Design, Synthesis, and Pharmacological Evaluation of Novel β2/3 Subunit-Selective γ-Aminobutyric Acid Type A (GABAA) Receptor Modulators

J Med Chem. 2019 Jan 10;62(1):317-341. doi: 10.1021/acs.jmedchem.8b00859. Epub 2018 Oct 23.

Abstract

Subunit-selective modulation of γ-aminobutyric acid type A receptors (GABAAR) is considered to exert fewer side effects compared to unselective clinically used drugs. Here, the β2/3 subunit-selective GABAAR modulators valerenic acid (VA) and loreclezole (LOR) guided the synthesis of novel subunit-selective ligands with simplified structures. We studied their effects on GABAARs expressed in Xenopus laevis oocytes using two-microelectrode voltage clamp technique. Five compounds showed significantly more efficacious modulation of GABA-evoked currents than VA and LOR with retained potency and selectivity. Compound 18 [( E)-2-Cyano-3-(2,4-dichlorophenyl)but-2-enamide] induced the highest maximal modulation of GABA-induced chloride currents ( Emax: 3114 ± 242%), while 12 [( Z)-3-(2,4-dichlorophenyl)but-2-enenitrile] displayed the highest potency (EC50: 13 ± 2 μM). Furthermore, in hippocampal neurons 12 facilitated phasic and tonic GABAergic inhibition, and in vivo studies revealed significantly more potent protection against pentylenetetrazole (PTZ)-induced seizures compared to VA and LOR. Collectively, compound 12 constitutes a novel, simplified, and subunit-selective GABAAR modulator with low-dose anticonvulsant activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / chemistry*
  • Amides / metabolism
  • Amides / therapeutic use
  • Animals
  • Anticonvulsants / chemical synthesis*
  • Anticonvulsants / metabolism
  • Anticonvulsants / therapeutic use
  • Drug Design*
  • Female
  • Hippocampus / metabolism
  • Indenes / chemistry
  • Oocysts / metabolism
  • Patch-Clamp Techniques
  • Pentylenetetrazole / toxicity
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism
  • Receptors, GABA-A / chemistry*
  • Receptors, GABA-A / genetics
  • Receptors, GABA-A / metabolism
  • Seizures / chemically induced
  • Seizures / drug therapy
  • Seizures / pathology
  • Sesquiterpenes / chemistry
  • Structure-Activity Relationship
  • Triazoles / chemistry
  • Xenopus laevis / metabolism

Substances

  • Amides
  • Anticonvulsants
  • Indenes
  • Protein Subunits
  • Receptors, GABA-A
  • Sesquiterpenes
  • Triazoles
  • valerenic acid
  • loreclezole
  • dopastin
  • Pentylenetetrazole