DETERMINATION OF 3 ACTIVE PRINCIPLES IN LICORICE EXTRACT BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

An improved high-performance liquid chromatographic technique with a photodiode-array detection system for the determination of the active principles of licorice extract such as glycyrrhizin or glycyrrhizic acid (GL), 18-alpha-glycyrrhetinic acid (18-alpha-GA) and 18-beta-glycyrrhetinic acid (18-beta-GA) is presented. A reversed-phase column (LiChrospher RP-18, 5-mu-m) was eluted with a linear gradient of methanol-perchlorate buffer (pH 7.5-7.7) from 1:9 to 10:0 in 120 min. It was found that 58.53 +/- 9.14 mg of GL, 5.94 +/- 1.60-mu-g of 18-alpha-GA and 95.25 +/- 27.20-mu-g of 18-beta-GA were contained in the aqueous extract of 1 g of licorice. The method can determine these components in one analytical step without any pretreatment of the tested sample. Hence this simple method can be used to determine GL and stereoisomers of glycyrrhetinic acid in any licorice extract and traditional Chinese prescriptions.