WB2838 [3-chloro-4-(2-amino-3-chlorophenyl)-pyrrole]: non-steroidal androgen-receptor antagonist produced by a Pseudomonas.

In the course of our search for non-steroidal androgen-receptor antagonists of microbial origin, Pseudomonas sp. No. 2838 was found to produce an inhibitor of androgen binding to its receptor. This compound, named WB2838, was isolated and identified as 3-chloro-4-(2-amino-3-chlorophenyl)-pyrrole. The IC50 value of WB2838 for partially purified rat prostate cytosol receptor was 8.0 x 10(-7) M. However, the IC50 value of WB2838 against estrogen-receptor binding was about 90-fold greater than that against androgen-receptor binding. WB2838 inhibited the growth of androgen-responsive mouse mammary carcinoma SC-3 cells in the presence of 10(-8) M testosterone at IC50 value of 4.1 x 10(-7) M. This inhibition was reversed by adding 10(-5) M testosterone to the culture medium. WB2838 also showed the inhibitory activity against the growth of the ventral prostate induced by testosterone propionate in castrated immature rats. Therefore, it was concluded that WB2838 was a non-steroidal androgen-receptor antagonist.