18-methyl-11α-hydroxygona-4-en-3,17-dione is a very important intermediate of some highly effective oral contraceptives. 18 methylgona -4-en-3,17-dione was subjected to enzymatic hydroxylation by rhizopus nigricans to afford a mixture of some hydroxylated products including 11α-hydroxylated derivative. aspergillus ochroceus was also used for the same substrate to afford the similar results. 18-methy-17 β- hydroxygona-4-en-3-one was enzymaticly hydroxylated by Aspergillus ochraceus to yield 15α-hydroxylated derivative as the major product and 7β-hydroxylated derivative as a minor product. 15α-hydroylated derivative shich could be used for synthesis of an highly effective oral contraceptive Gestodene, was isolated from this microorganism for the first time.

Key words: STERONE, ENZYME, ASPERGILLUS SP, HYDROXYLATION, CATALYSIS