[Isolation and structure determination of steroidal saponin from Dioscorea zingiberensis]

To study the chemical constituents of Dioscorea zingiberensis Wright, the EtOH extract of fresh rhizomes of D. zingiberensis was concentrated and partitioned further to produce petroleum ether-, ethylacetate-, n-butanol- and water-soluble fractions. The water-soluble fraction was subjected to column chromatography on macro resin AB-8, and the final products were obtained by repeated reversed-phase ODS and MCI gel CHP 20P column chromatography. Structures of compounds were elucidated by 1H NMR, 13C NMR, 135DEPT, HMQC, HMBC and TOCSY spectroscopic analyses. A new steroidal saponin was isolated, which was identified as (25R)-26-O-(beta-D-glucopyranosyl)-furost-5-en-3 beta, 16, 20, 26-tetraol-22-seco-3-O-beta-D-glucopyranosyl-(1--> 3)-beta-D-glucopyranosyl-(1--> 4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside. The compound is a novel skeletally steroidal saponin, named as zingiberenin F (1). It was reported for the first time from D. zingiberensis Wright.