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Ahmed H, Haider A, Ametamey SM. N-Methyl-D-Aspartate (NMDA) receptor modulators: a patent review (2015-present). Expert Opin Ther Pat 2020; 30:743-767. [PMID: 32926646 DOI: 10.1080/13543776.2020.1811234] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION - The NMDA receptor is implicated in various diseases including neurodegenerative, neurodevelopmental and mood disorders. However, only a limited number of clinically approved NMDA receptor modulators are available. Today, apparent NMDA receptor drug development strategies entail 1) exploring the unknown chemical space to identify novel scaffolds; 2) using the clinically available NMDA receptor modulators to expand the therapeutic indication space; 3) and to trace physiological functions of the NMDA receptor. AREAS COVERED - The current review reflects on the functional and pharmacological facets of NMDA receptors and the current clinical status quo of NMDA receptor modulators. Patent literature covering 2015 till April 2020 is discussed with emphasis on new indications. EXPERT OPINION - Supporting evidence shows that subtype-selective NMDA receptor antagonists show an improved safety profile compared to broad-spectrum channel blockers. Although GluN2B-selective antagonists are by far the most extensively investigated subtype-selective modulators, they have shown only modest clinical efficacy so far. To overcome the limitations that have hampered the clinical development of previous subtype-selective NMDA receptor antagonists, future studies with improved animal models that better reflect human NMDA receptor pathophysiology are warranted. The increased availability of subtype-selective probes will allow target engagement studies and proper dose finding in future clinical trials.
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Affiliation(s)
- Hazem Ahmed
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich , Zurich, Switzerland
| | - Ahmed Haider
- Department of Nuclear Medicine, University Hospital Zurich , Zurich, Switzerland.,Center for Molecular Cardiology, University of Zurich , Schlieren, Switzerland
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich , Zurich, Switzerland
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2
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Jakobsson J, Gourni E, Khanapur S, Brito B, Riss PJ. Synthesis and Characterization in Rodent Brain of the Subtype-Selective NR2B NMDA Receptor Ligand [ 11C]Ro04-5595 as a Potential Radiotracer for Positron Emission Tomography. ACS OMEGA 2019; 4:9925-9931. [PMID: 31460083 PMCID: PMC6648642 DOI: 10.1021/acsomega.9b00357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/22/2019] [Indexed: 06/10/2023]
Abstract
The NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor has been implicated in controlling synaptic plasticity, memory, and learning. Herein, we describe an 11C-labeled PET radiotracer based on 1-(4-chlorophenethyl)-6-methoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-ol, Ro04-5595. The radiotracer was evaluated in rats using PET. The PET study showed a good pharmacokinetic profile with rapid uptake and washout over 90 min. Complementary high-resolution autoradiographic images using [3H]Ro04-5595 demonstrated strong binding in NR2B receptor-rich regions and low binding in cerebellum where NR2B concentration is low. We conclude to have developed a selective NR2B receptor radioligand suitable for quantitative and qualitative imaging of a NR2B receptor distribution in vitro and in vivo.
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Affiliation(s)
- Jimmy
E. Jakobsson
- Realomics
SRI, Kjemisk Institutt, Universitetet i
Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Eleni Gourni
- Realomics
SRI, Kjemisk Institutt, Universitetet i
Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Shivashankar Khanapur
- Realomics
SRI, Kjemisk Institutt, Universitetet i
Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Beatriz Brito
- Realomics
SRI, Kjemisk Institutt, Universitetet i
Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Patrick J. Riss
- Realomics
SRI, Kjemisk Institutt, Universitetet i
Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
- Klinik
for Kirurgi og Nevrofag, Oslo Universitets
Sykehus HF-Rikshospitalet, Postboks 4950
Nydalen, 0424 Oslo, Norway
- Norsk
Medisinsk Syklotronsenter AS, Gaustad, Postboks 4950 Nydalen, 0424 Oslo, Norway
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3
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Fu H, Tang W, Chen Z, Belov VV, Zhang G, Shao T, Zhang X, Yu Q, Rong J, Deng X, Han W, Myers SJ, Giffenig P, Wang L, Josephson L, Shao Y, Davenport AT, Daunais JB, Papisov M, Yuan H, Li Z, Traynelis SF, Liang SH. Synthesis and Preliminary Evaluations of a Triazole-Cored Antagonist as a PET Imaging Probe ([ 18F]N2B-0518) for GluN2B Subunit in the Brain. ACS Chem Neurosci 2019; 10:2263-2275. [PMID: 30698943 PMCID: PMC6727982 DOI: 10.1021/acschemneuro.8b00591] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
GluN2B is the most studied subunit of N-methyl-d-aspartate receptors (NMDARs) and implicated in the pathologies of various central nervous system disorders and neurodegenerative diseases. As pan NMDAR antagonists often produce debilitating side effects, new approaches in drug discovery have shifted to subtype-selective NMDAR modulators, especially GluN2B-selective antagonists. While positron emission tomography (PET) studies of GluN2B-selective NMDARs in the living brain would enable target engagement in drug development and improve our understanding in the NMDAR signaling pathways between normal and disease conditions, a suitable PET ligand is yet to be identified. Herein we developed an 18F-labeled potent antagonist, 2-((1-(4-[18F]fluoro-3-methylphenyl)-1 H-1,2,3-triazol-4-yl)methoxy)-5-methoxypyrimidine ([18F]13; also called [18F]N2B-0518) as a PET tracer for imaging the GluN2B subunit. The radiofluorination of [18F]13 was efficiently achieved by our spirocyclic iodonium ylide (SCIDY) method. In in vitro autoradiography studies, [18F]13 displayed highly region-specific binding in brain sections of rat and nonhuman primate, which was in accordance with the expression of GluN2B subunit. Ex vivo biodistribution in mice revealed that [18F]13 could penetrate the blood-brain barrier with moderate brain uptake (3.60% ID/g at 2 min) and rapid washout. Altogether, this work provides a GluN2B-selective PET tracer bearing a new chemical scaffold and shows high specificity to GluN2B subunit in vitro, which may pave the way for the development of a new generation of GluN2B PET ligands.
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Affiliation(s)
- Hualong Fu
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Weiting Tang
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, P. R. China
| | - Zhen Chen
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Vasily V. Belov
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, and the Shriners Burns Hospital, Boston, Massachusetts 02114, United States
| | - Genwei Zhang
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Tuo Shao
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Xiaofei Zhang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Qingzhen Yu
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Jian Rong
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Xiaoyun Deng
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Wei Han
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Department of Neurology, Children’s Hospital of Chongqing Medical University, Chongqing, 400014, P. R. China
| | - Scott J. Myers
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Pilar Giffenig
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, and the Shriners Burns Hospital, Boston, Massachusetts 02114, United States
| | - Lu Wang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
- Department of Nuclear Medicine and PET/CT-MRI Center, the First Affiliated Hospital of Jinan University & Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, P. R. China
| | - Lee Josephson
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
| | - Yihan Shao
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - April T. Davenport
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157, United States
| | - James B. Daunais
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157, United States
| | - Mikhail Papisov
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, and the Shriners Burns Hospital, Boston, Massachusetts 02114, United States
| | - Hongjie Yuan
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Zijing Li
- State Key Laboratory of Molecular Vaccinology, Molecular Diagnosis & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen 361102, P. R. China
| | - Stephen F. Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Steven H. Liang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
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Fu H, Chen Z, Josephson L, Li Z, Liang SH. Positron Emission Tomography (PET) Ligand Development for Ionotropic Glutamate Receptors: Challenges and Opportunities for Radiotracer Targeting N-Methyl-d-aspartate (NMDA), α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA), and Kainate Receptors. J Med Chem 2019; 62:403-419. [PMID: 30110164 PMCID: PMC6393217 DOI: 10.1021/acs.jmedchem.8b00714] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate excitatory neurotransmission within the mammalian central nervous system. iGluRs exist as three main groups: N-methyl-d-aspartate receptors (NMDARs), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), and kainate receptors. The past decades have witnessed a remarkable development of PET tracers targeting different iGluRs including NMDARs and AMPARs, and several of the tracers have advanced to clinical imaging studies. Here, we assess the recent development of iGluR PET probes, focusing on tracer design, brain kinetics, and performance in PET imaging studies. Furthermore, this review will not only present challenges in the tracer development but also provide novel approaches in conjunction with most recent drug discovery efforts on these iGluRs, including subtype-selective NMDAR and transmembrane AMPAR regulatory protein modulators and positive allosteric modulators (PAMs) of AMPARs. These approaches, if successful as PET tracers, may provide fundamental knowledge to understand the roles of iGluR receptors under physiological and pathological conditions.
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Affiliation(s)
- Hualong Fu
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zijing Li
- State Key Laboratory of Molecular Vaccinology, Molecular Diagnosis & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen 361102, P. R. China
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
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5
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Szermerski M, Börgel F, Schepmann D, Haider A, Betzel T, Ametamey SM, Wünsch B. Fluorinated GluN2B Receptor Antagonists with a 3-Benzazepine Scaffold Designed for PET Studies. ChemMedChem 2018. [DOI: 10.1002/cmdc.201700819] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Marina Szermerski
- Institut für Pharmazeutische und Medizinische Chemie der; Universität Münster; Corrensstraße 48 48149 Münster Germany
| | - Frederik Börgel
- Institut für Pharmazeutische und Medizinische Chemie der; Universität Münster; Corrensstraße 48 48149 Münster Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie der; Universität Münster; Corrensstraße 48 48149 Münster Germany
| | - Ahmed Haider
- Department of Chemistry and Applied Biosciences; Institute of Pharmaceutical Sciences; ETH Zurich; Zurich Switzerland
| | - Thomas Betzel
- Department of Chemistry and Applied Biosciences; Institute of Pharmaceutical Sciences; ETH Zurich; Zurich Switzerland
| | - Simon M. Ametamey
- Department of Chemistry and Applied Biosciences; Institute of Pharmaceutical Sciences; ETH Zurich; Zurich Switzerland
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der; Universität Münster; Corrensstraße 48 48149 Münster Germany
- Cells-in-Motion Cluster of Excellence (EXC 1003-CiM); Westfälische Wilhelms-Universität; Münster Germany
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6
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Development of PET and SPECT probes for glutamate receptors. ScientificWorldJournal 2015; 2015:716514. [PMID: 25874256 PMCID: PMC4385697 DOI: 10.1155/2015/716514] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 08/29/2014] [Indexed: 01/16/2023] Open
Abstract
l-Glutamate and its receptors (GluRs) play a key role in excitatory neurotransmission within the mammalian central nervous system (CNS). Impaired regulation of GluRs has also been implicated in various neurological disorders. GluRs are classified into two major groups: ionotropic GluRs (iGluRs), which are ligand-gated ion channels, and metabotropic GluRs (mGluRs), which are coupled to heterotrimeric guanosine nucleotide binding proteins (G-proteins). Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of GluRs could provide a novel view of CNS function and of a range of brain disorders, potentially leading to the development of new drug therapies. Although no satisfactory imaging agents have yet been developed for iGluRs, several PET ligands for mGluRs have been successfully employed in clinical studies. This paper reviews current progress towards the development of PET and SPECT probes for GluRs.
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7
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Majo VJ, Prabhakaran J, Mann JJ, Kumar JSD. PET and SPECT tracers for glutamate receptors. Drug Discov Today 2012; 18:173-84. [PMID: 23092894 DOI: 10.1016/j.drudis.2012.10.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 07/10/2012] [Accepted: 10/15/2012] [Indexed: 12/19/2022]
Abstract
Radioligands for PET imaging of glutamate receptors will have the potential for studying neurological and neuropsychiatric disorders and their diagnosis and therapeutic intervention. Glutamate is the major excitatory neurotransmitter in the brain and is implicated in the pathophysiology of many neurodegenerative and neuropsychiatric disorders. Glutamate and its receptors are potential targets in the treatment of these disorders. Glutamate signaling is mediated through ionotropic and metabotropic receptors. The abundant concentration of these receptors can facilitate their in vivo quantification using positron emission tomography (PET). Glutamate receptors are a potentially important set of targets for monitoring disease progression, for evaluating the effect of therapy and for new treatment development based on the quantification of receptor occupancy. Here, we review the PET and single-photon emission computed tomography (SPECT) radioligands that have been developed for imaging glutamate receptors in living brain.
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Affiliation(s)
- Vattoly J Majo
- Division of Molecular Imaging and Neuropathology, Department of Psychiatry, Columbia University, New York, NY 10032, USA
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8
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Fuchigami T, Yamaguchi H, Ogawa M, Biao L, Nakayama M, Haratake M, Magata Y. Synthesis and biological evaluation of radio-iodinated benzimidazoles as SPECT imaging agents for NR2B subtype of NMDA receptor. Bioorg Med Chem 2010; 18:7497-506. [DOI: 10.1016/j.bmc.2010.08.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/27/2010] [Accepted: 08/28/2010] [Indexed: 10/19/2022]
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9
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Besret L, Dollé F, Hérard AS, Guillermier M, Demphel S, Hinnen F, Coulon C, Ottaviani M, Bottlaender M, Hantraye P, Kassiou M. Dopamine D1 Receptor Imaging in the Rodent and Primate Brain Using the Isoquinoline (+)-[11C]A-69024 and Positron Emission Tomography. J Pharm Sci 2008; 97:2811-9. [PMID: 17786986 DOI: 10.1002/jps.21168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In vivo pharmacokinetic and brain binding characteristics of (+)-[(11)C]A-69024, a high-affinity-D1-selective dopamine receptor antagonist, were assessed with micro-PET and beta-microprobes in the rat and PET in the baboon. The biodistribution of (+)-[(11)C]A-69024 in rats and baboons showed a rapid brain uptake (reaching a maximal value at 5 and 15 min postinjection in rats and baboons, respectively), followed by a slow wash out. The region/cerebellum concentration ratio was characterized by a fourfold higher uptake in striatum and a twofold higher uptake in cortical regions, consistent with in vivo specific binding of the radiotracer in these cerebral regions. Furthermore, this specific (+)-[(11)C]A-69024 binding significantly correlated with the reported in vitro distribution of dopamine D1-receptors. Finally, the specific uptake of the tracer in the striatum and cortical regions was completely prevented by either a pretreatment with large doses of nonradioactive (+/-)A-69024 or of the D1-selective antagonist SCH23390, resulting in a similar uptake in the reference region (cerebellum) and in other brain regions. Thus, (+)-[(11)C]A-69024 appears to be a specific and enantioselective radioligand to visualize and quantify brain dopamine D1 receptors in vivo using positron emission tomography.
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Affiliation(s)
- Laurent Besret
- CNRS, URA 2210, 4 place du Général Leclerc, F-91406 Orsay, France
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10
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Kuhnast B, Valette H, Besret L, Demphel S, Coulon C, Ottaviani M, Guillermier M, Bottlaender M, Dollé F. Synthesis and radiolabeling of N-[4-[4-(2-[11C]methoxyphenyl)piperazin-1-yl]butyl]benzo[b]thiophene-2-carboxamide — a potential radiotracer for D3 receptor imaging with PET. Nucl Med Biol 2006; 33:785-95. [PMID: 16934697 DOI: 10.1016/j.nucmedbio.2006.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 05/24/2006] [Accepted: 05/25/2006] [Indexed: 11/23/2022]
Abstract
FAUC346 (N-[4-[4-(2-methoxyphenyl)piperazin-1-yl]butyl]benzo[b]thiophene-2-carboxamide), an in vitro D(3)-selective ligand, and its normethyl derivative have been synthesized from commercially available 1-(2-substituted-phenyl)piperazines. FAUC346 has been labeled using [(11)C]methyl triflate in acetone containing aqueous NaOH (5 Eq) at -10 degrees C for 1 min, purified on semipreparative reverse-phase high-performance liquid chromatography (HPLC) and formulated as an intravenous injectable solution using a Sep-Pak Plus C(18) device. Up to 5.5 GBq of [(11)C]FAUC346 (N-[4-[4-(2-[methyl-(11)C]methoxyphenyl)piperazin-1-yl]butyl]benzo[b]thiophene-2-carboxamide), with a specific radioactivity of 45-75 GBq/micromol, could be obtained in 30-35 min, including HPLC purification and formulation starting from 44.4 GBq of [(11)C]carbon dioxide. Preliminary pharmacological evaluation of [(11)C]FAUC346 in rat brain clearly demonstrated in vivo selectivity for D(3) receptors and the absence of radiolabeled metabolite within the brain. These encouraging results, however, could not be confirmed in nonhuman primates; therefore, this radioligand does not appear to have the required pharmacological profile for a positron emission tomography probe for imaging D(3) receptors.
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Affiliation(s)
- Bertrand Kuhnast
- Service Hospitalier Frédéric Joliot, SHFJ/CEA/DSV, 4 place du Général Leclerc, 91401 Orsay, France
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11
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Thominiaux C, de Bruin B, Bramoullé Y, Hinnen F, Demphel S, Valette H, Bottlaender M, Besret L, Kassiou M, Dollé F. Radiosynthesis of (E)-N-(2-[11C]methoxybenzyl)-3-phenyl-acrylamidine, a novel subnanomolar NR2B subtype-selective NMDA receptor antagonist. Appl Radiat Isot 2006; 64:348-54. [PMID: 16307887 DOI: 10.1016/j.apradiso.2005.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Accepted: 08/26/2005] [Indexed: 11/18/2022]
Abstract
Recently, a novel series of amidines has been described, exhibiting high NR2B-subtype selective N-methyl-D-aspartate (NMDA) antagonist activity with nanomolar or subnanomolar affinity. Within the styrylamidine subclass, (E)-N-(2-methoxybenzyl)-3-phenyl-acrylamidine (1), displayed the highest affinity (Ki=0.7 nM versus [(3)H]ifenprodil) and was considered an appropriate candidate for isotopic labelling with carbon-11 (T(1/2): 20.38 min) at its methoxy group for imaging of NMDA receptors with PET. Derivative 1 has been labelled from the corresponding nor-analogue using [(11)C]methyl triflate and the following experimental conditions : (1) trapping at -10 degrees C of [(11)C]methyl triflate in 300 microL of acetone containing 0.6-0.8 mg of precursor 5 (2.4-3.2 micromol) and 5 microL of a 3M solution of NaOH in water (about 5 eq.); (2) concentration to dryness of the reaction mixture (at 110 degrees C, using a helium stream for 1-2 min); (3) taking up the residue with 0.5 mL of the HPLC mobile phase and (4) purification using semi-preparative HPLC (SymmetryPrep) C-18, Waters, 300 x 7.8 mm). Typically, starting from a 1.5 Ci (55.5 GBq) [(11)C]CO(2) production batch, 120-240 m Ci (4.44-8.88 GBq) of [(11)C]-1 (20-40% decay-corrected radiochemical yield, n=5) was obtained within a total synthesis time of 25-30 min. Specific radioactivities ranged from 0.8 to 1.2 Ci/micromol (29.6-44.4 GBq/micromol) at the end of radiosynthesis. No attempts were made to further optimise these reactions, as sufficient material was obtained to allow for preliminary pharmacological characterisation.
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Affiliation(s)
- Cyrille Thominiaux
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, CEA/DSV, 4 place du Général Leclerc, F-91401 Orsay, France
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12
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Dollé F, Emond P, Mavel S, Demphel S, Hinnen F, Mincheva Z, Saba W, Valette H, Chalon S, Halldin C, Helfenbein J, Legaillard J, Madelmont JC, Deloye JB, Bottlaender M, Guilloteau D. Synthesis, radiosynthesis and in vivo preliminary evaluation of [11C]LBT-999, a selective radioligand for the visualisation of the dopamine transporter with PET. Bioorg Med Chem 2006; 14:1115-25. [PMID: 16219467 DOI: 10.1016/j.bmc.2005.09.035] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 09/05/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Abstract
LBT-999 (8-((E)-4-fluoro-but-2-enyl)-3beta-p-tolyl-8-aza-bicyclo[3.2.1]octane-2beta-carboxylic acid methyl ester), a cocaine derivative belonging to a new generation of highly selective dopamine transporter (DAT) ligands, and its corresponding carboxylic acid derivative, the latter used as precursor for labelling both with tritium and the positron-emitter carbon-11 (half-life: 20.38 min), were synthesized from (R)-cocaine. [(3)H]LBT-999 (>99% radiochemically pure, specific radioactivity of 3.1 TBq/mmol) was prepared from [(3)H]methyl iodide, allowing its in vitro pharmacological evaluation (K(D): 9 nM for DAT and IC(50) > 1000 nM for SERT and NET). Routine production batches of 4.5-9.0 GBq of iv injectable solutions of [(11)C]LBT-999 (with specific radioactivities ranging from 30 to 45 GBq/mumol) were prepared in 25-30 min (HPLC purification and formulation included) using the efficient methylation reagent [(11)C]methyl triflate. The preliminary in vivo pharmacological evaluation of [(11)C]LBT-999, using both biodistributions in rats and brain imaging in monkeys with positron emission tomography (PET), clearly illustrates that this ligand is an excellent candidate for quantification with PET of DAT in humans.
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Affiliation(s)
- Frédéric Dollé
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, CEA/DSV, Orsay, France.
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13
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Roeda D, Dollé F. [11C]Methanol production by a fast and mild aqueous-phase reduction of [11C]formic acid with samarium diiodide. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.1041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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