(1-Benzylindole-3-yl)alkanoic acids; novel nonsteroidal inhibitors of steroid 5 alpha-reductase (I).

A novel series of indole-3-alkanoic acids with varied N-benzyl substituents were synthesized as nonsteroidal inhibitors of steroid 5 alpha-reductase. The structure-activity relationships in this series were studied and the optimum carboxylic acid side chain was butyric acid, Furthermore, compounds with a diaryl substituent at the 1-position of the indole ring displayed strong inhibitory activities in vitro. Amongst these derivatives, 4-[1-(6,6-dimethyl-6H-dibenzo[b,d]pyran-3-yl)methylindol-3-yl]butyric acid (FR119680) displayed very high inhibitory activity in vitro against rat prostatic 5 alpha-reductase (IC50=5.0 nM) and good in vivo activity in the castrated young rat model.