Systematic Quality Evaluation Of Licorice And Honey-fried Licorice Decoction Pieces

Licorice（Gancao）is the dried rhizome of Glycyrrhiza uralensis Fisch.,G.Bat.and G.L.,which was initially recorded in shen nong ben cao jing,and regarded as a top grade herbal medicine.It mainly contains flavonoids,saponins and polysaccharides with the effect of invigorating spleen,resolving phlegm and compatibility with other drugs,which has been widely used in the formula.At present,Inner Mongolia,Xinjiang and Gansu provinces are recognized as the main cultivation production areas of licorice,which takes a large account in the market.However,there are still some problems including incomplete evaluation indexes,unclear origin difference and imperfect quality specifications of licorice processed products.The key to solve the above problems is to establish a systematic and comprehensive quality evaluation.Therefore,the quality of 23 batches of licorice and 17 batches of honey-fried licorice decoction pieces samples from Inner Mongolia,Xinjiang and Gansu was systematically evaluated in this paper.Firstly,40 batches of samples were evaluated by quality evaluation based on Chinese Pharmacopoeia（2020 edition）.The quality of these samples were qualified except 6 batches of samples.The innovation of this chapter lied in the addition of liquiritin and liquiritigenin standard substances in TLC,and simultaneous determination of water soluble and alcohol soluble extraction to achieve the more comprehensive quality evaluation.In addition,a reliable method for the determination of glycyrrhiza polysaccharide（GP）content was established based on the summary of polysaccharide methods of five herb materials in Chineses Pharmacopoeia.The optimal solution was obtained by single-factor and orthogonal experiments with the the liquid-solid ratio at 400:1,extraction time at 2 h and extraction three times.GP content in 40 batches of samples revealed that the yield of GP was high and stable under this method,and GP content in honey-fried licorice were higher than licorice.Samples from Xinjiang province had the highest content of GP overall,which may be related to the climate factors such as sunshine and temperature difference.HCA results revealed that there was some crossover between different producing areas,and the samples from different producing areas are similar to some extent.Secondly,all samples were systematically evaluated by multi-components quantitative,chromatographic fingerprints analyses and chemometrics methods.The results of fingerprints showed that licorice and honey-fried licorice samples had high correspondence and similarity,respectively.Multi-components quantification（liquiritin（LQ）,isoliquiritin（ILQ）,liquiritigenin（LQG）,isoliquiritigenin（ILQG）,glycyrrhizic acid（GA））showed that liquiritin and GA were the dominant compounds,and licorice from Inner Mongolia and honey-fried licorice from Gansu had the highest total content.Resluts of the total phenols（TP）,total flavonoids（TF）and total saponins（TS）showed that all samples showed a higher amount of TFc.Activity tests in vitro indicated the samples from Inner Mongolia province exhibted excellent anti-oxidant activity andα-Glu inhibitory capacity.All samples manifestated a higherα-glucosidase inhibitory than anti-oxidant activity.The chemical compositions（LQ,ILQ,LQG,ILQG,GA,GPc,TPc,TFc and TSc）,H₂O and Et OH extraction,anti-oxidant activity（DPPH,OH and ABTS）andα-glucosidase inhibitory activity（α-Glu）set as 15 variables,were further analyzed by chemometrics methods.PCA results showed that the licorice decoction pieces from different origins could be achieve a better distinction compared in pairs,but honey-fried licorice can’t.OPLS-DA further showed that the licorice samples could be well distinguished without cross,and the VIP analysis indicated thatα-Glu,H₂O extraction and LQ were three common factors strongly contributing to the licorice classification.The honey-fried licorice were also well distinguished by LQ,α-Glu,TPC and TSC.Correlation analysis showed that licorice from Gansu and Xinjiang provinces with higher content of TFc and GPc were more suitable as antioxidants,and honey-fried licorice from Inner Mongolia with high TPc can be used as hypoglycemic agents.Finally,Network pharmacology was introduced to study the internal mechanism of licorice in the treatment of diabetes.39 compounds with a good oral bioavailability（OB）and drug-likeness（DL）in licorice mainly including liquiritin were screened and41 intersection targets proteins were obtained by Venny analysis.8 core proteins（AKT1,MAPK3,MAPK1,PTGS2,CASP3,PPARG and JUN）were further identified by PPI network.GO and KEGG enrichment analysis further showed that the target proteins of diabetes were mainly related to biological processes（BP）and molecular functions（MF）,and licorice may have a certain therapeutic effect on diabetes by regulating the inflammatory factors and the PI3K-AKT signaling pathway.