Modulation of gut microbiota by glycyrrhizic acid may contribute to its anti-NAFLD effect in rats fed a high-fat diet

Glycyrrhizic acid is a natural anti-non-alcoholic fatty liver disease (NAFLD) compound isolated from licorice, while its action mechanism deserves to be fully elucidated.Enlightened by the widely discovered associations between the NAFLD and gut microbiota, this study aimed to explore whether glycyrrhizic acid, licorice flavonoids, and licorice extract can regulate the gut microbiota of rats fed a high-fat diet.It was found that glycyrrhizic acid, licorice flavonoids, and licorice extract could significantly reduce the level of triglycerides in the liver of NAFLD model rats, and the effect of glycyrrhizic acid was stronger than licorice flavonoids and licorice extract. Moreover, they caused significant changes in the structural composition of the gut microbiota. Correlation analysis showed that the regulation of hepatic total cholesterol and triglyceride levels by glycyrrhizic acid treatment was closely related to the decrease of the relative abundances of Lachnospiraceae, Coriobacteriaceae, Blautia, and Collinsella and the increase of the relative abundances of Romboutsia and Turicibacter on the gut microbiota. Meanwhile, the functional predictive analysis of the gut microbiota indicated that the function of carbohydrate transport and metabolism was significantly decreased by drugs treatment, which might contribute to the decrease of fat accumulation in the liver of rats.In conclusion, this study revealed the ameliorating effects of glycyrrhizic acid, licorice flavonoids, and licorice extract on NAFLD, and suggested that the effect of glycyrrhizic acid on NAFLD may be related to the improvement of the dysbiosis of gut microbiota.