Analysis and comparison of Radix Glycyrrhizae (licorice) from Europe and China by capillary-zone electrophoresis (CZE)

Abstract

A simple capillary-zone electrophoresis (CZE) method for the analysis of plant specimens, Glycyrrhiza glabra L., G. uralensis Fisch. and G. inflata B at. (Leguminosae) as well as commercial licorices from Europe and China was developed. Contents of glycyrrhizin (GL), glycyrrhetic acid (GA), glabridin (GLAB), liquiritin (LQ) and licochalcone A (LC A) in ethanolic extracts were investigated. Optimum separation was achieved with sodium tetraborate buffer (pH 9.22; 70 mM); voltage, 25 kV. Recovery rate for GL was found to be 101.90 ± 2.54%. Adequate correlation was observed between GL contents measured by CZE and HPLC ( r = 0.977). Advantages over conventional HPLC analysis of Glycyrrhiza species are short analysis time (<15 min), simple running buffer preparation and the none-use of organic solvents. Using the present CZE method, it was demonstrated that (1) G. glabra was distinguished from G. uralensis especially by phenolic compounds GLAB ( G. glabra: 0.19 ± 0.11%; n = 53) and LQ ( G. uralensis, 1.34 ± 0.34%, n = 10); (2) on average, GL contents were higher in Chinese commercial licorices; (3) relatively high LC A contents were especially detected in a Chinese commercial licorice (origin estimated as G. inflata); (4) Glycyrrhiza species were also distinguished by applying PCA on the basis of CZE peak area data of GL, GLAB, GA, LQ and LC A; and (5) liquiritin apioside was found in all samples.