenson NA. Revisiting the Radiosynthesis of [ 18F]FPEB and Preliminary PET Imaging in a Mouse Model of Alzheimer's Disease. Molecules 2020; 25:molecules25040982. [PMID: 32098347 PMCID: PMC7070414 DOI: 10.3390/molecules25040982] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 11/24/2022] Open
Abstract
[18F]FPEB is a positron emission tomography (PET) radiopharmaceutical used for imaging the abundance and distribution of mGluR5 in the central nervous system (CNS). Efficient radiolabeling of the aromatic ring of [18F]FPEB has been an ongoing challenge. Herein, five metal-free precursors for the radiofluorination of [18F]FPEB were compared, namely, a chloro-, nitro-, sulfonium salt, and two spirocyclic iodonium ylide (SCIDY) precursors bearing a cyclopentyl (SPI5) and a new adamantyl (SPIAd) auxiliary. The chloro- and nitro-precursors resulted in a low radiochemical yield (<10% RCY), whereas both SCIDY precursors and the sulfonium salt precursor produced [18F]FPEB in the highest RCYs of 25% and 36%, respectively. Preliminary PET/CT imaging studies with [18F]FPEB were conducted in a transgenic model of Alzheimer’s Disease (AD) using B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J (APP/PS1) mice, and data were compared with age-matched wild-type (WT) B6C3F1/J control mice. In APP/PS1 mice, whole brain distribution at 5 min post-injection showed a slightly higher uptake (SUV = 4.8 ± 0.4) than in age-matched controls (SUV = 4.0 ± 0.2). Further studies to explore mGluR5 as an early biomarker for AD are underway.
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Affiliation(s)
- Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Emily Murrell
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
| | - Jason P. Holland
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Alina Kassenbrock
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
| | - Whitney Shannon
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N OX2, Canada
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Psychiatry, University of Toronto, Toronto, ON M5T-1R8, Canada
- Correspondence: (N.V.); (N.A.S.); Tel.: +416-535-8501 (ext. 30988) (N.V.); +1-876-927-1910 (N.A.S.)
| | - Nickeisha A. Stephenson
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Chemistry, The University of West Indies at Mona, Kingston 7, Jamaica
- Correspondence: (N.V.); (N.A.S.); Tel.: +416-535-8501 (ext. 30988) (N.V.); +1-876-927-1910 (N.A.S.)
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13
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Rokka J, Schlein E, Eriksson J. Improved synthesis of SV2A targeting radiotracer [ 11C]UCB-J. EJNMMI Radiopharm Chem 2019; 4:30. [PMID: 31784919 PMCID: PMC6884603 DOI: 10.1186/s41181-019-0080-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/18/2019] [Indexed: 12/30/2022] Open
Abstract
Introduction [11C]UCB-J is a tracer developed for PET (positron emission tomography) that has high affinity towards synaptic vesicle glycoprotein 2A (SV2A), a protein believed to participate in the regulation of neurotransmitter release in neurons and endocrine cells. The localisation of SV2A in the synaptic terminals makes it a viable target for in vivo imaging of synaptic density in the brain. Several SV2A targeting compounds have been evaluated as PET tracers, including [11C]UCB-J, with the aim to facilitate studies of synaptic density in neurological diseases. The original two-step synthesis method failed in our hands to produce sufficient amounts of [11C]UCB-J, but served as an excellent starting point for further optimizations towards a high yielding and simplified one-step method. [11C]Methyl iodide was trapped in a clear THF-water solution containing the trifluoroborate substituted precursor, potassium carbonate and palladium complex. The resulting reaction mixture was heated at 70 °C for 4 min to produce [11C]UCB-J. Results After semi-preparative HPLC purification and reformulation in 10% ethanol/phosphate buffered saline, the product was obtained in 39 ± 5% radiochemical yield based on [11C]methyl iodide, corresponding to 1.8 ± 0.5 GBq at EOS. The radiochemical purity was > 99% and the molar activity was 390 ± 180 GBq/μmol at EOS. The product solution contained < 2 ppb palladium. Conclusions A robust and high yielding production method has been developed for [11C]UCB-J, suitable for both preclinical and clinical PET applications.
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Affiliation(s)
- Johanna Rokka
- Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 751 85, Uppsala, Sweden
| | - Eva Schlein
- Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 751 85, Uppsala, Sweden
| | - Jonas Eriksson
- Department of Medicinal Chemistry, Uppsala Biomedical Center, Uppsala University, SE-751 23, Uppsala, Sweden. .,PET Centre, Uppsala University Hospital, SE-751 85, Uppsala, Sweden.
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14
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Crabbé M, Dirkx N, Casteels C, Laere KV. Excitotoxic neurodegeneration is associated with a focal decrease in metabotropic glutamate receptor type 5 availability: an in vivo PET imaging study. Sci Rep 2019; 9:12916. [PMID: 31501497 PMCID: PMC6733799 DOI: 10.1038/s41598-019-49356-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 08/23/2019] [Indexed: 11/09/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) have been proposed as promising therapeutic targets to correct the dysregulated glutamate signaling, associated with neurodegenerative pathologies. Of all mGluR subtypes, especially mGluR5 acts as a modulator of glutamate-induced excitotoxicity. To study the behavior of mGluR5 following localized excitotoxicity, we utilised a pharmacological model that portrays exacerbated neuronal glutamate release, mediated by the endogenous excitotoxin quinolinic acid (QA). Using longitudinal positron emission tomography (PET) with [18F]FPEB, we investigated cerebral changes in mGluR5 following striatal QA-lesioning. Behavioral tests were executed to monitor motor and cognitive performance. Decreased mGluR5 binding potential (BPND) was found in the affected striatum and globus pallidus of QA-lesioned rats at week 3, and further decreased at week 7, as compared to sham-injected controls. mGluR5 availability in the ipsilateral nucleus accumbens was significantly decreased at 7 weeks post-injection. QA rats performed significantly worse on motor coordination and balance compared to control rats. Correlation analysis indicated a positive correlation between striatal mGluR5 BPND and rotarod performance whereas print width of the unaffected forepaws showed a positive relation with mGluR5 BPND in the contralateral motor cortex. Together, our results suggest decreased mGluR5 availability to be related to excitotoxin-induced neurodegeneration and symptomatology although late stage effects do indicate possible cortical mGluR5-mediated effects on motor behavior.
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Affiliation(s)
- Melissa Crabbé
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium. .,MoSAIC - Molecular Small Animal Imaging Centre, KU Leuven, Leuven, Belgium.
| | - Nina Dirkx
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.,MoSAIC - Molecular Small Animal Imaging Centre, KU Leuven, Leuven, Belgium
| | - Cindy Casteels
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.,MoSAIC - Molecular Small Animal Imaging Centre, KU Leuven, Leuven, Belgium
| | - Koen Van Laere
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.,MoSAIC - Molecular Small Animal Imaging Centre, KU Leuven, Leuven, Belgium
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15
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Bdair H, Tsai IH, Smart K, Benkelfat C, Leyton M, Kostikov A. Radiosynthesis of the diastereomerically pure (E)-[ 11 C]ABP688. J Labelled Comp Radiopharm 2019; 62:860-864. [PMID: 31418468 DOI: 10.1002/jlcr.3802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 11/12/2022]
Abstract
We report an efficient protocol for the radiosynthesis of diastereomerically pure (E)-[11 C]ABP688, a positron emission tomography (PET) tracer for metabotropic glutamate type 5 (mGlu5) receptor imaging. The protocol reliably provides sterile and pyrogen-free formulation of (E)-[11 C]ABP688 suitable for preclinical and clinical PET imaging with >99% diastereomeric excess (d.e.), >99% overall radiochemical purity (RCP), 14.9 ± 4.3% decay-corrected radiochemical yield (RCY), and 148.86 ± 79.8 GBq/μmol molar activity in 40 minutes from the end of bombardment.
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Affiliation(s)
- Hussein Bdair
- McGill University, Montreal Neurological Institute, Montreal, Quebec, Canada.,McGill University, Department of Psychiatry, Montreal, Quebec, Canada
| | - I-Huang Tsai
- McGill University, McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Quebec, Canada
| | - Kelly Smart
- Yale University School of Medicine, Yale PET Center, New Haven, Connecticut
| | - Chawki Benkelfat
- McGill University, Department of Psychiatry, Montreal, Quebec, Canada
| | - Marco Leyton
- McGill University, Department of Psychiatry, Montreal, Quebec, Canada
| | - Alexey Kostikov
- McGill University, Montreal Neurological Institute, Montreal, Quebec, Canada.,McGill University, McConnell Brain Imaging Centre, Montreal Neurological Institute, Montreal, Quebec, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
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16
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Jung KH, Oh SJ, Kang KJ, Han SJ, Nam KR, Park JA, Lee KC, Lee YJ, Choi JY. Effects of P-gp and Bcrp as brain efflux transporters on the uptake of [ 18 F]FPEB in the murine brain. Synapse 2019; 73:e22123. [PMID: 31269310 DOI: 10.1002/syn.22123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/11/2019] [Accepted: 06/28/2019] [Indexed: 01/16/2023]
Abstract
The purpose of this study was to determine whether the brain uptake of [18 F]FPEB is influenced by P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) as efflux transporters in rodents. To assess this possible modulation, positron emission tomography studies were performed in animal models of pharmacological or genetic ablation of these transporters. Compared with the control conditions, when P-gp was blocked with tariquidar, there was an 8%-12% increase in the brain uptake of [18 F]FPEB. In P-gp knockout mice, such as Mdr1a/b(-/-) and Mdr1a/b(-/-) Bcrp1(-/-) , genetic ablation models, there was an increment of 8%-53% in [18 F]FPEB uptake compared with that in the wild-type mice. In contrast, Bcrp knockout mice showed a decrement of 5%-12% uptake and P-gp/Bcrp knockout group displayed an increment of 5%-17% compared with wild type. These results indicate that [18 F]FPEB is possibly a weak substrate for P-gp.
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Affiliation(s)
- Ki-Hye Jung
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Se Jong Oh
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Kyung Jun Kang
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Sang Jin Han
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Kyung Rok Nam
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Ji Ae Park
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Kyo Chul Lee
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Yong Jin Lee
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
| | - Jae Yong Choi
- Division of Applied RI, Korea Institute of Radiological and Medical Sciences, Seoul, South Korea
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17
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Facile 18F labeling of non-activated arenes via a spirocyclic iodonium(III) ylide method and its application in the synthesis of the mGluR 5 PET radiopharmaceutical [ 18F]FPEB. Nat Protoc 2019; 14:1530-1545. [PMID: 30980032 DOI: 10.1038/s41596-019-0149-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 02/12/2019] [Indexed: 01/08/2023]
Abstract
Non-activated (electron-rich and/or sterically hindered) arenes are prevalent chemical scaffolds in pharmaceuticals and positron emission tomography (PET) diagnostics. Despite substantial efforts to develop a general method to introduce 18F into these moieties for molecular imaging by PET, there is an urgent and unmet need for novel radiofluorination strategies that result in sufficiently labeled tracers to enable human imaging. Herein, we describe an efficient method that relies on spirocyclic iodonium ylide (SCIDY) precursors for one-step and regioselective radiofluorination, as well as proof-of-concept translation to the radiosynthesis of a clinically useful PET tracer, 3-[18F]fluoro-5-[(pyridin-3-yl)ethynyl] benzonitrile ([18F]FPEB). The protocol begins with the preparation of a SCIDY precursor for FPEB, followed by radiosynthesis of [18F]FPEB, by either manual operation or an automated synthesis module. [18F]FPEB can be obtained in quantities >7.4 GBq (200 mCi), ready for injection (20 ± 5%, non-decay corrected), and has excellent chemical and radiochemical purity (>98%) as well as high molar activity (666 ± 51.8 GBq/μmol; 18 ± 1.4 Ci/μmol). The total time for the synthesis and purification of the corresponding labeling SCIDY precursor is 10 h. The subsequent radionuclide production, experimental setup, 18F labeling, and formulation of a product that is ready for injection require 2 h.
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18
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Xu Y, Li Z. Imaging metabotropic glutamate receptor system: Application of positron emission tomography technology in drug development. Med Res Rev 2019; 39:1892-1922. [DOI: 10.1002/med.21566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Youwen Xu
- Independent Consultant and Contractor, Radiopharmaceutical Development, Validation and Bio-Application; Philadelphia Pennsylvania
| | - Zizhong Li
- Pharmaceutical Research and Development, SOFIE Biosciences; Somerset New Jersey
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19
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Kang Y, Henchcliffe C, Verma A, Vallabhajosula S, He B, Kothari PJ, Pryor KO, Mozley PD. 18F-FPEB PET/CT Shows mGluR5 Upregulation in Parkinson's Disease. J Neuroimaging 2018; 29:97-103. [DOI: 10.1111/jon.12563] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 11/28/2022] Open
Affiliation(s)
- Yeona Kang
- Department of Radiology; Weill Cornell Medicine; New York NY
| | | | | | | | - Bin He
- Department of Radiology; Weill Cornell Medicine; New York NY
| | | | - Kane O. Pryor
- Department of Anesthesiology; Weill Cornell Medicine; New York NY
| | - P. David Mozley
- Department of Radiology; Weill Cornell Medicine; New York NY
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20
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Gendron T, Sander K, Cybulska K, Benhamou L, Sin PKB, Khan A, Wood M, Porter MJ, Årstad E. Ring-Closing Synthesis of Dibenzothiophene Sulfonium Salts and Their Use as Leaving Groups for Aromatic 18F-Fluorination. J Am Chem Soc 2018; 140:11125-11132. [PMID: 30132661 PMCID: PMC6128620 DOI: 10.1021/jacs.8b06730] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Herein, we report a novel intramolecular ring-closing reaction of biaryl thioethers that give access to highly functionalized dibenzothiophene sulfonium salts under mild conditions. The resulting precursors react regioselectively with [18F]fluoride to give [18F]fluoroarenes in predictable radiochemical yields. The strategy expands the available radiochemical space and provides superior labeling efficiency for clinically relevant PET tracers.
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Affiliation(s)
- Thibault Gendron
- Institute of Nuclear Medicine , University College London , 235 Euston Road (T-5) , London NW1 2BU , United Kingdom.,Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Kerstin Sander
- Institute of Nuclear Medicine , University College London , 235 Euston Road (T-5) , London NW1 2BU , United Kingdom.,Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Klaudia Cybulska
- Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Laure Benhamou
- Institute of Nuclear Medicine , University College London , 235 Euston Road (T-5) , London NW1 2BU , United Kingdom.,Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Pak Kwan Brian Sin
- Institute of Nuclear Medicine , University College London , 235 Euston Road (T-5) , London NW1 2BU , United Kingdom.,Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Aqsa Khan
- Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Michael Wood
- Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Michael J Porter
- Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
| | - Erik Årstad
- Institute of Nuclear Medicine , University College London , 235 Euston Road (T-5) , London NW1 2BU , United Kingdom.,Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AJ , United Kingdom
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21
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Wilson TC, Cailly T, Gouverneur V. Boron reagents for divergent radiochemistry. Chem Soc Rev 2018; 47:6990-7005. [DOI: 10.1039/c8cs00499d] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review discusses boron reagents as precursors for divergent radiolabelling with a focus on carbon-11, fluorine-18 and iodine-123, -125, -131.
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Affiliation(s)
| | - Thomas Cailly
- Normandie Univ
- UNICAEN
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN)
- 14000 Caen
- France
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22
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Imaging the glutamate receptor subtypes-Much achieved, and still much to do. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017; 25:27-36. [PMID: 29233264 DOI: 10.1016/j.ddtec.2017.10.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 11/20/2022]
Abstract
Functional imaging of glutamate receptors using PET imaging modality can be used to study numerous CNS disorders and also to select appropriate doses of clinically relevant glutamate-receptor-targeting candidate drugs. Great strides have been made in developing PET imaging probes for the non-invasive detection of glutamate receptors in the brain. This review highlights recent progress made towards the development of glutamatergic PET imaging agents. Focus is placed on PET imaging probes that have been labelled with either carbon-11 or fluorine-18.
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23
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Park JY, Son J, Yun M, Ametamey SM, Chun JH. Automated cGMP-compliant radiosynthesis of [ 18 F]-(E)-PSS232 for brain PET imaging of metabotropic glutamate receptor subtype 5. J Labelled Comp Radiopharm 2017; 61:30-37. [PMID: 28948638 DOI: 10.1002/jlcr.3566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/12/2017] [Accepted: 09/15/2017] [Indexed: 11/10/2022]
Abstract
(E)-3-(Pyridin-2-yl ethynyl)cyclohex-2-enone O-(3-(2-[18 F]-fluoroethoxy)propyl) oxime ([18 F]-(E)-PSS232, [18 F]2a) is a recently developed radiotracer that can be used to visualize metabotropic glutamate receptor subtype 5 (mGlu5 ) in vivo. The mGlu5 has become an attractive therapeutic and diagnostic target owing to its role in many neuropsychiatric disorders. Several carbon-11-labeled and fluorine-18-labeled radiotracers have been developed to measure mGlu5 receptor occupancy in the human brain. The radiotracer [18 F]2a, which is used as an analogue for [11 C]ABP688 ([11 C]1) and has a longer physical half-life, is a selective radiotracer that exhibits high binding affinity for mGlu5 . Herein, we report the fully automated radiosynthesis of [18 F]2a using a commercial GE TRACERlab™ FX-FN synthesizer for routine production and distribution to nearby satellite clinics. Nucleophilic substitution of the corresponding mesylate precursor with cyclotron-produced [18 F]fluoride ion at 100°C in dimethyl sulfoxide (DMSO), followed by high-performance liquid chromatography (HPLC) purification and formulation, readily provided [18 F]2a with a radiochemical yield of 40 ± 2% (decay corrected, n = 5) at the end of synthesis. Radiochemical purity for the [18 F]-(E)-conformer was greater than 95%. Molar activity was determined to be 63.6 ± 9.6 GBq/μmol (n = 5), and the overall synthesis time was 70 minutes.
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Affiliation(s)
- Jun Young Park
- Department of Nuclear Medicine, Severance Hospital, Yonsei University Health System, Seoul, Republic of Korea
| | - Jeongmin Son
- Department of Nuclear Medicine, Severance Hospital, Yonsei University Health System, Seoul, Republic of Korea
| | - Mijin Yun
- Department of Nuclear Medicine, Severance Hospital, Yonsei University Health System, Seoul, Republic of Korea.,Department of Nuclear Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Simon M Ametamey
- Department of Applied Biosciences of ETH Zurich, Center for Radiopharmaceutical Sciences of ETH, PSI, and USZ, Zurich, Switzerland
| | - Joong-Hyun Chun
- Department of Nuclear Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
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24
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Dahl K, Halldin C, Schou M. New methodologies for the preparation of carbon-11 labeled radiopharmaceuticals. Clin Transl Imaging 2017; 5:275-289. [PMID: 28596949 PMCID: PMC5437136 DOI: 10.1007/s40336-017-0223-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/01/2017] [Indexed: 12/04/2022]
Abstract
Purpose This short review aims to cover the more recent and promising developments of carbon-11 (11C) labeling radiochemistry and its utility in the production of novel radiopharmaceuticals, with special emphasis on methods that have the greatest potential to be translated for clinical positron emission tomography (PET) imaging. Methods A survey of the literature was undertaken to identify articles focusing on methodological development in 11C chemistry and their use within novel radiopharmaceutical preparation. However, since 11C-labeling chemistry is such a narrow field of research, no systematic literature search was therefore feasible. The survey was further restricted to a specific timeframe (2000–2016) and articles in English. Results From the literature, it is clear that the majority of 11C-labeled radiopharmaceuticals prepared for clinical PET studies have been radiolabeled using the standard heteroatom methylation reaction. However, a number of methodologies have been developed in recent years, both from a technical and chemical point of view. Amongst these, two protocols may have the greatest potential to be widely adapted for the preparation of 11C-radiopharmaceuticals in a clinical setting. First, a novel method for the direct formation of 11C-labeled carbonyl groups, where organic bases are utilized as [11C]carbon dioxide-fixation agents. The second method of clinical importance is a low-pressure 11C-carbonylation technique that utilizes solvable xenon gas to effectively transfer and react [11C]carbon monoxide in a sealed reaction vessel. Both methods appear to be general and provide simple paths to 11C-labeled products. Conclusion Radiochemistry is the foundation of PET imaging which relies on the administration of a radiopharmaceutical. The demand for new radiopharmaceuticals for clinical PET imaging is increasing, and 11C-radiopharmaceuticals are especially important within clinical research and drug development. This review gives a comprehensive overview of the most noteworthy 11C-labeling methods with clinical relevance to the field of PET radiochemistry.
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Affiliation(s)
- Kenneth Dahl
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, Karolinska Institutet, 171 76 Stockholm, Sweden.,Department of Clinical Neuroscience, AstraZeneca Translational Science Centre, Karolinska Institutet, 171 76 Stockholm, Sweden
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25
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Positron emission tomography in amyotrophic lateral sclerosis: Towards targeting of molecular pathological hallmarks. Eur J Nucl Med Mol Imaging 2016; 44:533-547. [DOI: 10.1007/s00259-016-3587-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/23/2016] [Indexed: 12/18/2022]
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26
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Wilson TC, McSweeney G, Preshlock S, Verhoog S, Tredwell M, Cailly T, Gouverneur V. Radiosynthesis of SPECT tracers via a copper mediated 123I iodination of (hetero)aryl boron reagents. Chem Commun (Camb) 2016; 52:13277-13280. [PMID: 27775106 DOI: 10.1039/c6cc07417k] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2024]
Abstract
A general method for the copper mediated nucleophilic 123I-iodination of (hetero)aryl boronic esters and acids has been developed. The broad substrate scope of this radiosynthetic approach allows access to [123I]DPA-713, [123I]IMPY, [123I]MIBG and [123I]IPEB that are four commonly used SPECT radiotracers. Our results infer that aryl boronic reagents can now be employed as common precursors for both fluorine-18 and iodine-123 radiolabelling.
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Affiliation(s)
- Thomas C Wilson
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK.
| | - Greg McSweeney
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK.
| | - Sean Preshlock
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK.
| | - Stefan Verhoog
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK.
| | - Matthew Tredwell
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK. and Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Thomas Cailly
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK. and Normandie University, UNICAEN, CERMN, F-14032 Caen, France
| | - Véronique Gouverneur
- Chemistry Research Laboratory, Department of Chemistry, Oxford University, OX1 3TA, UK.
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Makaravage KJ, Brooks AF, Mossine AV, Sanford MS, Scott PJH. Copper-Mediated Radiofluorination of Arylstannanes with [ 18F]KF. Org Lett 2016; 18:5440-5443. [PMID: 27718581 PMCID: PMC5078836 DOI: 10.1021/acs.orglett.6b02911] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
A copper-mediated nucleophilic radiofluorination
of aryl- and vinylstannanes
with [18F]KF is described. This method is fast, uses commercially
available reagents, and is compatible with both electron-rich and
electron-deficient arene substrates. This method has been applied
to the manual synthesis of a variety of clinically relevant radiotracers
including protected [18F]F-phenylalanine and [18F]F-DOPA. In addition, an automated synthesis of [18F]MPPF
is demonstrated that delivers a clinically validated dose of 200 ±
20 mCi with a high specific activity of 2400 ± 900 Ci/mmol.
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Affiliation(s)
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | - Andrew V Mossine
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | | | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
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28
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Jenkins BG, Zhu A, Poutiainen P, Choi JK, Kil KE, Zhang Z, Kuruppu D, Aytan N, Dedeoglu A, Brownell AL. Functional modulation of G-protein coupled receptors during Parkinson disease-like neurodegeneration. Neuropharmacology 2016; 108:462-73. [PMID: 26581500 PMCID: PMC4896842 DOI: 10.1016/j.neuropharm.2015.11.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 09/24/2015] [Accepted: 11/06/2015] [Indexed: 01/11/2023]
Abstract
G-protein coupled dopamine and metabotropic glutamate receptors (mGlu) can modulate neurotransmission during Parkinson's disease (PD)-like neurodegeneration. PET imaging studies in a unilateral dopamine denervation model (6-OHDA) showed a significant inverse correlation of presynaptic mGlu4 and postsynaptic mGlu5 expression in the striatum and rapidly declining mGlu4 and enhanced mGlu5 expression in the hippocampus during progressive degeneration over time. Immunohistochemical studies verified the decreased mGlu4 expression in the hippocampus on the lesion side but did not show difference in mGlu5 expression between lesion and control side. Pharmacological MRI studies showed enhanced hemodynamic response in several brain areas on the lesion side compared to the control side after challenge with mGlu4 positive allosteric modulator or mGlu5 negative allosteric modulator. However, mGlu4 response was biphasic having short enhancement followed by negative response on both sides of brain. Studies in mGlu4 expressing cells demonstrated that glutamate induces cooperative increase in binding of mGlu4 ligands - especially at high glutamate levels consistent with in vivo concentration. This suggests that mGlu allosteric modulators as drug candidates will be highly sensitive to changes in glutamate concentration and hence metabolic state. These experiments demonstrate the importance of the longitudinal imaging studies to investigate temporal changes in receptor functions to obtain individual response for experimental drugs.
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Affiliation(s)
- Bruce G Jenkins
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Aijun Zhu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Pekka Poutiainen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Kun-Eek Kil
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Zhaoda Zhang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA
| | - Darshini Kuruppu
- Surgical Oncology, Department of Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - Nurgul Aytan
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, MA 02130, USA
| | - Alpaslan Dedeoglu
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, MA 02130, USA; Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Anna-Liisa Brownell
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 13th Street, Charlestown, MA 02129, USA.
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Preshlock S, Calderwood S, Verhoog S, Tredwell M, Huiban M, Hienzsch A, Gruber S, Wilson TC, Taylor NJ, Cailly T, Schedler M, Collier TL, Passchier J, Smits R, Mollitor J, Hoepping A, Mueller M, Genicot C, Mercier J, Gouverneur V. Enhanced copper-mediated (18)F-fluorination of aryl boronic esters provides eight radiotracers for PET applications. Chem Commun (Camb) 2016; 52:8361-4. [PMID: 27241832 DOI: 10.1039/c6cc03295h] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
[(18)F]FMTEB, [(18)F]FPEB, [(18)F]flumazenil, [(18)F]DAA1106, [(18)F]MFBG, [(18)F]FDOPA, [(18)F]FMT and [(18)F]FDA are prepared from the corresponding arylboronic esters and [(18)F]KF/K222 in the presence of Cu(OTf)2py4. The method was successfully applied using three radiosynthetic platforms, and up to 26 GBq of non-carrier added starting activity of (18)F-fluoride.
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Affiliation(s)
- Sean Preshlock
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Samuel Calderwood
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Stefan Verhoog
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Matthew Tredwell
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Mickael Huiban
- Imanova, Burlington Danes building Imperial College, London Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Antje Hienzsch
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Stefan Gruber
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Thomas C Wilson
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Nicholas J Taylor
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Thomas Cailly
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK. and Normandie University, UNICAEN, CERMN, F-14032 Caen, France
| | - Michael Schedler
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | | | - Jan Passchier
- Imanova, Burlington Danes building Imperial College, London Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - René Smits
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Jan Mollitor
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | | | - Marco Mueller
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Christophe Genicot
- Global Chemistry, UCB New Medicines, UCB Biopharma sprl, 1420 Braine-L'Alleud, Belgium
| | - Joël Mercier
- Global Chemistry, UCB New Medicines, UCB Biopharma sprl, 1420 Braine-L'Alleud, Belgium
| | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
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30
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Methylation as a method for synthesis of radiopharmaceuticals for positron emission tomography. Russ Chem Bull 2016. [DOI: 10.1007/s11172-015-1038-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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31
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Chaturvedi S, Mishra AK. Small Molecule Radiopharmaceuticals - A Review of Current Approaches. Front Med (Lausanne) 2016; 3:5. [PMID: 26942181 PMCID: PMC4763069 DOI: 10.3389/fmed.2016.00005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/15/2016] [Indexed: 12/24/2022] Open
Abstract
Radiopharmaceuticals are an integral component of nuclear medicine and are widely applied in diagnostics and therapy. Though widely applied, the development of an “ideal” radiopharmaceutical can be challenging. Issues such as specificity, selectivity, sensitivity, and feasible chemistry challenge the design and synthesis of radiopharmaceuticals. Over time, strategies to address the issues have evolved by making use of new technological advances in the fields of biology and chemistry. This review presents the application of few advances in design and synthesis of radiopharmaceuticals. The topics covered are bivalent ligand approach and lipidization as part of design modifications for enhanced selectivity and sensitivity and novel synthetic strategies for optimized chemistry and radiolabeling of radiopharmaceuticals.
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Affiliation(s)
- Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Defence Research and Development Organisation , Delhi , India
| | - Anil K Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Defence Research and Development Organisation , Delhi , India
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32
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Leurquin-Sterk G, Postnov A, de Laat B, Casteels C, Celen S, Crunelle CL, Bormans G, Koole M, Van Laere K. Kinetic modeling and long-term test-retest reproducibility of the mGluR5 PET tracer18F-FPEB in human brain. Synapse 2016; 70:153-62. [DOI: 10.1002/syn.21890] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/15/2016] [Accepted: 01/15/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Gil Leurquin-Sterk
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
| | - Andrey Postnov
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
| | - Bart de Laat
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
- MoSAIC, Molecular Small Animal Imaging Center, KU Leuven - University of Leuven; Leuven Belgium
| | - Cindy Casteels
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
- MoSAIC, Molecular Small Animal Imaging Center, KU Leuven - University of Leuven; Leuven Belgium
| | - Sofie Celen
- Laboratory for Radiopharmacy, KU Leuven - University of Leuven; Leuven Belgium
| | | | - Guy Bormans
- Laboratory for Radiopharmacy, KU Leuven - University of Leuven; Leuven Belgium
| | - Michel Koole
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
- MoSAIC, Molecular Small Animal Imaging Center, KU Leuven - University of Leuven; Leuven Belgium
| | - Koen Van Laere
- Division of Nuclear Medicine; KU Leuven - University of Leuven and University Hospital Leuven; Herestraat 49 Leuven 3000 Belgium
- MoSAIC, Molecular Small Animal Imaging Center, KU Leuven - University of Leuven; Leuven Belgium
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33
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Preshlock S, Tredwell M, Gouverneur V. (18)F-Labeling of Arenes and Heteroarenes for Applications in Positron Emission Tomography. Chem Rev 2016; 116:719-66. [PMID: 26751274 DOI: 10.1021/acs.chemrev.5b00493] [Citation(s) in RCA: 465] [Impact Index Per Article: 58.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Diverse radiochemistry is an essential component of nuclear medicine; this includes imaging techniques such as positron emission tomography (PET). As such, PET can track diseases at an early stage of development, help patient care planning through personalized medicine and support drug discovery programs. Fluorine-18 is the most frequently used radioisotope in PET radiopharmaceuticals for both clinical and preclinical research. Its physical and nuclear characteristics (97% β(+) decay, 109.8 min half-life, 635 keV positron energy) and high specific activity make it an attractive nuclide for labeling and molecular imaging. Arenes and heteroarenes are privileged candidates for (18)F-incorporation as they are metabolically robust and therefore widely used by medicinal chemists and radiochemists alike. For many years, the range of (hetero)arenes amenable to (18)F-fluorination was limited by the lack of chemically diverse precursors, and of radiochemical methods allowing (18)F-incorporation in high selectivity and efficiency (radiochemical yield and purity, specific activity, and radio-scalability). The appearance of late-stage fluorination reactions catalyzed by transition metal or small organic molecules (organocatalysis) has encouraged much research on the use of these activation manifolds for (18)F-fluorination. In this piece, we review all of the reactions known to date to install the (18)F substituent and other key (18)F-motifs (e.g., CF3, CHF2, OCF3, SCF3, OCHF2) of medicinal relevance onto (hetero)arenes. The field has changed significantly in the past five years, and the current trend suggests that the radiochemical space available for PET applications will expand rapidly in the near future.
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Affiliation(s)
- Sean Preshlock
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Matthew Tredwell
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
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34
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Metabotropic glutamate receptor 5 – a promising target in drug development and neuroimaging. Eur J Nucl Med Mol Imaging 2016; 43:1151-70. [DOI: 10.1007/s00259-015-3301-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
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35
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Pike VW. Considerations in the Development of Reversibly Binding PET Radioligands for Brain Imaging. Curr Med Chem 2016; 23:1818-69. [PMID: 27087244 PMCID: PMC5579844 DOI: 10.2174/0929867323666160418114826] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/04/2016] [Accepted: 04/15/2016] [Indexed: 12/17/2022]
Abstract
The development of reversibly binding radioligands for imaging brain proteins in vivo, such as enzymes, neurotransmitter transporters, receptors and ion channels, with positron emission tomography (PET) is keenly sought for biomedical studies of neuropsychiatric disorders and for drug discovery and development, but is recognized as being highly challenging at the medicinal chemistry level. This article aims to compile and discuss the main considerations to be taken into account by chemists embarking on programs of radioligand development for PET imaging of brain protein targets.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Rm. B3C346A, 10 Center Drive, Bethesda, MD 20892, USA.
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36
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Comparative assessment of parametric neuroreceptor mapping approaches based on the simplified reference tissue model using [¹¹C]ABP688 PET. J Cereb Blood Flow Metab 2015; 35:2098-108. [PMID: 26243707 PMCID: PMC4671133 DOI: 10.1038/jcbfm.2015.190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 06/17/2015] [Accepted: 07/02/2015] [Indexed: 11/08/2022]
Abstract
In recent years, several linearized model approaches for fast and reliable parametric neuroreceptor mapping based on dynamic nuclear imaging have been developed from the simplified reference tissue model (SRTM) equation. All the methods share the basic SRTM assumptions, but use different schemes to alleviate the effect of noise in dynamic-image voxels. Thus, this study aimed to compare those approaches in terms of their performance in parametric image generation. We used the basis function method and MRTM2 (multilinear reference tissue model with two parameters), which require a division process to obtain the distribution volume ratio (DVR). In addition, a linear model with the DVR as a model parameter (multilinear SRTM) was used in two forms: one based on linear least squares and the other based on extension of total least squares (TLS). Assessment using simulated and actual dynamic [(11)C]ABP688 positron emission tomography data revealed their equivalence with the SRTM, except for different noise susceptibilities. In the DVR image production, the two multilinear SRTM approaches achieved better image quality and regional compatibility with the SRTM than the others, with slightly better performance in the TLS-based method.
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37
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Mossine AV, Brooks AF, Makaravage KJ, Miller JM, Ichiishi N, Sanford MS, Scott PJH. Synthesis of [18F]Arenes via the Copper-Mediated [18F]Fluorination of Boronic Acids. Org Lett 2015; 17:5780-3. [PMID: 26568457 PMCID: PMC4672358 DOI: 10.1021/acs.orglett.5b02875] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
A copper-mediated
radiofluorination of aryl- and vinylboronic acids
with K18F is described. This method exhibits high functional
group tolerance and is effective for the radiofluorination of a range
of electron-deficient, -neutral, and -rich aryl-, heteroaryl-, and
vinylboronic acids. This method has been applied to the synthesis
of [18F]FPEB, a PET radiotracer for quantifying metabotropic
glutamate 5 receptors.
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Affiliation(s)
- Andrew V Mossine
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | - Katarina J Makaravage
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jason M Miller
- Department of Medicinal Chemistry, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109, United States
| | - Naoko Ichiishi
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States.,Department of Medicinal Chemistry, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109, United States
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Calderwood S, Collier TL, Gouverneur V, Liang SH, Vasdev N. Synthesis of 18F-Arenes from Spirocyclic Iodonium(III) Ylides via Continuous-Flow Microfluidics. J Fluor Chem 2015; 178:249-253. [PMID: 27512233 PMCID: PMC4976495 DOI: 10.1016/j.jfluchem.2015.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Spirocyclic hypervalent iodine(III) ylides have proven to be synthetically versatile precursors for efficient radiolabelling of a diverse range of non-activated (hetero)arenes, highly functionalised small molecules, building blocks and radiopharmaceuticals from [18F]fluoride ion. Herein, we report the implementation of these reactions onto a continuous-flow microfluidic platform, thereby offering an alterative and automated synthetic procedure of a radiopharmaceutical, 3-[18F]fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ([18F]FPEB) and a routinely used building block for click-radiochemistry, 4-[18F]fluorobenzyl azide. This new protocol was applied to the synthesis of [18F]FPEB (radiochemical conversion (RCC) = 68 ± 5%) and 4-[18F]fluorobenzyl azide (RCC=68 ± 5%; isolated radiochemical yield = 24±0%). We anticipate that the high throughput microfluidic platform will accelerate the discovery and applications of 18F-labelled building blocks and labelled compounds prepared by iodonium ylide precursors as well as the production of radiotracers for preclinical imaging studies.
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Affiliation(s)
- Samuel Calderwood
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, UK
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
| | - Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
- Advion BioSystems, 10 Brown Road, Suite 101, Ithaca, New York, USA
| | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, UK
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
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de Laat B, Leurquin-Sterk G, Celen S, Bormans G, Koole M, Van Laere K, Casteels C. Preclinical Evaluation and Quantification of 18F-FPEB as a Radioligand for PET Imaging of the Metabotropic Glutamate Receptor 5. J Nucl Med 2015; 56:1954-9. [PMID: 26405172 DOI: 10.2967/jnumed.115.162636] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/10/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED The metabotropic glutamate receptor 5 (mGluR5) is a high-interest target for PET imaging because it plays a role in several pathologies, including addiction, schizophrenia, and fragile X syndrome. METHODS We studied the pharmacokinetics of (18)F-FPEB (3-(18)F-fluoro-5-(2-pyridinylethynyl)benzonitrile), a selective PET radioligand for mGluR5, and used it to quantify mGluR5 in rat brain. Quantification was performed using both arterial sampling in combination with compartment models and simplified reference methods. The simplified reference tissue model (SRTM), Ichise's original multi-linear reference tissue model (MRTMO), and Logan noninvasive were tested as reference models with nondisplaceable binding (BPND) as outcome parameter. Additionally, test-retest scans were obtained in 6 animals. RESULTS (18)F-FPEB uptake in rat brain was consistent with its known distribution. No radiometabolites were present in the brain, and binding was specific as shown in blocking experiments, which also confirmed the cerebellum as a viable reference region. A 2-tissue-compartment model was used to determine BPND for the striatum (11.7 ± 1.5), nucleus accumbens (10.6 ± 2.0), hippocampus (9.0 ± 1.2), cortex (7.2 ± 1.0), and thalamus (4.0 ± 0.9). Reference methods were able to estimate these values with small bias (<2%). Test-retest analysis showed high repeatability between scans below 6%, also for shorter scan durations of 30 and 60 min. CONCLUSION Because of its favorable reversible kinetics, high specificity, and absence of brain radiometabolites (18)F-FPEB proves a highly useful tracer for in vivo visualization of the mGluR5 in rat brain. Moreover, reference tissue models allow noninvasive, rapid scanning with good test-retest.
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Affiliation(s)
- Bart de Laat
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven/University Hospital Leuven, Division of Nuclear Medicine, Leuven, Belgium; and
| | - Gil Leurquin-Sterk
- KU Leuven-University of Leuven/University Hospital Leuven, Division of Nuclear Medicine, Leuven, Belgium; and
| | - Sofie Celen
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven, Laboratory for Radiopharmacy, Leuven, Belgium
| | - Guy Bormans
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven, Laboratory for Radiopharmacy, Leuven, Belgium
| | - Michel Koole
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven/University Hospital Leuven, Division of Nuclear Medicine, Leuven, Belgium; and
| | - Koen Van Laere
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven/University Hospital Leuven, Division of Nuclear Medicine, Leuven, Belgium; and
| | - Cindy Casteels
- KU Leuven-University of Leuven, MoSAIC, Molecular Small Animal Imaging Center, Leuven, Belgium KU Leuven-University of Leuven/University Hospital Leuven, Division of Nuclear Medicine, Leuven, Belgium; and
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[carbonyl-11C]4-Fluoro-N-methyl-N-(4-(6-(methylamino)pyrimidin-4-yl)thiazol-2-yl)benzamide ([11C]FIMX) is an effective radioligand for PET imaging of metabotropic glutamate receptor 1 (mGluR1) in monkey brain. Nucl Med Biol 2015; 42:967-74. [PMID: 26320813 DOI: 10.1016/j.nucmedbio.2015.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/14/2015] [Accepted: 07/18/2015] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Metabotropic glutamate subtype receptor 1 (mGluR1) is implicated in several neuropsychiatric disorders and is a target for drug development. [(18)F]FIMX ([(18)F]4-fluoro--N-methyl-N--(4-(6-(methylamino)pyrimidin-4-yl)thiazol-2-yl)benzamide) is an effective radioligand for imaging brain mGluR1 with PET. A similarly effective radioligand with a shorter half-life would usefully allow PET studies of mGluR1 at baseline and after pharmacological or other challenge on the same day. Here we describe the preparation of [(11)C]FIMX for evaluation in monkey with PET. METHODS [(11)C]FIMX was prepared via Pd-promoted carbonylation of 1-fluoro-4-iodobenzene with [(11)C]carbon monoxide, aminolysis of the [(11)C]acyl-palladium complex with the requisite Boc-protected amine, and deprotection with HCl in THF. PET scans of [(11)C]FIMX injected into a monkey were performed at baseline and after preblock of mGluR1 with measurement of the arterial input function. RESULTS The radiosynthesis required 42 min and gave [(11)C]FIMX in about 5% overall decay-corrected radiochemical yield and with a specific activity of about 100 GBq/μmol. PET in rhesus monkey at baseline showed that radioactivity peaked high in receptor-rich cerebellum and much lower in receptor-poor occipital cortex. Radioactivity in cerebellum declined to 32% of peak at 85 min. VT at baseline appeared stable in all brain regions after 60 min. Under mGluR1 pre-blocked condition, radioactivity uptake in all regions declined more rapidly to a low level. Receptor pre-block reduced VT from 13.0 to 1.5 in cerebellum and from 2.9 to 1.4 in occipital cortex. CONCLUSION [(11)C]FIMX is an effective radioligand for imaging mGluR1 in monkey with PET.
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Development of PET and SPECT probes for glutamate receptors. ScientificWorldJournal 2015; 2015:716514. [PMID: 25874256 PMCID: PMC4385697 DOI: 10.1155/2015/716514] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 08/29/2014] [Indexed: 01/16/2023] Open
Abstract
l-Glutamate and its receptors (GluRs) play a key role in excitatory neurotransmission within the mammalian central nervous system (CNS). Impaired regulation of GluRs has also been implicated in various neurological disorders. GluRs are classified into two major groups: ionotropic GluRs (iGluRs), which are ligand-gated ion channels, and metabotropic GluRs (mGluRs), which are coupled to heterotrimeric guanosine nucleotide binding proteins (G-proteins). Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of GluRs could provide a novel view of CNS function and of a range of brain disorders, potentially leading to the development of new drug therapies. Although no satisfactory imaging agents have yet been developed for iGluRs, several PET ligands for mGluRs have been successfully employed in clinical studies. This paper reviews current progress towards the development of PET and SPECT probes for GluRs.
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Doi H. Pd-mediated rapid cross-couplings using [11C]methyl iodide: groundbreaking labeling methods in11C radiochemistry. J Labelled Comp Radiopharm 2015; 58:73-85. [DOI: 10.1002/jlcr.3253] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/28/2014] [Accepted: 11/28/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Hisashi Doi
- Labeling Chemistry Team; Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies (CLST); 6-7-3 Minatojima-minamimachi, Chuo-ku Kobe Hyogo 650-0047 Japan
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Stephenson NA, Holland JP, Kassenbrock A, Yokell DL, Livni E, Liang SH, Vasdev N. Iodonium ylide-mediated radiofluorination of 18F-FPEB and validation for human use. J Nucl Med 2015; 56:489-92. [PMID: 25655630 DOI: 10.2967/jnumed.114.151332] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Translation of new methodologies for labeling nonactivated aromatic molecules with (18)F remains a challenge. Here, we report a one-step, regioselective, metal-free (18)F-labeling method that uses a hypervalent iodonium(III) ylide precursor, to prepare the radiopharmaceutical (18)F-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ((18)F-FPEB). METHODS Automated radiosynthesis of (18)F-FPEB was achieved by reaction of the ylide precursor (4 mg) with (18)F-Et4NF in dimethylformamide at 80°C for 5 min and formulated for injection within 1 h. RESULTS (18)F-FPEB was synthesized in 20% ± 5% (n = 3) uncorrected radiochemical yields relative to (18)F-fluoride, with specific activities of 666 ± 51.8 GBq (18 ± 1.4 Ci)/μmol at the end of synthesis and was validated for human use. CONCLUSION Radiofluorination of iodonium (III) ylides proved to be an efficient radiosynthetic strategy for synthesis of (18)F-labeled radiopharmaceuticals.
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Affiliation(s)
- Nickeisha A Stephenson
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Jason P Holland
- Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Alina Kassenbrock
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and
| | - Daniel L Yokell
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and
| | - Eli Livni
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
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Rook JM, Tantawy MN, Ansari MS, Felts AS, Stauffer SR, Emmitte KA, Kessler RM, Niswender CM, Daniels JS, Jones CK, Lindsley CW, Conn PJ. Relationship between in vivo receptor occupancy and efficacy of metabotropic glutamate receptor subtype 5 allosteric modulators with different in vitro binding profiles. Neuropsychopharmacology 2015; 40:755-65. [PMID: 25241804 PMCID: PMC4289965 DOI: 10.1038/npp.2014.245] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 09/06/2014] [Accepted: 09/09/2014] [Indexed: 11/09/2022]
Abstract
Allosteric modulators of the metabotropic glutamate receptor subtype 5 (mGlu5) have exciting potential as therapeutic agents for multiple brain disorders. Translational studies with mGlu5 modulators have relied on mGlu5 allosteric site positron emission tomography (PET) radioligands to assess receptor occupancy in the brain. However, recent structural and modeling studies suggest that closely related mGlu5 allosteric modulators can bind to overlapping but not identical sites, which could complicate interpretation of in vivo occupancy data, even when PET ligands and drug leads are developed from the same chemical scaffold. We now report that systemic administration of the novel mGlu5 positive allosteric modulator VU0092273 displaced the structurally related mGlu5 PET ligand, [(18)F]FPEB, with measures of in vivo occupancy that closely aligned with its in vivo efficacy. In contrast, a close analog of VU0092273 and [(18)F]FPEB, VU0360172, provided robust efficacy in rodent models in the absence of detectable occupancy. Furthermore, a structurally unrelated mGlu5 negative allosteric modulator, VU0409106, displayed measures of in vivo occupancy that correlated well with behavioral effects, despite the fact that VU0409106 is structurally unrelated to [(18)F]FPEB. Interestingly, all three compounds inhibit radioligand binding to the prototypical MPEP/FPEB allosteric site in vitro. However, VU0092273 and VU0409106 bind to this site in a fully competitive manner, whereas the interaction of VU0360172 is noncompetitive. Thus, while close structural similarity between PET ligands and drug leads does not circumvent issues associated with differential binding to a given target, detailed molecular pharmacology analysis accurately predicts utility of ligand pairs for in vivo occupancy studies.
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Affiliation(s)
- Jerri M Rook
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mohammed N Tantawy
- Vanderbilt University Institute of Imaging Sciences, Nashville, TN, USA,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mohammad S Ansari
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andrew S Felts
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shaun R Stauffer
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Chemistry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kyle A Emmitte
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Chemistry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robert M Kessler
- Department of Radiology, University of Alabama, Birmingham, AL, USA
| | - Colleen M Niswender
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - J Scott Daniels
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Carrie K Jones
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Craig W Lindsley
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Chemistry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - P Jeffrey Conn
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, 1215D Light Hall, 2215-B Garland Avenue, Nashville, TN 37232-0697, USA, Tel: +1 615 936 2478, Fax: +1 615 343 3088, E-mail:
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45
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Lim K, Labaree D, Li S, Huang Y. Preparation of the metabotropic glutamate receptor 5 (mGluR5) PET tracer [(18)F]FPEB for human use: An automated radiosynthesis and a novel one-pot synthesis of its radiolabeling precursor. Appl Radiat Isot 2014; 94:349-354. [PMID: 25305528 DOI: 10.1016/j.apradiso.2014.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 08/24/2014] [Accepted: 09/09/2014] [Indexed: 12/11/2022]
Abstract
The radiotracer 3-[(18)F]fluoro-5-(2-pyridinylethynyl)benzonitrile, or [(18)F]FPEB, is a promising PET imaging agent for the metabotropic glutamate subtype 5 receptor (mGluR5). In an effort to develop a routine production method of this radiotracer for use in clinical research we adapted its radiosynthesis to an automated chemistry module. In the meanwhile, we also developed a simplified "one-pot" method for the preparation of the nitrobenzonitrile radiolabeling precursor for [(18)F]FPEB and its reference standard to replace the existing multi-step synthetic approach.
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Affiliation(s)
- Keunpoong Lim
- PET Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - David Labaree
- PET Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Songye Li
- PET Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Yiyun Huang
- PET Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
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Mathews WB, Kuwabara H, Stansfield K, Valentine H, Alexander M, Kumar A, Hilton J, Dannals RF, Wong DF, Gasparini F. Dose-dependent, saturable occupancy of the metabotropic glutamate subtype 5 receptor by fenobam as measured with [ 11 C]ABP688 PET imaging. Synapse 2014; 68:565-573. [PMID: 25098663 DOI: 10.1002/syn.21775] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 06/25/2014] [Accepted: 07/06/2014] [Indexed: 12/24/2022]
Abstract
Fenobam is a negative allosteric modulator of the metabotropic glutamate receptor subtype 5 (mGluR5) with inverse agonist activity and is expected to contribute to the treatment of neuropsychiatric disorders involving dysfunction of mGluR5 including Fragile X syndrome. This study examined whether [11 C]ABP688, an antagonist PET radioligand, competes with fenobam for the same binding site in the nonhuman primate brain and would allow examination of occupancy-plasma concentration relationships in the evaluation of the drug for target disorders in the human brain. Four paired PET studies with [11 C]ABP688 were performed in baboons at a baseline condition and after intravenous treatment with fenobam at different dose levels (0.3-1.33 mg/kg). Total distribution volume (VT ) and binding potential (BPND ) using the cerebellum as a reference region were obtained by the plasma reference graphical method. Then it was examined whether occupancy follows a dose-dependent, saturating pattern that was predicted by a modified first-order Hill equation in individual regions. Baseline regional VT and BPND values agreed with previously published data. Occupancy showed dose-dependent and saturating patterns in individual regions, reaching >90% occupancy at 1.33 mg/kg dose of fenobam in the majority of regions. To our knowledge, this is the first use of PET to characterize the mGluR5 therapeutic drug fenobam. This study demonstrates a proof of principle for determining the in vivo occupancy of fenobam in primates. The results indicate that [11 C]ABP688 and PET may be useful for examination of occupancy of mGluR5 by fenobam, which should prove to be useful for designing future studies and treatment of human disease states. Synapse 68:565-573, 2014. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- William B Mathews
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Hiroto Kuwabara
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | | | - Heather Valentine
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Mohab Alexander
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Anil Kumar
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - John Hilton
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Robert F Dannals
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Dean F Wong
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland.,Department of Psychiatry, Johns Hopkins University, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland.,Department of Environmental Health Sciences, Johns Hopkins University, Baltimore, Maryland
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Kil KE, Zhu A, Zhang Z, Choi JK, Kura S, Gong C, Brownell AL. Development of [(123)I]IPEB and [(123)I]IMPEB as SPECT Radioligands for Metabotropic Glutamate Receptor Subtype 5. ACS Med Chem Lett 2014; 5:652-6. [PMID: 24944738 DOI: 10.1021/ml500007z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/06/2014] [Indexed: 12/17/2022] Open
Abstract
mGlu5 play an important role in physiology and pathology to various central nervous system (CNS) diseases. Several positron emission tomography (PET) radiotracers have been developed to explore the role of mGlu5 in brain disorders. However, there are no single photon emission computed tomography (SPECT) radioligands for mGlu5. Here we report development of [(123)I]IPEB ([(123)I]1) and [(123)I]IMPEB ([(123)I]2) as mGlu5 radioligands for SPECT. [(123)I]1 and [(123)I]2 were produced by copper(I) mediated aromatic halide displacement reactions. The SPECT imaging using mouse models demonstrated that [(123)I]1 readily entered the brain and accumulated specifically in mGlu5-rich regions of the brain such as striatum and hippocampus. However, in comparison to the corresponding PET tracer [(18)F]FPEB, [(123)I]1 showed faster washout from the brain. The binding ratios of the striatum and the hippocampus compared to the cerebellum for [(123)I]1 and [(18)F]FPEB were similar despite unfavorable pharmacokinetics of [(123)I]1. Further structural optimization of 1 may lead to more viable SPECT radiotracers for the imaging of mGlu5.
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Affiliation(s)
- Kun-Eek Kil
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Aijun Zhu
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Zhaoda Zhang
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Ji-Kyung Choi
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Sreekanth Kura
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Chunyu Gong
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
| | - Anna-Liisa Brownell
- Athinoula A. Martinos Center
for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
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Hulka LM, Treyer V, Scheidegger M, Preller KH, Vonmoos M, Baumgartner MR, Johayem A, Ametamey SM, Buck A, Seifritz E, Quednow BB. Smoking but not cocaine use is associated with lower cerebral metabotropic glutamate receptor 5 density in humans. Mol Psychiatry 2014; 19:625-32. [PMID: 23628984 DOI: 10.1038/mp.2013.51] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 03/18/2013] [Indexed: 12/18/2022]
Abstract
Long-lasting neuroadaptations in the glutamatergic corticostriatal circuitry have been suggested to be responsible for the persisting nature of drug addiction. In particular, animal models have linked the metabotropic glutamate receptor 5 (mGluR5) to drug-seeking behavior and extinction learning. Accordingly, blocking mGluR5s attenuated self-administration of cocaine and other addictive drugs in rats. How these animal findings extend to humans remains unclear. Therefore, we investigated if human cocaine users (CU) exhibit altered mGluR5 availability compared with drug-naïve control subjects. Seventeen male controls (11 smokers) and 18 male cocaine users (13 smokers) underwent positron emission tomography with (11)C-ABP688 to quantify mGluR5 availability in 12 volumes of interest in addiction-related brain areas. Drug use was assessed by self-report and quantitative hair toxicology. CU and controls did not significantly differ in regional mGluR5 availability. In contrast, smokers (n=24) showed significantly lower mGluR5 density throughout the brain (mean 20%) compared with non-smokers (n=11). In terms of effect sizes, lower mGluR5 availability was most pronounced in the caudate nucleus (d=1.50, 21%), insula (d=1.47, 20%), and putamen (d=1.46, 18%). Duration of smoking abstinence was positively associated with mGluR5 density in all brain regions of interest, indicating that lower mGluR5 availability was particularly pronounced in individuals who had smoked very recently. Specifically tobacco smoking was associated with lower mGluR5 availability in both CU and controls, while cocaine use was not linked to detectable mGluR5 alterations. These findings have important implications regarding the development of novel pharmacotherapies aimed at facilitating smoking cessation.
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Affiliation(s)
- L M Hulka
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - V Treyer
- Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - M Scheidegger
- 1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
| | - K H Preller
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - M Vonmoos
- Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland
| | - M R Baumgartner
- Institute of Legal Medicine, University of Zurich, Zurich, Switzerland
| | - A Johayem
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland
| | - S M Ametamey
- 1] Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University of Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - A Buck
- 1] Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - E Seifritz
- 1] Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - B B Quednow
- 1] Experimental and Clinical Pharmacopsychology, University Hospital of Psychiatry Zurich, Zurich, Switzerland [2] Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Gottschalk S, Engelmann J, Rolla GA, Botta M, Parker D, Mishra A. Comparative in vitro studies of MR imaging probes for metabotropic glutamate subtype-5 receptor targeting. Org Biomol Chem 2014; 11:6131-41. [PMID: 23925571 DOI: 10.1039/c3ob41297k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A series of magnetic resonance imaging probes has been evaluated to target selectively the metabotropic glutamate receptor subtype 5 (mGluR5). Eight imaging probes based on the contrast agent [Gd·DOTA], previously derived by linking it to a series of specific and selective mGluR5 antagonists, have been extensively tested for their functionality in vitro. The Nuclear Magnetic Relaxation Dispersion (NMRD) profiles of selected probes have been examined via field-cycling relaxometry in the presence and absence of a model protein. The properties of the targeted contrast agents were evaluated using a primary astrocyte model, as these cells mimic the in vivo situation effectively. The probes were non-toxic (up to 200 μM) to these mGluR5 expressing primary cells. Cellular proton longitudinal relaxation rate enhancements of up to 35% were observed by MRI at 200 μM of probe concentration. The antagonistic effect of all compounds was tested using an assay measuring changes of intracellular calcium levels. Furthermore, treatment at two different temperatures (4 °C vs. 37 °C) and of an mGluR5-negative cell line provided further insight into the selectivity and specificity of these probes towards cell surface mGluR5. Finally, two out of eight probes demonstrated an antagonistic effect as well as significant enhancement of receptor mediated cellular relaxation rates, strongly suggesting that they would be viable probes for the mapping of mGluR5 by MRI in vivo.
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Affiliation(s)
- Sven Gottschalk
- High-Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Spemannstrasse 41, Tuebingen, D-72076, Germany.
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Bunev AS, Rudakova YI, Statsyuk VE, Ostapenko GI, Khrustalev VN. 2-Bromo-4-phenyl-1,3-thia-zole. Acta Crystallogr Sect E Struct Rep Online 2014; 70:o139. [PMID: 24764865 PMCID: PMC3998304 DOI: 10.1107/s160053681400066x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 01/10/2014] [Indexed: 06/03/2023]
Abstract
In the title mol-ecule, C9H6BrNS, the planes of the 2-bromo-1,3-thia-zole and phenyl rings are inclined at 7.45 (10)° with respect to each other. In the crystal, mol-ecules related by a centre of symmetry are held together via π-π inter-actions, with a short distance of 3.815 (2) Å between the centroids of the five- and six-membered rings. The crystal packing exhibits short inter-molecular S⋯Br contacts of 3.5402 (6) Å.
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Affiliation(s)
- Alexander S. Bunev
- Department of Chemistry and Chemical Technology, Togliatti State University, 14 Belorusskaya St, Togliatti 445667, Russian Federation
| | - Yana I. Rudakova
- Department of Chemistry and Chemical Technology, Togliatti State University, 14 Belorusskaya St, Togliatti 445667, Russian Federation
| | - Vladimir E. Statsyuk
- Department of Chemistry and Chemical Technology, Togliatti State University, 14 Belorusskaya St, Togliatti 445667, Russian Federation
| | - Gennady I. Ostapenko
- Department of Chemistry and Chemical Technology, Togliatti State University, 14 Belorusskaya St, Togliatti 445667, Russian Federation
| | - Victor N. Khrustalev
- X-Ray Structural Centre, A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov Street, B-334, Moscow 119991, Russian Federation
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