Neurosteroid analogues. 18. Structure-activity studies of ent-steroid potentiators of γ-aminobutyric acid type A receptors and comparison of their activities with those of alphaxalone and allopregnanolone

J Med Chem. 2014 Jan 9;57(1):171-90. doi: 10.1021/jm401577c. Epub 2013 Dec 24.


A model of the alignment of neurosteroids and ent-neurosteroids at the same binding site on γ-aminobutyric acid type A (GABAA) receptors was evaluated for its ability to identify the structural features in ent-neurosteroids that enhance their activity as positive allosteric modulators of this receptor. Structural features that were identified included: (1) a ketone group at position C-16, (2) an axial 4α-OMe group, and (3) a C-18 methyl group. Two ent-steroids were identified that were more potent than the anesthetic steroid alphaxalone in their threshold for and duration of loss of the righting reflex in mice. In tadpoles, loss of righting reflex for these two ent-steroids occurs with EC50 values similar to those found for allopregnanolone. The results indicate that ent-steroids have considerable potential to be developed as anesthetic agents and as drugs to treat brain disorders that are ameliorated by positive allosteric modulators of GABAA receptor function.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bridged Bicyclo Compounds, Heterocyclic / metabolism
  • GABA Modulators / chemical synthesis*
  • GABA Modulators / pharmacology
  • HEK293 Cells
  • Humans
  • Models, Molecular
  • Neurotransmitter Agents / chemical synthesis*
  • Neurotransmitter Agents / pharmacology
  • Pregnanediones / pharmacology*
  • Pregnanolone / pharmacology*
  • Rats
  • Receptors, GABA-A / drug effects*
  • Structure-Activity Relationship
  • Xenopus laevis


  • Bridged Bicyclo Compounds, Heterocyclic
  • GABA Modulators
  • Neurotransmitter Agents
  • Pregnanediones
  • Receptors, GABA-A
  • tert-butylbicyclophosphorothionate
  • alphaxalone
  • Pregnanolone