401
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Donohue SR, Dannals RF, Halldin C, Pike VW. N-(4-cyanotetrahydro-2H-pyran-4-yl) and N-(1-cyanocyclohexyl) derivatives of 1,5-diarylpyrazole-3-carboxamides showing high affinity for 18 kDa translocator protein and/or cannabinoid receptors. J Med Chem 2011; 54:2961-70. [PMID: 21428406 PMCID: PMC3085958 DOI: 10.1021/jm2000536] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In order to develop improved radioligands for imaging brain CB(1) receptors with positron emission tomography (PET) based on rimonabant (5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide, 1), we synthesized compounds 9a-s in which the N-piperidinyl ring was replaced with a 4-(4-cyanotetrahydro-2H-pyranyl) or 1-cyanocyclohexyl ring. Such changes were expected to be almost isosteric with 1, confer greater metabolic resistance, and in the case of the 4-(4-cyanotetrahydro-2H-pyranyl) compounds, substantially reduce lipophilicity. One derivative, 1-(2-bromophenyl)-N-(1-cyanocyclohexyl)-5-(4-methoxyphenyl)-4-methylpyrazole-3-carboxamide (9n), showed high affinity (K(i) = 15.7 nM) and selectivity for binding to CB(1) receptors. The corresponding 4-(4-cyanotetrahydro-2H-pyranyl) derivative (9m) also showed quite high affinity for CB(1) receptors (K(i) = 62 nM) but was found to have even higher affinity (K(i) = 29 nM) for the structurally unrelated 18 kDa translocator protein (TSPO). Some other minor structural changes among 9a-s were also found to switch binding selectivity from CB(1) receptors to TSPO or vice versa. These unexpected findings and their implications for the development of selective ligands or PET radioligands for CB(1) receptors or TSPO are discussed in relation to current pharmacophore models of CB(1) receptor and TSPO binding sites.
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Affiliation(s)
- Sean R. Donohue
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1003, United States
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176, Stockholm, Sweden
- Division of Nuclear Medicine, The Johns Hopkins PET Center, Baltimore, Maryland 21287, United States
| | - Robert F. Dannals
- Division of Nuclear Medicine, The Johns Hopkins PET Center, Baltimore, Maryland 21287, United States
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176, Stockholm, Sweden
| | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1003, United States
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402
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Fodero-Tavoletti MT, Okamura N, Furumoto S, Mulligan RS, Connor AR, McLean CA, Cao D, Rigopoulos A, Cartwright GA, O'Keefe G, Gong S, Adlard PA, Barnham KJ, Rowe CC, Masters CL, Kudo Y, Cappai R, Yanai K, Villemagne VL. 18F-THK523: a novel in vivo tau imaging ligand for Alzheimer's disease. Brain 2011; 134:1089-100. [PMID: 21436112 DOI: 10.1093/brain/awr038] [Citation(s) in RCA: 246] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While considerable effort has focused on developing positron emission tomography β-amyloid imaging radiotracers for the early diagnosis of Alzheimer's disease, no radiotracer is available for the non-invasive quantification of tau. In this study, we detail the characterization of (18)F-THK523 as a novel tau imaging radiotracer. In vitro binding studies demonstrated that (18)F-THK523 binds with higher affinity to a greater number of binding sites on recombinant tau (K18Δ280K) compared with β-amyloid(1-42) fibrils. Autoradiographic and histofluorescence analysis of human hippocampal serial sections with Alzheimer's disease exhibited positive THK523 binding that co-localized with immunoreactive tau pathology, but failed to highlight β-amyloid plaques. Micro-positron emission tomography analysis demonstrated significantly higher retention of (18)F-THK523 (48%; P < 0.007) in tau transgenic mice brains compared with their wild-type littermates or APP/PS1 mice. The preclinical examination of THK523 has demonstrated its high affinity and selectivity for tau pathology both in vitro and in vivo, indicating that (18)F-THK523 fulfils ligand criteria for human imaging trials.
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403
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Vasdev N, Dorff PN, O'Neil JP, Chin FT, Hanrahan S, VanBrocklin HF. Metabolic stability of 6,7-dialkoxy-4-(2-, 3- and 4-[18F]fluoroanilino)quinazolines, potential EGFR imaging probes. Bioorg Med Chem 2011; 19:2959-65. [PMID: 21478021 DOI: 10.1016/j.bmc.2011.03.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/07/2011] [Accepted: 03/14/2011] [Indexed: 01/19/2023]
Abstract
Epidermal growth factor receptors (EGFR), upregulated in many tumor types, have been a target for therapeutic development and molecular imaging. The objective of this study was to evaluate the distribution and metabolic characteristics of fluorine-18 labeled anilinoquinazolines as potential imaging agents for EGFR tyrosine kinase expression. Fluorine-18 labeled fluoronitrobenzenes were prepared by reaction of potassium cryptand [(18)F]fluoride with 1,2- and 1,4-dinitrobenzenes, and 3-nitro-N,N,N-trimethylanilinium triflate in 5min. Decay-corrected radiochemical yields of [(18)F]fluoride incorporation into the nitro-aromatic compounds were 81±2%, 44±4% and 77±5% (n=3-5) for the 2-, 3- and 4-fluoro isomers, respectively. Sodium borohydride reduction to the corresponding [(18)F]fluoroanilines was achieved with greater than 80% conversion in 5min. Coupling of [(18)F]fluoroaniline-hydrochlorides to 6,7-dimethoxy-4-chloro-quinazoline gave the corresponding 6,7-dimethoxy-4-(2-, 3- and 4-[(18)F]fluoroanilino)quinazolines in 31±5%, 17±2% and 55±2% radiochemical yield, respectively, while coupling to the 6,7-diethoxy-4-chloro-quinazoline produced 6,7-diethoxy-4-(2-, 3- and 4-[(18)F]fluoroanilino)quinazolines in 19±6%, 9±3% and 36±6% radiochemical yield, respectively, in 90min to end of synthesis from [(18)F]fluoride. Biodistribution of 2- and 4-[(18)F]fluoroanilinoquinazolines was conducted in tumor-bearing mice (MDA-MB-435 and MDA-MB-468 xenografts). Low tumor uptake (<1% injected dose per gram (ID/g) of tissue up to 3h postinjection of the radiotracers) was observed. High bone uptake (5-15% ID/g) was noted with the 4-[(18)F]fluoroanilinoquinazolines. The metabolic stabilities of radiolabeled quinazolines were further evaluated by incubation with human female cryopreserved isolated hepatocytes. Rapid degeneration of the 4-fluoro-substituted compounds to baseline polar metabolites was observed by radio-TLC, whereas, the 2- and 3-[(18)F]fluoroaniline derivatives were significantly more stable, up to 2h, corroborating the in vivo biodistribution studies. para-Substituted [(18)F]fluoroanilines, a common structural motif in radiopharmaceuticals, are highly susceptible to metabolic degradation.
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Affiliation(s)
- Neil Vasdev
- Department of Radiotracer Development and Imaging Technology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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404
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Abstract
Brain serotonergic circuitries interact with other neurotransmitter systems on a multitude of different molecular levels. In humans, as in other mammalian species, serotonin (5-HT) plays a modulatory role in almost every physiological function. Furthermore, serotonergic dysfunction is thought to be implicated in several psychiatric and neurodegenerative disorders. We describe the neuroanatomy and neurochemistry of brain serotonergic circuitries. The contribution of emergent in vivo imaging methods to the regional localization of binding site receptors and certain aspects of their functional connectivity in correlation to behavior is also discussed. 5-HT cell bodies, mainly localized in the raphe nuclei, send axons to almost every brain region. It is argued that the specificity of the local chemocommunication between 5-HT and other neuronal elements mainly depends on mechanisms regulating the extracellular concentration of 5-HT the diversity of high-affinity membrane receptors, and their specific transduction modalities.
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Affiliation(s)
- Yves Charnay
- Hôpitaux Universitaires de Genève, Département de Psychiatrie, Service de Neuropsychiatrie, Ch. Du Petit-Bel-Air, 2, CH-1225 Chêne-Bourg, Switzerland.
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405
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Hall MD, Pike VW. Avoiding barriers to PET radioligand development: cellular assays of brain efflux transporters. J Nucl Med 2011; 52:338-40. [PMID: 21321273 DOI: 10.2967/jnumed.110.081125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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406
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Tournier N, Valette H, Peyronneau MA, Saba W, Goutal S, Kuhnast B, Dollé F, Scherrmann JM, Cisternino S, Bottlaender M. Transport of Selected PET Radiotracers by Human P-Glycoprotein (ABCB1) and Breast Cancer Resistance Protein (ABCG2): An In Vitro Screening. J Nucl Med 2011; 52:415-23. [DOI: 10.2967/jnumed.110.079608] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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407
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Fujinaga M, Yamasaki T, Kawamura K, Kumata K, Hatori A, Yui J, Yanamoto K, Yoshida Y, Ogawa M, Nengaki N, Maeda J, Fukumura T, Zhang MR. Synthesis and evaluation of 6-[1-(2-[18F]fluoro-3-pyridyl)-5-methyl-1H-1,2,3-triazol-4-yl]quinoline for positron emission tomography imaging of the metabotropic glutamate receptor type 1 in brain. Bioorg Med Chem 2011; 19:102-10. [DOI: 10.1016/j.bmc.2010.11.048] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/18/2010] [Accepted: 11/20/2010] [Indexed: 11/25/2022]
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408
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Pike VW, Taliani S, Lohith TG, Owen DRJ, Pugliesi I, Da Pozzo E, Hong J, Zoghbi SS, Gunn RN, Parker CA, Rabiner EA, Fujita M, Innis RB, Martini C, Da Settimo F. Evaluation of novel N1-methyl-2-phenylindol-3-ylglyoxylamides as a new chemotype of 18 kDa translocator protein-selective ligand suitable for the development of positron emission tomography radioligands. J Med Chem 2010; 54:366-73. [PMID: 21133364 DOI: 10.1021/jm101230g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel series of N(1)-methyl-(2-phenylindol-3-yl)glyoxylamides, 19-31, designed in accordance with our previously reported pharmacophore/topological model, showed high affinity for the 18 kDa translocator protein (TSPO) and paved the way for developing a new radiolabeled probe. Thus ligand 31, N,N-di-n-propyl-(N(1)-methyl-2-(4'-nitrophenyl)indol-3-yl)glyoxylamide, featuring the best combination of affinity and lipophilicity, was labeled with carbon-11 for evaluation with positron emission tomography (PET) in monkey. After intravenous injection, [(11)C]31 entered brain to give a high proportion of TSPO-specific binding. These findings augur well for the future application of [(11)C]31 in humans. Consequently, the binding of 31 to human TSPO was tested on samples of brain membranes from deceased subjects who through ethically approved in vitro study had previously been established to be high-affinity binders (HABs), mixed-affinity binders (MABs), or low-affinity binders (LABs) for the known TSPO ligand, PBR28 (2). 31 showed high affinity for HABs, MABs, and LABs. In conclusion, [(11)C]31 represents a promising new chemotype for developing novel TSPO radioligands as biomarkers of neuroinflammation.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States.
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409
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Kawamura K, Yamasaki T, Konno F, Yui J, Hatori A, Yanamoto K, Wakizaka H, Ogawa M, Yoshida Y, Nengaki N, Fukumura T, Zhang MR. Synthesis and in vivo evaluation of ¹⁸F-fluoroethyl GF120918 and XR9576 as positron emission tomography probes for assessing the function of drug efflux transporters. Bioorg Med Chem 2010; 19:861-70. [PMID: 21185730 DOI: 10.1016/j.bmc.2010.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to synthesize two new positron emission tomography (PET) probes, N-(4-(2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl)phenyl)-9,10-dihydro-5-[¹⁸F]fluoroethoxy-9-oxo-4-acridine carboxamide ([¹⁸F]3) and quinoline-3-carboxylic acid [2-(4-{2-[7-(2-[¹⁸F]fluoroethoxy)-6-methoxy-3,4-dihydro-1H-isoquinolin-2-yl]ethyl}phenylcarbamoyl)-4,5-dimethoxyphenyl]amide ([¹⁸F]4), and to evaluate the potential of these PET probes for assessing the function of two major drug efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). [¹⁸F]3 and [¹⁸F]4 were synthesized by ¹⁸F-alkylation of each O-desmethyl precursor with [¹⁸F]2-fluoroethyl bromide for injection as PET probes. In vitro accumulation assay showed that treatment with P-gp/BCRP inhibitors (1 and 2) enhanced the intracellular accumulation capacity of P-gp- and BCRP-overexpressing MES-SA/Dx5 cells. In PET studies, the uptake (AUC(brain[0-)₆₀ (min])) of [¹⁸F]3 and [¹⁸F]4 in wild-type mice co-injected with 1 were approximately sevenfold higher than that in wild-type mice, and the uptake of [¹⁸F]3 and [¹⁸F]4 in P-gp/Bcrp knockout mice were eight- to ninefold higher than that in wild-type mice. The increased uptake of [¹⁸F]3 and [¹⁸F]4 was similar to that of parent compounds ([¹¹C]1 and [¹¹C]2) previously described, indicating that radioactivity levels in the brain after injection of [¹⁸F]3 and [¹⁸F]4 are related to the function of drug efflux transporters. Also, these results suggest that the structural difference between parent compounds ([¹¹C]1 and [¹¹C]2) and fluoroethyl analogs ([¹⁸F]3 and [¹⁸F]4) do not obviously affect the potency against drug efflux transporters. In metabolite analysis of mice, the unchanged form in the brain and plasma at 60 min after co-injection of [¹⁸F]4 plus 1 were higher (95% for brain; 81% for plasma) than that after co-injection of [¹⁸F]3 plus 1. [¹⁸F]4 is a promising PET probe to assess the function of drug efflux transporters.
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Affiliation(s)
- Kazunori Kawamura
- Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan.
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410
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Lacivita E, De Giorgio P, Lee IT, Rodeheaver SI, Weiss BA, Fracasso C, Caccia S, Berardi F, Perrone R, Zhang MR, Maeda J, Higuchi M, Suhara T, Schetz JA, Leopoldo M. Design, synthesis, radiolabeling, and in vivo evaluation of carbon-11 labeled N-[2-[4-(3-cyanopyridin-2-yl)piperazin-1-yl]ethyl]-3-methoxybenzamide, a potential positron emission tomography tracer for the dopamine D(4) receptors. J Med Chem 2010; 53:7344-55. [PMID: 20873719 DOI: 10.1021/jm100925m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Here we describe the design, synthesis, and evaluation of physicochemical and pharmacological properties of D(4) dopamine receptor ligands related to N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (2). Structural features were incorporated to increase affinity for the target receptor, to improve selectivity over D(2) and σ(1) receptors, to enable labeling with carbon-11 or fluorine-18, and to adjust lipophilicity within the range considered optimal for brain penetration and low nonspecific binding. Compounds 7 and 13 showed the overall best characteristics: nanomolar affinity for the D(4) receptor, >100-fold selectivity over D(2) and D(3) dopamine receptors, 5-HT(1A), 5-HT(2A), and 5-HT(2C) serotonin receptors and σ(1) receptors, and log P = 2.37-2.55. Following intraperitoneal administration in mice, both compounds rapidly entered the central nervous system. The methoxy of N-[2-[4-(3-cyanopyridin-2-yl)piperazin-1-yl]ethyl]-3-methoxybenzamide (7) was radiolabeled with carbon-11 and subjected to PET analysis in non-human primate. [(11)C]7 time-dependently accumulated to saturation in the posterior eye in the region of the retina, a tissue containing a high density of D(4) receptors.
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Affiliation(s)
- Enza Lacivita
- Dipartimento Farmaco-Chimico, Università degli Studi di Bari A Moro, Via Orabona 4, 70125 Bari, Italy
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411
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Xu R, Hong J, Morse CL, Pike VW. Synthesis, structure-affinity relationships, and radiolabeling of selective high-affinity 5-HT4 receptor ligands as prospective imaging probes for positron emission tomography. J Med Chem 2010; 53:7035-47. [PMID: 20812727 DOI: 10.1021/jm100668r] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a search for high-affinity receptor ligands that might serve for development as radioligands for the imaging of brain 5-HT(4) receptors in vivo with positron emission tomography (PET), structural modifications were made to the high-affinity 5-HT(4) antagonist (1-butylpiperidin-4-yl)methyl 8-amino-7-iodo-2,3-dihydrobenzo[b][1,4]dioxine-5-carboxylate (1, SB 207710). These modifications were made mainly on the aryl side of the ester bond to permit possible rapid labeling of the carboxylic acid component with a positron emitter, either carbon-11 (t(1/2) = 20.4 min) or fluorine-18 (t(1/2) = 109.7 min), and included (i) replacement of the iodine atom with a small substituent such as nitrile, methyl, or fluoro, (ii) methylation of the 8-amino group, (iii) opening of the dioxan ring, and (iv) alteration of the length of the N-alkyl goup. High-affinity ligands were discovered for recombinant human 5-HT(4) receptors with amenability to labeling with a positron emitter and potential for development as imaging probes. The ring-opened radioligand, (([methoxy-(11)C]1-butylpiperidin-4-yl)methyl 4-amino-3-methoxybenzoate; [(11)C]13), showed an especially favorable array of properties for future evaluation as a PET radioligand for brain 5-HT(4) receptors.
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Affiliation(s)
- Rong Xu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, USA
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412
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Siméon FG, Wendahl MT, Pike VW. The [F]2-Fluoro-1,3-thiazolyl Moiety - an Easily-Accessible Structural Motif for Prospective Molecular Imaging Radiotracers. Tetrahedron Lett 2010; 51:6034-6036. [PMID: 21057601 DOI: 10.1016/j.tetlet.2010.09.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
2-Fluoro-1,3-thiazoles were rapidly and efficiently labeled with no-carrier-added fluorine-18 (t(1/2) = 109.7 min) by treatment of readily prepared 2-halo precursors with cyclotron-produced [(18)F]fluoride ion. The [(18)F]2-fluoro-1,3-thiazolyl moiety constitutes a new and easily-labeled structural motif for prospective molecular imaging radiotracers.
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Affiliation(s)
- Fabrice G Siméon
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Rm. B3 C346A, 10 Center Drive, Bethesda, MD 20892-1003, USA
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413
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Wang B, Cerny RL, Uppaluri S, Kempinger JJ, DiMagno SG. Fluoride-Promoted Ligand Exchange in Diaryliodonium Salts. J Fluor Chem 2010; 131:1113-1121. [PMID: 21057607 PMCID: PMC2967785 DOI: 10.1016/j.jfluchem.2010.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. The aryl exchange reaction may be of practical use for the preparation of hitherto inaccessible diaryliodonium salts, thus it also has implications for labeling radiotracers for molecular imaging with (18)F-fluoride (t(1/2) = 109.7 min).
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Affiliation(s)
- Bijia Wang
- Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA Fax: 402 472-9402; Tel: 402 472-9895
| | - Ronald L. Cerny
- Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA Fax: 402 472-9402; Tel: 402 472-9895
| | - ShriHarsha Uppaluri
- Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA Fax: 402 472-9402; Tel: 402 472-9895
| | - Jayson J. Kempinger
- Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA Fax: 402 472-9402; Tel: 402 472-9895
| | - Stephen G. DiMagno
- Department of Chemistry and Nebraska Center for Materials and Nanoscience University of Nebraska, Lincoln, NE 68588-0304, USA Fax: 402 472-9402; Tel: 402 472-9895
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414
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Celen S, Koole M, De Angelis M, Sannen I, Chitneni SK, Alcazar J, Dedeurwaerdere S, Moechars D, Schmidt M, Verbruggen A, Langlois X, Van Laere K, Andrés JI, Bormans G. Preclinical evaluation of 18F-JNJ41510417 as a radioligand for PET imaging of phosphodiesterase-10A in the brain. J Nucl Med 2010; 51:1584-91. [PMID: 20847170 DOI: 10.2967/jnumed.110.077040] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Phosphodiesterases are enzymes that inactivate the intracellular second messengers 3',5'-cyclic adenosine-monophosphate and/or cyclic guanosine-monophosphate. Of all 11 known phosphodiesterase families, phosphodiesterase-10A (PDE10A) has the most restricted distribution, with high expression in the striatum. PDE10A inhibitors are pursued as drugs for treatment of neuropsychiatric disorders. We have synthesized and evaluated (18)F-JNJ41510417 as a selective and high-affinity radioligand for in vivo brain imaging of PDE10A using PET. METHODS The biodistribution of (18)F-JNJ41510417 was evaluated in rats. Rat plasma and perfused brain homogenates were analyzed by high-performance liquid chromatography to quantify radiometabolites. Dynamic small-animal PET was performed in rats and in wild-type and PDE10A knock-out mice and compared with ex vivo autoradiography. Blocking and displacement experiments were performed using the nonradioactive analog and other selective PDE10A inhibitors. RESULTS Tissue distribution studies showed predominant hepatobiliary excretion, sufficient brain uptake (0.56 ± 0.00 percentage injected dose at 2 min after tracer injection), and continuous accumulation of the tracer in the striatum over time; rapid washout of nonspecific binding from other brain regions was observed. Polar radiometabolites were detected in plasma and brain tissue. Dynamic small-animal PET showed continuous tracer accumulation in the striatum, with rapid decline in the cortex and cerebellum. Pretreatment and chase experiments with PDE10A inhibitors showed that the tracer binding to PDE10A was specific and reversible. Imaging in PDE10A knock-out and wild-type mice further confirmed that binding in the striatum was specific for PDE10A. CONCLUSION Experiments in rats and PDE10A knock-out mice indicate that (18)F-JNJ41510417 binds specifically and reversibly to PDE10A in the striatum, suggesting that this new fluorinated quinoline derivative is a promising candidate for in vivo imaging of PDE10A using PET.
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Affiliation(s)
- Sofie Celen
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, K.U. Leuven, Leuven, Belgium
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415
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Synthesis and characterization of a iodine-125-labeled pyrrolo[1,2-a]thieno[3,2-e]pyrazine and evaluation as a potential 5-HT4R SPECT tracer. Eur J Med Chem 2010; 45:5465-7. [PMID: 20817325 DOI: 10.1016/j.ejmech.2010.07.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 07/20/2010] [Accepted: 07/27/2010] [Indexed: 11/21/2022]
Abstract
In the aim to find new radiotracers for the in vivo imaging of 5-HT(4) receptors by ultra-high resolution quantitative SPECT, we have developed the synthesis of a radioiodinated 5-HT(4) ligand using an iododestannylation procedure. The [(125)I]-ligand was obtained in a high radiochemical yield. Preliminary autoradiographic and ex vivo studies failed to show a specific labeling of 5-HT(4) receptors.
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416
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Syntheses and pharmacological characterization of novel thiazole derivatives as potential mGluR5 PET ligands. Bioorg Med Chem 2010; 18:6044-54. [DOI: 10.1016/j.bmc.2010.06.070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 06/08/2010] [Accepted: 06/20/2010] [Indexed: 11/19/2022]
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417
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Synthesis of [11C]SSR149415 and preliminary imaging studies using positron emission tomography. Bioorg Med Chem Lett 2010; 20:3103-6. [DOI: 10.1016/j.bmcl.2010.03.108] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 03/26/2010] [Accepted: 03/26/2010] [Indexed: 11/20/2022]
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418
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General Method for the11C-Labeling of 2-Arylpropionic Acids and Their Esters: Construction of a PET Tracer Library for a Study of Biological Events Involved in COXs Expression. Chemistry 2010; 16:4250-8. [DOI: 10.1002/chem.200903044] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Seneca N, Zoghbi SS, Shetty HU, Tuan E, Kannan P, Taku A, Innis RB, Pike VW. Effects of ketoconazole on the biodistribution and metabolism of [11C]loperamide and [11C]N-desmethyl-loperamide in wild-type and P-gp knockout mice. Nucl Med Biol 2010; 37:335-45. [PMID: 20346873 PMCID: PMC2847595 DOI: 10.1016/j.nucmedbio.2009.12.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 12/01/2009] [Accepted: 12/28/2009] [Indexed: 12/27/2022]
Abstract
INTRODUCTION [(11)C]Loperamide and [(11)C]N-desmethyl-loperamide ([(11)C]dLop) have been proposed as radiotracers for imaging brain P-glycoprotein (P-gp) function. A major route of [(11)C]loperamide metabolism is N-demethylation to [(11)C]dLop. We aimed to test whether inhibition of CYP3A4 with ketoconazole might reduce the metabolism of [(11)C]loperamide and [(11)C]dLop in mice, and thereby improve the quality of these radiotracers. METHODS Studies were performed in wild-type and P-gp knockout (mdr-1a/b -/-) mice. During each of seven study sessions, one pair of mice, comprising one wild-type and one knockout mouse, was pretreated with ketoconazole (50 mg/kg, ip), while another such pair was left untreated. Mice were sacrificed at 30 min after injection of [(11)C]loperamide or [(11)C]dLop. Whole brain and plasma samples were measured for radioactivity and analyzed with radio-high-performance liquid chromatography. RESULTS Ketoconazole increased the plasma concentrations of [(11)C]loperamide and its main radiometabolite, [(11)C]dLop, by about twofold in both wild-type and knockout mice, whereas the most polar radiometabolite was decreased threefold. Furthermore, ketoconazole increased the brain concentrations of [(11)C]loperamide and the radiometabolite [(11)C]dLop by about twofold in knockout mice, and decreased the brain concentrations of the major and most polar radiometabolite in wild-type and knockout mice by 82% and 49%, respectively. In contrast, ketoconazole had no effect on plasma and brain distribution of administered [(11)C]dLop and its radiometabolites in either wild-type or knockout mice, except to increase the low plasma [(11)C]dLop concentration. The least polar radiometabolite of [(11)C]dLop was identified with LC-MS(n) as the N-hydroxymethyl analog of [(11)C]dLop and this also behaved as a P-gp substrate. CONCLUSION In this study, ketoconazole (50 mg/kg, ip) proved partially effective for inhibiting the N-demethylation of [(11)C]loperamide in mouse in vivo but had relatively smaller or no effect on [(11)C]dLop.
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Affiliation(s)
- Nicholas Seneca
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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Charnay Y, Léger L. Brain serotonergic circuitries. DIALOGUES IN CLINICAL NEUROSCIENCE 2010; 12:471-87. [PMID: 21319493 PMCID: PMC3181988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2023]
Abstract
Brain serotonergic circuitries interact with other neurotransmitter systems on a multitude of different molecular levels. In humans, as in other mammalian species, serotonin (5-HT) plays a modulatory role in almost every physiological function. Furthermore, serotonergic dysfunction is thought to be implicated in several psychiatric and neurodegenerative disorders. We describe the neuroanatomy and neurochemistry of brain serotonergic circuitries. The contribution of emergent in vivo imaging methods to the regional localization of binding site receptors and certain aspects of their functional connectivity in correlation to behavior is also discussed. 5-HT cell bodies, mainly localized in the raphe nuclei, send axons to almost every brain region. It is argued that the specificity of the local chemocommunication between 5-HT and other neuronal elements mainly depends on mechanisms regulating the extracellular concentration of 5-HT the diversity of high-affinity membrane receptors, and their specific transduction modalities.
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Affiliation(s)
- Yves Charnay
- Hôpitaux Universitaires de Genève, Département de Psychiatrie, Service de Neuropsychiatrie, Ch. Du Petit-Bel-Air, 2, CH-1225 Chêne-Bourg, Switzerland.
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