Neurosteroid analogues: structure-activity studies of benz[e]indene modulators of GABAA receptor function. 1. The effect of 6-methyl substitution on the electrophysiological activity of 7-substituted benz[e]indene-3-carbonitriles

J Med Chem. 1993 Nov 26;36(24):3956-67. doi: 10.1021/jm00076a025.


The effect of 6-methyl substitution of the ability of 7-(2-hydroxyethyl)benz[e]indene-3-carbonitriles to potentiate GABA-mediated chloride current and to directly gate a chloride current in the absence of GABA in cultured rat hippocampal neurons was investigated. Structurally analogous steroid 17-carbonitriles that either contained or did not contain a 19-methyl group were also investigated. Compounds were evaluated at 1 microM for their ability to potentiate GABA-mediated currents and at 10 microM for current activation in the absence of GABA. The benz[e]indene 3(R)-carbonitriles and analogous steroid 17 alpha-carbonitriles had no effects in either assay. The benz[e]indene-3(S)-carbonitriles and analogous steroid 17 alpha-carbonitriles were active in both assays. Relative to the 6-unsubstituted benz[e]indene 3(S)-carbonitrile, the following effects of 6-methyl substituents were observed: a 6(a)-methyl group increased both activities; a 6(e)-methyl group decreased both activities; and 6,6-dimethyl substituents had opposing effects so that both activities remained similar to those of the 6-unsubstituted compound. The activities of the steroid 17 beta-carbonitriles were not affected significantly by the presence or absence of a 19-methyl group. A conformational analysis using molecular modeling methods was also performed for the benz[e]indene 3S-carbonitriles and the steroid 17 beta-carbonitriles. The ability of the different 6-methyl substituents to differentially effect the conformations of the flexible benz[e]indenes and the inability of the steroid 19-methyl group to alter the conformations of the rigid steroid 17 beta-carbonitriles are suggested to explain the results.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Androstanols / chemistry
  • Androstanols / pharmacology*
  • Animals
  • Cells, Cultured
  • Chloride Channels / drug effects
  • Chloride Channels / physiology
  • Computer Simulation
  • Electrophysiology
  • Estranes / chemical synthesis
  • Estranes / pharmacology*
  • Hippocampus / drug effects
  • Hippocampus / physiology
  • Ion Channel Gating / drug effects
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Structure
  • Neurons / drug effects
  • Neurons / physiology
  • Nitriles / chemical synthesis
  • Nitriles / chemistry
  • Nitriles / pharmacology*
  • Rats
  • Receptors, GABA / drug effects
  • Receptors, GABA / physiology*
  • Structure-Activity Relationship
  • gamma-Aminobutyric Acid / pharmacology


  • Androstanols
  • Chloride Channels
  • Estranes
  • Nitriles
  • Receptors, GABA
  • 3-hydroxy-5-estrane-17-carbonitrile
  • 3-hydroxy-5-androstane-17-carbonitrile
  • gamma-Aminobutyric Acid