Microbial transformation of ginsenoside-Rg1 by Absidia coerulea and the reversal activity of the metabolites towards multi-drug resistant tumor cells

Biotransformation of ginsenoside-Rg(1) (1) by the fungus Absidia coerulea AS 3.2462 yielded five metabolites (2-6). On the basis of spectroscopic data analyses, the metabolites were identified as ginsenoside-F-1 (2), 6 alpha,12 beta-dihydroxydammar-3-one-20(S)-O-beta-D-glucopyranoside (3), 3-oxo-20(S)-protopanaxatriol (4), 3-oxo-7 beta-hydroxy-20(S)-protopanaxatriol (5), and 3-oxo-7 beta,15 alpha-dihydroxy-20(S)-protopanaxatriol (6), respectively. Among them, 5 and 6 are new compounds. These results indicated that Absidia coerulea AS 3.2462 could catalyze the specific C-3 dehydrogenation of derivatives of ginsenoside-Rg(1), as well as hydroxylation at the 7 beta and 15 alpha positions. Metabolites 2,4 and 5 exhibited moderate reversal activity towards A549/taxol MDR tumor cells in vitro. (C) 2011 Elsevier B.V. All rights reserved.