Pachymic acid alleviates hepatic lipid accumulation and oxidative stress in MASLD via regulation of the Keap1–Nrf2–HO-1 signaling axis

BackgroundMetabolic dysfunction-associated steatotic liver disease (MASLD) is a rapidly growing metabolic disorder with no FDA-approved treatment. Pachymic acid (PA; synonym: 3-O-acetyltumulosic acid), a lanostane-type triterpenoid, shows potential for treating MASLD. However, its mechanisms remain underexplored.ObjectiveThis work evaluated the therapeutic efficacy and mechanisms of PA in treating MASLD.MethodsThe high-cholesterol diet (HCD)-induced zebrafish model, high-fat diet induced C57BL/6 mice model and free fatty acid (FFA)-treated BRL-3A cells was used to assess PA’s anti- MASLD effects in vivo and in vitro.ResultsPA improved lipid metabolism disrupted by HCD, reduced hepatic oxidative stress, as indicated by decreased MDA levels and increased SOD activity, and lowered inflammatory markers, including TNF-α, IL-6, and IL-1β. PA also enhanced antioxidant activity by regulating the Keap1-Nrf2-HO-1 pathway. PA decreased Keap1 mRNA expression induced by reactive oxygen species (ROS), upregulated Nrf2 and HO-1 expression, and promoted Nrf2 nuclear translocation. These effects suggest that PA inhibits ROS production by activating the Keap1-Nrf2-HO-1 pathway and possibly by inhibiting Nrf2 degradation.ConclusionPA improves MASLD through lipid metabolism regulation and antioxidant effects, primarily by activating the Keap1-Nrf2-HO-1 pathway. These findings highlight PA’s potential as a therapeutic agent for MASLD.