Formononetin promotes fatty acid β-oxidation to treat non-alcoholic steatohepatitis through SIRT1/PGC-1α/PPARα pathway

Background: Non-alcoholic steatohepatitis (NASH), the progressive form of non-alcoholic fatty liver disease (NAFLD), carries a high risk of cirrhosis and hepatocellular carcinoma. With the increasing incidence of NASH, the accompanying medical burden is also increasing rapidly, so the development of safe and reliable drugs is urgent. Formononetin (FMNT) has a variety of pharmacological effects such as antioxidant and antiinflammation, and plays a major role in regulating lipid metabolism, reducing hepatic steatosis and so on, but the mechanism for alleviating NASH is unclear. Materials and methods: We firstly established a mouse model on NASH through methionine-choline deficient (MCD) diet to investigate the improvement of FMNT as well as the effects of fatty acid beta oxidation and SIRT1/ PGC-1 alpha/PPAR alpha pathway. Then, we explored the mechanisms of FMNT regulation in SIRT1/PGC-1 alpha/PPAR alpha pathway and fatty acid beta oxidation based on genes silencing of SIRT1 and PGC1A. In addition, SIRT1 agonist (SRT1720) and inhibitor (EX527) were used to verify the mechanism of FMNT on improvement of NASH. Results: Our study found that after FMNT intervention, activities of ALT and AST and TG level were improved, and liver function and hepatocellular steatosis on NASH mice were significantly improved. The detection of beta oxidation related indicators showed that FMNT intervention up-regulated FAO capacity, level of carnitine, and the levels of ACADM and CPT1A. The detection of factors related to the SIRT1/PGC-1 alpha/PPAR alpha pathway showed that FMNT activated and promoted the expression of SIRT1/PGC-1 alpha/PPAR alpha pathway, including up-regulating the expression level of SIRT1, improving the activity of SIRT1, promoting the deacetylation of PGC-1 alpha, and promoting the transcriptional activity of PPAR alpha. Furthermore, after genes silencing of SIRT1 and PGC1A, we found that FMNT intervention could not alleviate NASH, including improvement of hepatocellular steatosis, enhancement of beta oxidation, and regulation of SIRT1/PGC-1 alpha/PPAR alpha pathway. Afterwards, we used SRT1720 as a positive control, and the results indicated that FMNT and SRT1720 intervention had no significant difference on improving hepatocellular steatosis and promoting fatty acid beta oxidation. Besides, we found that when EX527 intervention inhibited expression of SIRT1, the improvement of FMNT on NASH was weakened or even disappeared. Conclusion: In summary, our results demonstrated that FMNT intervention activated SIRT1/PGC-1 alpha/PPAR alpha pathway to promote fatty acid beta oxidation and regulate lipid metabolism in liver, ultimately improved hepatocellular steatosis on NASH mice.