Abstract
Two new steroidal saponins, dioscins E (1) and F (2), along with nine known steroidal saponins, were isolated from the biotransformation product of the rhizomes of Dioscorea nipponica using Aspergillus oryzae. The structures of new compounds were established as 25(R)-spirost-5-en-21β-methyl-3β-ol-3-O-α- l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranoside (1) and (25R)-spirost-5-en-3β-ol-7-one 3-O-α- l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranoside (2) by detailed spectroscopic analyses including 1D and 2D NMR spectral data (1H–1H COSY, HSQC, and HMBC) and MS spectrometry.
Acknowledgments
This work was financially supported by the Major Program of Municipal Natural Science Foundation of Beijing (7090001) and the NSFC-Union Foundation of Yunnan Province (U10132601). The authors are grateful to Miss Yan Xue and Mr He-Bing Chen in the National Center of Biomedical Analysis for the measurements of MS and NMR spectra.