Chemical and pharmacological difference between honey-fried licorice and fried licorice

According to textual research of books from ancient times till now, there are three main preparation methods of "fried licorice", including frying licorice without excipients (F), frying licorice after dipping with water (W), and frying licorice with honey (H). However, with the development over many successive generations, honey frying has gradually become the main processing form of licorice, whereas the fried licorice is nowadays rarely used.

The objectives of this study were to clarify the differences of the three forms of "fried licorice" in chemical composition and pharmacological activities, and to screen quality markers for differently processed licorice. It is expected to provide a scientific basis for the rational choice of "fried licorice" as medicine.

Non-target metabolomic analysis based on UHPLC-QE-Orbitrap-MS was conducted to compare the chemical differences between the differently processed licorice material. Pharmacodynamically, the differences in immunomodulatory activity (including intestinal flora experiment), anti-inflammatory activity, and hepatoprotective activity of the differently processed licorice were evaluated. Furthermore, multivariate statistical analysis was performed to screen potential quality markers of honey-fried licorice. The serum concentration of selected markers was determined by UHPLC-QqQ-MS.

Metabolomic analysis showed no difference in the chemical composition of F and W, whereas the chemical composition of H was significantly different from that of F and R. The immunomodulatory activity, anti-acute inflammatory effect, and hepatoprotective effect of licorice were significantly improved after frying with honey; No significant differences were observed between F and H in term of immunomodulatory activity and anti-acute inflammatory effect, whereas, H is better than F in terms of liver-protective activity. The intestinal flora experiment confirmed that H does have immunomodulatory activity, while F may induce an increased abundance of certain pathogenic bacteria in the intestine. Multivariate statistical analysis suggests that the content of liquiritin (2), liquiritigenin (3), isoliquiritin (5), isoliquiritigenin (6) and glycyrrhizic acid (7) plusing glycyrrhetinic acid (8) in H group is closely correlated with its improved effects.

This study provides a scientific rational for the selection of "fried licorice" processing methods. In addition, it provides a scientific basis for the selection of quality markers of differently processed licorice.