title: Prostatic cancer. I. 6-Methylene-4-pregnen-3-ones as irreversible inhibitors of rat prostatic delta 4-3 ketosteroid 5 alpha-reductase.
abstract: Some derivatives of 6-methylene-4-pregnen-3-one were studied as inhibitors of delta 4-3-ketosteroid 5 alpha-reductase. Maximum inhibitory activity was shown by 17-acetoxy-6-methylene-4-pregnene-3,20-dione (AMPD). Irreversible inactivation was observed following preincubation of the enzyme with NADPH and AMPD. This inactivation was found to occur only in the presence of NADPH. As such enzyme inactivation was not due to the formation of a more inhibitory metabolic product, or to the formation of superoxide via a cytochrome P-450/NADPH pathway, it seemed likely that the observed inactivation was derived from an irreversible combination of the enzyme with AMPD. That this was probably the case was established by kinetic studies which revealed a pattern compatible with a kcat type of mechanism.
mesh_terms: D058891:5-alpha Reductase Inhibitors; D000818:Animals; D007700:Kinetics; D008297:Male; D009249:NADP / Q000378:metabolism; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D011374:Progesterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D011467:Prostate / Q000201:enzymology*; D011471:Prostatic Neoplasms / Q000188:drug therapy; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000378:metabolism
chemical_list: D058891:5-alpha Reductase Inhibitors; C032364:17-acetoxy-6-methylene-4-pregnene-3,20-dione; D013739:Testosterone; D011374:Progesterone; D009249:NADP; D010088:Oxidoreductases