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

In order to find a simple, generic, efficient separation method for 25 R / S -spirostanol saponin diastereomers, the liquid chromatographic retention behaviors of C12 carbonylation and C12 unsubstituted 25 R / 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 25 R / S -spirostanol saponin diastereomers, while MeOH-1% CH₃COOH possessed better selectivity for C12 carbonylation ones. Using the abovementioned analysis method, six pairs of 25 R / 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 (25 R )-Yucca spirostanoside E₁ ( 1a ), (25 S )-Yucca spirostanoside E₁ ( 1b ), (25 R )-Yucca spirostanoside E₂ ( 2a ), (25 S )-Yucca spirostanoside E₂ ( 2b ), (25 R )-Yucca spirostanoside E₃ ( 3a ), (25 S )-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.