Microbiological transformation of diosgenin by resting cells of filamentous fungus, Cunninghamella echinulata CGMCC 3.2716

Microbial transformation of the steroidal sapogenin diosgenin (1) by resting cells of the filamentous fungus, Cunninghamella echinulata CGMCC 3.2716 was studied. Four metabolites were isolated and unambiguously characterized as (25R)-spirost-5-ene-3β,7β-diol-11-one (2), (25R)-spirost-5-ene-3β,7β-diol (3), (25R)-spirost-5-ene-3β,7β,11α-triol (4), and (25R)-spirost-5-ene-3β,7β,12β-triol (5), by various spectroscopic methods (1H, 13C NMR, DEPT, 1H–1H COSY, HMBC, HSQC and NOESY). Compound 2 is a new metabolite. The NMR data and full assignment for the known metabolites (25R)-spirost-5-ene-3β,7β-diol (3) and (25R)-spirost-5-ene-3β,7β,11α-triol (4) are described here for the first time. The biotransformation characteristics observed included were C-7β, C-11α and C-12β hydroxylations. Compounds 1–5 exhibited no significant cytotoxic activity to human glioma cell line U87.

Incubations of diosgenin (1) with the fungus Cunninghamella echinulata afforded four hydroxylated metobolites 2–5.Figure optionsDownload as PowerPoint slideResearch highlights▶ Microbiological transformation of diosgenin using resting cells of filamentous fungus, Cunninghamella echinulata was reported for the first time. ▶ Cunninghamella echinulata yielded various monooxygenases to introduce hydroxyl groups at C-7β, 11α, and 12β positions of steroids. ▶ C. echinulata afforded dehydrogenase to insert one 11-oxo group into steroidal skeleton. ▶ (25R)-spirost-5-ene-3β,7β-diol-11-one was a novel metabolic product of diosgenin transformed with C. echinulata.