Effect of chin brick tea [Camellia sinensis (L.) Kuntze] on lipid metabolism and inflammation by modulating intestinal flora and bile acids in mice with non-alcoholic fatty liver disease

Tea (Camellia sinensis) has been consumed for centuries as a traditional remedy for various metabolic diseases. The pharmacological mechanisms of many conventional medicines, including tea, often need to be clarified. Chin brick tea is a unique Chinese black tea grown in Hubei, China, rich in tea elements such as tea polyphenols and tea polysaccharides.We focus on the effects of commercial chin brick tea on non-alcoholic fatty liver disease by altering intestinal flora and its metabolite, bile acids.Targeted UPLC-MS/MS was employed to quantify the tea elements in commercial chin brick tea. In this study, we performed an integrated approach of animal experiments, 16 S rDNA, and ultra-performance liquid chromatography-tandem mass spectrometry to explore the potential mechanism of action of chin brick tea in preventing non-alcoholic fatty liver disease (NAFLD).After 14 weeks of administration, CBT extract could signiffcantly decrease the levels of body weight, liver weight, LDL-C, TC, ALT, IL-1β and IL-18, and slight increase HDL-C levels in NAFLD mice. The results indicated that the interventional impact of CBT with high-fat diet-induced NAFLD might depend on intestinal flora and its metabolites bile acids. Moreover, sequencing of 16 S rRNA genes demonstrated that CBT could signiffcantly improve the intestinal flora disorder of NAFLD mice. Speciffcally, CBT increased the levels of Lactobacillus, Alloprevotella, and Ruminococcaceae, while reducing the levels of Bacteroides in NAFLD mice. Then, a total of 23 bile acids were identified, 17 differential bile acids were obtained by screening, and CBT increase the primary bile acids/secondary bile acids ratio in NAFLD mice. Additionally, correlation analysis revealed that Bacteroides was negatively correlated with DCA and ωMCA, Lactobacillus was positively correlated with DCA and ωMCA, Bacteroides was positively correlated with NAFLD, Lactobacillus was negatively associated with NAFLD, and DCA and ωMCA were negatively correlated with NAFLD.CBT extract has a good interventional impact on NAFLD mice. The mechanism by which this extract exerts its action is, at least partly, related to its regulation of intestinal flora and its metabolites bile acids.