Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb-1, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[beta-D-glucopyranosyl-(1,2)-beta-D-glucopyranosyl]- 20-O-[beta-D-glucopyranosyl]-3beta,12beta, 20(S)-trihydroxydammar-24-ene (1), 3-O-[beta-D-glucopyranosyl-(1,2)-beta-D-glucopyranosyl]-20-O-[beta-D-glucopyranosyl]-3beta,12beta, 20(S)-trihydroxydammar-24-ol (2), 3-O-[beta-D- glucopyranosyl-(1,2)-beta-D-glucopyranosyl]-3beta,12beta, 20(S)-trihydroxydammar-24-ene(3), and 3-O-beta-D-glucopyranosyl- 3beta,12beta,20(S)-trihydroxydammar-24-ene(4), identified by TOF-MS, H-1- and C-13-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.