Biotransformation of steroidal ruscogenins (neoruscogenin and ruscogenin) was carried out with Cunninghamella blakesleeana NRRL 1369 and endophytic fungus Neosartorya hiratsukae yielding mainly P450 monooxygenase products together with a glycosylated compound. Fermentation of ruscogenins (75:25, neoruscogenin-ruscogenin mixture) with C. blakesleeana yielded 8 previously undescribed hydroxylated compounds. Furthermore, microbial transformation of neoruscogenin by endophytic fungus N. hiratsukae afforded three previously undescribed neoruscogenin derivatives. While hydroxylation at C-7, C-12, C-14, C-21 with further oxidation at C-1 and C-7 were observed with C. blakesleeana, N. hiratsukae biotransformation provided C-7 and C-12 hydroxylated compounds along with C-12 oxidized and C-1(O) glycosylated derivatives. The structures of the metabolites were elucidated by 1-D (1H, 13C and DEPT135) and 2-D NMR (COSY, HMBC, HMQC, NOESY, ROESY) as well as HR-MS analyses.
Keywords: Cunninghamella blakesleeana; Microbial biotransformation; Neoruscogenin; Neosartorya hiratsukae; Ruscogenins; Ruscus.
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