WS-9659 A and B, novel testosterone 5.ALPHA.-reductase inhibitors isolated from a Streptomyces. III. Biological characteristics and pharmacological characteristics

WS-9659 A, a novel phenazine, produced by a Streptomyces sp., had testosterone 5 alpha-reductase inhibition activity on rat, dog and human prostates. However, WS-9659 A did not show any inhibitory activities for aldose reductase on rabbit lenses and lactate dehydrogenase on pig hearts. WS-9659 A was a competitive inhibitor against testosterone 5 alpha-reductase on rat prostates by use of testosterone as a substrate. Radio receptor binding assay of androgen receptor of rat prostates revealed that WS-9659 A had no affinity for this receptor. WS-9659 A was tested subcutaneously in immature castrated rats to confirm its effect on the growth of the ventral prostates induced by testosterone propionate.