Extracts of Gleditsia sinensis Lam. thorn ameliorates ulcerative colitis through PPARγ/GPX4 pathway-mediated inhibition of enterocyte ferroptosis

BACKGROUND Extracts from Gleditsia sinensis thorns (EGST) have demonstrated anti-inflammatory effects. However, the involvement of ferroptosis and bile acid (BA) metabolism in their mechanisms remains unexplored. AIM To elucidate the mechanism by which EGST mitigate ulcerative colitis through suppression of enterocyte ferroptosis via the peroxisome proliferator-activated receptor gamma (PPARγ)/glutathione peroxidase 4 (GPX4) axis and modulation of BA metabolism. METHODS A murine ulcerative colitis model was established using 3% dextran sulfate sodium (DSS) and treated with EGST at varying doses over 7 days. In vitro , ferroptosis in Caco-2 cells was induced by erastin. EGST’s protective effects were evaluated through histopathological analysis, inflammatory mediator quantification, transmission electron microscopy, and mitochondrial membrane potential assessment. Network pharmacology was used to identify potential molecular targets, followed by molecular docking and dynamics simulations to validate ligand-receptor interactions. Additionally, targeted metabolomics employing liquid chromatography-mass spectrometry quantified over 50 BAs. RESULTS EGST significantly alleviated DSS-induced colitis by restoring colon length, reducing histopathological damage, and modulating cytokine levels (interleukin-6, tumor necrosis factor α, interleukin-10). In vitro , EGST countered erastin-induced alterations in glutathione, Fe2+, malondialdehyde, and reactive oxygen species, while also restoring mitochondrial membrane potential and mitochondrial ultrastructure. Network pharmacology analysis identified 45 overlapping targets, with core hub proteins including prostaglandin-endoperoxide synthase 2 and PPARγ. Molecular dynamics simulations confirmed stable binding of β-sitosterol, a bioactive compound in EGST, to the PPARγ ligand pocket. Mechanistic studies confirmed that EGST activate the PPARγ/GPX4 axis, upregulating PPARγ and GPX4 expression to levels comparable with the agonist rosiglitazone. Moreover, metabolomic analysis revealed a significant upregulation of taurohyodeoxycholic acid (THDCA), indicating that THDCA enhancement and BA metabolism regulation contribute to the improvement of colonic injury. CONCLUSION EGST significantly alleviate DSS-induced colitis by inhibiting intestinal epithelial cell ferroptosis through activation of the PPARγ/GPX4 signaling pathway and restoration of metabolic balance, particularly through the upregulation of THDCA.