HPLC analysis of a bioactive chalcone and triterpene in the buds of Cleistocalyx operculatus

Cleistocalyx operculatus is a well-known medicinal plant, the buds of which are commonly used as an ingredient of tonic drinks in southern China. To evaluate the quality of C. operculatus material, a simple, rapid and accurate HPLC method was developed for the quantitative/ qualitative assessment of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone and ursolic acid, the principal bioactive compounds in the buds of C. operculatus. The HPLC system was equipped with a C18 reversed phase column, and methanol and aqueous H3PO4 were used as the mobile phase. Peaks were detected at 220nm. The recovery of the compounds was 97.5% and 99.3%, respectively, for compounds 2',4'-dihydroxy-6'-methoxy- 3',5'-dimethylchalcone and ursolic acid, and the two compounds showed good linearity (r2 ≥ 0.9997) in a relatively wide concentration range. The concentration of these two phytochemicals in the buds of C. operculatus, growing at three different locations in China, was determined to establish the effectiveness of the method as well as the variability of the plant material.