Microbial transformation of diosgenin by Syncephalastrum racemosum (Cohn) Schroeter

Microbial transformation of diosgenin (1) by Syncephalastrum racemosum yielded five new polar metabolites, which were identified as (25R)-spirost-5-en-3β,7α,9α-triol-12-one (2), (25R)-spirost-5-en-3β,9α,12α-triol-7-one (3), (25R)-spirost-5-en-3β,9α-diol-7,12-dione(4), (25R)-spirost-4-en-9α,12β,14α-triol-3-one(5), and (25S)-spirost-4-en-9α,14α,25β-triol-3-one (6). Compounds 1–6 exhibited moderate cytotoxicity against K562 cells and among them compounds 2, 3, and 6 were more potent than the parent compound 1.