Jiuwei Xiaozhi Decoction Alleviates High-Fat Diet-Induced MASLD by Suppressing Hepatic SREBP2-Driven Cholesterogenesis and Restoring PPARα-Mediated Fatty Acid Oxidation.

Jiuwei Xiaozhi Decoction (JWXZ) is a nine-herb traditional Chinese medicine formula clinically used for hepatic steatosis and dyslipidemia, but its chemical basis and pharmacological mechanisms in metabolic dysfunction-associated steatotic liver disease (MASLD) remain incompletely defined. The chemical profile of JWXZ was characterized by UHPLC-HRMS/MS. Its therapeutic effects were evaluated in a high-fat diet (HFD)-induced mouse model of MASLD, followed by hepatic transcriptomic analysis, network pharmacology, molecular docking, Western blotting, and immunofluorescence validation. UHPLC-HRMS/MS identified 178 chemical constituents in JWXZ, including phenolic acids, flavonoids, flavonoid glycosides, alkaloids, isoflavones, and coumarins. In HFD-fed mice, JWXZ attenuated body weight gain, white adipose accumulation, dyslipidemia, hepatic triglyceride and cholesterol accumulation, serum transaminase elevation, and hepatic steatosis, while improving glucose tolerance and partially restoring whole-body metabolic flexibility. Hepatic transcriptomics identified 124 HFD-dysregulated genes reversed by high-dose JWXZ, with prominent enrichment in cholesterol and sterol biosynthesis, endoplasmic reticulum proteostasis, oxidative stress response, and PPARα-related lipid handling. Integrated transcriptomic and network pharmacology analyses further identified 157 shared targets and 18 overlapping pathways, converging mainly on cholesterol metabolism and PPAR signaling. Protein-level validation showed that JWXZ suppressed SREBP2 proteolytic activation, reduced nuclear SREBP2 abundance, and downregulated HMGCR, SQLE, and PCSK9, indicating inhibition of the hepatic cholesterogenic program. In parallel, JWXZ restored nuclear PPARα abundance and CPT1A expression, consistent with reactivation of fatty acid oxidation. JWXZ also reduced hepatic EGFR phosphorylation and lowered hepatic and circulating TNF-α, IL-6, IL-1β, and MCP-1 levels. Molecular docking provided supportive evidence for potential interactions between representative JWXZ constituents and key regulators, including naringin-HMGCR, chlorogenic acid-SQLE, rhoifolin-PPARα, and rhoifolin-SREBP2. These findings suggest that JWXZ ameliorates HFD-induced MASLD mainly by rebalancing hepatic lipid metabolism through coordinated suppression of SREBP2-mediated cholesterogenesis and restoration of PPARα-mediated fatty acid oxidation, with associated attenuation of EGFR-linked inflammatory responses.