Rationalizing the binding and α subtype selectivity of synthesized imidazodiazepines and benzodiazepines at GABAA receptors by using molecular docking studies

Bioorganic & Medicinal Chemistry Letters
2022.0

Abstract

The pharmacological actions exerted by benzodiazepines are dependent on the discrete α protein subunits of the γ-aminobutyric acid type A receptor (GABA<sub>A</sub> R). Recent developments via a cryo-EM structure of the α1β3γ2L GABA<sub>A</sub> R ion channel provide crucial insights into ligand efficacy and binding affinity at this subtype. We investigated the molecular interactions of diazepam and alprazolam bound GABA<sub>A</sub> R structures (6HUP and 6HUO) to determine key binding interaction domains. A halogen bond between the chlorine atoms of diazepam and alprazolam with the group on the backbone of the α1 histidine amino acid 102 is important to the positive allosteric modulatory actions of diazepam and alprazolam in the α1β3γ2L GABA<sub>A</sub> R ion channel. In order to gain insight into α subtype selectivity we designed and synthesized close structural analogs of diazepam and alprazolam. These compounds were then docked into the recently publish cryo-EM structures of GABA<sub>A</sub> Rs (6HUP and 6HUO). This modeling along with radio-ligand binding data resulted in the conclusion that the non-classical bioisosteric replacement of the chlorine atom at C7 with an ethinyl group (compound 5) resulted in an 11-fold gain in α5 binding selectivity over the α1 subtype. Moreover, the potency of compound 5 resulted in a ligand with less sedation than diazepam, while still maintaining the same anxiolytic potency. These modeling data extend our understanding of the structural requirements for α-subtype-selective compounds that can be utilized to achieve improved medical treatments. It is clear that the ethinyl group in place of a halogen atom decreases the affinity and efficacy of benzodiazepines and imidazodiazepines at α1 subtypes, which results in less sedation and ataxia.

Knowledge Graph

Similar Paper

Rationalizing the binding and α subtype selectivity of synthesized imidazodiazepines and benzodiazepines at GABAA receptors by using molecular docking studies
Bioorganic &amp; Medicinal Chemistry Letters 2022.0
New Insight into the Central Benzodiazepine Receptor–Ligand Interactions: Design, Synthesis, Biological Evaluation, and Molecular Modeling of 3-Substituted 6-Phenyl-4H-imidazo[1,5-a][1,4]benzodiazepines and Related Compounds
Journal of Medicinal Chemistry 2011.0
Subtype Selective γ-Aminobutyric Acid Type A Receptor (GABA<sub>A</sub>R) Modulators Acting at the Benzodiazepine Binding Site: An Update
Journal of Medicinal Chemistry 2020.0
Four amino acid exchanges convert a diazepam-insensitive, inverse agonist-preferring GABAA receptor into a diazepam-preferring GABAA receptor
Journal of Medicinal Chemistry 1994.0
Synthesis and Benzodiazepine Receptor Affinity of Pyrazolo[1,5-a]pyrimidine Derivatives. 3. New 6-(3-Thienyl) Series as α1 Selective Ligands
Journal of Medicinal Chemistry 2003.0
Selective Influence on Contextual Memory: Physiochemical Properties Associated with Selectivity of Benzodiazepine Ligands at GABA<sub>A</sub>Receptors Containing the α5 Subunit
Journal of Medicinal Chemistry 2008.0
Pharmacophore/Receptor Models for GABA<sub>A</sub>/BzR Subtypes (α1β3γ2, α5β3γ2, and α6β3γ2) via a Comprehensive Ligand-Mapping Approach
Journal of Medicinal Chemistry 2000.0
3-Phenyl-6-(2-pyridyl)methyloxy-1,2,4-triazolo[3,4-a]phthalazines and Analogues:  High-Affinity γ-Aminobutyric Acid-A Benzodiazepine Receptor Ligands with α2, α3, and α5-Subtype Binding Selectivity over α1
Journal of Medicinal Chemistry 2004.0
Molecular Basis of Peripheral vs Central Benzodiazepine Receptor Selectivity in a New Class of Peripheral Benzodiazepine Receptor Ligands Related to Alpidem
Journal of Medicinal Chemistry 1996.0
4-Quinolone Derivatives:  High-Affinity Ligands at the Benzodiazepine Site of Brain GABA<sub>A</sub>Receptors. Synthesis, Pharmacology, and Pharmacophore Modeling
Journal of Medicinal Chemistry 2006.0