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% CH&sub3;COOH and CH&sub3;CN-1% CH&sub3;COOH) 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 CH&sub3;CN-1% CH&sub3;COOH and MeOH-1% CH&sub3;COOH eluate systems were selective for C12 unsubstituted 25R/S-spirostanol saponin diastereomers, while MeOH-1% CH&sub3;COOH 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 E&sub1; (1a), (25S)-Yucca spirostanoside E&sub1; (1b), (25R)-Yucca spirostanoside E&sub2; (2a), (25S)-Yucca spirostanoside E&sub2; (2b), (25R)-Yucca spirostanoside E&sub3; (3a), (25S)-Yucca spirostanoside E&sub3; (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.