14 alpha-hydroxyandrost-4-ene-3,6,17-trione as a mechanical-based irreversible inhibitor of estrogen biosynthesis

Various derivatives of androst-4-ene-3,17-dione derived from microbial transformation were evaluated as inhibitors of human placental aromatase. 14 alpha-Hydroxyandrost-4-ene-3,6,17-trione was the most potent inhibitor showing a time-dependent, pseudo-first-order inactivation of aromatase in the presence of reduced nicotinamide adenine dinucleotide phosphate with apparent Ki of 1.3 microM and Kinact of 0.23 min-1. This compound also inhibited aromatase in rat ovary and suppressed serum estradiol levels in in vivo experiments.