• Natural Product Sciences
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• v.26 no.4
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• pp.283-288
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• 2020

Microbial transformation of a potent progestin, norethisterone (17��-hydroxy-19-nor-17α-pregn-4-en-20-yn-3-one) (1) was carried out by using two filamentous fungi Aspergillus niger and Penicillium citrinum. Biotransformation of 1 with A. niger yielded a hydroxylated transformed product 10��,17��-diydroxy-19-nor-17α-pregn-4-en-20-yn-3-one (2) whereas 11��,17��-diydroxy-19-nor-17α-pregn-4-en-20-yn-3-one (3) was obtained through microbial transformation of 1 by P. citrinum. It is the first report of their production from 1 by using A. niger and P. citrinum with complete 1H- and 13C-NMR assignment. The structures of both metabolites were characterized by various spectroscopic techniques and reported data.