Preparative separation of liquiritigenin and glycyrrhetic acid from <i>Glycyrrhiza uralensis</i> Fisch using hydrolytic extraction combined with high‐speed countercurrent chromatography
Hao Wang, Hu Shan, Haitao Lü
Abstract
Abstract The objective of this paper was to develop a preparative method for the isolation and purification of liquiritigenin and glycyrrhetic acid from Glycyrrhiza uralensis Fisch using hydrolytic extraction combined with high‐speed countercurrent chromatography (HSCCC). Liquiritigenin and glycyrrhetic acid were well hydrolyzed from liquiritin and glycyrrhizic acid by hydrochloric acid, respectively. The optimal extraction conditions were obtained by single‐factor and orthogonal experiments, which were 100% ethanol, 1.5 mol/L hydrochloric acid, 1:25 ratio of solid to liquid, and extracted 2 h for one time. Using the two‐phase solvent system of n ‐hexane‐ethyl acetate‐methanol–water (4:5:4:5, v/v), 2.1 mg liquiritigenin (the purity was 96.5% with a recovery of 87.6%) and 12.3 mg glycyrrhetic acid (the purity was 97.1% with a recovery of 74.4%) were obtained from 315‐mg crude extraction by HSCCC. The retention ratio of stationary phase was 47.2%. Their structures were identified by HPLC, melting points, UV, Fourier‐transform infrared, Electrospray ionization‐MS, 1 H nuclear magnetic resonance (NMR), and 13 C NMR spectra. According to the antioxidant activity assays, liquiritigenin and glycyrrhetic acid had some scavenging abilities on 1,1‐diphenyl‐2‐picrylhydrazyl free radicals; liquiritigenin had stronger scavenging ability on hydroxyl radicals.