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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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2
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Shegani A, Kealey S, Luzi F, Basagni F, Machado JDM, Ekici SD, Ferocino A, Gee AD, Bongarzone S. Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds. Chem Rev 2022; 123:105-229. [PMID: 36399832 PMCID: PMC9837829 DOI: 10.1021/acs.chemrev.2c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.
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Affiliation(s)
- Antonio Shegani
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Steven Kealey
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Federico Luzi
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Filippo Basagni
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−University of Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | - Joana do Mar Machado
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Sevban Doğan Ekici
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Alessandra Ferocino
- Institute
of Organic Synthesis and Photoreactivity, Italian National Research Council, via Piero Gobetti 101, 40129 Bologna, Italy
| | - Antony D. Gee
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,A.G.: email,
| | - Salvatore Bongarzone
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,S.B.:
email,
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3
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Synthesis and evaluation of (-)- and (+)-[¹¹C]galanthamine as PET tracers for cerebral acetylcholinesterase imaging. Bioorg Med Chem 2013; 22:285-91. [PMID: 24315193 DOI: 10.1016/j.bmc.2013.11.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/11/2013] [Accepted: 11/13/2013] [Indexed: 11/22/2022]
Abstract
Improved radiopharmaceuticals for imaging cerebral acetylcholinesterase (AChE) are needed for the diagnosis of Alzheimer's disease (AD). Thus, (11)C-labeled (-)-galanthamine and its enantiomers were synthesized as novel agents for imaging the localization and activity of AChE by positron emission tomography (PET). C-11 was incorporated into (-)- and (+)-[(11)C]galanthamine by N-methylation of norgalanthamines with [(11)C]methyl triflate. Simple accumulation of (11)C in the brain was measured in an in vivo biodistribution study using mice, whilst donepezil was used as a blocking agent in analogous in vivo blocking studies. In vitro autoradiography of rat brain tissue was performed to investigate the distribution of (-)-[(11)C]galanthamine, and confirmed the results of PET studies in mice. The radiochemical yields of N-methylation of (-)- and (+)-norgalanthamines were 13.7% and 14.4%, respectively. The highest level of accumulation of (11)C in the brains of mice was observed at 10 min after administration (2.1% ID/g). Intravenous pretreatment with donepezil resulted in a 30% decrease in accumulation of (-)-[(11)C]galanthamine in the striatum; however, levels in the cerebellum were unchanged. In contrast, use of (+)-[(11)C]galanthamine led to accumulation of radioactivity in the striatum equal to that in the cerebellum, and these levels were unaffected by pretreatment with donepezil. In in vitro autoradiography of regional radioactive signals of brain sections showed that pretreatment with either (-)-galanthamine or donepezil blocked the binding of (-)-[(11)C]galanthamine to the striatum, while sagittal PET imaging revealed accumulation of (-)-[(11)C]galanthamine in the brain. These results indicate that (-)-[(11)C]galanthamine showed specific binding to AChE, whereas (+)-[(11)C]-galanthamine accumulated in brain tissue by non-specific binding. Thus, optically pure (-)-[(11)C]galanthamine could be a useful PET tracer for imaging cerebral AChE.
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Kikuchi T, Okamura T, Zhang MR, Irie T. PET probes for imaging brain acetylcholinesterase. J Labelled Comp Radiopharm 2013; 56:172-9. [DOI: 10.1002/jlcr.3002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 11/08/2012] [Accepted: 11/08/2012] [Indexed: 12/31/2022]
Affiliation(s)
- Tatsuya Kikuchi
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Toshimitsu Okamura
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Ming-Rong Zhang
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Toshiaki Irie
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
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5
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XIIth international symposium on radiopharmaceutical chemistry: Abstracts and programme. J Labelled Comp Radiopharm 2010. [DOI: 10.1002/jlcr.2580401001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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6
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Morita M, Sone T, Yamatsugu K, Sohtome Y, Matsunaga S, Kanai M, Watanabe Y, Shibasaki M. A method for the synthesis of an oseltamivir PET tracer. Bioorg Med Chem Lett 2008; 18:600-2. [DOI: 10.1016/j.bmcl.2007.11.079] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 11/19/2007] [Accepted: 11/19/2007] [Indexed: 10/22/2022]
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7
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Roeda D, Kuhnast B, Hammadi A, Dollé F. The Service Hospitalier Frédéric Joliot – contributions to PET chemistry over the years. J Labelled Comp Radiopharm 2007. [DOI: 10.1002/jlcr.1420] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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8
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Funaki Y, Kato M, Iwata R, Sakurai E, Sakurai E, Tashiro M, Ido T, Yanai K. Evaluation of the binding characteristics of [5-(11)C-methoxy]Donepezil in the rat brain for in vivo visualization of acetylcholinesterase. J Pharmacol Sci 2003; 91:105-12. [PMID: 12686754 DOI: 10.1254/jphs.91.105] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Donepezil, an acetylcholinesterase (AChE) inhibitor, has not been evaluated for its binding characteristics using a radioactive tracer, although its inhibitory action on AChE has been studied. The aim of this research is to examine whether AChE can be visualized in vivo and in vitro with [(11)C]donepezil. [5-(11)C-methoxy]Donepezil was synthesized by O-methylation using [(11)C]methyl triflate. The binding of [(11)C]donepezil to brain homogenates was higher in the brain stem and striatum, and it was lowest in the cerebellum. The in vitro autoradiographic study successfully demonstrated the specific binding of [(11)C]donepezil to AChE in the rat brain. The IC(50) value of binding was approximately 10 nM, which is comparable to the reported value for inhibiting enzyme activity (6 nM). Saturation experiments revealed that the B(max) and K(d) of [(11)C]donepezil binding in vitro are 65 fmol/mg tissue and 39.8 nM, respectively. In accordance with the in vitro bindings, the in vivo distribution of [(11)C]donepezil was heterogeneous in the rat brain. In the blocking experiments, the heterogeneous distribution disappeared in the presence of a large amount of unlabeled donepezil. These data suggest that [5-(11)C-methoxy]donepezil can be potentially useful to image AChE non-invasively in the human brain by positron emission tomography.
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Abstract
Over the past 30 years, advances in radiotracer chemistry and positron emission tomography instrumentation have merged to make positron emission tomography a powerful scientific tool in the biomedical sciences. However, despite the increasing reliance of the biomedical sciences on imaging and the new needs for functional information created by the sequencing of the human genome, the development of new radiotracers with the specificity and kinetic characteristics for quantitative analysis in vivo remains a slow process. In this article, we focus on advances in the development of the radiotracers involved in neurotransmission, amino acid transport, protein synthesis, and DNA synthesis. We conclude with a brief section on newer radiotracers that image other molecular targets and conclude with a summary of some of the scientific and infrastructure needs that would expedite the development and introduction of new radiotracers into biomedical research and the practice of medicine.
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Affiliation(s)
- Joanna S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Musachio JL, Flesher JE, Scheffel UA, Rauseo P, Hilton J, Mathews WB, Ravert HT, Dannals RF, Frost JJ. Radiosynthesis and mouse brain distribution studies of [11C] CP-126,998: a PET ligand for in vivo study of acetylcholinesterase. Nucl Med Biol 2002; 29:547-52. [PMID: 12088724 DOI: 10.1016/s0969-8051(02)00299-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The selective, reversible acetylcholinesterase inhibitor 5,7-Dihydro-7-methyl-3- [2-[1-(phenylmethyl]-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol3-6-one (CP-126,998) was labeled with C-11 iodomethane via base-promoted alkylation of the lactam nitrogen. [11C] CP-126,998 was synthesized in good radiochemical yield (13-29% non-decay corrected) and high specific radioactivity (177-418 GBq/micromol). In vivo mouse biodistribution studies reveal [11C] CP-126,998 to localize preferentially in striatal tissue, a region known to be rich in acetylcholinesterase. Competitive blocking studies using a variety of acetylcholinesterase inhibitors (diisopropylfluorophosphate, tacrine, CP-118,954) verified the specificity of the PET radiotracer for brain acetylcholinesterase.
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Affiliation(s)
- John L Musachio
- Johns Hopkins University School of Medicine, Department of Radiology, Division of Nuclear Medicine, Baltimore, MD 21287, USA.
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11
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Zhang MR, Tsuchiyama A, Haradahira T, Furutsuka K, Yoshida Y, Kida T, Noguchi J, Irie T, Suzuki K. Synthesis and preliminary evaluation of [18F]FEtP4A, a promising PET tracer for mapping acetylcholinesterase in vivo. Nucl Med Biol 2002; 29:463-8. [PMID: 12031881 DOI: 10.1016/s0969-8051(01)00315-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-[18F]Fluoroethyl-4-piperidyl acetate ([18F]FEtP4A), an analog of [11C]MP4A for mapping brain acetylcholineseterase (AchE) activity, was prepared by reacting 4-piperidyl acetate (P4A) with [18F]fluoroethyl bromide ([18F]FEtBr) using a newly developed automated system. Preliminary evaluation showed that the initial uptake of [18F]FEtP4A in the mouse brain was > 8% injected dose/g tissue. The distribution pattern of [18F]FEtP4A in the brain was striatum>cerebral cortex>cerebellum within 10-120 min post-injection, which reflected the distribution rank pattern of AchE activity in the brain. Moreover, chemical analysis of in vivo radioactive metabolites in the mouse brain indicated that 83% of [18F]FEtP4A was hydrolyzed to N-[18F]fluoroethyl-4-piperidinol ([18F]FEtP4OH) after 1 min intravenous injection. From these results, [18F]FEtP4A may become a promising PET tracer for mapping the AchE in vivo.
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Affiliation(s)
- Ming-Rong Zhang
- Department of Medical Imaging, National Institute of Radiological Sciences, Chiba, Japan
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Blomqvist G, Tavitian B, Pappata S, Crouzel C, Jobert A, Doignon I, Di Giamberardino L. Quantitative measurement of cerebral acetylcholinesterase using. J Cereb Blood Flow Metab 2001; 21:114-31. [PMID: 11176277 DOI: 10.1097/00004647-200102000-00003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
[11C]physostigmine, an acetylcholinesterase inhibitor, has been shown to be a promising positron emission tomography ligand to quantify the cerebral concentration of the enzyme in animals and humans in vivo. Here, a quantitative and noninvasive method to measure the regional acetylcholinesterase concentration in the brain is presented. The method is based on the observation that the ratio between regions rich in acetylcholinesterase and white matter, a region almost entirely deprived of this enzyme, was found to become approximately constant after 20 to 30 minutes, suggesting that at late time points the uptake mainly contains information about the distribution volume. Taking the white matter as the reference region, a simplified reference tissue model, with effectively one reversible tissue compartment and three parameters, was found to give a good description of the data in baboons. One of these parameters, the ratio between the total distribution volumes in the target and reference regions, showed a satisfactory correlation with the acetylcholinesterase concentration measured postmortem in two baboon brains. Eight healthy male subjects were also analyzed and the regional enzyme concentrations obtained again showed a good correlation with the known acetylcholinesterase concentrations measured in postmortem studies of human brain.
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Affiliation(s)
- G Blomqvist
- INSERM U334, Service Hospitalier Frédéric Joliot, Orsay, France
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Choe YS, Oh S, Shim I, Naruto S, Chi DY, Kim SE, Lee K, Choi Y, Kim B. Syntheses and biological evaluation of (18)F-labeled 3-(1-benzyl-piperidin-4-yl)-1-(1-methyl-1H-indol-3-yl)propan-1-ones for in vivo mapping of acetylcholinesterase. Nucl Med Biol 2000; 27:263-7. [PMID: 10832083 DOI: 10.1016/s0969-8051(00)00086-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We synthesized novel (18)F-labeled acetylcholinesterase (AChE) inhibitors, 3-[1-(3- and 4-[(18)F]fluoromethylbenzyl)piperidin-4-yl]-1-(1-methyl-1H-i ndol-3-yl )propan-1-ones ([(18)F]1 and [(18)F]2) and 3-[1-(4-[(18)F]fluorobenzyl)piperidin-4-yl]-1-(1-methyl-1H-i ndol-3-yl )propan-1-one ([(18)F]3) in high yields (decay-corrected, 25%-40%) and with high effective specific activities (>37 GBq/micromol). Tissue distribution studies of the [(18)F]1 and the [(18)F]3 in mice showed the nonspecific bindings in brain regions, with metabolic defluorination of the [(18)F]1. The result suggests that these radioligands may not be suitable agents for in vivo mapping of AChE, despite their potent in vitro anti-AChE activities.
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Affiliation(s)
- Y S Choe
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
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Naturally Occurring Cyclotryptophans and Cyclotryptamines. ALKALOIDS: CHEMICAL AND BIOLOGICAL PERSPECTIVES 1999. [DOI: 10.1016/s0735-8210(99)80025-9] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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15
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Poullain D, Noël JP. Synthesis of high specific activity [14CO] methyl isocyanate and its use in the preparation of [14CO] eserine, [14CO] carbaryl and [14CO] IPMU. J Labelled Comp Radiopharm 1998. [DOI: 10.1002/(sici)1099-1344(199805)41:5<387::aid-jlcr92>3.0.co;2-s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Bormans G, Sherman P, Snyder SE, Kilbourn MR. Synthesis of carbon-11- and fluorine-18-labeled 1-methyl-4-piperidyl-4'-fluorobenzoate and their biodistribution in mice. Nucl Med Biol 1996; 23:513-7. [PMID: 8832709 DOI: 10.1016/0969-8051(96)00033-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Carbon-11- and fluorine-18-labeled forms of 1-methyl-4-piperidyl-4'-fluorobenzoate were prepared as potential in vivo substrates for brain acetylcholinesterase. The 1-methyl-4-piperidyl-4'-[18F]fluorobenzoate was prepared by aromatic nucleophilic substitution using the nitro precursor and no-carrier added [18F]fluoride ion. The 1-[11C]methyl-4-piperidyl-4'-fluorobenzoate was synthesized by N-[11C]methylation of the appropriate nor-methyl precursor. Biodistribution studies in mice showed high brain uptake of these radiotracers followed by a fast washout with no significant retention of radioactivity in areas of high acetylcholinesterase enzymatic activity. This is contrasted with 1-[11C]methyl-4-piperidylacetate, which is rapidly trapped in brain tissues through hydrolysis by AChE. Further in vivo and in vitro studies demonstrated that 1-methyl-4-piperidyl-4'-fluorobenzoate was not a substrate for AChE, and thus not suitable as an in vivo radiotracer for studying this enzyme in the brain.
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Affiliation(s)
- G Bormans
- Laboratory for Radiopharmaceutical Chemistry, K.U. Leuven, Belgium
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Maziere M. Cholinergic neurotransmission studied in vivo using positron emission tomography or single photon emission computerized tomography. Pharmacol Ther 1995; 66:83-101. [PMID: 7630931 DOI: 10.1016/0163-7258(95)00003-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During the past decade, considerable efforts have been made in the development of radiopharmaceuticals for the in vivo study of the cholinergic neurotransmission using positron emission tomography or single photon emission computerized tomography. The main cholinergic radioligands, labelled with positron- or gamma-photon-emitting radionuclides, are reviewed with respect to use as in vivo markers of either acetylcholinesterase, vesicular acetylcholine transporter, brain and heart muscarinic receptors, or cholinergic nicotinic receptors. The main results obtained in the in vivo study of the physiology, pharmacology or pathology of the different steps of the cholinergic neurotransmission using single photon emission computerized tomography and positron emission tomography are discussed.
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Affiliation(s)
- M Maziere
- CNRS URA 1285, Service Hospitalier Frédéric Joliot, DRIPP, CEA, Orsay, France
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Crouzel C, Hinnen F, Maitre E. Radiosynthesis of methyl and heptyl [11C]Isocyanates from [11C]phosgene, application to the synthesis of carbamates: [11C]physostygmine and [11C]heptylphysostigmine. Appl Radiat Isot 1995. [DOI: 10.1016/0969-8043(94)00126-k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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19
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Irie T, Fukushi K, Akimoto Y, Tamagami H, Nozaki T. Design and evaluation of radioactive acetylcholine analogs for mapping brain acetylcholinesterase (AchE) in vivo. Nucl Med Biol 1994; 21:801-8. [PMID: 9234329 DOI: 10.1016/0969-8051(94)90159-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
For mapping brain acetylcholinesterase (AchE) in vivo, seven radioactive acetylcholine analogs, N-[14C]methylpiperidyl-3- and 4-acetates, propionates, isobutyrates, and 3-butyrate were newly synthesized and evaluated in mice. The esters readily entered the brain and were hydrolyzed into the hydrophilic metabolite, which was trapped. In brain homogenates, the esters showed a wide range of enzymatic reactivity (about 40-fold), and high specificity for AchE (more than 82%) except the butyrate. Intra-brain distribution of the esters reflected a pattern of AchE activity.
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Affiliation(s)
- T Irie
- Division of Clinical Research, National Institute of Radiological Sciences, Chiba, Japan
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