Separation and Bioactive Assay of 25R/S-Spirostanol Saponin Diastereomers from Yucca schidigera Roezl (Mojave) Stems

Abstract

In order to find a simple, generic, efficient separation method for 25R/S-spirostanol saponin diastereomers, the liquid chromatographic retention behaviors of C12 carbonylation and C12 unsubstituted 25R/S-spirostanol saponin diastereomers on different stationary phases (C8, C18, C30 columns) and different mobile phases (MeOH-1% CH3COOH and CH3CN-1% CH3COOH) were investigated. A C30 column was firstly found to offer the highest efficiency for the separation of this kind of diastereomers than C8 and C18 columns. Meanwhile, the analysis results indicated that both CH3CN-1% CH3COOH and MeOH-1% CH3COOH eluate systems were selective for C12 unsubstituted 25R/S-spirostanol saponin diastereomers, while MeOH-1% CH3COOH possessed better selectivity for C12 carbonylation ones. Using the abovementioned analysis method, six pairs of 25R/S-spirostanol saponin diastereomers 1a–6a and 1b–6b from Yucca schidigera Roezl (Mojave) were isolated successfully by using HPLC on C30 column for the first time. Among them, three pairs were new ones, named as (25R)-Yucca spirostanoside E1 (1a), (25S)-Yucca spirostanoside E1 (1b), (25R)-Yucca spirostanoside E2 (2a), (25S)-Yucca spirostanoside E2 (2b), (25R)-Yucca spirostanoside E3 (3a), (25S)-Yucca spirostanoside E3 (3b), respectively. Moreover, 3a, 5a, 6a, 3b–6b showed strong inhibitory activities on the growth of SW620 cell lines with the IC50 values of 12.02–69.17 μM.