Study on content variation of four flavonoids by acid-hydrolysis of licorice

Objective:To develop an HPLC method for the analysis of four flavonoid marker compounds(liquiritin,isoliquiritin,liquiritigenin,isoliquiritigenin) in Glycyrrhiza uralensis Fisch.extracts,and evaluate the influence of acid-hydrolysis method by comparing the content of the four mark components.Methods:The contents of four active components,both of the ethanol extract and the acid-hydroolysis extract were determined by HPLC.The separation was performed on a reversed-phase Agilent HC-C18(150 mm×4.6 mm,5 μm)column by using a gradient elution with mobile phase of water-formic acid(pH 3)and acetonitrile.The assay was carried out at a flow rate of 0.8 mL·min-1at 25 ℃(room temperature).The detection wavelength for liquiritin and liquiritigenin can be determined at 276 nm while isoliquiritin and isoliquiritigenin at 370 nm.Results:The contents of liquiritin,isoliquiritin and isoliquiritigenin of ethanol extract were separately 1.29%,0.33% and 0.01% comparing with its original medicinal,the content of liquiritigenin was too low to be detected.For the acid-hydrolysis extract,the content of liquiritin,isoliquiritin,liquiritigenin,and isoliquiritigenin were separately 0.71%,0.32%,0.26% and 0.11% comparing with its original medicinal.Conclusion:Acid-hydrolysis method can markedly enhance the measured value of content of liquiritigenin and isoliquiritigenin.