Protosappanin A Alleviates Atherosclerosis by Regulating the MDM2/GPX4 Axis-Mediated Endothelial Ferroptosis

Endothelial ferroptosis is a crucial pathogenic driver of atherosclerosis (AS) progression. Protosappanin A (PTA), a bioactive compound from Caesalpinia sappan L., protects cardiovascular vessels by regulating ferroptosis. However, whether PTA inhibits AS specifically through suppressing endothelial ferroptosis remains unclear. To address this, ApoE^-/- mice were fed a high-fat diet for 16 weeks to induce atherosclerosis, and PTA or simvastatin was administered daily from Week 4 through Week 16 (12 weeks of intervention). PTA markedly reduced aortic plaque area (en face Oil Red O and H&E staining) and improved serum lipid profiles (TG, TC, LDL-C, HDL-C). It also alleviated endothelial injury, evidenced by decreased VCAM-1 and ICAM-1 expression. Mechanistically, PTA ameliorated mitochondrial ferroptosis in endothelial cells, lowered intracellular Fe²⁺ and lipid peroxidation (MDA, lipid ROS), and restored the expression of GPX4, xCT, and FTH1. Immunofluorescence confirmed that PTA upregulated GPX4 within the aortic endothelium. To explore the underlying mechanism, we performed RNA-seq on ox-LDL-treated HUVECs and integrated the data with ferroptosis-related databases. MDM2 was identified as a key target, which was validated by qPCR and Western blotting. Overexpression of MDM2 activated endothelial ferroptosis and reversed the protective effects of PTA both in vitro and in vivo. Collectively, these findings demonstrate that PTA alleviates AS by suppressing endothelial ferroptosis via the MDM2/GPX4 axis.