Red yeast rice extract's impact on liver health: a pharmacological and metabolomic exploration

This study aimed to investigate the therapeutic mechanism of red yeast rice extract (RYRE) in high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) through untargeted metabolomics analysis and experimental validation.

An untargeted metabolomics analysis based on UHPLC-QTOF/MS was performed to identify differential metabolites in liver tissues. A NAFLD model was established in hamsters by HFD feeding. Forty hamsters were randomly allocated into four groups (n = 10 per group): control (CON), model (MOD), red yeast rice extract (Xuezhikang, XZK), and simvastatin (SVT). Serum levels of lipids (TG, CHO, HDL-C, LDL-C), liver function parameters (ALT, AST, ALB, ALP, γ-GT, TBiL, DBiL, TBA), and inflammatory cytokines (TNF-α, IL-4, IL-1β, TGF-β) were measured by biochemical assays and ELISA. Liver tissues were subjected to Oil Red O, hematoxylin-eosin (HE), and Masson staining for histopathological evaluation. Additionally, qPCR and immunohistochemistry were employed to investigate the underlying signaling pathways.

XZK significantly reduced serum levels of DBiL, TBiL, TBA, CHO, TG, and LDL-C, while increasing HDL-C in HFD-fed hamsters. Both XZK and SVT markedly decreased pro-inflammatory cytokines. Untargeted metabolomics identified 135 differential metabolites between the MOD and XZK groups (83 down-regulated, 52 up-regulated), which were primarily involved in carbon metabolism, lipid metabolism, and hormone metabolism. Mechanistically, XZK attenuated the JNK/AP-1/TNF-α signaling pathway, as evidenced by reduced mRNA expression of cFos, cJUN, JAK1/2/3, and TNF-α, along with decreased protein levels of p-JNK, cFos, cJUN, and TNF-α. Notably, the p-cJun/total cJun ratio showed a distinct regulatory pattern, suggesting complex modulation of AP-1 subunit phosphorylation.

XZK effectively ameliorates hepatic steatosis, dyslipidemia, and inflammation in HFD-induced NAFLD hamsters. The therapeutic effects are mediated through restoration of metabolic homeostasis and suppression of the JNK/AP-1/TNF-α signaling pathway.