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Kamilya C, Gorad SS, Ghorai P. An Organocatalytic Highly Enantioselective Stereospecific Synthesis of 1,1-Disubstituted-1,3-Dihydroisobenzofurans. Chemistry 2024; 30:e202303980. [PMID: 38391113 DOI: 10.1002/chem.202303980] [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: 11/29/2023] [Revised: 02/16/2024] [Accepted: 02/22/2024] [Indexed: 02/24/2024]
Abstract
Herein, we disclosed the asymmetric construction of an oxa-quaternary stereocenter via an intramolecular oxa-Michael (IOM) reaction in β-substituted ortho-hydroxymethyl chalcone by the formation of 1,1-disubstituted-1,3-dihydroisobenzofuran using cinchona alkaloid-based chiral amino-squaramide catalyst. Both the (E- and Z)-β-substituted ortho-hydroxymethyl chalcone provide (S)- and (R)-enantiomers of the 1,1-disubstituted-1,3-dihydroisobenzofuran with excellent stereospecificity. In general, excellent yields (up to 95 %) and enantioselectivity (up to 98 % ee) were obtained. Furthermore, the resulting 1,1-disubstituted isobenzofuran or phthalan was converted to corresponding chiral 3,3-disubstituted phthalides without losing the enantioselectivity. This methodology provides the core moiety of the (S)-citalopram drug.
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Affiliation(s)
- Chandan Kamilya
- Department of Chemistry Indian Institute of Science Education and Research (IISER)Bhopal, Bhopal By-pass Road, Bhauri
| | - Sachin S Gorad
- Department of Chemistry Indian Institute of Science Education and Research (IISER)Bhopal, Bhopal By-pass Road, Bhauri
| | - Prasanta Ghorai
- Department of Chemistry Indian Institute of Science Education and Research (IISER)Bhopal, Bhopal By-pass Road, Bhauri
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Ludwig FA, Laurini E, Schmidt J, Pricl S, Deuther-Conrad W, Wünsch B. [ 18F]Fluspidine-A PET Tracer for Imaging of σ 1 Receptors in the Central Nervous System. Pharmaceuticals (Basel) 2024; 17:166. [PMID: 38399380 PMCID: PMC10892410 DOI: 10.3390/ph17020166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/18/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
σ1 receptors play a crucial role in various neurological and neurodegenerative diseases including pain, psychosis, Alzheimer's disease, and depression. Spirocyclic piperidines represent a promising class of potent σ1 receptor ligands. The relationship between structural modifications and σ1 receptor affinity and selectivity over σ2 receptors led to the 2-fluoroethyl derivative fluspidine (2, Ki = 0.59 nM). Enantiomerically pure (S)-configured fluspidine ((S)-2) was prepared by the enantioselective reduction of the α,β-unsaturated ester 23 with NaBH4 and the enantiomerically pure co-catalyst (S,S)-24. The pharmacokinetic properties of both fluspidine enantiomers (R)-2 and (S)-2 were analyzed in vitro. Molecular dynamics simulations revealed very similar interactions of both fluspidine enantiomers with the σ1 receptor protein, with a strong ionic interaction between the protonated amino moiety of the piperidine ring and the COO- moiety of glutamate 172. The 18F-labeled radiotracers (S)-[18F]2 and (R)-[18F]2 were synthesized in automated syntheses using a TRACERlab FX FN synthesis module. High radiochemical yields and radiochemical purity were achieved. Radiometabolites were not found in the brains of mice, piglets, and rhesus monkeys. While both enantiomers revealed similar initial brain uptake, the slow washout of (R)-[18F]2 indicated a kind of irreversible binding. In the first clinical trial, (S)-[18F]2 was used to visualize σ1 receptors in the brains of patients with major depressive disorder (MDD). This study revealed an increased density of σ1 receptors in cortico-striato-(para)limbic brain regions of MDD patients. The increased density of σ1 receptors correlated with the severity of the depressive symptoms. In an occupancy study with the PET tracer (S)-[18F]2, the selective binding of pridopidine at σ1 receptors in the brain of healthy volunteers and HD patients was shown.
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Affiliation(s)
- Friedrich-Alexander Ludwig
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, D-04318 Leipzig, Germany; (F.-A.L.); (W.D.-C.)
| | - Erik Laurini
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTS), DEA, University of Trieste, 34127 Trieste, Italy; (E.L.); (S.P.)
| | - Judith Schmidt
- Institut für Pharmazeutische und Medizinische Chemie, Universität Münster, Corrensstraße 48, D-48149 Münster, Germany;
| | - Sabrina Pricl
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTS), DEA, University of Trieste, 34127 Trieste, Italy; (E.L.); (S.P.)
- Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 90-136 Lodz, Poland
| | - Winnie Deuther-Conrad
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, D-04318 Leipzig, Germany; (F.-A.L.); (W.D.-C.)
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie, Universität Münster, Corrensstraße 48, D-48149 Münster, Germany;
- GRK 2515, Chemical Biology of Ion Channels (Chembion), Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
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3
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Shigeno T, Kozaka T, Kitamura Y, Ogawa K, Taki J, Kinuya S, Shiba K. In vitro and in vivo evaluation of [ 125/123I]-2-[4-(2-iodophenyl)piperidino]cyclopentanol([ 125/123I]-OI5V) as a potential sigma-1 receptor ligand for SPECT. Ann Nucl Med 2021; 35:167-175. [PMID: 33417152 DOI: 10.1007/s12149-020-01552-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/28/2020] [Indexed: 11/26/2022]
Abstract
INTRODUCTION We investigated the characteristics of radio-iodinated 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) as a single photon emission computed tomography (SPECT) ligand for mapping sigma-1 receptor (σ-1R), which plays an important role in stress remission in many organs. METHODS OI5V was synthesized from o-bromobenzaldehyde in three steps. OI5V was evaluated for its affinity to VAChT, σ-1 and σ-2 receptor by in vitro competitive binding assays using rat tissues and radioligands, [3H]vesamicol, ( +)-[3H]pentazocine and [3H]DTG, respectively. [125/123I]OI5V was prepared from o-trimethylstannyl-cyclopentanevesamicol (OT5V) by the iododestannylation reaction under no-carrier-added conditions. In vivo biodistribution study of [125I]OI5V in blood, brain regions and major organs of rats was performed at 2, 10, 30 and 60 min post-injection. In vivo blocking study and ex vivo autoradiography were performed to assess the binding selectivity of [125I]OI5V for σ-1 receptor. SPECT-CT imaging study was performed using [123I]OI5V. RESULTS OI5V demonstrated high selective binding affinity for σ-1R in vitro. In the biodistribution study, the blood-brain barrier (BBB) permeability of [125I]OI5V was high and the accumulation of [125I]OI5V in the rat cortex at 2 min post-injection exceeded 2.00%ID/g. In the in vivo blocking study, the accumulation of [125I]OI5V in the brain was significantly blocked by co-administration of 0.5 μmol of SA4503 and 1.0 μmol of pentazocine. Ex vivo autoradiography revealed that the regional brain accumulation of [125I]OI5V was similar to σ-1R-rich regions of the rat brain. SPECT images of [123I]OI5V in the rat brain reflected the distribution of sigma receptors in the brain. CONCLUSIONS This study confirmed that [125/123I]OI5V selectively binds σ-1R in the rat brain in vivo. [123I]OI5V was suggested to be useful as a σ-1R ligand for SPECT.
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Affiliation(s)
- Taiki Shigeno
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa, Ishikawa, Japan
| | - Takashi Kozaka
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa, Ishikawa, Japan
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa , Ishikawa, Japan
| | - Yoji Kitamura
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa, Ishikawa, Japan
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa , Ishikawa, Japan
| | - Kazuma Ogawa
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa , Ishikawa, Japan
| | - Junichi Taki
- Department of Nuclear Medicine, Kanazawa University Hospital, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Seigo Kinuya
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa, Ishikawa, Japan
- Department of Nuclear Medicine, Kanazawa University Hospital, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Kazuhiro Shiba
- Division of Tracer Kinetics, Advanced Science Research Center, Kanazawa, Ishikawa, Japan.
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa , Ishikawa, Japan.
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Ludwig FA, Fischer S, Houska R, Hoepping A, Deuther-Conrad W, Schepmann D, Patt M, Meyer PM, Hesse S, Becker GA, Zientek FR, Steinbach J, Wünsch B, Sabri O, Brust P. In vitro and in vivo Human Metabolism of ( S)-[ 18F]Fluspidine - A Radioligand for Imaging σ 1 Receptors With Positron Emission Tomography (PET). Front Pharmacol 2019; 10:534. [PMID: 31263411 PMCID: PMC6585474 DOI: 10.3389/fphar.2019.00534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/29/2019] [Indexed: 12/26/2022] Open
Abstract
(S)-[18F]fluspidine ((S)-[18F]1) has recently been explored for positron emission tomography (PET) imaging of sigma-1 receptors in humans. In the current report, we have used plasma samples of healthy volunteers to investigate the radiometabolites of (S)-[18F]1 and elucidate their structures with LC-MS/MS. For the latter purpose additional in vitro studies were conducted by incubation of (S)-[18F]1 and (S)-1 with human liver microsomes (HLM). In vitro metabolites were characterized by interpretation of MS/MS fragmentation patterns from collision-induced dissociation or by use of reference compounds. Thereby, structures of corresponding radio-HPLC-detected radiometabolites, both in vitro and in vivo (human), could be identified. By incubation with HLM, mainly debenzylation and hydroxylation occurred, beside further mono- and di-oxygenations. The product hydroxylated at the fluoroethyl side chain was glucuronidated. Plasma samples (10, 20, 30 min p.i., n = 5-6), obtained from human subjects receiving 250–300 MBq (S)-[18F]1 showed 97.2, 95.4, and 91.0% of unchanged radioligand, respectively. In urine samples (90 min p.i.) the fraction of unchanged radioligand was only 2.6% and three major radiometabolites were detected. The one with the highest percentage, also found in plasma, matched the glucuronide formed in vitro. Only a small amount of debenzylated metabolite was detected. In conclusion, our metabolic study, in particular the high fractions of unchanged radioligand in plasma, confirms the suitability of (S)-[18F]1 as PET radioligand for sigma-1 receptor imaging.
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Affiliation(s)
- Friedrich-Alexander Ludwig
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Steffen Fischer
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Richard Houska
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | | | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Dirk Schepmann
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Marianne Patt
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Philipp M Meyer
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany.,Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University, Leipzig, Germany
| | | | - Franziska Ruth Zientek
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany.,Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University, Leipzig, Germany
| | - Jörg Steinbach
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Bernhard Wünsch
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
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Galster M, Löppenberg M, Galla F, Börgel F, Agoglitta O, Kirchmair J, Holl R. Phenylethylene glycol-derived LpxC inhibitors with diverse Zn2+-binding groups. Tetrahedron 2019. [DOI: 10.1016/j.tet.2018.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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6
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Yang X, Pang S, Cheng F, Zhang Y, Lin YW, Yuan Q, Zhang FL, Huang YY. Enantioselective Synthesis of 1,3-Disubstituted 1,3-Dihydroisobenzofurans via a Cascade Allylboration/Oxo-Michael Reaction of o-Formyl Chalcones Catalyzed by a Chiral Phosphoric Acid. J Org Chem 2017; 82:10388-10397. [DOI: 10.1021/acs.joc.7b01856] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Xing Yang
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Shuai Pang
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Feng Cheng
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Yue Zhang
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Ya-Wei Lin
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Quan Yuan
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Fang-Lin Zhang
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
| | - Yi-Yong Huang
- Department of Chemistry,
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, P.R. China
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Shishkina IN, Sokolovskaya EY, Demyanovich VM. Stereoselective synthesis of 1,3-disubstituted phthalans by cyclization of (1S)-1-{2-[hydroxy(diaryl)methyl]phenyl}ethanols. Russ Chem Bull 2017. [DOI: 10.1007/s11172-016-1573-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Weber F, Brust P, Laurini E, Pricl S, Wünsch B. Fluorinated PET Tracers for Molecular Imaging of σ 1 Receptors in the Central Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:31-48. [PMID: 28315263 DOI: 10.1007/978-3-319-50174-1_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
At first the role of σ1 receptors in various neurological, psychiatric and neurodegenerative disorders is discussed. In the second part, the principle of positron emission tomography (PET ) is described and the known fluorinated PET tracers for labeling of σ1 receptors are presented. The third part focuses on fluoroalkyl substituted spirocyclic PET tracers, which represent the most promising class of fluorinated PET tracers reported so far. The homologous fluoroalkyl derivatives 12-15 show high σ1 affinity (K i = 0.59-1.4 nM) and high selectivity over the σ2 subtype (408-1331-fold). The enantiomers of the fluoroethyl derivative fluspidine 13 were prepared and pharmacologically characterized. Whereas the (S)-configured enantiomer (S)-13 (K i = 2.3 nM) is 4-fold less active than the (R)-enantiomer (R)-13 (K i = 0.57 nM), (S)-13 is metabolically more stable. The interactions of (S)-13 and (R)-13 with the σ1 receptor were analyzed at the molecular level using the 3D homology model. In an automated radiosynthesis [18F](S)-13 and [18F](R)-13 were prepared by nucleophilic substitution of the tosylates (S)-17 and (R)-17 with K[18F]F in high radiochemical yield, high radiochemical purity and short reaction time. Application of both enantiomers [18F](S)-13 and [18F](R)-13 to mice and piglets led to fast uptake into the brain, but [18F](R)-13 did not show washout from the brain indicating a quasi-irreversible binding. Both radiotracers [18F](S)-13 and [18F](R)-13 were able to label regions in the mouse and piglet brain with high σ1 receptor density. The specific binding of the enantiomeric tracers [18F](S)-13 and [18F](R)-13 could be replaced by the selective σ1 ligand SA4503.
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Affiliation(s)
- Frauke Weber
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, D-04318, Leipzig, Germany
| | - Erik Laurini
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste, Via Valerio 6, 34127, Trieste, Italy
| | - Sabrina Pricl
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste, Via Valerio 6, 34127, Trieste, Italy
- National Interuniversity Consortium for Material Science and Technology (INSTM), Research Unit MOSE-DEA, University of Trieste, Via Valerio 6, 32127, Trieste, Italy
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany.
- Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University Münster, Münster, Germany.
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Weber F, Wünsch B. Medicinal Chemistry of σ 1 Receptor Ligands: Pharmacophore Models, Synthesis, Structure Affinity Relationships, and Pharmacological Applications. Handb Exp Pharmacol 2017; 244:51-79. [PMID: 28620761 DOI: 10.1007/164_2017_33] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
In the first part of this chapter, we summarize the various pharmacophore models for σ1 receptor ligands. Common to all of them is a basic amine flanked by two hydrophobic regions, representing the pharmacophoric elements. The development of computer-based models like the 3D homology model is described as well as the first crystal structure of the σ1 receptor. The second part focuses on the synthesis and biological properties of different σ1 receptor ligands, identified as 1-9. Monocyclic piperazines 1 and bicyclic piperazines 2 and 3 were developed as cytotoxic compounds, thus the IC50 values of cell growth and survival inhibition studies are given for all derivatives. The mechanism of cell survival inhibition, induction of time-dependent apoptosis, of compound ent-2a is discussed. Experimentally determined σ1 affinity shows good correlation with the results from molecular dynamics simulations based on a 3D homology model. Spirocyclic compounds 4 and 5 represent well-established σ1 receptor ligands. The homologous fluoroalkyl derivatives 4 have favorable pharmacological properties for use as fluorinated PET tracers. The (S)-configured fluoroethyl substituted compound (S)-4b is under investigation as PET tracer for imaging of σ1 receptors in the brain of patients affected by major depression. 1,3-Dioxanes 6c and 6d display a very potent σ1 antagonist profile and the racemic 1,3-dioxane 6c has high anti-allodynic activity at low doses. The arylpropenylamines 7 are very potent σ1 receptor ligands with high σ1/σ2 selectivity. The top compound 7g acts as an agonist as defined by its ability to potentiate neurite outgrowth at low concentrations. Among the morpholinoethoxypyrazoles 8, 8c (known as S1RA) reveals the most promising pharmacokinetic and physicochemical properties. Due to its good safety profile, 8c is currently being investigated in a phase II clinical trial for the treatment of neuropathic pain. The most potent ligand 9e of 3,4-dihydro-2(1H)-quinolones 9 shows promising anti-nociceptive activity in the formalin test.
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Affiliation(s)
- Frauke Weber
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, Münster, 48149, Germany.
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 48, Münster, 48149, Germany
- Cells-in-Motion Cluster of Excellence (EXC 1003 - CIM), University Münster, Münster, Germany
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10
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Wiese C, Große Maestrup E, Galla F, Schepmann D, Hiller A, Fischer S, Ludwig FA, Deuther-Conrad W, Donat CK, Brust P, Büter L, Karst U, Wünsch B. Comparison of in Silico, Electrochemical, in Vitro and in Vivo Metabolism of a Homologous Series of (Radio)fluorinated σ 1 Receptor Ligands Designed for Positron Emission Tomography. ChemMedChem 2016; 11:2445-2458. [PMID: 27677767 DOI: 10.1002/cmdc.201600366] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/29/2016] [Indexed: 11/05/2022]
Abstract
The imaging of σ1 receptors in the brain by fluorinated radiotracers will be used for the validation of σ1 receptors as drug targets as well as for differential diagnosis of diseases in the central nervous system. The biotransformation of four homologous fluorinated PET tracers 1'-benzyl-3-(ω-fluoromethyl to ω-fluorobutyl)-3H-spiro[2]benzofuran-1,4'-piperidine] ([18 F]1-4) was investigated. In silico studies using fast metabolizer (FAME) software, electrochemical oxidations, in vitro studies with rat liver microsomes, and in vivo metabolism studies after application of the PET tracers [18 F]1-4 to mice were performed. Combined liquid chromatography and mass spectrometry (HPLC-MS) analysis allowed structural identification of non-radioactive metabolites. Radio-HPLC and radio-TLC provided information about the presence of unchanged parent radiotracers and their radiometabolites. Radiometabolites were not found in the brain after application of [18 F]2-4, but liver, plasma, and urine samples contained several radiometabolites. Less than 2 % of the injected dose of [18 F]4 reached the brain, rendering [18 F]4 less appropriate as a PET tracer than [18 F]2 and [18 F]3. Compounds [18 F]2 and [18 F]3 possess the most promising properties for imaging of σ1 receptors in the brain. High σ1 affinity (Ki =0.59 nm), low lipophilicity (logD7.4 =2.57), high brain penetration (4.6 % of injected dose after 30 min), and the absence of radiometabolites in the brain favor the fluoroethyl derivative [18 F]2 slightly over the fluoropropyl derivative [18 F]3 for human use.
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Affiliation(s)
- Christian Wiese
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, 48149, Münster, Germany
| | - Eva Große Maestrup
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, 48149, Münster, Germany
| | - Fabian Galla
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, 48149, Münster, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, 48149, Münster, Germany
| | - Achim Hiller
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Permoserstraße 15, 04318, Leipzig, Germany
| | - Lars Büter
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC 100-CiM), Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
| | - Uwe Karst
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, 48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC 100-CiM), Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, 48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC 100-CiM), Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
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Kranz M, Sattler B, Wüst N, Deuther-Conrad W, Patt M, Meyer PM, Fischer S, Donat CK, Wünsch B, Hesse S, Steinbach J, Brust P, Sabri O. Evaluation of the Enantiomer Specific Biokinetics and Radiation Doses of [(18)F]Fluspidine-A New Tracer in Clinical Translation for Imaging of σ₁ Receptors. Molecules 2016; 21:E1164. [PMID: 27598110 PMCID: PMC6273209 DOI: 10.3390/molecules21091164] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/22/2016] [Accepted: 08/26/2016] [Indexed: 11/17/2022] Open
Abstract
The enantiomers of [(18)F]fluspidine, recently developed for imaging of σ₁ receptors, possess distinct pharmacokinetics facilitating their use in different clinical settings. To support their translational potential, we estimated the human radiation dose of (S)-(-)-[(18)F]fluspidine and (R)-(+)-[(18)F]fluspidine from ex vivo biodistribution and PET/MRI data in mice after extrapolation to the human scale. In addition, we validated the preclinical results by performing a first-in-human PET/CT study using (S)-(-)-[(18)F]fluspidine. Based on the respective time-activity curves, we calculated using OLINDA the particular organ doses (ODs) and effective doses (EDs). The ED values of (S)-(-)-[(18)F]fluspidine and (R)-(+)-[(18)F]fluspidine differed significantly with image-derived values obtained in mice with 12.9 μSv/MBq and 14.0 μSv/MBq (p < 0.025), respectively. A comparable ratio was estimated from the biodistribution data. In the human study, the ED of (S)-(-)-[(18)F]fluspidine was calculated as 21.0 μSv/MBq. Altogether, the ED values for both [(18)F]fluspidine enantiomers determined from the preclinical studies are comparable with other (18)F-labeled PET imaging agents. In addition, the first-in-human study confirmed that the radiation risk of (S)-(-)-[(18)F]fluspidine imaging is within acceptable limits. However, as already shown for other PET tracers, the actual ED of (S)-(-)-[(18)F]fluspidine in humans was underestimated by preclinical imaging which needs to be considered in other first-in-human studies.
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Affiliation(s)
- Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
| | - Bernhard Sattler
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
| | - Nathanael Wüst
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
| | - Marianne Patt
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
| | - Philipp M Meyer
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
- Division of Brain Sciences, Department of Medicine, Hammersmith Hospital Campus, Imperial College London, London SW7 2AZ, UK.
| | - Bernhard Wünsch
- Pharmaceutical and Medicinal Chemistry, University Münster, Münster 48149, Germany.
| | - Swen Hesse
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
- Integrated Research and Treatment Center (IFB) Adiposity Diseases, University Hospital Leipzig, Leipzig 04103, Germany.
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig 04318, Germany.
| | - Osama Sabri
- Department of Nuclear Medicine, University Hospital Leipzig, Leipzig 04103, Germany.
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Oxa-Pictet–Spengler reaction as key step in the synthesis of novel σ receptor ligands with 2-benzopyran structure. Bioorg Med Chem 2016; 24:4045-4055. [DOI: 10.1016/j.bmc.2016.06.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/17/2016] [Accepted: 06/23/2016] [Indexed: 01/09/2023]
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Perrin DM. [(18)F]-Organotrifluoroborates as Radioprosthetic Groups for PET Imaging: From Design Principles to Preclinical Applications. Acc Chem Res 2016; 49:1333-43. [PMID: 27054808 DOI: 10.1021/acs.accounts.5b00398] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Positron emission tomography (PET) is revolutionizing our ability to visualize in vivo targets for target validation and personalized medicine. Of several classes of imaging agents, peptides afford high affinity and high specificity to distinguish pathologically distinct cell types by the presence of specific molecular targets. Of various available PET isotopes, [(18)F]-fluoride ion is preferred because of its excellent nuclear properties and on-demand production in hospitals at Curie levels. However, the short half-life of (18)F and its lack of reactivity in water continue to challenge peptide labeling. Hence, peptides are often conjugated to a metal chelator for late-stage, one-step labeling. Yet radiometals, while effective, are neither as desirable nor as available as [(18)F]-fluoride ion. Despite considerable past success in identifying semifeasible radiosyntheses, significant challenges continue to confound tracer development. These interrelated challenges relate to (1) isotope/prosthetic choice; (2) bioconjugation for high affinity; (3) high radiochemical yields, (4) specific activities of >1 Ci/μmol to meet FDA microdose requirements; and (5) rapid clearance and in vivo stability. These enduring challenges have been extensively highlighted, while a single-step, operationally simple, and generally applicable means of labeling a peptide with [(18)F]-fluoride ion in good yield and high specific activity has eluded radiochemists and nuclear medicine practitioners for decades. Radiosynthetic ease is of primordial importance since multistep labeling reactions challenge clinical tracer production. In the past decade, as we sought to meet this challenge, appreciation of reactions with aqueous fluoride led us to consider organotrifluoroborate (RBF3(-)) synthesis as a means of rapid aqueous peptide labeling. We have applied principles of mechanistic chemistry, knowledge of chemical reactivity, and synthetic chemistry to design stable RBF3(-)s. Over the past 10 years, we have developed several new [(18)F]-RBF3(-) radioprosthetic groups, all of which guarantee radiosynthetic ease while in most cases providing high tumor:nontumor (T:NT) ratios and moderate-to-high tumor uptake. Although others have developed methods for labeling of peptides with [(18)F]-silylfluorides or [(18)F]-Al-NOTA chelates, this Account focuses on the synthesis of [(18)F]-organotrifluoroborates. In this Account, I detail mechanistic, kinetic, thermodynamic, synthetic, and radiosynthetic approaches that enabled the translation of fundamental principles regarding the chemistry of RBF3(-)s into a tantalizingly close realization of a clinical application of an [(18)F]-organotrifluoroborate-peptide conjugate for imaging of neuroendocrine tumors and the generalization of this method for labeling of several other peptides.
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Affiliation(s)
- David M. Perrin
- Chemistry Department, 2036 Main Mall, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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14
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Shang XS, Li NT, Li DY, Liu PN. Palladium-Catalyzed Tandem Reaction of Alkyne-Based Aryl Iodides and SalicylN-Tosylhydrazones to Construct the Spiro[benzofuran-3,2′-chromene] Skeleton. Adv Synth Catal 2016. [DOI: 10.1002/adsc.201501150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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15
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Bioactive benzofuran derivatives: An insight on lead developments, radioligands and advances of the last decade. Eur J Med Chem 2015; 97:356-76. [PMID: 25703339 DOI: 10.1016/j.ejmech.2015.01.021] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 12/19/2014] [Accepted: 01/10/2015] [Indexed: 02/08/2023]
Abstract
Benzofuran core is a highly versatile, presents in many important natural products and natural drugs. Many benzofuran containing synthetic drugs and clinical candidates have been derived from natural products. The present review will provide an insight on lead design-developments of the decade, clinical candidates and PET tracer radio-ligands containing benzofuran core along with brief target biology. Brief of the all approved drugs containing benzofuran core also have been enclosed. Main therapeutic areas covered are Cancer, Neurological disorders including anti-psychotic agent and diabetes.
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Chen YY, Wang X, Zhang JM, Deuther-Conrad W, Zhang XJ, Huang Y, Li Y, Ye JJ, Cui MC, Steinbach J, Brust P, Liu BL, Jia HM. Synthesis and evaluation of a 18F-labeled spirocyclic piperidine derivative as promising σ1 receptor imaging agent. Bioorg Med Chem 2014; 22:5270-8. [DOI: 10.1016/j.bmc.2014.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/18/2014] [Accepted: 08/05/2014] [Indexed: 12/16/2022]
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Development of (18)F-labeled radiotracers for neuroreceptor imaging with positron emission tomography. Neurosci Bull 2014; 30:777-811. [PMID: 25172118 DOI: 10.1007/s12264-014-1460-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/02/2014] [Indexed: 12/14/2022] Open
Abstract
Positron emission tomography (PET) is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide routinely used in the radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109.8 min. The delivery of such radiotracers into the brain provides images of transport, metabolic, and neurotransmission processes on the molecular level. After a short introduction into the principles of PET, this review mainly focuses on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as described here provides molecular probes which not only are useful for imaging of human brain diseases, but also allow molecular neuroreceptor imaging studies in various small-animal models of disease, including genetically-engineered animals. Furthermore, they provide a powerful tool for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo.
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18
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Brust P, Deuther-Conrad W, Becker G, Patt M, Donat CK, Stittsworth S, Fischer S, Hiller A, Wenzel B, Dukic-Stefanovic S, Hesse S, Steinbach J, Wünsch B, Lever SZ, Sabri O. Distinctive in vivo kinetics of the new σ1 receptor ligands (R)-(+)- and (S)-(-)-18F-fluspidine in porcine brain. J Nucl Med 2014; 55:1730-6. [PMID: 25071097 DOI: 10.2967/jnumed.114.137562] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Because of their involvement in growth and survival signaling cascades, the σ(1) receptors (σ(1)Rs) represent a novel target for the treatment of cancer and several brain diseases such as depression and neurodegeneration. From a series of σ1R-specific (18)F-fluoroalkylated spirocyclic piperidines, we have chosen (18)F-fluspidine for detailed investigation of the in vivo kinetics of the (R)-(+)- and (S)-(-)-enantiomers to identify their potential for imaging in humans. METHODS Enantiopure tosylate precursors for radiolabeling were obtained using chiral preparative high-performance liquid chromatography and used for radiosynthesis of both (18)F-fluspidine enantiomers by nucleophilic substitution with K-(18)F-F-Kryptofix 222-carbonate complex in a synthesis module. Brain pharmacokinetics were investigated by dynamic PET studies in piglets under baseline and blocking conditions using the highly selective σ1R agonist SA4503. Standardized uptake values (SUVs) were calculated for 24 MR-defined brain regions. Total distribution volume (V(T)) and binding potentials (k3'/k4) of (S)-(-)- and (R)-(+)-(18)F-fluspidine were estimated. Furthermore, V(T) values were estimated by graphical analysis using Logan plots. RESULTS The (S)- and (R)-tosylates were obtained in excellent enantiomeric purities (>98% and >96% enantiomeric excess, respectively). (S)-(-)- and (R)-(+)-(18)F-fluspidine were synthesized within approximately 70 min (radiochemical yield, 35%-45%; specific activity, 650-870 GBq/μmol; radiochemical purity, >99%). Both radiotracers displayed different brain uptake kinetics. Although the initial brain uptake was similar, the SUV at the end of the study differed significantly (P < 0.05), with (R)-(+)-(18)F-fluspidine showing about 60%-150% higher values. Administration of SA4503 reduced SUV almost equally for both radiotracers by approximately 65%. Furthermore, k(3)' was significantly decreased under blocking conditions in almost all regions ((S)-(-)-(18)F-fluspidine, -90%-95%; (R)-(+)-(18)F-fluspidine, -70%-90%) whereas effects on k(4) differed according to the particular brain region. V(T) estimated by both graphical analysis using Logan plots and full nonlinear kinetic analysis revealed significant inhibition for both radiotracers under blocking conditions. CONCLUSION Both (S)-(-)- and (R)-(+)-(18)F-fluspidine appear to be suitable for σ1R imaging in humans. The different pharmacokinetics of (S)-(-)-(18)F-fluspidine and (R)-(+)-(18)F-fluspidine may have the potential for application in the diagnostics of different pathologic conditions.
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Affiliation(s)
- Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Georg Becker
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Marianne Patt
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | | | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Achim Hiller
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Bernhard Wünsch
- Department of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany; and
| | - Susan Z Lever
- Department of Chemistry, University of Missouri, Columbia, Missouri MU Research Reactor, University of Missouri, Columbia, Missouri
| | - Osama Sabri
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
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19
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Banister SD, Manoli M, Kassiou M. The development of radiotracers for imaging sigma (σ) receptors in the central nervous system (CNS) using positron emission tomography (PET). J Labelled Comp Radiopharm 2014; 56:215-24. [PMID: 24285328 DOI: 10.1002/jlcr.3010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 11/10/2022]
Abstract
Sigma (σ) receptors are unique mammalian proteins, distributed in the central nervous system and elsewhere, which are increasingly implicated in the pathophysiology of virtually all major central nervous system disorders. The heterogeneous but wide distribution of σ1 in the brain has prompted the development of selective radiotracers for imaging these sites using positron emission tomography (PET). To date, some 50 carbon-11-labelled and fluorine-18-labelled candidate PET radioligands targeting σ receptors have been reported. The historical development of selective σ1 receptor ligands as potential PET imaging agents, as well as the radiochemistry and application of the most recently developed examples, is described herein.
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Affiliation(s)
- Samuel D Banister
- Brain and Mind Research Institute, The University of Sydney, NSW, 2050, Australia; School of Chemistry, The University of Sydney, NSW, 2006, Australia
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20
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Hasebein P, Frehland B, Schepmann D, Wünsch B. Synthesis, σ Receptor Affinity, and Pharmacological Evaluation of 5-Phenylsulfanyl- and 5-Benzyl-Substituted Tetrahydro-2-benzazepines. ChemMedChem 2014; 9:1697-703. [DOI: 10.1002/cmdc.201402110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Indexed: 11/06/2022]
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21
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Holl K, Schepmann D, Daniliuc CG, Wünsch B. Sharpless asymmetric dihydroxylation as the key step in the enantioselective synthesis of spirocyclic σ1 receptor ligands. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.tetasy.2013.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Maisonial-Besset A, Funke U, Wenzel B, Fischer S, Holl K, Wünsch B, Steinbach J, Brust P. Automation of the radiosynthesis and purification procedures for [18F]Fluspidine preparation, a new radiotracer for clinical investigations in PET imaging of σ1 receptors in brain. Appl Radiat Isot 2014; 84:1-7. [DOI: 10.1016/j.apradiso.2013.10.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/05/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
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23
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Holl K, Schepmann D, Fischer S, Ludwig FA, Hiller A, Donat CK, Deuther-Conrad W, Brust P, Wünsch B. Asymmetric Synthesis of Spirocyclic 2-Benzopyrans for Positron Emission Tomography of σ1 Receptors in the Brain. Pharmaceuticals (Basel) 2014; 7:78-112. [PMID: 24451404 PMCID: PMC3915196 DOI: 10.3390/ph7010078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/15/2014] [Accepted: 01/16/2014] [Indexed: 11/16/2022] Open
Abstract
Sharpless asymmetric dihydroxylation of styrene derivative 6 afforded chiral triols (R)-7 and (S)-7, which were cyclized with tosyl chloride in the presence of Bu2SnO to provide 2-benzopyrans (R)-4 and (S)-4 with high regioselectivity. The additional hydroxy moiety in the 4-position was exploited for the introduction of various substituents. Williamson ether synthesis and replacement of the Boc protective group with a benzyl moiety led to potent σ1 ligands with high σ1/σ2-selectivity. With exception of the ethoxy derivative 16, the (R)-configured enantiomers represent eutomers with eudismic ratios of up to 29 for the ester (R)-18. The methyl ether (R)-15 represents the most potent σ1 ligand of this series of compounds, with a Ki value of 1.2 nM and an eudismic ratio of 7. Tosylate (R)-21 was used as precursor for the radiosynthesis of [18F]-(R)-20, which was available by nucleophilic substitution with K[18F]F K222 carbonate complex. The radiochemical yield of [18F]-(R)-20 was 18%–20%, the radiochemical purity greater than 97% and the specific radioactivity 175–300 GBq/µmol. Although radiometabolites were detected in plasma, urine and liver samples, radiometabolites were not found in brain samples. After 30 min, the uptake of the radiotracer in the brain was 3.4% of injected dose per gram of tissue and could be reduced by coadministration of the σ1 antagonist haloperidol. [18F]-(R)-20 was able to label those regions of the brain, which were reported to have high density of σ1 receptors.
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Affiliation(s)
- Katharina Holl
- Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Corrensstraße 48, Münster D-48149, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Corrensstraße 48, Münster D-48149, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Achim Hiller
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Forschungsstelle Leipzig, Abteilung Neuroradiopharmaka, Permoserstraße 15, Leipzig D-04318, Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Corrensstraße 48, Münster D-48149, Germany.
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Liu Z, Hundal-Jabal N, Wong M, Yapp D, Lin KS, Bénard F, Perrin DM. A new18F-heteroaryltrifluoroborate radio-prosthetic with greatly enhanced stability that is labelled by18F–19F-isotope exchange in good yield at high specific activity. MEDCHEMCOMM 2014. [DOI: 10.1039/c3md00328k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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25
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Jin H, Fan J, Zhang X, Li J, Flores HP, Perlmutter JS, Parsons SM, Tu Z. Radiosynthesis and in vivo evaluation of a novel σ 1 selective PET ligand. MEDCHEMCOMM 2014; 5:1669-1677. [PMID: 25584182 DOI: 10.1039/c4md00240g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The σ1 receptor is an important target for CNS disorders. We previously identified a σ1 ligand TZ3108 having highly potent (Ki-σ1 = 0.48 nM) and selective affinity for σ1 versus σ2 receptors. TZ3108 was 18F-labeled with F-18 for in vivo evaluation. Biodistribution and blocking studies of [18F]TZ3108 in male Sprague-Dawley rats demonstrated high brain uptake, which was σ1-specific with no in vivo defluorination. MicroPET studies in cynomolgus macaques showed high brain penetration of [18F]TZ3108; the regional brain distribution was consistent with that of the σ1 receptor. Pseudo-equilibrium in the brain was reached ~ 45 min post-injection. Metabolite analysis of [18F]TZ3108 in NHP blood and rodent blood and brain revealed that ~ 70% parent remained in the plasma of NHPs 60 min post-injection and the major radiometabolite did not cross the blood-brain barrier in rats. In summary, the potent, selective and metabolically stable σ1 specific radioligand [18F]TZ3108 represents a potentially useful PET radioligand for quantifying the σ1 receptor in the brain.
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Affiliation(s)
- Hongjun Jin
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jinda Fan
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Xiang Zhang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Junfeng Li
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hubert P Flores
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Joel S Perlmutter
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA. ; Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Stanley M Parsons
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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Holl K, Falck E, Köhler J, Schepmann D, Humpf HU, Brust P, Wünsch B. Synthesis, Characterization, and Metabolism Studies of Fluspidine Enantiomers. ChemMedChem 2013; 8:2047-56. [DOI: 10.1002/cmdc.201300322] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/03/2013] [Indexed: 11/12/2022]
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27
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Liu Z, Li Y, Lozada J, Wong MQ, Greene J, Lin KS, Yapp D, Perrin DM. Kit-like 18F-labeling of RGD-19F-arytrifluroborate in high yield and at extraordinarily high specific activity with preliminary in vivo tumor imaging. Nucl Med Biol 2013; 40:841-9. [PMID: 23810487 DOI: 10.1016/j.nucmedbio.2013.05.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/01/2013] [Accepted: 05/07/2013] [Indexed: 02/01/2023]
Abstract
INTRODUCTION Positron Emission Tomography (PET) is a rapidly expanding, cutting edge technology for preclinical evaluation, cancer diagnosis and staging, and patient management. A one-step aqueous (18)F-labeling method, which can be applied to peptides to provide functional in vivo images, has been a long-standing challenge in PET imaging. Over the past few years, we have sought a rapid and mild radiolabeling method based on the aqueous radiosynthesis of in vivo stable aryltrifluoroborate (ArBF(3)(-)) conjugates. Recent access to production levels of (18)F-Fluoride led to a fluorescent-(18)F-ArBF(3)(-) at unprecedentedly high specific activities of 15Ci/μmol. However, extending this method to labeling peptides as imaging agents has not been explored. METHODS In order to extend these results to a peptide of clinical interest in the context of production-level radiosynthesis, we applied this new technology for labeling RGD, measured its specific activity by standard curve analysis, and carried out a preliminary evaluation of its imaging properties. RESULTS RGD was labeled in excellent radiochemical yields at exceptionally high specific activity (~14Ci/μmol) (n = 3). Preliminary tumor-specific images corroborated by ex vivo biodistribution data with blocking controls show statistically significant albeit relatively low tumor uptake along with reasonably high tumor:blood ratios (n = 3). CONCLUSIONS Isotope exchange on a clinically useful (18)F-ArBF(3)(-) radiotracer leads to excellent radiochemical yields and exceptionally high specific activities while the anionic nature of the aryltrifluoroborate prosthetic results in very rapid clearance. Since rapid clearance of the radioactive tracer is generally desirable for tracer development, these results suggest new directions for varying linker arm composition to slightly retard clearance rather than enhancing it. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE This work is the first to use production levels of (18)F-activity to directly label RGD at specific activities that are an order of magnitude higher than most reports and thereby increases the distribution window for radiotracer production and delivery.
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Affiliation(s)
- Zhibo Liu
- Chemistry Department, 2036 Main Mall, University of British Columbia, Vancouver, B.C., Canada
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Li Y, Wang X, Zhang J, Deuther-Conrad W, Xie F, Zhang X, Liu J, Qiao J, Cui M, Steinbach J, Brust P, Liu B, Jia H. Synthesis and Evaluation of Novel 18F-Labeled Spirocyclic Piperidine Derivatives as σ1 Receptor Ligands for Positron Emission Tomography Imaging. J Med Chem 2013; 56:3478-91. [DOI: 10.1021/jm301734g] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yan Li
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Xia Wang
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Jinming Zhang
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Fang Xie
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Xiaojun Zhang
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Jian Liu
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Jinping Qiao
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Mengchao Cui
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Jörg Steinbach
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Peter Brust
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Boli Liu
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Hongmei Jia
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
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James ML, Shen B, Zavaleta CL, Nielsen CH, Mesangeau C, Vuppala PK, Chan C, Avery BA, Fishback JA, Matsumoto RR, Gambhir SS, McCurdy CR, Chin FT. New positron emission tomography (PET) radioligand for imaging σ-1 receptors in living subjects. J Med Chem 2012; 55:8272-8282. [PMID: 22853801 PMCID: PMC4106900 DOI: 10.1021/jm300371c] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
σ-1 receptor (S1R) radioligands have the potential to detect and monitor various neurological diseases. Herein we report the synthesis, radiofluorination, and evaluation of a new S1R ligand 6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ([(18)F]FTC-146, [(18)F]13). [(18)F]13 was synthesized by nucleophilic fluorination, affording a product with >99% radiochemical purity (RCP) and specific activity (SA) of 2.6 ± 1.2 Ci/μmol (n = 13) at end of synthesis (EOS). Positron emission tomography (PET) and ex vivo autoradiography studies of [(18)F]13 in mice showed high uptake of the radioligand in S1R rich regions of the brain. Pretreatment with 1 mg/kg haloperidol (2), nonradioactive 13, or BD1047 (18) reduced the binding of [(18)F]13 in the brain at 60 min by 80%, 82%, and 81%, respectively, suggesting that [(18)F]13 accumulation in mouse brain represents specific binding to S1Rs. These results indicate that [(18)F]13 is a promising candidate radiotracer for further evaluation as a tool for studying S1Rs in living subjects.
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Affiliation(s)
- Michelle L. James
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
| | - Bin Shen
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
| | - Cristina L. Zavaleta
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
| | - Carsten H. Nielsen
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
- Cluster for Molecular Imaging & Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Denmark
| | - Christophe Mesangeau
- Department of Medicinal Chemistry, The University of Mississippi, University, MS 38677-1848, USA
| | - Pradeep K. Vuppala
- Department of Pharmaceutics, The University of Mississippi, University, MS 38677-1848, USA
| | - Carmel Chan
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
| | - Bonnie A. Avery
- Department of Pharmaceutics, The University of Mississippi, University, MS 38677-1848, USA
| | - James A. Fishback
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University Morgantown, WV 26506-9500, USA
| | - Rae R. Matsumoto
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University Morgantown, WV 26506-9500, USA
| | - Sanjiv S. Gambhir
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
| | - Christopher R. McCurdy
- Department of Medicinal Chemistry, The University of Mississippi, University, MS 38677-1848, USA
| | - Frederick T. Chin
- Molecular Imaging Program at Stanford (MIPS) Department of Radiology, Stanford University, Palo Alto CA 94305-5484, USA
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Meyer C, Schepmann D, Yanagisawa S, Yamaguchi J, Itami K, Wünsch B. Late-Stage C-H Bond Arylation of Spirocyclic σ1Ligands for Analysis of Complementary σ1Receptor Surface. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200837] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Microwave assisted synthesis of spirocyclic pyrrolidines – σ1 receptor ligands with modified benzene-N-distance. Eur J Med Chem 2012; 53:327-36. [DOI: 10.1016/j.ejmech.2012.04.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/12/2012] [Accepted: 04/13/2012] [Indexed: 11/23/2022]
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Maisonial A, Große Maestrup E, Wiese C, Hiller A, Schepmann D, Fischer S, Deuther-Conrad W, Steinbach J, Brust P, Wünsch B. Synthesis, radiofluorination and pharmacological evaluation of a fluoromethyl spirocyclic PET tracer for central σ1 receptors and comparison with fluoroalkyl homologs. Bioorg Med Chem 2012; 20:257-69. [DOI: 10.1016/j.bmc.2011.11.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/31/2011] [Accepted: 11/02/2011] [Indexed: 11/17/2022]
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Brune S, Schepmann D, Lehmkuhl K, Frehland B, Wünsch B. Characterization of ligand binding to the σ(1) receptor in a human tumor cell line (RPMI 8226) and establishment of a competitive receptor binding assay. Assay Drug Dev Technol 2011; 10:365-74. [PMID: 22192304 DOI: 10.1089/adt.2011.0376] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The standard assay for the determination of σ(1) receptor affinities of novel compounds is a competitive binding assay using [(3)H]-(+)-pentazocine as radioligand and membrane preparations from guinea pig brain. Herein, a novel competitive binding assay was developed employing the hematopoietic cell line of human multiple myeloma (RPMI 8226), which expresses a large amount of the human σ(1) receptor. Membrane fragments of RPMI 8226 cells were prepared and characterized. A Western blot analysis confirmed the high density of σ(1) receptors in this cell line. Assay conditions were carefully optimized leading to an incubation period of 120 min, an incubation temperature of 37°C, and receptor material for each well was prepared from 300,000 cells. It was shown that a large excess (10 μM) of (+)-pentazocine, haloperidol, and di-o-tolylguanidine provided the same results during determination of the nonspecific binding. Saturation experiments with the radioligand [(3)H]-(+)-pentazocine led to a K(d)-value of 36±0.3 nM and a B(max)-value of 477±7 fmol/mg protein. These data resulted in approximately 122,000 σ(1) binding sites per cell. The assay was validated by using six known σ(1) ligands and eight σ(1) ligands prepared in our lab. The K(i)-values determined with RPMI 8226-derived receptor material are in good accordance with the K(i)-values obtained with guinea pig brain membrane preparations. Compared with guinea pig brain preparations, the RPMI 8226-derived receptor material represents a better standardized receptor material with a high density of human σ(1) receptors.
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Affiliation(s)
- Stefanie Brune
- Institute of Pharmaceutical and Medicinal Chemistry, Westfalian Wilhelms-University of Münster, Münster, Germany
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Schläger T, Schepmann D, Lehmkuhl K, Holenz J, Vela JM, Buschmann H, Wünsch B. Combination of two pharmacophoric systems: synthesis and pharmacological evaluation of spirocyclic pyranopyrazoles with high σ₁ receptor affinity. J Med Chem 2011; 54:6704-13. [PMID: 21859078 DOI: 10.1021/jm200585k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The novel class of spirocyclic σ(1) ligands 3 (6',7'-dihydro-1'H-spiro[piperidine-4,4'-pyrano[4,3-c]pyrazoles]) was designed by the combination of the potent σ(1) ligands 1 and 2 in one molecule. Thorough structure affinity relationships were derived by the variation of the substituents in position 1', 1, and 6'. Whereas the small electron rich methylpyrazole heterocycle was less tolerated by the σ(1) receptor protein, the introduction of a phenyl substituent instead of the methyl group led to ligands with a high σ(1) affinity. It is postulated that the additional phenyl substituent occupies a previously unrecognized hydrophobic region of the σ(1) receptor resulting in additional lipophilic interactions. The spirocyclic pyranopyrazoles are very selective against the σ(2) subtype, the PCP binding site of the NMDA receptor, and further targets. Despite high σ(1) affinity, the cyclohexylmethyl derivative 17i (K(i) (σ(1)) = 0.55 nM) and the isopentenyl derivative 17p (K(i) (σ(1)) = 1.6 nM) showed only low antiallodynic activity in the capsaicin assay.
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Affiliation(s)
- Torsten Schläger
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstrasse 58-62, D-48149 Münster, Germany
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Banister SD, Moussa IA, Jorgensen WT, Chua SW, Kassiou M. Molecular hybridization of 4-azahexacyclo[5.4.1.02,6.03,10.05,9.08,11]dodecane-3-ol with sigma (σ) receptor ligands modulates off-target activity and subtype selectivity. Bioorg Med Chem Lett 2011; 21:3622-6. [DOI: 10.1016/j.bmcl.2011.04.098] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 04/19/2011] [Accepted: 04/21/2011] [Indexed: 01/27/2023]
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Maisonial A, Große Maestrup E, Fischer S, Hiller A, Scheunemann M, Wiese C, Schepmann D, Steinbach J, Deuther-Conrad W, Wünsch B, Brust P. A 18F-Labeled Fluorobutyl-Substituted Spirocyclic Piperidine Derivative as a Selective Radioligand for PET Imaging of Sigma1 Receptors. ChemMedChem 2011; 6:1401-10. [DOI: 10.1002/cmdc.201100108] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 04/11/2011] [Indexed: 11/09/2022]
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Fischer S, Wiese C, Maestrup EG, Hiller A, Deuther-Conrad W, Scheunemann M, Schepmann D, Steinbach J, Wünsch B, Brust P. Molecular imaging of σ receptors: synthesis and evaluation of the potent σ1 selective radioligand [18F]fluspidine. Eur J Nucl Med Mol Imaging 2011; 38:540-51. [PMID: 21072511 DOI: 10.1007/s00259-010-1658-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 10/20/2010] [Indexed: 11/28/2022]
Abstract
PURPOSE Neuroimaging of σ(1) receptors in the human brain has been proposed for the investigation of the pathophysiology of neurodegenerative and psychiatric diseases. However, there is a lack of suitable (18)F-labelled PET radioligands for that purpose. METHODS The selective σ(1) receptor ligand [(18)F]fluspidine (1'-benzyl-3-(2-[(18)F]fluoroethyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]) was synthesized by nucleophilic (18)F(-) substitution of the tosyl precursor. In vitro receptor binding affinity and selectivity were assessed by radioligand competition in tissue homogenate and autoradiographic approaches. In female CD-1 mice, in vivo properties of [(18)F]fluspidine were evaluated by ex vivo brain section imaging and organ distribution of intravenously administered radiotracer. Target specificity was validated by organ distribution of [(18)F]fluspidine after treatment with 1 mg/kg i.p. of the σ receptor antagonist haloperidol or the emopamil binding protein (EBP) inhibitor tamoxifen. In vitro metabolic stability and in vivo metabolism were investigated by LC-MS(n) and radio-HPLC analysis. RESULTS [(18)F]Fluspidine was obtained with a radiochemical yield of 35-45%, a radiochemical purity of ≥ 99.6% and a specific activity of 150-350 GBq/μmol (n = 6) within a total synthesis time of 90-120 min. In vitro, fluspidine bound specifically and with high affinity to σ(1) receptors (K (i) = 0.59 nM). In mice, [(18)F]fluspidine rapidly accumulated in brain with uptake values of 3.9 and 4.7%ID/g and brain to blood ratios of 7 and 13 at 5 and 30 min after intravenous application of the radiotracer, respectively. By ex vivo autoradiography of brain slices, resemblance between binding site occupancy of [(18)F]fluspidine and the expression of σ(1) receptors was shown. The radiotracer uptake in the brain as well as in peripheral σ(1) receptor expressing organs was significantly inhibited by haloperidol but not by tamoxifen. Incubation with rat liver microsomes led to a fast biotransformation of fluspidine. After an incubation period of 30 min only 13% of the parent compound was left. Seven metabolites were identified by HPLC-UV and LC-MS(n) techniques. However, [(18)F]fluspidine showed a higher metabolic stability in vivo. In plasma samples ∼ 94% of parent compound remained at 30 min and ∼ 67% at 60 min post-injection. Only one major radiometabolite was detected. None of the radiometabolites crossed the blood-brain barrier. CONCLUSION [(18)F]Fluspidine demonstrated favourable target affinity and specificity as well as metabolic stability both in vitro and in animal experiments. The in vivo properties of [(18)F]fluspidine offer a high potential of this radiotracer for neuroimaging and quantitation of σ(1) receptors in vivo.
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Affiliation(s)
- Steffen Fischer
- Forschungszentrum Dresden-Rossendorf, Research Site Leipzig, Institute of Radiopharmacy, Leipzig, Germany
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Wiese C, Grosse Maestrup E, Schepmann D, Grimme S, Humpf HU, Brust P, Wünsch B. Enantioselective σ1 receptor binding and biotransformation of the spirocyclic PET tracer 1'-benzyl-3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]. Chirality 2011; 23:148-54. [PMID: 20845431 DOI: 10.1002/chir.20893] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It was shown that racemic (±)-2 [1'-benzyl-3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidine], WMS-1813] represents a promising positron emission tomography (PET) tracer for the investigation of centrally located σ(1) receptors. To study the pharmacological activity of the enantiomers of 2, a preparative HPLC separation of (R)-2 and (S)-2 was performed. The absolute configuration of the enantiomers was determined by CD-spectroscopy together with theoretical calculations of the CD-spectrum of a model compound. In receptor binding studies with the radioligand [(3)H]-(+)-pentazocine, (S)-2 was thrice more potent than its (R)-configured enantiomer (R)-2. The metabolic degradation of the more potent (S)-enantiomer was considerably slower than the metabolism of (R)-2. The structures of the main metabolites of both enantiomers were elucidated by determination of the exact mass using an Orbitrap-LC-MS system. These experiments showed a stereoselective biotransformation of the enantiomers of 2.
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Affiliation(s)
- Christian Wiese
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstraße 58-62, Münster, Germany
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Abstract
Sigma receptors (σ-1 and σ-2) are non-opioid proteins implicated in the pathophysiology of various neurological disorders and cancer. The σ-1 subtype is a chaperon protein widely distributed in the CNS and peripheral tissues. These receptors are involved in the modulation of K+- and Ca2+-dependent signaling cascades at the endoplasmic reticulum and modulation of neurotransmitter release. σ-1 receptors are emerging targets for the treatment of neurophychiatric diseases (schizophrenia and depression) and cocaine addiction. σ-2 receptors are lipid raft proteins. They are highly expressed on many tumor cells and hence considered potential targets for anticancer drugs. σ receptors bind to a diverse class of pharmacological compounds like cocaine, methamphetamine, benzomorphans like (±)-pentazocine, (±)-SKF-10,047 and endogenous neurosteroids and sphingolipids. In this review we focus on the early development of σ receptor-specific ligands and radiolabeling agents.
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Maestrup EG, Wiese C, Schepmann D, Brust P, Wünsch B. Synthesis, pharmacological activity and structure affinity relationships of spirocyclic σ(1) receptor ligands with a (2-fluoroethyl) residue in 3-position. Bioorg Med Chem 2010; 19:393-405. [PMID: 21126878 DOI: 10.1016/j.bmc.2010.11.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 11/03/2010] [Accepted: 11/06/2010] [Indexed: 11/30/2022]
Abstract
In order to develop a fluorinated radiotracer for imaging of σ(1) receptors in the central nervous system a series of (2-fluoroethyl) substituted spirocyclic piperidines 3 has been prepared. In the key step of the synthesis 2-bromocinnamaldehyde acetal 5 was added to piperidones 6 with various substituents at the N-atom. Unexpectedly, this reaction led to 2-benzoxepines 8, which were contracted with acid to afford the spirocyclic 2-benzofuranacetaldehydes 9. The best yields were obtained, when the transformations up to the alcohols 10 were performed without isolation of intermediates. Generally the (2-fluoroethyl) derivatives 3 have higher σ(1) affinity and σ(1)/σ(2) selectivity than the corresponding (3-fluoropropyl) derivatives 2. The most promising candidate for the development as radiotracer is the (2-fluoroethyl) derivative 3a (WMS-1828, fluspidine, 1'-benzyl-3-(2-fluoroethyl)-3H-spiro[[2]benzofuran-1,4'-piperidine]), which shows subnanomolar σ(1) affinity (K(i)=0.59nM) and excellent selectivity over the σ(2) subtype (1331-fold) as well as some other receptor systems. The novel synthetic strategy also allows the systematic pharmacological evaluation of intermediate alcohols 10. Despite their high σ(1) affinity (K(i)=6-32nM) and selectivity the alcohols 10 are 10-30-fold less potent than the bioisosteric fluoro derivatives 3.
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Affiliation(s)
- Eva Grosse Maestrup
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstraße 58-62, D-48149 Münster, Germany
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Sunnam SK, Schepmann D, Rack E, Fröhlich R, Korpis K, Bednarski PJ, Wünsch B. Synthesis and biological evaluation of conformationally restricted σ(1) receptor ligands with 7,9-diazabicyclo[4.2.2]decane scaffold. Org Biomol Chem 2010; 8:5525-40. [PMID: 20953473 DOI: 10.1039/c0ob00402b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The key step in the synthesis of the 7,9-diazabicyclo[4.2.2]decane system was a modified Dieckmann condensation of piperazinebutyrate 11, which makes use of trapping the first cyclized intermediate with TMS-Cl. Reduction of the bicyclic ketone 14 with LiBH(4) at -90 °C provided diastereoselectively (>99 : 1) the syn-configured alcohol 15a, which was converted into the final alcohol and ethers 16a-g. The configuration at the 2-position was established by X-ray structure analysis of methyl and ethyl ethers 15b and 15c. In contrast to bicyclic systems with a three-carbon bridge, inversion of the configuration at the 2-position of the alcohol 15a failed to give the inverted alcohol 19a. However, an unselective reduction of the ketone 24 with L-Selectride led to the diastereomeric alcohols 16a and 25a in the ratio 36 : 64. LiAlH(4) reduction of the tosylate 20 and the alkene 18 yielded the diazabicyclo-decane 26 and -decene 27 without further substituents at the four-carbon bridge. The σ(1) and σ(2) receptor affinities were investigated in receptor binding studies with radioligands. All test compounds showed a lower σ(1) affinity than the corresponding bicyclic derivatives with a three-membered bridge. The reduced σ(1) receptor affinity is attributed to the larger four-membered bridge. This hypothesis is supported by the alkene 27, which represents the most potent σ(1) ligand of this series (K(i) = 7.5 nM). In the alkene 27 the size and flexibility of the bridge is considerably reduced by the double bond. The methyl ether 25b and the unsubstituted derivatives 26 and 27 revealed moderate inhibition of the growth of the human tumor cell lines A-427, 5637 and MCF-7. Again, these compounds are less potent than the analogues with a three-membered bridge. The IC(50)-value of the most potent σ(1) ligand 27 against the small cell lung cancer cell line A-427 (IC(50) = 10 μM) should be emphasized, since this cell line is particularly sensitive to homologues with a three-carbon bridge.
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Affiliation(s)
- Sunil K Sunnam
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstraße 58-62, D-48149, Münster, Germany
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Chen RQ, Li Y, Zhang QY, Jia HM, Deuther-Conrad W, Schepmann D, Steinbach J, Brust P, Wünsch B, Liu BL. Synthesis and biological evaluation of a radioiodinated spiropiperidine ligand as a potential σ1 receptor imaging agent. J Labelled Comp Radiopharm 2010. [DOI: 10.1002/jlcr.1777] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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