Diosgenin attenuates nonalcoholic fatty liver disease through mTOR-mediated inhibition of lipid accumulation and inflammation

Excessive hepatic lipid accumulation and inflammatory injury are significant pathological manifestations of nonalcoholic fatty liver disease (NAFLD). Our previous research discovered that diosgenin, a natural steroidal saponin derived from Chinese herbs, can reduce hepatic lipid accumulation and steatosis; however, the exact mechanism remains unclear. This study aimed to investigate the protective mechanisms of diosgenin against NAFLD. We utilized network pharmacology and molecular docking approaches to identify the pathways through which diosgenin improves NAFLD. In high-fat diet (HFD)-fed rats, we measured biochemical markers in the serum and liver. Liver histopathology was assessed using HE and oil-red O staining. In free fatty acids (FFAs)-induced HepG2 cells, we employed the cell transfection overexpression method to verify the regulatory relationship of the identified pathways. The mechanisms in vitro and in vivo were examined using quantitative polymerase chain reaction and Western blot analyses. Bioinformatics analysis indicated that the mTOR-FASN/HIF-1α/RELA/VEGFA pathway may be the target pathway for diosgenin in alleviating NAFLD. Diosgenin inhibited hepatic lipid accumulation and pro-inflammatory cytokines in HFD-fed rats, and reduced intracellular lipid accumulation as well as TG, TC, IL-1β, and TNF-α levels in FFAs-induced HepG2 cells. Mechanistically, diosgenin downregulated the expression of p-mTOR, FASN, HIF-1α, RELA, and VEGFA, which are associated with lipid synthesis and inflammation. Overexpression of mTOR abolished the beneficial effects of diosgenin on lipid reduction and inflammation, as well as its inhibitory effects on the expression of FASN, HIF-1α, RELA, and VEGFA. In conclusion, diosgenin alleviates NAFLD through mTOR-mediated inhibition of lipid accumulation and inflammation.