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

A simple capillary-zone electrophoresis (CZE) method for the analysis of plant specimens, Glycyrrhiza glabra L., G. uralensisFisch. and G. inflata Bat. (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.