Background: Metabolic-associated fatty liver disease (MAFLD) is prevalent in individuals with liver disease; however, it lacks effective therapeutic approaches. Smilax china L., a traditional Chinese medicinal herb, possesses excellent anti-inflammatory and antioxidant activity. This research aimed to explore the therapeutic effects of Smilax china L. extract (SCE) on MAFLD and to elucidate the pharmacological mechanisms. Methods: A rat model of MAFLD was induced through a high-fat diet (HFD), and the model rats subsequently received SCE as a therapeutic intervention for six weeks. The analysis involved 16S rDNA sequencing, untargeted fecal metabolomics, and targeted bile acid metabolomics to investigate the effects of SCE on the gut microbiota and bile acid metabolism. Results: Hepatic steatosis and lipid accumulation were significantly alleviated by the SCE treatment. SCE treatment modulated the gut microbiota disorder, by enhancing the relative abundance of the beneficial gut microbiota, including Clostridium, Oscillospira, and Romboutsia. Untargeted fecal metabolomics revealed a significant enrichment of the metabolites in secondary bile acid biosynthesis. Targeted bile acid metabolomics revealed that SCE reversed the abnormal fecal bile acid metabolic profile, such as HDCA, LCA, and T-β-MCA. These changes activated FXR and PPARα receptors to improve the lipid metabolism by regulating bile acid synthesis. Conclusions: Our study provides evidence that SCE alleviates MAFLD through regulation of the gut microbiota, bile acid metabolism, and activation of the FXR/PPARα pathway, illustrating the mechanism of action of SCE in MAFLD from a novel perspective, and further highlights its therapeutic potential.

Background/Objectives: Ulcerative colitis (UC) involves inflammatory response, oxidative stress, changes in metabolites, and the gut microbiota. Jingangteng capsule (JGTC) has been utilized clinically for the treatment of inflammatory diseases for many years. However, the efficacy of JGTC in ameliorating UC remains unclear, and the underlying mechanisms have not yet been elucidated. This study aims to investigate the effect and mechanism of JGTC on UC. Methods: The chemical compositions of JGTC were examined using ultra-high-performance liquid chromatography with quadrupole time-of-fight mass spectrometry. The anti-UC effect of JGTC was evaluated by assessing the disease activity index (DAI), colon length, intestinal barrier recovery, and inflammatory factors in a dextran sulfate sodium (DSS)-induced colitis model. Mechanisms were investigated through fecal 16S rDNA sequencing, metabolomics analysis, enzyme-linked immunosorbent assay (ELISA), Western blotting, and network pharmacology analysis. Results: JGTC significantly reduced the DAI scores in UC mice, increased their body weight and colon length (p < 0.001), repairing damaged intestinal tissue. It decreased the levels of inflammatory cytokines TNF-α, IL-6, IL-1β, and LPS (p < 0.01, p < 0.001), alleviating intestinal inflammation. It also raised the expression of tight junction proteins ZO-1, Claudin-1, and Occludin (p < 0.05, p < 0.001), thereby enhancing intestinal barrier function. Fecal metabolomic analysis revealed that the favorable alterations in amino acid and lipid metabolites were more pronounced. Heat maps showed strong correlations between pharmacological indicators and gut microbiota, as well as between the main differential metabolites and gut microbial communities. UPLC-QTOF-MS detection yielded 33 components of JGTC, and network pharmacology analysis based on these components predicted pathways of action of JGTC in UC. Functional pathways closely associated with significantly differential metabolites and metabolic pathways were also investigated. The PI3K-AKT-mTOR pathway was one of them, which is consistent with the conclusions drawn from network pharmacology. JGTC significantly modulated key factors in this pathway, inhibiting the expression of PI3K, Akt, PDK1, and mTOR, while augmenting the expression of PTEN (p < 0.05, p < 0.01, p < 0.001). It also mitigated the levels of related oxidative stress factors MDA, MPO, and D-LA, and raised SOD levels (p < 0.01, p < 0.001). Conclusions: JGTC improved the excessive inflammatory response in UC by regulating intestinal flora and metabolic disorders, affecting the PI3K-AKT-mTOR signaling pathway, restoring intestinal tissue damage and intestinal barrier, and inhibiting inflammatory and oxidative stress factors.