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Singh K, Kumar P, Bhatia R, Mehta V, Kumar B, Akhtar MJ. Nipecotic acid as potential lead molecule for the development of GABA uptake inhibitors; structural insights and design strategies. Eur J Med Chem 2022; 234:114269. [DOI: 10.1016/j.ejmech.2022.114269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/05/2022] [Accepted: 03/05/2022] [Indexed: 11/04/2022]
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Zafar S, Jabeen I. GRID-independent molecular descriptor analysis and molecular docking studies to mimic the binding hypothesis of γ-aminobutyric acid transporter 1 (GAT1) inhibitors. PeerJ 2019; 7:e6283. [PMID: 30723616 PMCID: PMC6360079 DOI: 10.7717/peerj.6283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/14/2018] [Indexed: 12/13/2022] Open
Abstract
Background The γ-aminobutyric acid (GABA) transporter GAT1 is involved in GABA transport across the biological membrane in and out of the synaptic cleft. The efficiency of this Na+ coupled GABA transport is regulated by an electrochemical gradient, which is directed inward under normal conditions. However, in certain pathophysiological situations, including strong depolarization or an imbalance in ion homeostasis, the GABA influx into the cytoplasm is increased by re-uptake transport mechanism. This mechanism may lead to extra removal of extracellular GABA which results in numerous neurological disorders such as epilepsy. Thus, small molecule inhibitors of GABA re-uptake may enhance GABA activity at the synaptic clefts. Methods In the present study, various GRID-independent molecular descriptor (GRIND) models have been developed to shed light on the 3D structural features of human GAT1 (hGAT1) inhibitors using nipecotic acid and N-diarylalkenyl piperidine analogs. Further, a binding hypothesis has been developed for the selected GAT1 antagonists by molecular docking inside the binding cavity of hGAT1 homology model. Results Our results indicate that two hydrogen bond acceptors, one hydrogen bond donor and one hydrophobic region at certain distances from each other play an important role in achieving high inhibitory potency against hGAT1. Our docking results elucidate the importance of the COOH group in hGAT1 antagonists by considering substitution of the COOH group with an isoxazol ring in compound 37, which subsequently leads to a three order of magnitude decrease in biological activity of 37 (IC50 = 38 µM) as compared to compound 1 (IC50 = 0.040 µM). Discussion Our docking results are strengthened by the structure activity relationship of the data series as well as by GRIND models, thus providing a significant structural basis for understanding the binding of antagonists, which may be useful for guiding the design of hGAT1 inhibitors.
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Affiliation(s)
- Sadia Zafar
- Research Center for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Islamabad, Federal, Pakistan
| | - Ishrat Jabeen
- Research Center for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Islamabad, Federal, Pakistan
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Sowa AR, Brooks AF, Shao X, Henderson BD, Sherman P, Arteaga J, Stauff J, Lee AC, Koeppe RA, Scott PJH, Kilbourn MR. Development of Positron Emission Tomography Radiotracers for the GABA Transporter 1. ACS Chem Neurosci 2018; 9:2767-2773. [PMID: 29763549 DOI: 10.1021/acschemneuro.8b00183] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In vivo positron emission tomography (PET) imaging of the γ-aminobutyric acid (GABA) receptor complex has been accomplished using radiolabeled benzodiazepine derivatives, but development of specific presynaptic radioligands targeting the neuronal membrane GABA transporter type 1 (GAT-1) has been less successful. The availability of new structure-activity studies of GAT-1 inhibitors and the introduction of a GAT-1 inhibitor (tiagabine, Gabatril) into clinical use prompted us to reinvestigate the syntheses of PET ligands for this transporter. Initial synthesis and rodent PET studies of N-[11C]methylnipecotic acid confirmed the low brain uptake of that small and polar molecule. The common design approach to improve blood-brain barrier permeability of GAT-1 inhibitors is the attachment of a large lipophilic substituent. We selected an unsymmetrical bis-aromatic residue attached to the ring nitrogen by a vinyl ether spacer from a series recently reported by Wanner and coworkers. Nucleophilic aromatic substitution of an aryl chloride precursor with [18F]fluoride was used to prepare the desired candidate radiotracer ( R, E/ Z)-1-(2-((4-fluoro-2-(4-[18F]fluorobenzoyl)styryl)oxy)ethyl)piperidine-3-carboxylic acid (( R, E/ Z)-[18F]10). PET studies in rats showed no brain uptake, which was not altered by pretreatment of animals with the P-glycoprotein inhibitor cyclosporine A, indicating efflux by Pgp was not responsible. Subsequent PET imaging studies of ( R, E/ Z)-[18F]10 in rhesus monkey brain showed very low brain uptake. Finally, to test if the free carboxylic acid group was the likely cause of poor brain uptake, PET studies were done using the ethyl ester derivative of ( R, E/ Z)-[18F]10. Rapid and significant monkey brain uptake of the ester was observed, followed by a slow washout over 90 min. The blood-brain barrier permeability of the ester supports a hypothesis that the free acid function limits brain uptake of nipecotic acid-based GAT-1 radioligands, and future radiotracer efforts should investigate the use of carboxylic acid bioisosteres.
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Affiliation(s)
- Alexandra R. Sowa
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Allen F. Brooks
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Xia Shao
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Bradford D. Henderson
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Philip Sherman
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Janna Arteaga
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Jenelle Stauff
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Adam C. Lee
- E.I. du Pont de Nemours and Company, DuPont Haskell Global Center for Health Sciences, P.O. Box 30, Newark, Delaware 19714, United States
| | - Robert A. Koeppe
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Michael R. Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
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Zafar S, Jabeen I. Structure, Function, and Modulation of γ-Aminobutyric Acid Transporter 1 (GAT1) in Neurological Disorders: A Pharmacoinformatic Prospective. Front Chem 2018; 6:397. [PMID: 30255012 PMCID: PMC6141625 DOI: 10.3389/fchem.2018.00397] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 08/20/2018] [Indexed: 02/03/2023] Open
Abstract
γ-Aminobutyric acid (GABA) Transporters (GATs) belong to sodium and chloride dependent-transporter family and are widely expressed throughout the brain. Notably, GAT1 is accountable for sustaining 75% of the synaptic GABA concentration and entails its transport to the GABAA receptors to initiate the receptor-mediated inhibition of post-synaptic neurons. Imbalance in ion homeostasis has been associated with several neurological disorders related to the GABAergic system. However, inhibition of the GABA uptake by these transporters has been accepted as an effective approach to enhance GABAergic inhibitory neurotransmission in the treatment of seizures in epileptic and other neurological disorders. Here, we reviewed computational methodologies including molecular modeling, docking, and molecular dynamic simulations studies to underscore the structure and function of GAT1 in the GABAergic system. Additionally, various SAR and QSAR methodologies have been reviewed to probe the 3D structural features of inhibitors required to modulate GATs activity. Overall, present review provides an overview of crucial role of GAT1 in GABAergic system and its modulation to evade neurological disorders.
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Affiliation(s)
| | - Ishrat Jabeen
- Research Center for Modeling and Simulation, National University of Sciences and Technology, Islamabad, Pakistan
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Synthesis and biological evaluation of a series of N -alkylated imidazole alkanoic acids as mGAT3 selective GABA uptake inhibitors. Eur J Med Chem 2016; 124:852-880. [DOI: 10.1016/j.ejmech.2016.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/21/2016] [Accepted: 09/03/2016] [Indexed: 11/20/2022]
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Petrera M, Wein T, Allmendinger L, Sindelar M, Pabel J, Höfner G, Wanner KT. Development of Highly Potent GAT1 Inhibitors: Synthesis of Nipecotic Acid Derivatives by Suzuki-Miyaura Cross-Coupling Reactions. ChemMedChem 2015; 11:519-38. [DOI: 10.1002/cmdc.201500490] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Indexed: 12/29/2022]
Affiliation(s)
| | - Thomas Wein
- Department of Pharmacy; Center for Drug Research; Ludwigs-Maximilians-Universität München; Butenandtstr. 5-13 81377 Munich Germany
| | - Lars Allmendinger
- Department of Pharmacy; Center for Drug Research; Ludwigs-Maximilians-Universität München; Butenandtstr. 5-13 81377 Munich Germany
| | - Miriam Sindelar
- Department Pharmacology; Weill Cornell Medical College; LC-428 1300 York Avenue New York NY 10021 USA
| | - Jörg Pabel
- Department of Pharmacy; Center for Drug Research; Ludwigs-Maximilians-Universität München; Butenandtstr. 5-13 81377 Munich Germany
| | - Georg Höfner
- Department of Pharmacy; Center for Drug Research; Ludwigs-Maximilians-Universität München; Butenandtstr. 5-13 81377 Munich Germany
| | - Klaus T. Wanner
- Department of Pharmacy; Center for Drug Research; Ludwigs-Maximilians-Universität München; Butenandtstr. 5-13 81377 Munich Germany
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Jurik A, Reicherstorfer R, Zdrazil B, Ecker GF. Classification of High-Activity Tiagabine Analogs by Binary QSAR Modeling. Mol Inform 2013; 32:415-419. [PMID: 23956803 PMCID: PMC3743161 DOI: 10.1002/minf.201300020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 03/28/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Andreas Jurik
- University of Vienna, Department of Medicinal Chemistry Althanstraße 14, A-1090 Vienna, Austria phone/fax: +431-4277-55110/-9551
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