Study on separation and identification of steroidal saponins of Dioscorea nipponica Makino

OBJECTIVE To isolate and identify steroidal saponins from the rhizome of Dioscorea nipponica Makino. METHODS The compounds were isolated by solvent extraction, column chromatography on silica gel and preparative HPLC, and their struetures were elucidated on the basis of chemical and spectral analysis. RESULTS Four steroidal saponins were isolated from the rhizome of Dioscorea nipponica Makino, and their structures were determined as dioscin (Ⅰ), gracillin (Ⅱ), 26-O-β-D-glucopyranosyl-(25R)-22-hydroxy-5-ene-furostane-3β, 26-diol-3-O-{[α-L-rhamnopyranosyl(1→2)]-α-L-thamnopyranosyl(1→4)}-β-D-glucopyranoside (Ⅲ) and 26-O-β-D-glucopyranosyl(25R)-22-hydroxy-5-ene-furostane-3β, 26-diol-3-O-{[α-L-rhamnopyranosyl (1→2)]-α-L-glucopyranosyl(1→3)}-β-D-glucopyranoside (Ⅳ). CONCLUSION Compotmd Ⅲ and Ⅳ are obtained from the rhizome of Dioscorea nipponica Makino for the first time.