Preparative Isolation of Alisol B and Alisol B 23-Acetate from Alismatis Rhizoma by Centrifugal Partition Chromatography Coupled with ELSD

Centrifugal partition chromatography coupled with evaporative light scattering detection was applied to separate and purify alisol B and alisol B 23-acetate from a chloroform soluble extract of Alisma orientale. The chloroform soluble fraction (870 mg) of A. orientale was separated utilizing a two-phase solvent system composed of n-hexane–ethyl acetate–methanol–water (10:2:10:7, v/v) to give alisol B (37.5 mg) and alisol B 23-acetate (205.3 mg). The purities of the two triterpenoids were determined to be over 98% by LC-ELSD and their structures were elucidated by ESI-MS, 1H NMR and 13C NMR spectroscopy.