HPLC ANALYSIS OF LICORICE TRITERPENOIDS - APPLICATIONS TO THE QUALITY-CONTROL OF PHARMACEUTICALS

A reversed-phase HPLC method is proposed for the separation of five li quorice triterpenoids, 18 beta glycyrrhetic acid (beta GA), 18 alpha g lycyrrhetic acid (alpha GA), 24-hydroxy-18 beta-glycyrrhetic acid (24- OH-beta GA), alpha and beta liquiritic acid (alpha and beta LA), with potentially different biological activities. The method has been devel oped by studying the influence of the type of stationary phase, pH, am ine modifier and organic modifier on the resolution of the five compou nds. The optimized chromatographic conditions were then successfully a pplied to the analysis of alpha- and beta-GA in pharmaceutical prepara tions (toothpaste and creams) on a reversed-phase Phenomenex Ultracarb 5 ODS (30) column (150 x 4.6 mm i.d.), using as the mobile phase acet onitrile-THF-0.010 M dioctylammonium phosphate buffer (pH 6.5) (25:20: 55, v/v/v) at a flow-rate of 0.8 ml min(-1). SPE methods with diolic a nd C18 sorbents were developed to isolate and concentrate the analytes and to enhance the sensitivity for the determination of alpha-GA as a n impurity in the beta-GA preparations. The method was found to be rel iable and suitable for the quality control of beta-GA preparations.