A novel series of indolebutyric acids with varying benzoyl substituents were synthesized to develop nonsteroidal inhibitors of steroid 5α-reductase. We previously reported the discovery of a novel nonsteroidal 5α-reductase inhibitor, FR119680, which had an IC 50 value of 5.0 nM against the rat prostatic enzyme. However, this compound was not strongly active against the human prostatic enzyme. By further study of the structure-activity ...