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Giorgioni G, Bonifazi A, Botticelli L, Cifani C, Matteucci F, Micioni Di Bonaventura E, Micioni Di Bonaventura MV, Giannella M, Piergentili A, Piergentili A, Quaglia W, Del Bello F. Advances in drug design and therapeutic potential of selective or multitarget 5-HT1A receptor ligands. Med Res Rev 2024. [PMID: 38808959 DOI: 10.1002/med.22049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/14/2024] [Accepted: 05/03/2024] [Indexed: 05/30/2024]
Abstract
5-HT1A receptor (5-HT1A-R) is a serotoninergic G-protein coupled receptor subtype which contributes to several physiological processes in both central nervous system and periphery. Despite being the first 5-HT-R identified, cloned and studied, it still represents a very attractive target in drug discovery and continues to be the focus of a myriad of drug discovery campaigns due to its involvement in numerous neuropsychiatric disorders. The structure-activity relationship studies (SAR) performed over the last years have been devoted to three main goals: (i) design and synthesis of 5-HT1A-R selective/preferential ligands; (ii) identification of 5-HT1A-R biased agonists, differentiating pre- versus post-synaptic agonism and signaling cellular mechanisms; (iii) development of multitarget compounds endowed with well-defined poly-pharmacological profiles targeting 5-HT1A-R along with other serotonin receptors, serotonin transporter (SERT), D2-like receptors and/or enzymes, such as acetylcholinesterase and phosphodiesterase, as a promising strategy for the management of complex psychiatric and neurodegenerative disorders. In this review, medicinal chemistry aspects of ligands acting as selective/preferential or multitarget 5-HT1A-R agonists and antagonists belonging to different chemotypes and developed in the last 7 years (2017-2023) have been discussed. The development of chemical and pharmacological 5-HT1A-R tools for molecular imaging have also been described. Finally, the pharmacological interest of 5-HT1A-R and the therapeutic potential of ligands targeting this receptor have been considered.
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Affiliation(s)
- Gianfabio Giorgioni
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | - Alessandro Bonifazi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, Baltimore, Maryland, USA
| | - Luca Botticelli
- Pharmacology Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | - Carlo Cifani
- Pharmacology Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | - Federica Matteucci
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | | | | | - Mario Giannella
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | | | - Alessia Piergentili
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | - Wilma Quaglia
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
| | - Fabio Del Bello
- Medicinal Chemistry Unit, School of Pharmacy, University of Camerino, Camerino, Italy
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2
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Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
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Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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3
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Dahl K, Johnström P, Forsberg-Morén A, Gustafsson B, Miranda-Azpiazu P, Khani Y, Halldin C, Farde L, Elmore CS, Schou M. Synthesis and Preclinical Evaluation of [ 11C]AZ11895530 for PET Imaging of the Serotonin 1A Receptor. ACS Chem Neurosci 2022; 13:2078-2083. [PMID: 35802379 DOI: 10.1021/acschemneuro.2c00205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The serotonin 1A (5-HT1A) receptor is a G-protein-coupled receptor implicated in the pathophysiology of several neuropsychiatric and neurodegenerative disorders. We here report the preparation of two candidate 5-HT1A radioligands, [11C]AZ11132132 ([11C]3) and [11C]AZ11895530 ([11C]4), and their subsequent evaluation in vitro using autoradiography and in vivo using positron emission tomography (PET). Compounds 3 and 4 were radiolabeled at high radiochemical purity (>99%) and high molar activity (>38 GBq/μmol) by heteroatom methylation with [11C]methyl iodide. Autoradiography on whole hemispheres from post-mortem human brain revealed substantial nonspecific binding of [11C]3, while the binding of [11C]4 to brain tissue was consistent with the distribution of 5-HT1A receptors and sensitive to co-incubation with the reference 5-HT1A antagonist WAY-100635 (10 μM). Following intravenous injection of [11C]4 into a cynomolgus monkey, brain radioactivity concentration (Cmax ∼ 2.2 SUV) was high whereafter it decreased rapidly. The regional binding potential (BPND) values were calculated using the simplified reference tissue model with cerebellum as reference region. The values varied between 0.2 and 1.0 for temporal cortex, raphe nuclei, frontal cortex, and hippocampus which is consistent with the known 5-HT1A expression pattern. After pretreatment with WAY100635 (0.5 mg/kg), a homogeneous distribution of radioactivity was observed in non-human primate (NHP) brain. Although [11C]4 fulfilled important criteria for successful in vivo neuroimaging, including good blood-brain-barrier permeability and high specific binding in vitro to human brain tissue, the regional BPND values for [11C]4 in NHP brain were low when compared to those obtained with existing radioligands and thus do not merit further investigation of [11C]4. Evaluation of structurally related analogues is underway in our laboratory to identify improved candidates for clinical imaging.
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Affiliation(s)
- Kenneth Dahl
- Department of Radiopharmacy, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.,Department of Oncology and Pathology, Kaolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Peter Johnström
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden.,PET Science Centre at Karolinska Institutet, Precision Medicine and Biosamples, AstraZeneca, S-171 76 Stockholm, Sweden
| | - Anton Forsberg-Morén
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Björn Gustafsson
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Patricia Miranda-Azpiazu
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Yaser Khani
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Lars Farde
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden
| | - Charles S Elmore
- Isotope Chemistry, Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, 431 50 Mölndal, Sweden
| | - Magnus Schou
- Karolinska Institutet, Department of Clinical Neuroscience, Centre for Psychiatric Research, Karolinska Hospital, S-171 76 Stockholm, Sweden.,PET Science Centre at Karolinska Institutet, Precision Medicine and Biosamples, AstraZeneca, S-171 76 Stockholm, Sweden
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4
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Zhou YP, Makaravage KJ, Brugarolas P. Radiolabeling with [ 11C]HCN for Positron emission tomography. Nucl Med Biol 2021; 102-103:56-86. [PMID: 34624831 PMCID: PMC8978408 DOI: 10.1016/j.nucmedbio.2021.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/20/2021] [Accepted: 09/20/2021] [Indexed: 12/22/2022]
Abstract
Hydrogen cyanide (HCN) is a versatile synthon for generating carbon‑carbon and carbon-heteroatom bonds. Unlike other one-carbon synthons (i.e., CO, CO2), HCN can function as a nucleophile (as in potassium cyanide, KCN) and an electrophile (as in cyanogen bromide, (CN)Br). The incorporation of the CN motif into organic molecules generates nitriles, hydantoins and (thio)cyanates, which can be converted to carboxylic acids, aldehydes, amides and amines. Such versatile chemistry is particularly attractive in PET radiochemistry where diverse bioactive small molecules incorporating carbon-11 in different positions need to be produced. The first examples of making [11C]HCN for radiolabeling date back to the 1960s. During the ensuing decades, [11C]cyanide labeling was popular for producing biologically important molecules including 11C-labeled α-amino acids, sugars and neurotransmitters. [11C]cyanation is now reemerging in many PET centers due to its versatility for making novel tracers. Here, we summarize the chemistry of [11C]HCN, review the methods to make [11C]HCN past and present, describe methods for labeling different types of molecules with [11C]HCN, and provide an overview of the reactions available to convert nitriles into other functional groups. Finally, we discuss some of the challenges and opportunities in [11C]HCN labeling such as developing more robust methods to produce [11C]HCN and developing rapid and selective methods to convert nitriles into other functional groups in complex molecules.
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Affiliation(s)
- Yu-Peng Zhou
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Katarina J Makaravage
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Pedro Brugarolas
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.
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Ferrat M, Dahl K, Schou M. One-Pot Synthesis of 11 C-Labelled Primary Benzamides via Intermediate [ 11 C]Aroyl Dimethylaminopyridinium Salts. Chemistry 2021; 27:8689-8693. [PMID: 33885193 PMCID: PMC8251633 DOI: 10.1002/chem.202100544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Indexed: 11/08/2022]
Abstract
Electrophilic 11C‐labelled aroyl dimethylaminopyridinium salts, obtained by carbonylative cross‐coupling of aryl halides with [11C]carbon monoxide, were prepared for the first time and shown to be valuable intermediates in the synthesis of primary [11C]benzamides. The methodology furnished a set of benzamide model compounds, including the two poly (ADP‐ribose) polymerase (PARP) inhibitors niraparib and veliparib, in moderate to excellent radiochemical yields. In addition to providing a convenient and practical route to primary [11C]benzamides, the current method paves the way for future application of [11C]aroyl dimethylaminopyridinium halide salts in positron emission tomography (PET) tracer synthesis.
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Affiliation(s)
- Mélodie Ferrat
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska, Institutet and Stockholm County Council, 171 76, Stockholm, Sweden
| | - Kenneth Dahl
- Department of Radiopharmacy, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska, Institutet and Stockholm County Council, 171 76, Stockholm, Sweden.,AstraZeneca PET Science Centre, Department of Clinical Neuroscience, Karolinska Institutet, 171 76, Stockholm, Sweden
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Hazari PP, Pandey A, Chaturvedi S, Mishra AK. New Trends and Current Status of Positron-Emission Tomography and Single-Photon-Emission Computerized Tomography Radioligands for Neuronal Serotonin Receptors and Serotonin Transporter. Bioconjug Chem 2017; 28:2647-2672. [PMID: 28767225 DOI: 10.1021/acs.bioconjchem.7b00243] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The critical role of serotonin (5-hydroxytryptamine; 5-HT) and its receptors (5-HTRs) in the pathophysiology of diverse neuropsychiatric and neurodegenerative disorders render them attractive diagnostic and therapeutic targets for brain disorders. Therefore, the in vivo assessment of binding of 5-HT receptor ligands under a multitude of physiologic and pathologic scenarios may support more-accurate identification of disease and its progression and the patient's response to therapy as well as the screening of novel therapeutic strategies. The present Review aims to focus on the current status of radioligands used for positron-emission tomography (PET) and single-photon-emission computerized tomography (SPECT) imaging of human brain serotonin receptors. We further elaborate upon and emphasize the attributes that qualify a radioligand for theranostics on the basis of its frequency of use in clinics, its benefit to risk assessment in humans, and its continuous evolution, along with the major limitations.
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Affiliation(s)
- Puja Panwar Hazari
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Ankita Pandey
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Anil Kumar Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
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7
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Ma L, Placzek MS, Hooker JM, Vasdev N, Liang SH. [ 11C]Cyanation of arylboronic acids in aqueous solutions. Chem Commun (Camb) 2017; 53:6597-6600. [PMID: 28580477 PMCID: PMC5584069 DOI: 10.1039/c7cc02886e] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A copper-mediated 11C-cyanation method employing arylboronic acids and [11C]HCN has been developed. This method was applied to the radiochemical synthesis of a wide range of aromatic 11C-nitriles in aqueous solutions. The use of readily accessible arylboronic acids as precursors makes this method complementary to the well-established 11C-cyanation methods that utilize aryl halide precursors.
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Affiliation(s)
- Longle Ma
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Michael S. Placzek
- Harvard Medical School, Boston, MA, USA
- McLean Hospital, Belmont, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, USA
| | - Jacob M. Hooker
- Harvard Medical School, Boston, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
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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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Paterson LM, Kornum BR, Nutt DJ, Pike VW, Knudsen GM. 5-HT radioligands for human brain imaging with PET and SPECT. Med Res Rev 2011; 33:54-111. [PMID: 21674551 DOI: 10.1002/med.20245] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The serotonergic system plays a key modulatory role in the brain and is the target for many drug treatments for brain disorders either through reuptake blockade or via interactions at the 14 subtypes of 5-HT receptors. This review provides the history and current status of radioligands used for positron emission tomography (PET) and single photon emission computerized tomography (SPECT) imaging of human brain serotonin (5-HT) receptors, the 5-HT transporter (SERT), and 5-HT synthesis rate. Currently available radioligands for in vivo brain imaging of the 5-HT system in humans include antagonists for the 5-HT(1A), 5-HT(1B), 5-HT(2A), and 5-HT(4) receptors, and for SERT. Here we describe the evolution of these radioligands, along with the attempts made to develop radioligands for additional serotonergic targets. We describe the properties needed for a radioligand to become successful and the main caveats. The success of a PET or SPECT radioligand can ultimately be assessed by its frequency of use, its utility in humans, and the number of research sites using it relative to its invention date, and so these aspects are also covered. In conclusion, the development of PET and SPECT radioligands to image serotonergic targets is of high interest, and successful evaluation in humans is leading to invaluable insight into normal and abnormal brain function, emphasizing the need for continued development of both SPECT and PET radioligands for human brain imaging.
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Affiliation(s)
- Louise M Paterson
- Neuropsychopharmacology Unit, Division of Experimental Medicine, Imperial College London, Burlington Danes Building, Du Cane Road, London, United Kingdom
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Pretze M, Große-Gehling P, Mamat C. Cross-coupling reactions as valuable tool for the preparation of PET radiotracers. Molecules 2011; 16:1129-65. [PMID: 21270732 PMCID: PMC6259626 DOI: 10.3390/molecules16021129] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 01/17/2011] [Accepted: 01/21/2011] [Indexed: 11/16/2022] Open
Abstract
The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of new radiotracers and novel radiolabeling procedures with the most prominent short-lived positron emitters carbon-11 and fluorine-18. Radiolabeling with these radionuclides represents a remarkable challenge. Special attention has to be paid to synthesis time and specific labeling techniques due to the short physical half life of the respective radionuclides 11C (t1/2 = 20.4 min) and 18F (t1/2 = 109.8 min). In the past, numerous transition metal-catalyzed reactions were employed in organic chemistry, even though only a handful of these coupling reactions were adopted in radiochemical practice. Thus, the implementation of modern synthesis methods like cross-coupling reactions offers the possibility to develop a wide variety of novel radiotracers. The introduction of catalysts based on transition metal complexes bears a high potential for rapid, efficient, highly selective and functional group-tolerating incorporation of carbon-11 and fluorine-18 into target molecules. This review deals with design, application and improvement of transition metal-mediated carbon-carbon as well as carbon-heteroatom cross-coupling reactions as a labeling feature with the focus on the preparation of radiolabeled compounds for molecular imaging.
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Affiliation(s)
- Marc Pretze
- Institut für Radiopharmazie, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Philipp Große-Gehling
- OncoRay – National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Fetscherstraße 74, P.O. Box 41, D-01307 Dresden, Germany
| | - Constantin Mamat
- Institut für Radiopharmazie, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden, Germany
- Author to whom correspondence should be addressed; ; Tel.: +49-351-260 2805; Fax: +49-351-260 3232
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11
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Measuring serotonin synthesis: from conventional methods to PET tracers and their (pre)clinical implications. Eur J Nucl Med Mol Imaging 2010; 38:576-91. [PMID: 21113591 PMCID: PMC3034914 DOI: 10.1007/s00259-010-1663-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 11/01/2010] [Indexed: 12/20/2022]
Abstract
The serotonergic system of the brain is complex, with an extensive innervation pattern covering all brain regions and endowed with at least 15 different receptors (each with their particular distribution patterns), specific reuptake mechanisms and synthetic processes. Many aspects of the functioning of the serotonergic system are still unclear, partially because of the difficulty of measuring physiological processes in the living brain. In this review we give an overview of the conventional methods of measuring serotonin synthesis and methods using positron emission tomography (PET) tracers, more specifically with respect to serotonergic function in affective disorders. Conventional methods are invasive and do not directly measure synthesis rates. Although they may give insight into turnover rates, a more direct measurement may be preferred. PET is a noninvasive technique which can trace metabolic processes, like serotonin synthesis. Tracers developed for this purpose are α-[11C]methyltryptophan ([11C]AMT) and 5-hydroxy-L-[β-11C]tryptophan ([11C]5-HTP). Both tracers have advantages and disadvantages. [11C]AMT can enter the kynurenine pathway under inflammatory conditions (and thus provide a false signal), but this tracer has been used in many studies leading to novel insights regarding antidepressant action. [11C]5-HTP is difficult to produce, but trapping of this compound may better represent serotonin synthesis. AMT and 5-HTP kinetics are differently affected by tryptophan depletion and changes of mood. This may indicate that both tracers are associated with different enzymatic processes. In conclusion, PET with radiolabelled substrates for the serotonergic pathway is the only direct way to detect changes of serotonin synthesis in the living brain.
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Bennacef I, Salinas CA, Bonasera TA, Gunn RN, Audrain H, Jakobsen S, Nabulsi N, Weinzimmer D, Carson RE, Huang Y, Holmes I, Micheli F, Heidbreder C, Gentile G, Rossi T, Laruelle M. Dopamine D3 receptor antagonists: The quest for a potentially selective PET ligand. Part 3: Radiosynthesis and in vivo studies. Bioorg Med Chem Lett 2009; 19:5056-9. [DOI: 10.1016/j.bmcl.2009.07.055] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/07/2009] [Accepted: 07/07/2009] [Indexed: 10/20/2022]
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13
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Kil KE, Biegon A, Ding YS, Fischer A, Ferrieri RA, Kim SW, Pareto D, Schueller MJ, Fowler JS. Synthesis and PET studies of [(11)C-cyano]letrozole (Femara), an aromatase inhibitor drug. Nucl Med Biol 2009; 36:215-23. [PMID: 19217534 DOI: 10.1016/j.nucmedbio.2008.11.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 10/18/2008] [Accepted: 11/19/2008] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Aromatase, a member of the cytochrome P450 family, converts androgens such as androstenedione and testosterone into estrone and estradiol, respectively. Letrozole (1-[bis-(4-cyanophenyl)methyl]-1H-1,2,4-triazole; Femara) is a high-affinity aromatase inhibitor (K(i)=11.5 nM) that has Food and Drug Administration approval for breast cancer treatment. Here we report the synthesis of carbon-11-labeled letrozole and its assessment as a radiotracer for brain aromatase in the baboon. METHODS Letrozole and its precursor (4-[(4-bromophenyl)-1H-1,2,4-triazol-1-ylmethyl]benzonitrile) were prepared in a two-step synthesis from 4-cyanobenzyl bromide and 4-bromobenzyl bromide, respectively. The [(11)C]cyano group was introduced via tetrakis(triphenylphosphine)palladium(0)-catalyzed coupling of [(11)C]cyanide with the bromo precursor. Positron emission tomography (PET) studies in the baboon brain were carried out to assess regional distribution and kinetics, reproducibility of repeated measures and saturability. Log D, the free fraction of letrozole in plasma and the [(11)C-cyano]letrozole fraction in arterial plasma were also measured. RESULTS [(11)C-cyano]Letrozole was synthesized in 60 min with a radiochemical yield of 79-80%, with a radiochemical purity greater than 98% and a specific activity of 4.16+/-2.21 Ci/mumol at the end of bombardment (n=4). PET studies in the baboon revealed initial rapid and high uptake and initial rapid clearance, followed by slow clearance of carbon-11 from the brain, with no difference between brain regions. Brain kinetics was not affected by coinjection of unlabeled letrozole (0.1 mg/kg). The free fraction of letrozole in plasma was 48.9%, and log D was 1.84. CONCLUSION [(11)C-cyano]Letrozole is readily synthesized via a palladium-catalyzed coupling reaction with [(11)C]cyanide. Although it is unsuitable as a PET radiotracer for brain aromatase, as revealed by the absence of regional specificity and saturability in brain regions such as amygdala, which are known to contain aromatase, it may be useful in measuring letrozole distribution and pharmacokinetics in the brain and peripheral organs.
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Affiliation(s)
- Kun-Eek Kil
- Medical Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Cai L, Cuevas J, Temme S, Herman MM, Dagostin C, Widdowson DA, Innis RB, Pike VW. Synthesis and structure-affinity relationships of new 4-(6-iodo-H-imidazo[1,2-a]pyridin-2-yl)-N-dimethylbenzeneamine derivatives as ligands for human beta-amyloid plaques. J Med Chem 2007; 50:4746-58. [PMID: 17722900 DOI: 10.1021/jm0702231] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new and extensive set of 4-(6-iodo-H-imidazo[1,2-a]pyridin-2-yl)-N-dimethylbenzeneamine (IMPY) derivatives was synthesized and assayed for affinity toward human Abeta plaques. 6-Ethylthio- (12h), 6-cyano- (12e), 6-nitro- (12f), and 6-p-methoxybenzylthio- (15d) analogues were discovered to have high affinity (KI < 10 nM). However, introduction of a hydrophilic thioether group in the 6-position (15a-c, 15e-g) reduced or abolished affinity. In secondary N-methyl analogues, a bromo substituent in the adjacent ring position (14a) imparted high affinity (KI = 7.4 nM) whereas a methyl substituent did not (14c). The tolerance for nonhydrophilic thioether substituents in the 6-position opens up the possibility of developing new sensitive positron emission tomography radioligands for imaging human Abeta plaques in Alzheimer's disease, especially in view of the amenability of thioethers to be labeled with carbon-11 or fluorine-18 through S-alkylation reactions. The structure-activity relationships revealed in this study extends insight into the topography of the binding site for IMPY-like ligands in human Abeta plaques.
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Affiliation(s)
- Lisheng Cai
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Scott Mason N, Mathis CA. Positron Emission Tomography Agents for Central Nervous System Drug Development Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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Pike VW, Halldin C, Wikström HV. Radioligands for the study of brain 5-HT1A receptors in vivo. PROGRESS IN MEDICINAL CHEMISTRY 2002; 38:189-247. [PMID: 11774795 DOI: 10.1016/s0079-6468(08)70094-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- V W Pike
- Chemistry and Engineering Group, MRC Cyclotron Unit, Imperial College School of Medicine, Hammersmith Hospital, Ducane Road, London W12 ONN, UK
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17
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Sandell J, Halldin C, Chou YH, Swahn CG, Thorberg SO, Farde L. PET-examination and metabolite evaluation in monkey of [(11)C]NAD-299, a radioligand for visualisation of the 5-HT(1A) receptor. Nucl Med Biol 2002; 29:39-45. [PMID: 11786274 DOI: 10.1016/s0969-8051(01)00272-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
NAD-299 is a selective 5-HT(1A) receptor antagonist that is currently developed as a putative antidepressant drug. [(11)C]NAD-299 was examined in the cynomolgus monkey brain with positron emission tomography (PET). After radioligand injection high accumulation of radioactivity was observed in the frontal and temporal cortex and the raphe nuclei, regions known to contain a high density of 5-HT(1A) receptors. Peak equilibrium appeared already at about 10 min after i.v. injection. Pre-treatment with a high dose of the antagonist WAY-100635 reduced the amount of radioactivity in the cortex and the raphe to the level of the cerebellum. A strong pre-treatment effect could also be achieved using pindolol, a partial agonist at the 5-HT(1A)-receptors. The appearance of labeled metabolites in monkey plasma was measured with HPLC. At 45 minutes after injection 49% (range 27-55%, n = 5) of radioactivity in monkey plasma represented unchanged radioligand. [(11)C]NAD-299 was metabolized to more polar labeled metabolites of which one has the same chromatographic mobility as the descyclobutyl analogue of NAD-299 (NAD-272). The results indicate that [(11)C]NAD-299 has potential as a PET radioligand for studies of 5-HT(1A) receptors in the primate brain.
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Affiliation(s)
- Johan Sandell
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-171 76 Stockholm, Sweden.
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18
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Cliffe IA. A retrospect on the discovery of WAY-100635 and the prospect for improved 5-HT(1A) receptor PET radioligands. Nucl Med Biol 2000; 27:441-7. [PMID: 10962248 DOI: 10.1016/s0969-8051(00)00109-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Abstract. An outline is given of the developments that led to the identification of [O-methyl-(11)C]WAY-100635 (4) as the first useful PET ligand for imaging serotonin(1A) (5-HT(1A)) receptors in the living human brain. Recent attempts to develop 5-HT(1A) receptor radioligands superior to 4 are reviewed, and [carbonyl-(11)C]WAY-100635 (6) has been shown to be the best currently available radioligand for human studies. Of other (11)C-radiolabelled compounds, [O-methyl-(11)C](R,S)-CPC-222 (9), DWAY (8), and [(11)C]NAD-299 (14) all demonstrate specific binding to 5-HT(1A) receptors in animals and warrant further expedited studies in humans. The trans-fluorocyclohexane, 12, and fluorobenzene, [(18)F]p-MPPF 13, are highlighted as examples of promising (18)F-labelled ligands.
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Affiliation(s)
- I A Cliffe
- Department of Chemistry, Vernalis Research, Oakdene Court, 613 Reading Road, Winnersh, Workingham RG41 5UA, United Kingdom.
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Andrée B, Halldin C, Thorberg SO, Sandell J, Farde L. Use of PET and the radioligand [carbonyl-(11)C]WAY-100635 in psychotropic drug development. Nucl Med Biol 2000; 27:515-21. [PMID: 10962260 DOI: 10.1016/s0969-8051(00)00121-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Positron-emission tomography (PET) provides potential in neuropsychiatric drug development by expanding knowledge of drug action in the living human brain and reducing time consumption and costs. The 5-hydroxytryptamine(1A) (5-HT(1A)) receptor is of central interest as a target for the treatment of anxiety, depression, and schizophrenia. Research on the clinical significance of the 5-HT(1A) receptor now benefits from the highly selective radioligand [carbonyl-(11)C]WAY-100635 (WAY) for quantitative determination of 5-HT(1A) receptors in the primate and human brain in vivo using PET. In this paper, three studies are reviewed to demonstrate the suitability of WAY as radioligand for quantification of central 5-HT(1A) receptors in brain and as an applicable tool for drug development. In the first study a monkey model was used to characterize WAY binding. It was confirmed that the reference ligand 8-OH-DPAT and psychoactive drugs such as buspirone and pindolol occupies 5-HT(1A) receptors in the primate brain. Pindolol is an beta-adrenoreceptor antagonist with a high affinity to 5-HT(1A) receptors. This drug has been suggested in combination with selective serotonin reuptake inhibitors for the treatment of depression and was given to healthy males in the second study. Pindolol induced a marked inhibition of central 5-HT(1A) receptors as calculated by the ratio-analysis method and simplified reference tissue model, 2 h after administration of 10 mg as a single oral dose. This observation suggests that pindolol may have a role for the suggested potentiation of selective serotonin reuptake inhibitor treatment of depression. The third study was on robalzotan (NAD-299), a recently developed 5-HT(1A) receptor antagonist and putative drug with implications for the treatment of depression. In the cynomolgus monkey brain, robalzotan in the dose range 2-100 microg/kg IV occupied 5-HT(1A) receptors in a dose-dependent and saturable manner with a maximal calculated occupancy of 70-80%. The relationship between robalzotan plasma concentration and 5-HT(1A) receptor occupancy could be described by a hyperbolic function that was used to guide the selection of appropriate doses in man. In a subsequent PET study of robalzotan binding to 5-HT(1A) receptors in the living human brain, similar results have been replicated recently. These studies reviewed here illustrate and corroborate that quantitative neuroimaging of receptor binding has potential for the evaluation and dose finding of new central nervous system drugs.
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Affiliation(s)
- B Andrée
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Stockholm, Sweden.
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Burns HD, Hamill TG, Eng WS, Francis B, Fioravanti C, Gibson RE. Positron emission tomography neuroreceptor imaging as a tool in drug discovery, research and development. Curr Opin Chem Biol 1999; 3:388-94. [PMID: 10419855 DOI: 10.1016/s1367-5931(99)80059-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Improved communication and cooperation between research-driven drug companies and academic positron emission tomography (PET) centers, coupled with improvements in PET camera resolution, the availability of small animal PET cameras and a growing list of neuroreceptor-specific PET tracers, have all contributed to a substantial increase in the use and value of PET as a tool in central nervous system drug discovery and development.
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Affiliation(s)
- H D Burns
- Department of Pharmacology, Merck Research Laboratories, WP44C-2, Sumneytown Pike, West Point, PA 19438, USA.
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