Preparative separation of dioscin derivatives from Dioscorea villosa by centrifugal partition chromatography coupled with evaporative light scattering detection.

Dioscin derivatives from the Dioscorea villosa roots were isolated and purified by centrifugal partition chromatography coupled with evaporative light scattering detection. The two-phase solvent system composed of chloroform-methanol-isopropanol-water (7:6:1:4, v/v/v/v) was used to obtain prosapogenin A of dioscin (1, 11.1 mg), dioscin (2, 8.9 mg), deltonin (3, 29.2 mg) and diosgenin 3-O-[alpha-L-rhamnopyranosyl(1 --> 2)]-[beta-D-glucopyranosyl(1 --> 3)-beta-D-glucopyranosyl(1 --> 4)]-beta-D-glucopyranoside (4, 6.2 mg) from 300 mg of saponin-rich extract from the roots of D. villosa. The purities of 1, 2, 3 and 4 were determined to be 98.9, 97.4, 99.2 and 99.5%, respectively. Their chemical structures were determined by spectroscopic data of ESI-MS, 1H NMR and 13C NMR and comparing with those of previously reported values.