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Gil-Rivas A, de Pascual-Teresa B, Ortín I, Ramos A. New Advances in the Exploration of Esterases with PET and Fluorescent Probes. Molecules 2023; 28:6265. [PMID: 37687094 PMCID: PMC10488407 DOI: 10.3390/molecules28176265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023] Open
Abstract
Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.
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Affiliation(s)
- Alba Gil-Rivas
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Beatriz de Pascual-Teresa
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Irene Ortín
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Ana Ramos
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
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KSNM60: The History of Radiopharmaceutical Sciences in Korea. Nucl Med Mol Imaging 2022; 56:114-126. [DOI: 10.1007/s13139-022-00744-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/17/2022] [Accepted: 03/10/2022] [Indexed: 10/18/2022] Open
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Saglam MF, Bingul M, Şenkuytu E, Boga M, Zorlu Y, Kandemir H, Sengul IF. Synthesis, characterization, UV–Vis absorption and cholinesterase inhibition properties of bis-indolyl imine ligand systems. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Bingul M, Ercan S, Boga M. The design of novel 4,6-dimethoxyindole based hydrazide-hydrazones: Molecular modeling, synthesis and anticholinesterase activity. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128202] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Lee BC, Moon BS, Park HS, Jung JH, Park HS, Park DD, de Candia M, Denora N, Altomare CD, Kim SE. The position of fluorine in CP-118,954 affects AChE inhibition potency and PET imaging quantification for AChE expression in the rat brain. Eur J Pharm Sci 2017; 109:209-216. [PMID: 28818531 DOI: 10.1016/j.ejps.2017.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/21/2017] [Accepted: 08/14/2017] [Indexed: 10/19/2022]
Abstract
The in vitro inhibition potency against acetylcholinesterase (AChE) of fluorinated derivatives of CP-118,954 (1) has been shown to depend upon the position of aromatic fluorine (F) substitution on the N-benzyl moiety. Indeed, the meta-F-substituted compound 3 (IC50=1.4nM) shows similar potency with the parent compound 1 (IC50=1.2nM), whereas the ortho-F derivative 2 (IC50=3.2nM) and para-F derivative 4 (IC50=10.8nM) were found to be less potent AChE inhibitors. A comparative in vivo microdialysis study in rats showed that 3 has the strongest effect on the neuropharmacological properties as AChE inhibitor. For PET imaging studies, a radiolabeled ligand ([18F]3) was synthesized through nucleophilic aromatic substitution reaction of diaryliodonium salt-based aldehyde precursor followed by reductive alkylation in a two-step radiolabeling procedure with 11.5 ± 1.2% (n=24, non-decay corrected) radiochemical yield and over 99% radiochemical purity. In a comparative PET imaging study of the three 18F-containing derivatives of CP-118,954 ([18F]2-4), [18F]3 showed the highest radioactivity in the AChE-rich region of normal rat brain which visually reflected the in vitro AChE-binding affinity of 3. These findings support [18F]3 as a promising AChE-targeted PET imaging ligand for the assessment of cholinergic activity into the brain, providing also insights into the AChE ligand disposition, which depends upon the position of the aromatic fluorine in the benzyl moiety.
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Affiliation(s)
- Byung Chul Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea; Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon 16229, Republic of Korea
| | - Byung Seok Moon
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea
| | - Hyun Soo Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea
| | - Jae Ho Jung
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea
| | - Hyun Sik Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea
| | - Do Dam Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea
| | - Modesto de Candia
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy
| | - Nunzio Denora
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy
| | - Cosimo D Altomare
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy
| | - Sang Eun Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Republic of Korea; Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon 16229, Republic of Korea; Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Republic of Korea.
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3-(Benzyloxy)-1-(5-[18F]fluoropentyl)-5-nitro-1H-indazole: a PET radiotracer to measure acetylcholinesterase in brain. Future Med Chem 2017. [DOI: 10.4155/fmc-2017-0023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Aim: Noninvasive studies of the acetylcholinesterase (AChE) level in Alzheimer's disease (AD) patients can contribute to a better understanding of the disease and its therapeutic. We propose 3-(benzyloxy)-1-(5-[18F]fluoropentyl)-5-nitro-1H-indazole, [18F]-IND1, structurally related to the AChE-inhibitor CP126,998, as a new positron emission tomography-radiotracer. Experimental: Radiosynthesis, with 18F, stability, lipophilicity and protein binding of [18F]-IND1 were studied. In vivo behavior, in normal mice and on AD mice models, were also analyzed. Results: [18F]-IND1 was obtained in good radiochemical yield, was stable for at least 2 h in different conditions, and had adequate lipophilicity for blood–brain barrier penetration. Biodistribution studies, in normal mice, showed that [18F]-IND1 was retained in the brain after 1 h. In vivo tacrine-blocking experiments indicated this uptake could be specifically due to AChE interaction. Studies in transgenic AD mice showed differential, compared with normal mice, binding in many brain regions. Conclusion: [18F]-IND1 can be used to detect AChE changes in AD patients.
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Ismail MM, Kamel MM, Mohamed LW, Faggal SI. Synthesis of new indole derivatives structurally related to donepezil and their biological evaluation as acetylcholinesterase inhibitors. Molecules 2012; 17:4811-23. [PMID: 22534665 PMCID: PMC6268345 DOI: 10.3390/molecules17054811] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 11/16/2022] Open
Abstract
New series of indole derivatives analogous to donepezil, a well known anti-Alzheimer and acetylcholinesterase inhibitor drug, was synthesized. A full chemical characterization of the new compounds is provided. Biological evaluation of the new compounds as acetylcholinesterase inhibitors was performed. Most of the compounds were found to have potent acetylcholinesterase inhibitor activity compared to donepezil as standard. The compound 1-(2-(4-(2-fluorobenzyl) piperazin-1-yl)acetyl)indoline-2,3-dione (IIId) was found to be the most potent.
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Affiliation(s)
| | | | - Lamia W. Mohamed
- Author to whom correspondence should be addressed; ; Tel.: +202-2363-2245; Fax: +202-2532-1900
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Namolingam V, Luthra SK, Brady F, Pike VW. Radiosynthesis of 1-[18F]fluoromethyl-4-methyl-benzene and a series of o-, m- or p-substituted 1-halomethyl- [18F]fluoromethyl-benzenes. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.25804401322] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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9
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Binding of 2-[18F]fluoro-CP-118,954 to mouse acetylcholinesterase: microPET and ex vivo Cerenkov luminescence imaging studies. Nucl Med Biol 2011; 38:541-7. [DOI: 10.1016/j.nucmedbio.2010.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 11/13/2010] [Accepted: 11/28/2010] [Indexed: 11/17/2022]
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Lee I, Choe YS, Ryu EK, Choi BW, Choi JY, Choi Y, Lee KH, Kim BT. Synthesis and evaluation of radioiodine-labelled CP-118,954 for the in-vivo imaging of acetylcholinesterase. Nucl Med Commun 2007; 28:561-6. [PMID: 17538398 DOI: 10.1097/mnm.0b013e328194f1f7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Alzheimer's disease (AD) is characterized by reduced acetylcholinesterase (AChE) activity in the post-mortem tissues of AD patients. Therefore, AChE has been an attractive target for the diagnosis of AD. In the present study, 5,7-dihydro-3-[2-(1-(phenylmethyl)-4-piperidinyl)ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one (CP-118,954), a potent AChE inhibitor, was labelled with radioiodine and evaluated as an AChE imaging agent for SPECT. METHODS Radioiodine-labelled CP-118,954 was prepared from CP-144,885 and [(125)I]iodobenzyl bromide, and anti-AChE activities of iodine-substituted CP-118,954 were measured. Metabolism studies were carried out in samples of blood and whole brain of mice injected with 2-[(123)I]iodo-CP-118,954 ((123)I-1). Tissue distribution studies were also performed in mice injected with I-1, and samples of blood, thyroid, stomach, and brain tissue (cerebellum, striatum and cortex) were removed, weighed and counted. RESULTS Of the ligands, 2-iodo-CP-118,954 exhibited higher binding affinity for AChE (IC50=24 nM) than the other positional isomers. 2-[(125)I]Iodo-CP-118,954 was found to have a lipophilicity (log P=2.1) favouring brain permeability and metabolic stability in mouse brain, but a marginal target (striatum) to non-target (cerebellum) uptake ratio (1.1) in mouse brain. CONCLUSION This result demonstrates that 2-[(125)I]iodo-CP-118,954 may be unsuitable for AChE imaging. These findings suggest that radioligands suitable for AChE imaging should have not only a specific structure but also a sub-nanomolar to low nanomolar IC50.
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Affiliation(s)
- Iljung Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Korea
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Ryu EK, Choe YS, Kim DH, Ko BH, Choi Y, Lee KH, Kim BT. In vitro metabolism studies of 18F-labeled 1-phenylpiperazine using mouse liver S9 fraction. Nucl Med Biol 2006; 33:165-72. [PMID: 16546670 DOI: 10.1016/j.nucmedbio.2005.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Revised: 11/26/2005] [Accepted: 12/04/2005] [Indexed: 11/17/2022]
Abstract
The in vitro metabolism of 1-(4-[(18)F]fluoromethylbenzyl)-4-phenylpiperazine ([(18)F]1) and 1-(4-[(18)F]fluorobenzyl)-4-phenylpiperazine ([(18)F]2) was investigated using mouse liver S9 fraction. Results were compared to those of in vivo metabolism using mouse blood and bone and to in vitro metabolism using mouse liver microsomes. Defluorination was the main metabolic pathway for [(18)F]1 in vitro and in vivo. Based on TLC, HPLC and LC-MS data, [(18)F]fluoride ion and less polar radioactive metabolites derived from aromatic ring oxidation were detected in vitro, and the latter metabolites were rapidly converted into the former with time, whereas only the [(18)F]fluoride ion was detected in vivo. Similarly, the in vitro metabolism of [(18)F]2 using either S9 fraction or microsomes showed the same pattern as the in vivo method using blood; however, the radioactive metabolites derived from aromatic ring oxidation were not detected in vivo. These results demonstrate that liver S9 fraction can be widely used to investigate the intermediate radioactive metabolites and to predict the in vivo metabolism of radiotracers.
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Affiliation(s)
- Eun Kyoung Ryu
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, South Korea
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Lee SY, Choe YS, Ryu EK, Iimura Y, Choi Y, Lee KH, Kim BT. Is subnanomolar binding affinity required for the in vivo imaging of acetylcholinesterase? Studies on 18F-labeled G379. Nucl Med Biol 2006; 33:91-4. [PMID: 16459263 DOI: 10.1016/j.nucmedbio.2005.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 09/27/2005] [Accepted: 10/03/2005] [Indexed: 11/26/2022]
Abstract
Acetylcholinesterase (AChE) is an important cholinergic marker of Alzheimer's disease (AD) and shows reduced activity in postmortem AD brain tissues. 1-(4-Fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-fluoro-2-yl)methyl]piperidine (G379, ), an AChE inhibitor with a subnanomolar IC(50) (0.56 nM), was prepared as a (18)F-labeled radioligand ([(18)F]) and evaluated in mice. Metabolism studies of [(18)F] showed no metabolites in the mouse brain. Tissue distribution studies demonstrated its uniform regional distribution in the mouse brain, suggesting that this radioligand is not suitable for the in vivo imaging of AChE. This result along with reports on radiolabeled N-benzylpiperidine lactam benzisoxazole (IC(50) < 1 nM) and other radiolabeled benzylpiperidine derivatives (IC(50) > 1 nM) suggested that a subnanomolar IC(50) may not be the only important factor in determining the suitability of a radioligand for in vivo studies of AChE.
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Affiliation(s)
- Sang-Yoon Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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Ryu EK, Choe YS, Park EY, Paik JY, Kim YR, Lee KH, Choi Y, Kim SE, Kim BT. Synthesis and evaluation of 2-[18F]fluoro-CP-118,954 for the in vivo mapping of acetylcholinesterase. Nucl Med Biol 2005; 32:185-91. [PMID: 15721764 DOI: 10.1016/j.nucmedbio.2004.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 09/13/2004] [Accepted: 09/17/2004] [Indexed: 10/25/2022]
Abstract
5,7-Dihydro-3-[2-[1-(2-fluorobenzyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2,f]-1,2-benzisoxazol-6-one (2-flouro-CP-118,954; 1), a potent acetylcholinesterase (AChE) inhibitor, was prepared as a radioligand by reductive alkylation of CP-144,885 the debenzylated form of CP 118,954, with 2-[18F]fluorobenzaldehyde. The decay-corrected radiochemical yield was 25-30% and the effective specific activity was 41-53 GBq/micromol. Tissue distribution studies of 2-[18F]fluoro-CP-118,954 ([18F]1) in mice showed that the regional brain distribution correlated well with the known density of AChE in the mouse brain. A high level of uptake in the striatum was also shown at all time points in the olfactory tubercle, which is known to have dopaminergic neurons. Blocking studies showed that radioligand uptake in all brain regions was not altered by either the dopamine receptor antagonists or the sigma receptor agonist. On the other hand, radioligand uptake in both the striatum and the olfactory tubercle was significantly blocked (80%) by ligand 1. The low level of bone uptake over time suggested that [18F]1 underwent little in vivo metabolic defluorination. The lack of metabolite formation in the mouse brain indicated that the regional distribution was attributed to [18F]1. These results demonstrated that [18F]1 binds specifically and selectively to AChE in mice and appears to be a suitable radioligand for the in vivo mapping of AChE.
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Affiliation(s)
- Eun Kyoung Ryu
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 135-710 Seoul, Republic of Korea
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Oh SJ, Lee KC, Lee SY, Ryu EK, Saji H, Choe YS, Chi DY, Kim SE, Lee J, Kim BT. Synthesis and evaluation of fluorine-substituted 1H-pyrrolo[2,3-b]pyridine derivatives for dopamine D4 receptor imaging. Bioorg Med Chem 2004; 12:5505-13. [PMID: 15465327 DOI: 10.1016/j.bmc.2004.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Accepted: 08/11/2004] [Indexed: 10/26/2022]
Abstract
Seven fluorine-substituted 1H-pyrrolo[2,3-b]pyridine derivatives were synthesized based on a lead ligand, 3-[[4-(4-iodophenyl)piperazin-1-yl]-methyl]-1H-pyrrolo[2,3-b]pyridine (L-750,667) and evaluated as potential dopamine D(4) receptor imaging agents by positron emission tomography (PET). Binding affinities of these ligands for the dopamine D(2), D(3), and D(4) receptor subtypes were measured in vitro. Most ligands showed high and selective binding for the D(4) receptor. Ligand 7 had high affinity for the D(4) receptor, whereas ligands 1, 2, and 6 showed high selectivity for the D(4) receptor. LogP values were calculated for the ligands in this series and ligand 6 had the lowest lipophilicity. (18)F-labeled ligand 7 demonstrated a uniform regional brain distribution and a rapid washout in mice, probably due to nonspecific binding. Based on their in vitro binding properties and calculated logP values, ligand 6 appears to have the most promise for dopamine D(4) receptor imaging.
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Affiliation(s)
- Seung-Jun Oh
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, South Korea
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Lee SY, Choe YS, Kim YR, Paik JY, Choi BW, Kim SE, Lee KH, Choi Y, Kim BT. Synthesis and evaluation of 5,7-dihydro-3-[2-[1-(4-[18F]-fluorobenzyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one for in vivo mapping of acetylcholinesterase*. Nucl Med Commun 2004; 25:591-6. [PMID: 15167519 DOI: 10.1097/01.mnm.0000126629.09543.1d] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Acetylcholinesterase (AChE) is an important cholinergic marker for the diagnosis of Alzheimer's disease (AD). A recent study has demonstrated that C-labelled 5,7-dihydro-7-methyl-3-[2-[1-(phenylmethyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one (CP-126,998) shows promising results. The demethylated form of this ligand (CP-118,954) is a more potent and selective inhibitor than CP-126,998. In this study, therefore, CP-118,954 was labelled with F and evaluated for the in vivo mapping of AChE. METHODS The 4-fluoro (1). and 2-fluoro (2). derivatives of CP-118,954 were synthesized from 4-methyl-3-nitroanisole in 11 steps. Their in vitro binding affinities to AChE were measured using Ellman's method. The preparation of [F]-1 was carried out by reductive alkylation of the piperidine precursor with 4-[F]-fluorobenzaldehyde, followed by high-performance liquid chromatography (HPLC) purification. In vitro autoradiography was performed by incubating rat brain coronal slices with [F]-1. Tissue distribution studies were performed in mouse brain and the data were expressed as the percentage of the injected dose per gram of tissue (%ID x g). RESULTS Two fluorine-substituted AChE inhibitors were synthesized and their in vitro binding data showed that the 4-fluoro and 2-fluoro derivatives (1 and 2) had similar or superior binding affinity to that of the unsubstituted ligand, CP-118,954. The F-labelled ligand was synthesized in 20-35% radiochemical yield (EOS) and with high effective specific activity (36-42 GBq x micromol). Autoradiography showed high uptake of [F]-1 in the striatum and this striatal uptake was completely inhibited by the unlabelled ligand 1. Tissue distribution studies demonstrated that high radioactivity was accumulated in the striatum, an AChE-rich region. CONCLUSIONS This study demonstrates that [F]-1 may hold promise as a radioligand for the in vivo mapping of AChE.
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Affiliation(s)
- Sang-Yoon Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Khan NUH, Lee BC, Lee SY, Choe YS, Jun CH, Chi DY. Hydroacylation of 4-[18F]fluorobenzaldehyde: a novel method for the preparation of 4?-[18F]phenylketones. J Labelled Comp Radiopharm 2002. [DOI: 10.1002/jlcr.623] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Lasne MC, Perrio C, Rouden J, Barré L, Roeda D, Dolle F, Crouzel C. Chemistry of β +-Emitting Compounds Based on Fluorine-18. Top Curr Chem (Cham) 2002. [DOI: 10.1007/3-540-46009-8_7] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Lee SY, Choe YS, Kim DH, Park BN, Kim SE, Choi Y, Lee KH, Lee J, Kim BT. A simple and efficient in vitro method for metabolism studies of radiotracers. Nucl Med Biol 2001; 28:391-5. [PMID: 11395311 DOI: 10.1016/s0969-8051(01)00203-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In vitro metabolism of acetylcholinesterase inhibitors containing 3-[(18)F]fluoromethylbenzyl- ([(18)F]1) and 4-[(18)F]fluorobenzyl-piperidine moieties ([(18)F]2) was studied and compared with the in vivo metabolism. Defluorination of the [(18)F]1 mainly occurred to generate [(18)F]fluoride ion both in vitro and in vivo. In contrast, the [(18)F]2 was converted into an unknown polar metabolite in both metabolism methods and another metabolite, 4-[(18)F]fluorobenzoic acid in vitro. These results demonstrated that the in vitro method can be used to predict the in vivo metabolism of both radiotracers.
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Affiliation(s)
- S Y Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Center for Clinical Research, Samsung Biomedical Research Institute, 50 Ilwon-dong, Kangnam-ku, Seoul, South Korea
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Lee SY, Choe YS, Sugimoto H, Kim SE, Hwang SH, Lee K, Choi Y, Lee J, Kim B. Synthesis and biological evaluation of 1-(4-[18F]fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-yl)methyl]piperidine for in vivo studies of acetylcholinesterase. Nucl Med Biol 2000; 27:741-4. [PMID: 11150705 DOI: 10.1016/s0969-8051(00)00164-5] [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: 11/25/2022]
Abstract
We synthesized and evaluated 1-(4-fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-yl)methyl]piperidine (4-FDP), which is an analog of donepezil. The 4-[(18)F]FDP was prepared by reductive alkylation of debenzylated donepezil with 4-[(18)F]fluorobenzaldehyde in high radiochemical yield (decay-corrected, 40-52%) and with high effective specific activity (30-38 GBq/micromol). Tissue distribution studies in mice demonstrated nonspecific distribution of the 4-[(18)F]FDP in brain regions, suggesting that this radioligand may not be a suitable agent for in vivo studies of acetylcholinesterase (AChE), despite its potent in vitro biological activity.
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Affiliation(s)
- S Y Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Center for Clinical Research, Samsung Biomedical Research Institute, Seoul, Korea
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