Fingerprint analysis and Q-marker prediction of processed liquorice products

Abstract

Licorice has long been regarded as one of the most popular herbs, with a very wide clinical application range. Whether being used alone or as an ingredient in prescription, it has an important role which cannot be ignored. However, the efficacy and chemical constituents of licorice will change after honey-processing. Therefore, it is necessary to find quality markers before and after honey-processing to lay the foundation for a comprehensive evaluation of the differences between raw and processed licorice pieces. HPLC-DAD was employed to establish fingerprints of raw and processed licorice. Multivariate statistical analysis methods including principal component analysis(PCA) and orthogonal partial least squares discrimination analysis(OPLS-DA) were applied to screen out the differential components before and after processing of licorice. Based on network pharmacology, the targets and pathways corresponding to the differential components were analyzed with databases such as Swiss Target Prediction and Metascape, and the "component-target-pathway" diagram was constructed with Cytoscape 3.6.0 software to predict the potential quality markers. A total of 17 common peaks were successfully identified in the established fingerprint, and seven differential components were selected as potential quality markers(licoricesaponin G2, glycyrrhizic acid, liquiritigenin, liquiritin, isoliquiritin, liquiritin apioside and isoliquiritigenin). The HPLC fingerprint method proposed in this study was efficient and feasible. The above seven differential chemical components screened out as potential quality markers of licorice can help to improve and promote the overall quality. These researches offer more sufficient theoretical basis for scientific application of licorice and its corresponding products.