Synthesis and Biochemical Studies of 16- Or 19-substituted androst-4-enes as Aromatase Inhibitors

J Med Chem. 1991 Aug;34(8):2496-504. doi: 10.1021/jm00112a028.

Abstract

Androst-4-en-17-one derivatives [19-acetoxide 4, 16-bromides 14 and 15, 19,19-difluoride 18, and (19R,S)-19-acetylenic alcohol 25] and androst-4-en-17 beta-ol derivatives 3, 5, 10, 12, and 19 were synthesized and tested for their ability to inhibit aromatase in human placental microsomes. All the 17-oxo steroids, except compound 25 and 17,19-diol 3 of this series, were effective competitive inhibitors with apparent Ki's ranging from 170 to 455 nM. 19,19-Difluoro steroid 18 and 19-acetylenic alcohol 25, a weak competitive inhibitor (Ki = 7.75 microM), caused a time-dependent, pseudo-first-order inactivation of aromatase activity with kinact's of 0.0213 and 0.1053 min-1 for compounds 18 and 25, respectively. NADPH and oxygen were required for the time-dependent inactivation, and the substrate, androst-4-ene-3,17-dione, prevented it, but a nucleophile, L-cysteine, did not in each case. The results strongly suggest that aromatase would attack the 19-carbon of steroids 18 and 25.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstenes / chemical synthesis*
  • Androstenes / metabolism
  • Androstenes / pharmacology
  • Androstenols / chemical synthesis
  • Androstenols / metabolism
  • Androstenols / pharmacology
  • Aromatase / metabolism
  • Aromatase Inhibitors*
  • Binding Sites
  • Chemical Phenomena
  • Chemistry
  • Female
  • Humans
  • Kinetics
  • Molecular Structure
  • NADP / pharmacology
  • Oxygen / pharmacology
  • Placenta / enzymology
  • Structure-Activity Relationship

Substances

  • Androstenes
  • Androstenols
  • Aromatase Inhibitors
  • 19,19-difluoroandrost-4-en-17-one
  • 19-ethynyl-19-hydroxyandrost-4-en-17-one
  • NADP
  • Aromatase
  • Oxygen