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Cybulska K, Perk L, Booij J, Laverman P, Rijpkema M. Huntington's Disease: A Review of the Known PET Imaging Biomarkers and Targeting Radiotracers. Molecules 2020; 25:molecules25030482. [PMID: 31979301 PMCID: PMC7038198 DOI: 10.3390/molecules25030482] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 12/19/2022] Open
Abstract
Huntington’s disease (HD) is a fatal neurodegenerative disease caused by a CAG expansion mutation in the huntingtin gene. As a result, intranuclear inclusions of mutant huntingtin protein are formed, which damage striatal medium spiny neurons (MSNs). A review of Positron Emission Tomography (PET) studies relating to HD was performed, including clinical and preclinical data. PET is a powerful tool for visualisation of the HD pathology by non-invasive imaging of specific radiopharmaceuticals, which provide a detailed molecular snapshot of complex mechanistic pathways within the brain. Nowadays, radiochemists are equipped with an impressive arsenal of radioligands to accurately recognise particular receptors of interest. These include key biomarkers of HD: adenosine, cannabinoid, dopaminergic and glutamateric receptors, microglial activation, phosphodiesterase 10 A and synaptic vesicle proteins. This review aims to provide a radiochemical picture of the recent developments in the field of HD PET, with significant attention devoted to radiosynthetic routes towards the tracers relevant to this disease.
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Affiliation(s)
- Klaudia Cybulska
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
- Radboud Translational Medicine B.V., Radboud University Medical Center, Geert Grooteplein 21 (route 142), 6525 EZ Nijmegen, The Netherlands;
- Correspondence:
| | - Lars Perk
- Radboud Translational Medicine B.V., Radboud University Medical Center, Geert Grooteplein 21 (route 142), 6525 EZ Nijmegen, The Netherlands;
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Peter Laverman
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
| | - Mark Rijpkema
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
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Thum S, Schepmann D, Ayet E, Pujol M, Nieto FR, Ametamey SM, Wünsch B. Tetrahydro-3-benzazepines with fluorinated side chains as NMDA and σ 1 receptor antagonists: Synthesis, receptor affinity, selectivity and antiallodynic activity. Eur J Med Chem 2019; 177:47-62. [PMID: 31129453 DOI: 10.1016/j.ejmech.2019.05.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 04/23/2019] [Accepted: 05/12/2019] [Indexed: 11/24/2022]
Abstract
The class of tetrahydro-1H-3-benzazepines was systematically modified in 1-, 3- and 7-position. In particular, a F-atom was introduced in β- or γ-position of the 4-phenylbutyl side chain in 3-position. Ligands with the F-atom in γ-position possess higher GluN2B affinity than analogs bearing the F-atom in β-position. This effect was attributed to the reduced basicity of β-fluoro amines. 3-Benzazepines with a benzylic OH moiety show moderate GluN2B affinity, but considerable selectivity over the σ2 receptor. However, removal of the benzylic OH moiety led to increased GluN2B affinity, but reduced GluN2B/σ2 selectivity. With respect to GluN2B affinity the phenol 17b with a γ-fluorophenylbutyl moiety in 3-position represents the most interesting fluorinated ligand (Ki(GluN2B) = 16 nM). Most of the synthesized ligands reveal either similar GluN2B and σ1 affinity or higher σ1 affinity than GluN2B affinity. The methyl ether 16b shows high σ1 affinity (Ki(σ1) = 6.6 nM) and high selectivity over a broad panel of receptors and transporters. The high antiallodynic activity in the mouse capsaicin assay proved the σ1 antagonistic activity of 16b.
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Affiliation(s)
- Simone Thum
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Eva Ayet
- Esteve Pharmaceuticals S.A, Baldiri Reixach 4-8, 08028 Barcelona, Spain
| | - Marta Pujol
- Esteve Pharmaceuticals S.A, Baldiri Reixach 4-8, 08028 Barcelona, Spain
| | - Francisco R Nieto
- Department of Pharmacology and Institute of Neuroscience, School of Medicine and Biomedical Research Center, University of Granada, Avenida de la Investigación 11, 18016 Granada, Spain
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Corrensstraße 48, D-48149 Münster, Germany; Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), Westfälische Wilhelms-Universität Münster, Germany.
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Twomey EC, Yelshanskaya MV, Vassilevski AA, Sobolevsky AI. Mechanisms of Channel Block in Calcium-Permeable AMPA Receptors. Neuron 2018; 99:956-968.e4. [PMID: 30122377 PMCID: PMC6181147 DOI: 10.1016/j.neuron.2018.07.027] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/20/2018] [Accepted: 07/17/2018] [Indexed: 01/14/2023]
Abstract
AMPA receptors mediate fast excitatory neurotransmission and are critical for CNS development and function. Calcium-permeable subsets of AMPA receptors are strongly implicated in acute and chronic neurological disorders. However, despite the clinical importance, the therapeutic landscape for specifically targeting them, and not the calcium-impermeable AMPA receptors, remains largely undeveloped. To address this problem, we used cryo-electron microscopy and electrophysiology to investigate the mechanisms by which small-molecule blockers selectively inhibit ion channel conductance in calcium-permeable AMPA receptors. We determined the structures of calcium-permeable GluA2 AMPA receptor complexes with the auxiliary subunit stargazin bound to channel blockers, including the orb weaver spider toxin AgTx-636, the spider toxin analog NASPM, and the adamantane derivative IEM-1460. Our structures provide insights into the architecture of the blocker binding site and the mechanism of trapping, which are critical for development of small molecules that specifically target calcium-permeable AMPA receptors.
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Affiliation(s)
- Edward C Twomey
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University, New York, NY 10032, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Alexander A Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia; Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Oblast 141700, Russia
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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Morrison RL, Fedgchin M, Singh J, Van Gerven J, Zuiker R, Lim KS, van der Ark P, Wajs E, Xi L, Zannikos P, Drevets WC. Effect of intranasal esketamine on cognitive functioning in healthy participants: a randomized, double-blind, placebo-controlled study. Psychopharmacology (Berl) 2018; 235:1107-1119. [PMID: 29392371 PMCID: PMC5869899 DOI: 10.1007/s00213-018-4828-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 01/03/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND The effect of intranasal esketamine on cognitive functioning in healthy participants is assessed in this study. METHODS Twenty-four participants (19-49 years) were randomized to one of two treatment sequences in which either esketamine 84 mg or placebo was intranasally administered in a double-blind, two-period crossover design. Primary measures included five tests of Cogstate® computerized test battery assessed at 1 h predose and 40 min, 2, 4, and 6 h postdose. Secondary measures included the Mental Effort Scale, Karolinska Sleepiness Scale (KSS), and safety. RESULTS Esketamine was associated with significant cognitive performance impairment at 40 min postdose for all five Cogstate® tests (Detection p = 0.0011, Identification p = 0.0006, One-Card Learning p = 0.0040, One Back p = 0.0017, and Groton Maze Learning Test p < 0.0001) versus placebo. In contrast, performance on these tests did not differ significantly between esketamine and placebo at 2, 4, or 6 h postdose. Secondary outcomes indicated a significant, transient increase from baseline under esketamine versus placebo at 40 min postdose on the Mental Effort Scale and at 40 min and 2 h postdose on KSS (p < 0.0001 for both); however, no significant difference was observed on these outcomes between esketamine and placebo at later timepoints. The most commonly reported adverse events were dizziness (67%), nausea (37.5%), disturbance in attention (29.2%), and fatigue (29.2%); the majority were considered mild in severity. CONCLUSIONS Esketamine was associated with cognitive performance decline, and greater effort was required to complete the test battery versus placebo at 40 min postdose, which returned to placebo-comparable levels by 2 h postdose. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02094378.
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Affiliation(s)
- Randall L Morrison
- Neuroscience Integrative Solutions, 1125 Trenton-Harbourton Road, Titusville, NJ, 08560, USA.
- Janssen Research & Development, LLC, Titusville, NJ, USA.
| | | | - Jaskaran Singh
- Janssen Research & Development, LLC, Titusville, NJ, USA
| | | | - Rob Zuiker
- Centre for Human Drug Research, Leiden, The Netherlands
| | - Kyoung Soo Lim
- Centre for Human Drug Research, Leiden, The Netherlands
- CHA University School of Medicine and CHA Budang Medical Center, Seongnam, South Korea
| | - Peter van der Ark
- Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Ewa Wajs
- Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Liwen Xi
- Janssen Research & Development, LLC, Titusville, NJ, USA
| | - Peter Zannikos
- Janssen Research & Development, LLC, Titusville, NJ, USA
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Swanger SA, Vance KM, Acker TM, Zimmerman SS, DiRaddo JO, Myers SJ, Bundgaard C, Mosley CA, Summer SL, Menaldino DS, Jensen HS, Liotta DC, Traynelis SF. A Novel Negative Allosteric Modulator Selective for GluN2C/2D-Containing NMDA Receptors Inhibits Synaptic Transmission in Hippocampal Interneurons. ACS Chem Neurosci 2018; 9:306-319. [PMID: 29043770 PMCID: PMC5924706 DOI: 10.1021/acschemneuro.7b00329] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
N-Methyl-d-aspartate receptors (NMDARs) are ionotropic glutamate receptors that mediate excitatory synaptic transmission and have been implicated in numerous neurological disorders. NMDARs typically comprise two GluN1 and two GluN2 subunits. The four GluN2 subtypes (GluN2A-GluN2D) have distinct functional properties and gene expression patterns, which contribute to diverse functional roles for NMDARs in the brain. Here, we present a series of GluN2C/2D-selective negative allosteric modulators built around a N-aryl benzamide (NAB) core. The prototypical compound, NAB-14, is >800-fold selective for recombinant GluN2C/GluN2D over GluN2A/GluN2B in Xenopus oocytes and has an IC50 value of 580 nM at recombinant GluN2D-containing receptors expressed in mammalian cells. NAB-14 inhibits triheteromeric (GluN1/GluN2A/GluN2C) NMDARs with modestly reduced potency and efficacy compared to diheteromeric (GluN1/GluN2C/GluN2C) receptors. Site-directed mutagenesis suggests that structural determinants for NAB-14 inhibition reside in the GluN2D M1 transmembrane helix. NAB-14 inhibits GluN2D-mediated synaptic currents in rat subthalamic neurons and mouse hippocampal interneurons, but has no effect on synaptic transmission in hippocampal pyramidal neurons, which do not express GluN2C or GluN2D. This series possesses some druglike physical properties and modest brain permeability in rat and mouse. Altogether, this work identifies a new series of negative allosteric modulators that are valuable tools for studying GluN2C- and GluN2D-containing NMDAR function in brain circuits, and suggests that the series has the potential to be developed into therapies for selectively modulating brain circuits involving the GluN2C and GluN2D subunits.
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Affiliation(s)
- Sharon A. Swanger
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
| | - Katie M. Vance
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
| | | | | | - John O. DiRaddo
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
- Department of Chemistry, Emory University, Atlanta, GA 30322
| | - Scott J. Myers
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
| | | | - Cara A. Mosley
- Department of Chemistry, Emory University, Atlanta, GA 30322
| | | | | | - Henrik S. Jensen
- H. Lundbeck A/S, Molecular Screening, Ottiliavej 9, DK-2500 Valby, Denmark
| | | | - Stephen F. Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
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Abstract
Current therapeutic options for major depressive disorder (MDD) and bipolar disorder (BD) are associated with a lag of onset that can prolong distress and impairment for patients, and their antidepressant efficacy is often limited. All currently approved antidepressant medications for MDD act primarily through monoaminergic mechanisms. Glutamate is the major excitatory neurotransmitter in the central nervous system, and glutamate and its cognate receptors are implicated in the pathophysiology of MDD, and in the development of novel therapeutics for this disorder. The rapid and robust antidepressant effects of the N-methyl-d-aspartate (NMDA) antagonist ketamine were first observed in 2000. Since then, other NMDA receptor antagonists have been studied in MDD. Most have demonstrated relatively modest antidepressant effects compared to ketamine, but some have shown more favorable characteristics. This article reviews the clinical evidence supporting the use of novel glutamate receptor modulators with direct affinity for cognate receptors: (1) non-competitive NMDA receptor antagonists (ketamine, memantine, dextromethorphan, AZD6765); (2) subunit (GluN2B)-specific NMDA receptor antagonists (CP-101,606/traxoprodil, MK-0657); (3) NMDA receptor glycine-site partial agonists (GLYX-13); and (4) metabotropic glutamate receptor (mGluR) modulators (AZD2066, RO4917523/basimglurant). We also briefly discuss several other theoretical glutamate receptor targets with preclinical antidepressant-like efficacy that have yet to be studied clinically; these include α-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid (AMPA) agonists and mGluR2/3 negative allosteric modulators. The review also discusses other promising, non-glutamatergic targets for potential rapid antidepressant effects, including the cholinergic system (scopolamine), the opioid system (ALKS-5461), corticotropin releasing factor (CRF) receptor antagonists (CP-316,311), and others.
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Affiliation(s)
- Rodrigo Machado-Vieira
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
| | - Ioline D Henter
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Carlos A Zarate
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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Affiliation(s)
- C A Zarate
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - R Machado-Vieira
- Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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Witkin JM, Ornstein PL, Mitch CH, Li R, Smith SC, Heinz BA, Wang XS, Xiang C, Carter JH, Anderson WH, Li X, Broad LM, Pasqui F, Fitzjohn SM, Sanger HE, Smith JL, Catlow J, Swanson S, Monn JA. In vitro pharmacological and rat pharmacokinetic characterization of LY3020371, a potent and selective mGlu 2/3 receptor antagonist. Neuropharmacology 2015; 115:100-114. [PMID: 26748052 DOI: 10.1016/j.neuropharm.2015.12.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/09/2015] [Accepted: 12/22/2015] [Indexed: 12/27/2022]
Abstract
Metabotropic glutamate 2/3 (mGlu2/3) receptors are of considerable interest owing to their role in modulating glutamate transmission via presynaptic, postsynaptic and glial mechanisms. As part of our ongoing efforts to identify novel ligands for these receptors, we have discovered (1S,2R,3S,4S,5R,6R)-2-amino-3-[(3,4-difluorophenyl)sulfanylmethyl]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid; (LY3020371), a potent and selective orthosteric mGlu2/3 receptor antagonist. In this account, we characterize the effects of LY3020371 in membranes and cells expressing human recombinant mGlu receptor subtypes as well as in native rodent and human brain tissue preparations, providing important translational information for this molecule. In membranes from cells expressing recombinant human mGlu2 and mGlu3 receptor subtypes, LY3020371.HCl competitively displaced binding of the mGlu2/3 agonist ligand [3H]-459477 with high affinity (hmGlu2 Ki = 5.26 nM; hmGlu3 Ki = 2.50 nM). In cells expressing hmGlu2 receptors, LY3020371.HCl potently blocked mGlu2/3 agonist (DCG-IV)-inhibited, forskolin-stimulated cAMP formation (IC50 = 16.2 nM), an effect that was similarly observed in hmGlu3-expressing cells (IC50 = 6.21 nM). Evaluation of LY3020371 in cells expressing the other human mGlu receptor subtypes revealed high mGlu2/3 receptor selectivity. In rat native tissue assays, LY3020371 demonstrated effective displacement of [3H]-459477 from frontal cortical membranes (Ki = 33 nM), and functional antagonist activity in cortical synaptosomes measuring both the reversal of agonist-suppressed second messenger production (IC50 = 29 nM) and agonist-inhibited, K+-evoked glutamate release (IC50 = 86 nM). Antagonism was fully recapitulated in both primary cultured cortical neurons where LY3020371 blocked agonist-suppressed spontaneous Ca2+ oscillations (IC50 = 34 nM) and in an intact hippocampal slice preparation (IC50 = 46 nM). Functional antagonist activity was similarly demonstrated in synaptosomes prepared from epileptic human cortical or hippocampal tissues, suggesting a translation of the mGlu2/3 antagonist pharmacology from rat to human. Intravenous dosing of LY3020371 in rats led to cerebrospinal fluid drug levels that are expected to effectively block mGlu2/3 receptors in vivo. Taken together, these results establish LY3020371 as an important new pharmacological tool for studying mGlu2/3 receptors in vitro and in vivo. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Affiliation(s)
- Jeffrey M Witkin
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Paul L Ornstein
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Charles H Mitch
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Renhua Li
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Stephon C Smith
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Beverly A Heinz
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Xu-Shan Wang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Chuanxi Xiang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Joan H Carter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Wesley H Anderson
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Xia Li
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | | | | | | | | | | | - John Catlow
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Steven Swanson
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - James A Monn
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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Demmer CS, Møller C, Brown PMGE, Han L, Pickering DS, Nielsen B, Bowie D, Frydenvang K, Kastrup JS, Bunch L. Binding mode of an α-amino acid-linked quinoxaline-2,3-dione analogue at glutamate receptor subtype GluK1. ACS Chem Neurosci 2015; 6:845-54. [PMID: 25856736 DOI: 10.1021/acschemneuro.5b00038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Two α-amino acid-functionalized quinoxalines, 1a (CNG-10301) and 1b (CNG-10300), of a quinoxaline moiety coupled to an amino acid moiety were designed, synthesized, and characterized pharmacologically. While 1a displayed low affinity at native AMPA, KA, and NMDA receptors, and at homomeric GluK1,3 receptors, the affinity for GluK2 was in the midmicromolar range (Ki = 136 μM), 1b displayed low to midmicromolar range binding affinity at all the iGluRs (Ki = 9-126 μM). In functional experiments (outside-out patches excised from transfected HEK293T cells), 100 μM 1a partially blocked GluK1 (33% peak response), while GluK2 was unaffected (96% peak response). Furthermore, 1a was shown not to be an agonist at GluK1 and GluK2 at 100 μM. On the other hand, 100 μM 1b fully antagonized GluK1 (8% peak response) but only partially blocked GluK2 (33% peak response). An X-ray structure at 2.3 Å resolution of 1b in the GluK1-LBD (ligand-binding domain) disclosed an unexpected binding mode compared to the predictions made during the design phase; the quinoxaline moiety remains to act as an amino acid bioisostere, but the amino acid moiety is oriented into a new area within the GluK1 receptor. The structure of the GluK1-LBD with 1b showed a large variation in domain openings of the three molecules from 25° to 49°, demonstrating that the GluK1-LBD is capable of undergoing major domain movements.
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He X, Lakkaraju SK, Hanscom M, Zhao Z, Wu J, Stoica B, MacKerell AD, Faden AI, Xue F. Acyl-2-aminobenzimidazoles: a novel class of neuroprotective agents targeting mGluR5. Bioorg Med Chem 2015; 23:2211-20. [PMID: 25801156 DOI: 10.1016/j.bmc.2015.02.054] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 02/13/2015] [Accepted: 02/26/2015] [Indexed: 01/08/2023]
Abstract
Positive allosteric modulators (PAMs) of the metabotropic glutamate receptor 5 (mGluR5) are promising therapeutic agents for treating traumatic brain injury (TBI). Using computational and medicinal methods, the structure-activity relationship of a class of acyl-2-aminobenzimidazoles (1-26) is reported. The new compounds are designed based on the chemical structure of 3,3'-difluorobenzaldazine (DFB), a known mGluR5 PAM. Ligand design and prediction of binding affinities of the new compounds have been performed using the site identification by ligand competitive saturation (SILCS) method. Binding affinities of the compounds to the transmembrane domain of mGluR5 have been evaluated using nitric oxide (NO) production assay, while the safety of the compounds is tested. One new compound found in this study, compound 22, showed promising activity with an IC₅₀ value of 6.4 μM, which is ∼20 fold more potent than that of DFB. Compound 22 represents a new lead for possible development as a treatment for TBI and related neurodegenerative conditions.
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Affiliation(s)
- Xinhua He
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States
| | - Sirish K Lakkaraju
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States
| | - Marie Hanscom
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Zaorui Zhao
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Bogdan Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Fengtian Xue
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States.
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11
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Hjerrild S, Bjerre J, Pedersen RH, Videbech P. [Ketamine for treatment of acute depression]. Ugeskr Laeger 2013; 175:2090-2093. [PMID: 24011203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In clinical trials a single dose of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has shown a rapid antidepressant effect in patients with treatment-resistant depression and bipolar depression. The implications of glutaminergic mechanisms in depression and the rapid effect of a single dose of ketamine could open new pathways to understand the pathophysiology of depression and the development of novel rapid-acting antidepressant drugs.
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Affiliation(s)
- Simon Hjerrild
- Center for Psykiatrisk Forskning, Aarhus Universitetshospital, Risskov, Skovagervej 2, 8240 Risskov.
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England PM. Developing a photoreactive antagonist. Methods Mol Biol 2013; 995:121-129. [PMID: 23494376 DOI: 10.1007/978-1-62703-345-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Light is an exquisite reagent for controlling the activity of biological systems, often offering improved temporal and spatial resolution over strictly genetic, biochemical, or pharmacological manipulations. This chapter describes a general approach for developing small molecules that, upon irradiation with light, may be used to rapidly inactivate targeted proteins expressed on the surfaces of cells. Highlighted is ANQX, a photoreactive AMPA receptor antagonist developed to irreversibly inactivate a subtype of glutamate-gated ion channels natively expressed on neurons.
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Affiliation(s)
- Pamela M England
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
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13
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Marchetti C, Gavazzo P, Stafford GI, Van Staden J. South African plants used in traditional medicine to treat epilepsy have an antagonistic effect on NMDA receptor currents. J Ethnopharmacol 2011; 137:382-388. [PMID: 21669274 DOI: 10.1016/j.jep.2011.05.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/12/2011] [Accepted: 05/26/2011] [Indexed: 05/30/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Several Searsia species (Anacardiaceae), including Searsia dentata and Searsia pyroides, are used in South Africa traditional medicine to treat epilepsy. Ethanol leaf extracts of these plants have been shown to act as possible antagonists of N-methyl-d-aspartate (NMDA)-type glutamate receptors. MATERIALS AND METHODS Leaf material of three Searsia species were collected from the Botanical Garden at the University of KwaZulu-Natal, Pietermaritzburg; dried and extracted with ethanol in an ultrasound bath. Filtered and dried extracts were resuspended in DMSO (100mg/ml) and diluted in the recording solution. The effect of Searsia dentata, Searsia pyroides and Searsia glauca extracts was investigated in dissociated cerebellar granule cells (CGCs) from 8-day-old rats and in transiently transfected HEK (human embryonic kidney) 293 cells (HEK), expressing either NR1a/NR2A or NR1a/NR2B receptors. In both systems we measured whole-cell currents elicited by 0.5mM NMDA (CGCs) or 50 μM glutamic acid (HEK) at -60 mV in 0Mg and 30 μM glycine and NMDA driven Ca influx in Fura2-loaded CGC. RESULTS Searsia dentata and Searsia pyroides ethanol extracts caused a dose-dependent decrease of NR current with ED(50) close to 0.03 mg/ml in CGC and a similar inhibition (80% with 1mg/ml) in HEK cells, while Searsia glauca was much less effective. The inhibition was dependent on time of incubation and slightly favored by opening of the NR channel. It was hardly reversible during the recording time, but was not caused by accelerated run-down or by interaction with the modulatory redox site. Searsia pyroides ethanol extract also depressed the NMDA stimulated increase in intracellular Ca. CONCLUSIONS The data confirm the specificity of Searsia dentata and Searsia pyroides and justify their use in traditional medicine. These plants may combine one or more γ-aminobutyric acid (GABA)(A) agonists with one or more NMDA antagonists, thus representing an efficient treatment for epilepsy.
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Affiliation(s)
- Carla Marchetti
- Institute of Biophysics, National Research Council, via De Marini 6, 16149 Genova, Italy.
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14
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Ohi Y, Tsunekawa S, Haji A. Dextromethorphan inhibits the glutamatergic synaptic transmission in the nucleus tractus solitarius of guinea pigs. J Pharmacol Sci 2011; 116:54-62. [PMID: 21487194 DOI: 10.1254/jphs.11008fp] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Dextromethorphan (DEX) is a widely used non-opioid antitussive. However, the precise site of action and its mechanism were not fully understood. We examined the effects of DEX on AMPA receptor-mediated glutamatergic transmission in the nucleus tractus solitarius (NTS) of guinea pigs. Excitatory postsynaptic currents (evoked EPSCs: eEPSCs) were evoked in the second-order neurons by electrical stimulation of the tractus solitarius. DEX reversibly decreased the eEPSC amplitude in a concentration-dependent manner. The DEX-induced inhibition of eEPSC was accompanied by an increased paired-pulse ratio. Miniature EPSCs (mEPSCs) were also recorded in the presence of Cd(2+) or tetrodotoxin. DEX decreased the frequency of mEPSCs without affecting their amplitude. Topically applied AMPA provoked an inward current in the neurons, which was unchanged during the perfusion of DEX. BD1047, a σ-1-receptor antagonist, did not block the inhibitory effect of DEX on the eEPSCs, but antagonized the inhibition of eEPSCs induced by SKF-10047, a σ-1 agonist. Haloperidol, a σ-1 and -2 receptor ligand, had no influence on the inhibitory action of DEX. These results suggest that DEX inhibits glutamate release from the presynaptic terminals projecting to the second-order NTS neurons, but this effect of DEX is not mediated by the activation of σ receptors.
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Affiliation(s)
- Yoshiaki Ohi
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Chikusa, Nagoya 464-8650, Japan
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15
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Abstract
The AMPA-type ionotropic glutamate receptors (AMPA-Rs) are tetrameric ligand-gated ion channels that play crucial roles in synaptic transmission and plasticity. Our knowledge about the ultrastructure and subunit assembly mechanisms of intact AMPA-Rs was very limited. However, the new studies using single particle EM and X-ray crystallography are revealing important insights. For example, the tetrameric crystal structure of the GluA2cryst construct provided the atomic view of the intact receptor. In addition, the single particle EM structures of the subunit assembly intermediates revealed the conformational requirement for the dimer-to-tetramer transition during the maturation of AMPA-Rs. These new data in the field provide new models and interpretations. In the brain, the native AMPA-R complexes contain auxiliary subunits that influence subunit assembly, gating, and trafficking of the AMPA-Rs. Understanding the mechanisms of the auxiliary subunits will become increasingly important to precisely describe the function of AMPA-Rs in the brain. The AMPA-R proteomics studies continuously reveal a previously unexpected degree of molecular heterogeneity of the complex. Because the AMPA-Rs are important drug targets for treating various neurological and psychiatric diseases, it is likely that these new native complexes will require detailed mechanistic analysis in the future. The current ultrastructural data on the receptors and the receptor-expressing stable cell lines that were developed during the course of these studies are useful resources for high throughput drug screening and further drug designing. Moreover, we are getting closer to understanding the precise mechanisms of AMPA-R-mediated synaptic plasticity.
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Affiliation(s)
- Terunaga Nakagawa
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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16
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Luo J, Li W, Zhao Y, Fu H, Ma DL, Tang J, Li C, Peoples RW, Li F, Wang Q, Huang P, Xia J, Pang Y, Han Y. Pathologically activated neuroprotection via uncompetitive blockade of N-methyl-D-aspartate receptors with fast off-rate by novel multifunctional dimer bis(propyl)-cognitin. J Biol Chem 2010; 285:19947-58. [PMID: 20404346 PMCID: PMC2888406 DOI: 10.1074/jbc.m110.111286] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 04/12/2010] [Indexed: 01/06/2023] Open
Abstract
Uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists with fast off-rate (UFO) may represent promising drug candidates for various neurodegenerative disorders. In this study, we report that bis(propyl)-cognitin, a novel dimeric acetylcholinesterase inhibitor and gamma-aminobutyric acid subtype A receptor antagonist, is such an antagonist of NMDA receptors. In cultured rat hippocampal neurons, we demonstrated that bis(propyl)-cognitin voltage-dependently, selectively, and moderately inhibited NMDA-activated currents. The inhibitory effects of bis(propyl)-cognitin increased with the rise in NMDA and glycine concentrations. Kinetics analysis showed that the inhibition was of fast onset and offset with an off-rate time constant of 1.9 s. Molecular docking simulations showed moderate hydrophobic interaction between bis(propyl)-cognitin and the MK-801 binding region in the ion channel pore of the NMDA receptor. Bis(propyl)-cognitin was further found to compete with [(3)H]MK-801 with a K(i) value of 0.27 mum, and the mutation of NR1(N616R) significantly reduced its inhibitory potency. Under glutamate-mediated pathological conditions, bis(propyl)-cognitin, in contrast to bis(heptyl)-cognitin, prevented excitotoxicity with increasing effectiveness against escalating levels of glutamate and much more effectively protected against middle cerebral artery occlusion-induced brain damage than did memantine. More interestingly, under NMDA receptor-mediated physiological conditions, bis(propyl)-cognitin enhanced long-term potentiation in hippocampal slices, whereas MK-801 reduced and memantine did not alter this process. These results suggest that bis(propyl)-cognitin is a UFO antagonist of NMDA receptors with moderate affinity, which may provide a pathologically activated therapy for various neurodegenerative disorders associated with NMDA receptor dysregulation.
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Affiliation(s)
- Jialie Luo
- From the Department of Applied Biology and Chemical Technology, Institute of Modern Chinese Medicine, Hong Kong Polytechnic University, Hong Kong, China
- the Departments of Biochemistry and
| | - Wenming Li
- From the Department of Applied Biology and Chemical Technology, Institute of Modern Chinese Medicine, Hong Kong Polytechnic University, Hong Kong, China
| | | | - Hongjun Fu
- From the Department of Applied Biology and Chemical Technology, Institute of Modern Chinese Medicine, Hong Kong Polytechnic University, Hong Kong, China
| | - Dik-Lung Ma
- the Department of Chemistry, University of Hong Kong, Hong Kong, China
| | - Jing Tang
- the Mayo Foundation for Medical Education and Research, Rochester, Minnesota 55905
| | - Chaoying Li
- the Wuhan Institute of Neuroscience and Drug Research, Jianghan University, Wuhan 430056, China
| | - Robert W. Peoples
- the Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53201, and
| | - Fushun Li
- the Department of Physiology, Medical School, Ningbo University, Ningbo 315211, China
| | - Qinwen Wang
- the Department of Physiology, Medical School, Ningbo University, Ningbo 315211, China
| | - Pingbo Huang
- Biology, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jun Xia
- the Departments of Biochemistry and
| | - Yuanping Pang
- the Mayo Foundation for Medical Education and Research, Rochester, Minnesota 55905
| | - Yifan Han
- From the Department of Applied Biology and Chemical Technology, Institute of Modern Chinese Medicine, Hong Kong Polytechnic University, Hong Kong, China
- the Departments of Biochemistry and
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17
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Dravolina OA, Bespalov AI, Zakharova ES, Zvartau EE. [Behavioral mechanisms of nicotine dependence: a search for new drugs]. Zh Nevrol Psikhiatr Im S S Korsakova 2010; 110:73-81. [PMID: 21465824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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18
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Fedorova IM, Magazanik LG, Tikhonov DB. Characterization of ionotropic glutamate receptors in insect neuro-muscular junction. Comp Biochem Physiol C Toxicol Pharmacol 2009; 149:275-80. [PMID: 18723120 DOI: 10.1016/j.cbpc.2008.07.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 07/28/2008] [Accepted: 07/29/2008] [Indexed: 11/24/2022]
Abstract
Pharmacological properties of ionotropic glutamate receptors from Calliphora vicina larvae neuro-muscular junction (C. vicina iGlurs) were studied by two-electrode voltage-clamp technique. Characteristics of the ion channel pore were analyzed using a 26-member series of channel blockers, which includes mono- and dicationic derivatives of adamantane and phenylcyclohexyl. Structure-activity relationships were found to be markedly similar to the Ca2+-permeable AMPA receptors (AMPAR) but not NMDA receptors (NMDAR) channel subtype seen in vertebrates. Like AMPARs the channels of C. vicina iGlurs are sensitive mainly to dicationic compounds with 6-7 spacers between hydrophobic headgroup and terminal aminogroup. Study of the voltage dependence of block demonstrated that, like AMPARs, the C. vicina iGlur channels, are permeable to organic cations with dimensions exceeding 10 A. Concentration dependence of block suggests the presence of two distinct channel populations with approximately 20-fold different sensitivity to cationic blockers. The recognition domain properties are more complex. Besides glutamate, the channels can be activated by kainate, quisqualate and domoate. Competitive antagonists of AMPAR and NMDAR are virtually inactive against the C. vicina iGlurs as well as allosteric modulators GYKI 52466 and PEPA. Surprisingly, the responses were potentiated 3 times by 100 mkM of cyclothiazide. We conclude that the channel-forming domain of C. vicina iGlurs is AMPAR-like, whereas the recognition domain is specific.
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Affiliation(s)
- I M Fedorova
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St-Petersburg, Russia
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19
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Missel PJ, Stevens LE. Adaptation of USP Types II and IV Controlled Release Assays for Sparingly Soluble Compounds by Direct Eluent HPLC Analysis. Pharm Dev Technol 2008; 11:87-91. [PMID: 16544912 DOI: 10.1080/10837450500464081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Measurement of drug release of a sparingly soluble drug by conventional methods proceeds very slowly without the aid of surfactants. Two preliminary automated methods were developed that increase sensitivity and accelerate such studies by working at very small reservoir volumes. All high pressure liquid chromatography (HPLC) equipment components were commercially available. Results are presented for the drug release of a single pellet of the sparingly soluble drug Eliprodil in two types of drug release experiments using (1) a stirred cell and (2) a flow-through method. Release rates measured from each method were comparable.
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Affiliation(s)
- P J Missel
- Drug Delivery, Alcon Research Ltd., Fort Worth, Texas, USA.
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20
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Gasparini F, Bilbe G, Gomez-Mancilla B, Spooren W. mGluR5 antagonists: discovery, characterization and drug development. Curr Opin Drug Discov Devel 2008; 11:655-665. [PMID: 18729017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Disturbances of glutamate-mediated neurotransmission have been implicated in a broad range of nervous system disorders. Numerous attempts to correct nervous system dysfunction by pharmacological intervention at glutamate receptors have been made, and some of the approaches have achieved a high level of preclinical validation. However, in a number of cases involving agents acting as blockers of the ionotropic glutamate receptors, clinical success could not be achieved, mostly because of the lack of a therapeutic window. The identification of the metabotropic glutamate receptor (mGluR) family and their modulatory role in the control of neurotransmission provided a new means to alter glutamatergic transmission. Furthermore, selective agents acting as allosteric antagonists at the mGluR5 subtype have demonstrated therapeutic potential. The identification and characterization of mGluR5 antagonists and recent progress in clinical development are summarized.
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Affiliation(s)
- Fabrizio Gasparini
- Novartis Pharma AG, Novartis Institutes for BioMedical Research Basel, Neurosciences Discovery, Basel, Switzerland.
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21
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Conti P, Pinto A, Tamborini L, Grazioso G, De Sarro G, Bräuner-Osborne H, Szabo G, Gábor Hársing L, De Micheli C. Synthesis of conformationally constrained glutamic acid homologues and investigation of their pharmacological profiles. ChemMedChem 2008; 2:1639-47. [PMID: 17849399 DOI: 10.1002/cmdc.200700118] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Homologation of the glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. We investigated the effects of a further increase in the distance between the amino acid moiety and the distal carboxylate group of model compounds (+/-)-1 and (+/-)-2 on their activity/selectivity profiles. We therefore synthesized new derivatives (+/-)-3-(+/-)-6, which are homologues of glutamic acid containing three additional carbon units. Moreover, because the potency of NMDA antagonists can be markedly increased by replacing the distal carboxylate with the bioisosteric phosphonate group, we also prepared the corresponding phosphonate derivatives (+/-)-7-(+/-)-10. All new compounds were submitted to binding assays with iGluRs, and derivatives (+/-)-3-(+/-)-6 were also tested in second messenger assays at representative mGluR subtypes. All the applied structural modifications were detrimental to the interaction with NMDA receptors. Conversely, structural variation of the nonselective mGluR ligand (+/-)-2 led to derivative (+/-)-5, which behaved as a selective group I metabotropic receptor antagonist. Notably, upon i.c.v. administration in DBA/2 mice, amino acid (+/-)-5 produced a significant protection against audiogenic seizures, whereas it was inactive after i.p. administration.
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Affiliation(s)
- Paola Conti
- Istituto di Chimica Farmaceutica e Tossicologica Pietro Pratesi, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy.
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22
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Szárics E, Simon A, Visy J, Simon-Trompler E, Banka Z, Héja L, Hársing LG, Blaskó G, Kardos J. Cyclothiazide binding to the GABAA receptor. Neurosci Lett 2008; 439:66-9. [PMID: 18502046 DOI: 10.1016/j.neulet.2008.04.092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 04/22/2008] [Accepted: 04/29/2008] [Indexed: 11/19/2022]
Abstract
In order to explore the molecular interaction between cyclothiazide (CTZ) and gamma-aminobutyric acidA (GABAA) receptors, possibly underlying inhibition of GABAA receptor currents, [3H]-CTZ was synthesized. Binding of [3H]-CTZ to rat brain synaptic membranes could be observed only in the presence of the GABAA receptor antagonist (-)[1S,9R]-bicuculline methiodide (BMI) (EC(50,BMI)=500+/-80microM). GABA decreased [(3)H]-CTZ binding induced by the presence 300microM and 3mM BMI with IC(50,GABA) values of 300+/-50microM and 5.0+/-0.7mM, respectively. Binding of CTZ to [3H]-CTZ labeled sites was characterized by IC(50,CTZ) values of 0.16+/-0.03muM ([BMI]=300microM) and 7.0+/-0.5microM ([BMI]=3mM). Binding of the diastereomeric fraction [3H]-(3R,1'S,4'S,5'R+3S,1'R,4'R,5'S)-CTZ induced by 3mM BMI was quantitatively the more significant in cerebrocortical and hippocampal membranes. It was characterized by IC(50,CTZ)=80+/-15nM and IC(50,GABA)=13+/-3mcapital EM, Cyrillic. In the absence of BMI, CTZ (1mM) significantly decreased GABA-induced enhancement of [3H]-flunitrazepam binding. Our findings suggest that functional inhibition may occur through binding of CTZ to an allosteric site of GABAA receptors. This allosteric site is possibly emerged in the receptor conformation, stabilized by BMI binding.
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Affiliation(s)
- Eva Szárics
- Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest, Hungary.
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23
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Noeske T, Jirgensons A, Starchenkovs I, Renner S, Jaunzeme I, Trifanova D, Hechenberger M, Bauer T, Kauss V, Parsons CG, Schneider G, Weil T. Virtual Screening for Selective Allosteric mGluR1 Antagonists and Structure–Activity Relationship Investigations for Coumarine Derivatives. ChemMedChem 2007; 2:1763-73. [PMID: 17868161 DOI: 10.1002/cmdc.200700151] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A virtual screening study towards novel noncompetitive antagonists of the metabotropic glutamate receptor 1 (mGluR1) is described. Alignment-free topological pharmacophore descriptors (CATS) were used to encode the screening compounds. All virtual hits were characterized with respect to their allosteric antagonistic effect on mGluR1 in both functional and binding assays. Exceptionally high hit rates of up to 26 % were achieved, confirming the applicability of this virtual screening concept. Most of the compounds were found to be moderately active, however, one potent and subtype selective mGluR1 antagonist, 13 (IC(50): 0.362 microM, SEM +/-0.031; K(i): 0.753 microM, SEM +/-0.048), based on a coumarine scaffold was discovered. In a following activity optimization program a series of coumarine derivatives was synthesized. This led to the discovery of potent (60, IC(50): 0.058 microM, SEM +/-0.008; K(i): 0.293 microM, SEM +/-0.022) and subtype selective (rmGluR5 IC(50): 28.6 microM) mGluR1 antagonists. From our homology model of mGluR1 we derived a potential binding mode within the allosteric transmembrane region. Potential interacting patterns are proposed considering the difference of the binding pockets between rat and human receptors. The study demonstrates the applicability of ligand-based virtual screening for noncompetitive antagonists of a G-protein coupled receptor, resulting in novel, potent, and selective agents.
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Affiliation(s)
- Tobias Noeske
- Merz Pharmaceuticals GmbH, Altenhöfer Allee 3, 60438 Frankfurt am Main, Germany
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24
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Takayama H, Yaegashi Y, Kitajima M, Han X, Nishimura K, Okuyama S, Igarashi K. Design, synthesis, and biological evaluation of tricyclic heterocycle-tetraamine conjugates as potent NMDA channel blockers. Bioorg Med Chem Lett 2007; 17:4729-32. [PMID: 17624774 DOI: 10.1016/j.bmcl.2007.06.069] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 06/20/2007] [Accepted: 06/22/2007] [Indexed: 11/22/2022]
Abstract
We have developed a new class of N-methyl-d-aspartate (NMDA) channel blockers having a conjugate structure that consists of a nitrogenous heterocyclic head and a tetraamine tail. Among them, dihydrodibenzazepine-homospermine conjugate (8) exhibited potent antagonistic activity at NR1/NR2A or NR1/NR2B NMDA subtype receptors compared with the lead compound, AQ343 (1), or memantine, as well as weak cytotoxicity. Its superior biological profiles compared with known compounds point to its potential use as therapeutic agents for neurological disorders.
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Affiliation(s)
- Hiromitsu Takayama
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
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25
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Bacilieri M, Varano F, Deflorian F, Marini M, Catarzi D, Colotta V, Filacchioni G, Galli A, Costagli C, Kaseda C, Moro S. Tandem 3D-QSARs approach as a valuable tool to predict binding affinity data: design of new Gly/NMDA receptor antagonists as a key study. J Chem Inf Model 2007; 47:1913-22. [PMID: 17722877 DOI: 10.1021/ci7001846] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantitative structure-activity relationships (QSARs) represent a very well consolidated computational approach to correlate structural or property descriptors of chemical compounds with their chemical or biological activities. We have recently reported that autocorrelation Molecular Electrostatic Potential (autoMEP) vectors in combination to Partial Least-Square (PLS) analysis or to Response Surface Analysis (RSA) can represent an interesting alternative 3D-QSAR strategy. In the present paper, we would like to present how the applicability of in tandem linear and nonlinear 3D-QSAR methods (autoMEP/PLS&RSA) can help to predict binding affinity data of a new set of N-methyl-d-aspartate (Gly/NMDA) receptor antagonists.
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Affiliation(s)
- M Bacilieri
- Molecular Modeling Section, Department of Pharmaceutical Sciences, University of Padova, via Marzolo 5, I-35131 Padova, Italy
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26
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Jacobs MT, Zhang YW, Campbell SD, Rudnick G. Ibogaine, a noncompetitive inhibitor of serotonin transport, acts by stabilizing the cytoplasm-facing state of the transporter. J Biol Chem 2007; 282:29441-7. [PMID: 17698848 DOI: 10.1074/jbc.m704456200] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ibogaine, a hallucinogenic alkaloid with purported anti-addiction properties, inhibited serotonin transporter (SERT) noncompetitively by decreasing V(max) with little change in the K(m) for serotonin (5-HT). Ibogaine also inhibited binding to SERT of the cocaine analog 2beta-2-carbomethoxy-3-(4-[(125)I]iodophenyl)tropane. However, inhibition of binding was competitive, increasing the apparent K(D) without much change in B(max). Ibogaine increased the reactivity of cysteine residues positioned in the proposed cytoplasmic permeation pathway of SERT but not at nearby positions out of that pathway. In contrast, cysteines placed at positions in the extracellular permeation pathway reacted at slower rates in the presence of ibogaine. These results are consistent with the proposal that ibogaine binds to and stabilizes the state of SERT from which 5-HT dissociates to the cytoplasm, in contrast with cocaine, which stabilizes the state that binds extracellular 5-HT.
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Affiliation(s)
- Miriam T Jacobs
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8066, USA
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27
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Gitto R, Ficarra R, Stancanelli R, Guardo M, De Luca L, Barreca ML, Pagano B, Rotondo A, Bruno G, Russo E, De Sarro G, Chimirri A. Synthesis, resolution, stereochemistry, and molecular modeling of (R)- and (S)-2-acetyl-1-(4′-chlorophenyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline AMPAR antagonists. Bioorg Med Chem 2007; 15:5417-23. [PMID: 17566746 DOI: 10.1016/j.bmc.2007.05.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 05/24/2007] [Accepted: 05/25/2007] [Indexed: 11/20/2022]
Abstract
Recently we identified (R,S)-2-acetyl-1-(4'-chlorophenyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (6) as a potent non-competitive AMPA receptor antagonist able to prevent epileptic seizures. We report here the optimized synthesis of compound 6, its resolution by chiral preparative HPLC, and the absolute configuration of (R)-enantiomer established by X-ray diffractometry. The biological tests of the single enantiomers revealed that higher anticonvulsant and antagonistic effects reside in (R)-enantiomer as also suggested by molecular modeling studies.
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Affiliation(s)
- Rosaria Gitto
- Dipartimento Farmaco-Chimico, Università di Messina, Viale Annunziata, I-98168 Messina, Italy
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Milbank JBJ, Knauer CS, Augelli-Szafran CE, Sakkab-Tan AT, Lin KK, Yamagata K, Hoffman JK, Zhuang N, Thomas J, Galatsis P, Wendt JA, Mickelson JW, Schwarz RD, Kinsora JJ, Lotarski SM, Stakich K, Gillespie KK, Lam WW, Mutlib AE. Rational design of 7-arylquinolines as non-competitive metabotropic glutamate receptor subtype 5 antagonists. Bioorg Med Chem Lett 2007; 17:4415-8. [PMID: 17590335 DOI: 10.1016/j.bmcl.2007.06.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 11/16/2022]
Abstract
Rational replacement of the alkyne linker of mGluR5 antagonist MPEP gave 7-arylquinolines. SAR optimization gave an orally active compound with high affinity for the MPEP binding site.
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Affiliation(s)
- Jared B J Milbank
- Pfizer Global Research and Development, Michigan Laboratories, 2800 Plymouth Road, Ann Arbor, MI 48105, USA.
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29
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Buyukbingol E, Sisman A, Akyildiz M, Alparslan FN, Adejare A. Adaptive neuro-fuzzy inference system (ANFIS): A new approach to predictive modeling in QSAR applications: A study of neuro-fuzzy modeling of PCP-based NMDA receptor antagonists. Bioorg Med Chem 2007; 15:4265-82. [PMID: 17434739 DOI: 10.1016/j.bmc.2007.03.065] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Accepted: 03/20/2007] [Indexed: 11/18/2022]
Abstract
This paper proposes a new method, Adaptive Neuro-Fuzzy Inference System (ANFIS) to evaluate physicochemical descriptors of certain chemical compounds for their appropriate biological activities in terms of QSAR models with the aid of artificial neural network (ANN) approach combined with the principle of fuzzy logic. The ANFIS was utilized to predict NMDA (N-methyl-d-Aspartate) receptor binding activities of phencyclidine (PCP) derivatives. A data set of 38 drug-like compounds was coded with 1244 calculated molecular structure descriptors (clustered in 20 data sets) which were obtained from several sources, mainly from Dragon software. Prior to the progress to the ANFIS system, descriptors from the best subsets were selected using unsupervised forward selection (UFS) to eliminate redundancy and multicollinearity followed by fuzzy linear regression algorithm (FLR) which was used for variable selection. ANFIS was applied to train the final descriptors (Mor22m, E3s, R3v+, and R1e+) using a hybrid algorithm consisting of back-propagation and least-square estimation while the optimum number and shape of related functions were obtained through the subtractive clustering algorithm. Comparison of the proposed method with traditional methods, that is, multiple linear regression (MLR) and partial least-square (PLS) was also studied and the results indicated that the ANFIS model obtained from data sets achieved satisfactory accuracy.
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Affiliation(s)
- Erdem Buyukbingol
- Ankara University, Faculty of Pharmacy (ECZACILIK), Department of Pharmaceutical Chemistry, Tandogan 06100, Ankara, Turkey.
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30
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Gwag BJ, Lee YA, Ko SY, Lee MJ, Im DS, Yun BS, Lim HR, Park SM, Byun HY, Son SJ, Kwon HJ, Lee JY, Cho JY, Won SJ, Kim KW, Ahn YM, Moon HS, Lee HU, Yoon SH, Noh JH, Chung JM, Cho SI. Marked prevention of ischemic brain injury by Neu2000, an NMDA antagonist and antioxidant derived from aspirin and sulfasalazine. J Cereb Blood Flow Metab 2007; 27:1142-51. [PMID: 17106444 DOI: 10.1038/sj.jcbfm.9600418] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Excitotoxicity and oxidative stress mediate neuronal death after hypoxic-ischemic brain injury. We examined the possibility that targeting both N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity and oxidative stress would result in enhanced neuroprotection against hypoxic-ischemia. 2-Hydroxy-5-(2,3,5,6-tetrafluoro-4-trifluoromethyl-benzylamino)-benzoic acid (Neu2000) was derived from aspirin and sulfasalazine to prevent both NMDA neurotoxicity and oxidative stress. In cortical cell cultures, Neu2000 was shown to be an uncompetitive NMDA receptor antagonist and completely blocked free radical toxicity at doses as low as 0.3 micromol/L. Neu2000 showed marked neuroprotection in a masked fashion using histology and behavioral testing in two rodent models of focal cerebral ischemia without causing neurotoxic side effects. Neu2000 protected against the effects of middle cerebral artery occlusion, even when delivered 8 h after reperfusion. Single bolus administration of the drug prevented gray and white matter degeneration and spared neurologic function for over 28 days after MACO. Neu2000 may be a novel therapy for combating both NMDA receptor-mediated excitotoxicity and oxidative stress, the two major routes of neuronal death in ischemia, offering profound neuroprotection and an extended therapeutic window.
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Affiliation(s)
- Byoung Joo Gwag
- Neurotech Pharmaceuticals Co., Ajou University School of Medicine, Suwon, Gyeonggido, South Korea.
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31
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Abstract
The N-methyl-D-aspartate receptor (NMDAR), a subtype of ionotropic glutamate receptor, has been implicated in a host of chronic and acute neurological disorders. Accordingly, much emphasis has been placed on the development of safe and effective therapeutic agents that specifically antagonize this target. The conantokins are a class of small, naturally occurring peptides that inhibit ion flow through the NMDAR. Some conantokins demonstrate receptor subunit selectivity, a pharmacological attribute of emerging importance in the search for suitable drug candidates. The current review summarizes the NMDAR inhibitory properties of the conantokins, including structure-function relationships and mechanism of action. This information is fundamental to the rational design of suitable agents that can effectively treat pathophysiologies linked to NMDAR dysfunction.
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Affiliation(s)
- Mary Prorok
- Department of Chemistry and Biochemistry and the W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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32
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Ciavarella AB, Gupta A, Sayeed VA, Khan MA, Faustino PJ. Development and application of a validated HPLC method for the determination of gabapentin and its major degradation impurity in drug products. J Pharm Biomed Anal 2007; 43:1647-53. [PMID: 17275240 DOI: 10.1016/j.jpba.2006.12.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 12/22/2006] [Accepted: 12/24/2006] [Indexed: 10/23/2022]
Abstract
A simple isocratic reversed-phase HPLC method for the determination of gabapentin and its major degradation impurity, 3,3-pentamethylene-4-butyrolactam, was developed and validated for use in the analysis of pharmaceutical tablets and capsules. Separation was achieved on a Brownlee Spheri-5 Cyano column using an acetonitrile-10 mM KH2PO4/10 mM K2HPO4 (pH 6.2) (8:92, v/v) mobile phase. The compounds were eluted isocratically at a flow rate of 1 mL/min. Both compounds were analyzed with UV detection at 210 nm. The method was validated according to USP Category I requirements for gabapentin and USP Category II for 3,3-pentamethylene-4-butyrolactam. The validation characteristics included accuracy, precision, linearity, range, specificity, limit of quantitation and robustness. Validation acceptance criteria were met in all cases. This method was used successfully for the quality assessment of four gabapentin drug products.
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Affiliation(s)
- Anthony B Ciavarella
- Division of Product Quality Research, Office of Pharmaceutical Science, Food and Drug Administration, Life Science Building 64, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
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33
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Abstract
Numerous studies over the last few years have suggested that modulating the glutamatergic system may be an efficient method to achieve an antidepressant effect. Data suggest that metabotropic glutamate receptors (mGlu receptors), related to long-term, modulatory effects on glutamatergic neurotransmission, may be a good target for the development of new, effective and safe therapeutic drugs to treat several CNS disorders including depression and anxiety. Several potent, selective and systemically active orthosteric and allosteric ligands of specific mGlu receptor subtypes have been discovered and these have been tested as potential antidepressants in models of depression in rodents. The mGluR5 antagonists and group II mGlu receptor antagonists seem to be the most promising compounds with potential antidepressant-like activity; however, the efficacy of mGlu receptor ligands in the clinical setting is still an unanswered question.
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Affiliation(s)
- Agnieszka Palucha
- Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31343 Kraków, Poland.
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Abstract
Lamotrigine is an antiepileptic drug employed in the treatment of partial epilepsies. We studied its possible interaction with channels other than its known therapeutic target, the voltage-gated sodium channel, using the adult muscle nicotinic acetylcholine receptor as a model system. At the single-channel level, lamotrigine caused a dose-dependent (a) diminution in mean open time, (b) increase in mean burst duration and (c) increase in the area of a new closed-time component. A simple linear channel blocking mechanism accounts for these results. Thus, lamotrigine exerts a blocking action on the muscle nicotinic acetylcholine receptor.
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Affiliation(s)
- Ana S Vallés
- UNESCO Chair of Biophysics and Molecular Neurobiology and Instituto de Investigaciones Bioquímicas de Bahía Blanca, Bahía Blanca, Buenos Aires, Argentina.
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35
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Noeske T, Sasse BC, Stark H, Parsons CG, Weil T, Schneider G. Predicting compound selectivity by self-organizing maps: cross-activities of metabotropic glutamate receptor antagonists. ChemMedChem 2007; 1:1066-8. [PMID: 16986201 DOI: 10.1002/cmdc.200600147] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tobias Noeske
- Johann Wolfgang Goethe University, Institute of Organic Chemistry and Chemical Biology ZAFES/CMP, Siesmayerstr 70, Frankfurt, Germany
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36
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Abstract
Quinoxaline derivatives have received much attention in recent years owing to their both biological properties and pharmaceutical applications. In this review we focus the attention on quinoxalin-2(3)-ones and quinoxalin-2,3-diones. These derivatives are particularly interesting since some of them showed antimicrobial (against several bacteria, viruses, fungi, etc), or anticancer activities. Furthermore, others are reported to be potent no-NMDA glutamate receptor antagonists, endowed with anxiolytic, deconditioning, analgesic, antispastic, antiallergic, antithrombotic activities. In this article we also report SAR studies and the most important methods of synthesis of the quinoxalin-2(3)-(di)ones.
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Affiliation(s)
- A Carta
- Dipartimento Farmaco Chimico Tossicologico, Facoltà di Farmacia, Università di Sassari, via Muroni 23/a, 07100 Sassari, Italy.
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Abstract
L-glutamate is considered the main excitatory neurotransmitter in the mammalian brain. Paradoxically, L-glutamate is also the most important excitotoxin pivotally involved in the aetiology of several neurodegenerative diseases such as stroke, Alzheimer, Parkinson, amyotropic lateral sclerosis, Huntington and neuropathic pain. L-glutamate signalling is transduced both presynaptically and postsynaptically by metabotropic and ionotropic receptors. Three types of glutamate-gated channels integrate the synaptic signal, namely AMPA, kainate and NMDA receptors. Sustained activation of these receptors, and especially of the NMDA receptor, is a casuistic phenomenon that leads to the neuronal death underlying neurodegeneration. Thus, pharmacological intervention at these neuronal receptors and their synaptic protein complexes is a valuable therapeutic strategy. The approval of memantine, a safe, well-tolerated uncompetitive NMDA antagonist for the treatment of moderate to severe Alzheimer dementia validates ionotropic glutamate receptors as key therapeutic targets of neurodegenerative diseases in humans. As a consequence, an enormous effort is being carried out to identify and develop safe and potent antagonists for the clinics. In this review, we will describe progress in this important arena of human health.
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38
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Donato P, Stancanelli R, Calabrò ML, Tommasini S, Cutroneo P, Guardo M, Pagano B, Chimirri A, Ficarra P, Ficarra R. Optimization of a LC method for the enantioseparation of a non-competitive glutamate receptor antagonist, by experimental design methodology. J Pharm Biomed Anal 2006; 42:543-8. [PMID: 16860510 DOI: 10.1016/j.jpba.2006.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 05/28/2006] [Accepted: 05/30/2006] [Indexed: 10/24/2022]
Abstract
The aim of this work was to obtain the direct optical resolution of a new glutamate receptor antagonist ((p-chloro)1-aryl-6,7,-dimethoxy-1,2,3,4-tetrahydroisoquinoline, PS3), by liquid chromatography on Chiralcel OD column. A response surface methodology (RSM) was employed to optimize the enantiomeric separation of the racemate with the lowest number of experiments; in particular, a face-centred design (FCD) was applied to evaluate the influence of critical parameters on the experimental response. Furthermore, in order to find the best compromise between several responses, a multicriteria decision-making approach, the Derringer's desirability function, was successful to simultaneously optimize the responses resolution and migration times of the two enantiomers. The proposed LC method provided the baseline enantioseparation of the investigated drug. 9.3% (v/v) ethanol added to n-hexane as mobile phase, 1.0 mL min(-1) flow rate, and 18 degrees C column temperature were the optimum experimental conditions allowing to achieve the highest enantioresolution of PS3 in less than 17 min.
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Affiliation(s)
- P Donato
- Dipartimento Farmaco-Chimico, Facoltà di Farmacia, Università di Messina, Viale Annunziata, 98168 Messina (ME), Italy
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39
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Abstract
This review provides an overview of ligands for the excitatory amino acid transporters (EAATs), a family of high-affinity glutamate transporters localized to the plasma membrane of neurons and astroglial cells. Ligand development from the perspective of identifying novel and more selective tools for elucidating transporter subtype function, and the potential of transporter ligands in a therapeutic setting are discussed. Acute pharmacological modulation of EAAT activity in the form of linear and conformationally restricted glutamate and aspartate analogs is presented, in addition to recent strategies aimed more toward modulating transporter expression levels, the latter of particular significance to the development of transporter based therapeutics.
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Affiliation(s)
- John Dunlop
- Neuroscience Discovery Research, Wyeth Research, CN 8000, Princeton NJ 08543, USA.
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40
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Kasper C, Pickering DS, Mirza O, Olsen L, Kristensen AS, Greenwood JR, Liljefors T, Schousboe A, Wätjen F, Gajhede M, Sigurskjold BW, Kastrup JS. The Structure of a Mixed GluR2 Ligand-binding Core Dimer in Complex with (S)-Glutamate and the Antagonist (S)-NS1209. J Mol Biol 2006; 357:1184-201. [PMID: 16483599 DOI: 10.1016/j.jmb.2006.01.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 01/03/2006] [Indexed: 11/25/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate fast synaptic transmission between cells of the central nervous system and are involved in various aspects of normal brain function. iGluRs are implicated in several brain disorders, e.g. in the high-frequency discharge of impulses during an epileptic seizure. (RS)-NS1209 functions as a competitive antagonist at 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionate receptors, and shows robust preclinical anticonvulsant and neuroprotective effects. This study explores 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionate receptor binding and selectivity of this novel class of antagonists. We present here the first X-ray structure of a mixed GluR2 ligand-binding core dimer, with the high-affinity antagonist (S)-8-methyl-5-(4-(N,N-dimethylsulfamoyl)phenyl)-6,7,8,9,-tetrahydro-1H-pyrrolo[3,2-h]-isoquinoline-2,3-dione-3-O-(4-hydroxybutyrate-2-yl)oxime [(S)-NS1209] in one protomer and the endogenous ligand (S)-glutamate in the other. (S)-NS1209 stabilises an even more open conformation of the D1 and D2 domains of the ligand-binding core than that of the apo structure due to steric hindrance. This is the first time ligand-induced hyperextension of the binding domains has been observed. (S)-NS1209 adopts a novel binding mode, including hydrogen bonding to Tyr450 and Gly451 of D1. Parts of (S)-NS1209 occupy new areas of the GluR2 ligand-binding cleft, and bind near residues that are not conserved among receptor subtypes. The affinities of (RS)-NS1209 at the GluR2 ligand-binding core as well as at GluR1-6 and mutated GluR1 and GluR3 receptors have been measured. Two distinct binding affinities were observed at the GluR3 and GluR4 receptors. In a functional in vitro assay, no difference in potency was observed between GluR2(Q)(o) and GluR3(o) receptors. The thermodynamics of binding of the antagonists (S)-NS1209, DNQX and (S)-ATPO to the GluR2 ligand-binding core have been determined by displacement isothermal titration calorimetry. The displacement of (S)-glutamate by all antagonists was shown to be driven by enthalpy.
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Affiliation(s)
- Christina Kasper
- Biostructural Research Department of Medicinal Chemistry, Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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41
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Abstract
In the mid 1960s the (dioxolan-4-yl)piperidine derivatives dexoxadrol ((S,S)-1a) and etoxadrol ((S,S,S)-2a) were synthesized. Their pharmacological potential as analgesics, anesthetics and local anesthetics was evaluated in animal models and later on in clinical trials with patients. However, severe side effects including psychotomimetic effects, unpleasant dreams and aberrations stopped the clinical evaluation of dexoxadrol and etoxadrol. Both dioxolane derivatives represent NMDA receptor antagonists, which possess high affinity to the phencyclidine binding site within the NMDA receptor associated ion channel. In this review relationships between the structure of acetalic dexoxadrol analogues and homologues and their affinity toward the phencyclidine binding site of the NMDA receptor are summarized. In particular, high affinity is attained with compounds bearing two phenyl residues or one phenyl residue and an alkyl residue with two or three carbon atoms at the acetalic center. At least one oxygen atom of the oxygen heterocycle is necessary. Instead of the entire piperidine ring aminoalkyl substructures are sufficient for strong receptor interactions. Compounds with a primary amino moiety generally display the highest receptor affinity, whereas tertiary amines possess low affinity. Enlargement of the 1,3-dioxolane ring to a 1,3-dioxane ring or elongation of the oxygen heterocycle / amino group distance results in compounds with considerable NMDA receptor affinity.
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Affiliation(s)
- Michael Sax
- Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Germany
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42
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Büttelmann B, Peters JU, Ceccarelli S, Kolczewski S, Vieira E, Prinssen EP, Spooren W, Schuler F, Huwyler J, Porter RHP, Jaeschke G. Arylmethoxypyridines as novel, potent and orally active mGlu5 receptor antagonists. Bioorg Med Chem Lett 2006; 16:1892-7. [PMID: 16439120 DOI: 10.1016/j.bmcl.2005.12.088] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 12/27/2005] [Accepted: 12/28/2005] [Indexed: 10/25/2022]
Abstract
Optimisation of affinity, chemical stability, metabolic stability and solubility led from a chemically labile HTS hit 1 to mGlu5 receptor antagonists (24-26) with high affinity for the allosteric MPEP binding site, improved microsomal metabolic stability and anxiolytic-like activity in vivo as assessed by the Vogel conflict drinking test.
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Affiliation(s)
- Bernd Büttelmann
- Pharma Division, Discovery Chemistry, F. Hoffman-La Roche Ltd, CH-4070 Basel, Switzerland
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43
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Abstract
Over activation of the NMDA receptor complex has been implicated in a number of neurological conditions. The use of NMDA antagonists as therapeutic agents has been limited by serious cognitive and motor side effects. Significant efforts have been reported in the development of NR2B subtype-selective antagonists, which have shown efficacy without the side effects observed with nonspecific NMDA antagonists. Classical ifenprodil-like molecules containing benzyl- and phenylpiperidines attached to a phenol or an appropriate isostere by a linker have provided valuable chemical leads as potential therapeutic agents. In this review, recent efforts in the discovery and development of structurally unique NR2B subtype-selective NMDA antagonists that do not fit the classical "ifenprodil-like" pharmacophore will be discussed.
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Affiliation(s)
- Mark E Layton
- Department of Medicinal Chemistry, Merck Research Laboratories, Merck & Co., West Point, PA 19486 USA.
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44
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Mayer ML, Ghosal A, Dolman NP, Jane DE. Crystal structures of the kainate receptor GluR5 ligand binding core dimer with novel GluR5-selective antagonists. J Neurosci 2006; 26:2852-61. [PMID: 16540562 PMCID: PMC6673968 DOI: 10.1523/jneurosci.0123-06.2005] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 01/30/2006] [Accepted: 01/31/2006] [Indexed: 12/31/2022] Open
Abstract
Glutamate receptor (GluR) ion channels mediate fast synaptic transmission in the mammalian CNS. Numerous crystallographic studies, the majority on the GluR2-subtype AMPA receptor, have revealed the structural basis for binding of subtype-specific agonists. In contrast, because there are far fewer antagonist-bound structures, the mechanisms for antagonist binding are much less well understood, particularly for kainate receptors that exist as multiple subtypes with a distinct biology encoded by the GluR5-7, KA1, and KA2 genes. We describe here high-resolution crystal structures for the GluR5 ligand-binding core complex with UBP302 and UBP310, novel GluR5-selective antagonists. The crystal structures reveal the structural basis for the high selectivity for GluR5 observed in radiolabel displacement assays for the isolated ligand binding cores of the GluR2, GluR5, and GluR6 subunits and during inhibition of glutamate-activated currents in studies on full-length ion channels. The antagonists bind via a novel mechanism and do not form direct contacts with the E723 side chain as occurs in all previously solved AMPA and kainate receptor agonist and antagonist complexes. This results from a hyperextension of the ligand binding core compared with previously solved structures. As a result, in dimer assemblies, there is a 22 A extension of the ion channel linkers in the transition from antagonist- to glutamate-bound forms. This large conformational change is substantially different from that described for AMPA receptors, was not possible to predict from previous work, and suggests that glutamate receptors are capable of much larger movements than previously thought.
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Affiliation(s)
- Mark L Mayer
- Porter Neuroscience Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.
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45
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Gouzoulis-Mayfrank E, Heekeren K, Neukirch A, Stoll M, Stock C, Obradovic M, Kovar KA. Psychological effects of (S)-ketamine and N,N-dimethyltryptamine (DMT): a double-blind, cross-over study in healthy volunteers. Pharmacopsychiatry 2006; 38:301-11. [PMID: 16342002 DOI: 10.1055/s-2005-916185] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Pharmacological challenges with hallucinogens are used as models for psychosis in experimental research. The state induced by glutamate antagonists such as phencyclidine (PCP) is often considered as a more appropriate model of psychosis than the state induced by serotonergic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin and N,N-dimethyltryptamine (DMT). However, so far, the psychological profiles of the two types of hallucinogenic drugs have never been studied directly in an experimental within-subject design. METHODS Fifteen healthy volunteers were included in a double-blind, cross-over study with two doses of the serotonin 5-HT2A agonist DMT and the glutamate N-methyl-D-aspartate (NMDA) antagonist (S)-ketamine. RESULTS Data are reported for nine subjects who completed both experimental days with both doses of the two drugs. The intensity of global psychological effects was similar for DMT and (S)-ketamine. However, phenomena resembling positive symptoms of schizophrenia, particularly positive formal thought disorder and inappropriate affect, were stronger after DMT. Phenomena resembling negative symptoms of schizophrenia, attention deficits, body perception disturbances and catatonia-like motor phenomena were stronger after (S)-ketamine. DISCUSSION The present study suggests that the NMDA antagonist model of psychosis is not overall superior to the serotonin 5-HT2A agonist model. Rather, the two classes of drugs tend to model different aspects or types of schizophrenia. The NMDA antagonist state may be an appropriate model for psychoses with prominent negative and possibly also catatonic features, while the 5-HT2A agonist state may be a better model for psychoses of the paranoid type.
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Affiliation(s)
- E Gouzoulis-Mayfrank
- Department of Psychiatry and Psychotherapy, University of Cologne, Kerpener Strasse 62, Cologne, Germany.
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46
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Takano Y, Shiga F, Asano J, Ando N, Uchiki H, Fukuchi K, Anraku T. Design, synthesis, and AMPA receptor antagonistic activity of a novel 6-nitro-3-oxoquinoxaline-2-carboxylic acid with a substituted phenyl group at the 7 position. Bioorg Med Chem 2005; 13:5841-63. [PMID: 15993606 DOI: 10.1016/j.bmc.2005.05.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 05/13/2005] [Accepted: 05/14/2005] [Indexed: 11/24/2022]
Abstract
We describe the design, synthesis, and biological properties of a novel series of 7-substituted 6-nitro-3-oxoquinoxaline-2-carboxylic acids. After designing, studying the structure-activity relationships, and evaluating the properties of various compounds, we found that 7-heterocyclic-6-nitro-3-oxoquinoxaline-2-carboxylic acids that contain a substituted phenyl group linked through urethane at the 7 position possess good alpha-amino-3-hydroxy-5-methylisoxazole propionate receptor (AMPA-R) antagonistic activity. Among the compounds tested, compound 29p (GRA-293), which has a 4-carboxy group on the terminal phenyl moiety, exhibited high potency and selectivity for the AMPA-R in vitro and good neuroprotective efficacy in vivo. It also showed good aqueous solubility.
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Affiliation(s)
- Yasuo Takano
- Discovery Research Laboratories, Kyorin Pharmaceutical Co., Ltd, 2399-1, Nogi, Nogi-machi, Simotsuga-gun, Tochigi 329-0114, Japan.
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47
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Tehrani LR, Smith ND, Huang D, Poon SF, Roppe JR, Seiders TJ, Chapman DF, Chung J, Cramer M, Cosford NDP. 3-[Substituted]-5-(5-pyridin-2-yl-2H-tetrazol-2-yl)benzonitriles: Identification of highly potent and selective metabotropic glutamate subtype 5 receptor antagonists. Bioorg Med Chem Lett 2005; 15:5061-4. [PMID: 16183275 DOI: 10.1016/j.bmcl.2005.07.062] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Revised: 07/28/2005] [Accepted: 07/29/2005] [Indexed: 11/23/2022]
Abstract
Structure-activity relationship studies on the phenyl ring of 3-(5-pyridin-2-yl-2H-tetrazol-2-yl)benzonitrile 2 led to the discovery that small, non-hydrogen bond donor substituents at the 3-position led to a substantial increase in in vitro potency. In particular, 3-fluoro-5-(5-pyridin-2-yl-2H-tetrazol-2-yl)benzonitrile (7) is a highly potent and selective mGlu5 receptor antagonist with good rat pharmacokinetics, brain penetration, and in vivo receptor occupancy.
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Affiliation(s)
- Lida R Tehrani
- Department of Medicinal Chemistry, Merck Research Laboratories, MRLSDB2, 3535 General Atomics Court, San Diego, CA 92121-1140, USA
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48
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Abstract
Schizophrenia is a neurodevelopmental mental disorder whose aetiology includes genetic and environmental factors. Because of its early onset, chronicity and characteristic interference with education, employment and socialisation, this illness represents a tremendous human and economic burden to those who suffer from it, their families and society as a whole. Conventional and atypical antipsychotics, which mainly affect dopaminergic and serotonergic neurotransmission, are currently the cornerstone of schizophrenia treatment. Although the introduction of atypical antipsychotics represents a major development and, overall, antipsychotics are efficacious against psychotic symptoms, there remains a critical unmet need for innovative medications with improved efficacy and tolerability for the negative symptoms and cognitive deficits associated with schizophrenia. These dysfunction domains are reliable predictors of long-term disability and treatment outcome and are presently viewed as crucial targets for new pharmacological treatments of schizophrenia. Within this medication development framework, the modulation of glutamatergic neurotransmission has become the focus of intense research. Glutamate (GLU)-mediated neuronal processes are critical throughout the brain and glutamatergic neurotransmission dysfunctions have been hypothesised to play a crucial role in schizophrenia pathophysiology. Glutamatergic neurotransmission may be modulated at multiple levels, with GLU receptor families and their subtypes representing a modulatory site-rich environment for drug research. Numerous types of neurotransmission modulators, acting at the NMDA, AMPA and metabotropic GLU receptors, and/or affecting GLU synaptic release, are hypothesised to be beneficial for schizophrenia treatment, and are presently in various stages of development. For some of these compounds, preliminary studies have furnished encouraging clinical data. Ongoing and planned research is expected to provide, in the near future, critical information regarding the practical utility and tolerability of glutamatergic approaches for schizophrenia pharmacotherapy.
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Affiliation(s)
- Uriel Heresco-Levy
- Ezrath Nashim-Sarah Herzog Memorial Hospital, Psychiatry Department, Hadassah Medical School, Hebrew University, PO Box 3900, Jerusalem 91035, Israel.
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49
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Grazioso G, Moretti L, Scapozza L, De Amici M, De Micheli C. Development of a three-dimensional model for the N-methyl-D-aspartate NR2A subunit. J Med Chem 2005; 48:5489-94. [PMID: 16107147 DOI: 10.1021/jm050174x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
NR2 subunits of N-methyl-d-aspartic acid (NMDA) receptors are known to bind the neurotransmitter glutamate, competitive agonists, and antagonists. Since crystallographic data of these proteins are not available, we built a homology model of the ligand binding domain of the NR2A subunit. A consensus binding mode of selected AP5-like NMDA antagonists has been ascertained using molecular docking. The present 3D model gives insights for the design of new NMDA subtype selective compounds.
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Affiliation(s)
- Giovanni Grazioso
- Istituto di Chimica Farmaceutica e Tossicologica, Università degli Studi di Milano, Viale Abruzzi 42, 20131 Milano, Italy
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50
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Abstract
The vesicular glutamate transporter (VGLUT) is responsible for the uptake of the excitatory amino acid, L-glutamate, into synaptic vesicles. VGLUT activity is coupled to an electrochemical gradient driven by a vacuolar ATPase and stimulated by low Cl-. VGLUT has relatively low affinity (K(m) = 1-3 mM) for glutamate and is pharmacologically and structurally distinct from the Na+-dependent, excitatory amino acid transporters (EAATs) found on the plasma membrane. Because glutamatergic neurotransmission begins with vesicular release, compounds that block the uptake of glutamate into the vesicle may reduce excitotoxic events. Several classes of competitive VGLUT inhibitors have emerged including amino acids and amino acid analogs, fatty acids, azo dyes, quinolines and alkaloids. The potency with which these agents inhibit VGLUT varies from millimolar (amino acids) to nanomolar (azo dyes) concentrations. These inhibitors represent highly diverse structures and have collectively begun to reveal key pharmacophore elements that may elucidate the key interactions important to binding VGLUT. Using known inhibitor structures and preliminary molecular modeling, a VGLUT pharmacophore is presented that will aid in the design of new, highly potent and selective agents.
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Affiliation(s)
- Charles M Thompson
- The Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA.
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