SEPARATION OF THREE TRITERPENE ACIDS IN LEAVES OF DIOSPYROS KAKI BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY USING HYDROXYPROPYL-β-CYCLODEXTRIN AS MOBILE PHASE MODIFIER

An improved high-performance liquid chromatography method for the separation and determination of rotungenic acid and two isomeric triterpene acids (oleanolic acid and ursolic acid) was developed. Results proved that these triterpene acids can be separated with high resolution by adding hydroxypropyl-beta-cyclodextrin (HP-beta-CD) into the mobile phase; the resolution of the triterpene acids increased and their retention time in the column decreased with HP-beta-CD concentrations increasing due to the formation of inclusion complexes between triterpene acids and HP-beta-CD. The formation of 1:1 inclusion complexes was assumed and apparent formation constants of triterpene acids with HP-beta-CD were determined experimentally at 20 degrees C and 35 degrees C. At last, the method was used to determine rotungenic acid, oleanolic acid, and ursolic acid in the leaves of Diospyros kaki and proved to be sensitive, rapid, accurate, and suitable.