Microbial Transformation of Antifertility Agents, Norethisterone and 17α-Ethynylestradiol

The microbial transformation of oral contraceptive norethisterone (1) by Cephalosporium aphidicola afforded an oxidized metabolite, 17a-ethynylestradiol (2), while the microbial transformation of 2 by Cunninghamella elegans yielded several metabolites, 19-nor-17α-pregna-1,3,5 (10)-trien-20-yne-3,4,17β-triol (3), 19-nor-17α-pregna-1,3,5(10)-trim-20-yne-3,7α,17β-triol (4), 19-nor-17α-pregna-1,3,5(10)-trien-20-yne-3,11α,17β-triol (5), 19-nor-17a-pregna-1,3,5(10)-trien-20-yne-3,6β,17β-triol (6) and 19-nor-17a-pregna-1,3,5 (10)-trien-20-yne-3,17β-diol-6β-methoxy (7). Metabolite 7 was found to be a new compound. These metabolites were structurally characterized on the basis of spectroscopic techniques.