Soyasaponin A2 Alleviates Steatohepatitis Possibly through Regulating Bile Acids and Gut Microbiota in the Methionine and Choline Deficient (MCD) Diet-induced Non-alcoholic Steatohepatitis (NASH) Mice.

SCOPE Nonalcoholic steatohepatitis (NASH) is a chronic progressive disease with complex pathogenesis of which the bile acids (BAs) and gut microbiota are involved. Soyasaponins (SS) exhibits many health-promoting effects including hepatoprotection, but its prevention against NASH is unclear. This study aims to investigate the preventive bioactivities of SS monomer (SS-A2 ) against NASH and further clarify its mechanism by targeting the BAs and gut microbiota. METHODS AND RESULTS The methionine and choline deficient (MCD) diet-fed male C57BL/6 mice were intervened with obeticholic acid or SS-A2 for 16 weeks. Hepatic pathology is assessed by hematoxylin-eosin and Masson's trichrome staining. BAs in serum, liver, and colon are measured by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQMS). Gut microbiota in caecum are determined by 16S rDNA amplicon sequencing. In the MCD diet-induced NASH mice, SS-A2 significantly reduces hepatic steatosis, lobular inflammation, ballooning, nonalcoholic fatty liver disease activity score (NAS) scores, and fibrosis, decreases Erysipelotrichaceae (Faecalibaculum) and Lactobacillaceae (Lactobacillus) and increases Desulfovibrionaceae (Desulfovibrio). Moreover, SS-A2 reduces serum BAs accumulation and promotes fecal BAs excretion. SS-A2 changes the BAs profiles in both liver and serum and specifically increases the taurohyodeoxycholic acid (THDCA) level. Faecalibaculum is negatively correlated with serum THDCA. CONCLUSION SS-A2 alleviates steatohepatitis possibly through regulating BAs and gut microbiota in the MCD diet-induced NASH mice.