Formononetin mediates the protective effect on diabetic cardiomyopathy through PPARγ-regulated ferroptosis suppression

To investigate the therapeutic mechanism of Gegen Qinlian capsule (GGQL) in diabetic cardiomyopathy (DbCM) and identify a key candidate bioactive constituent responsible for cardioprotection. A murine DbCM model was established by high-fat diet feeding combined with streptozotocin injection. GGQL was administered at three doses for 8 weeks. Cardiac injury was evaluated by echocardiography, histology, and serum biomarkers. Untargeted metabolomics and RNA sequencing were performed to characterize metabolic and transcriptional reprogramming. Network pharmacology, molecular docking, and cellular thermal shift assay (CETSA) were integrated to identify the principal active compound and its molecular target. Ferroptosis was assessed through GPX4/SLC7A11 protein expression, oxidative stress markers (MDA, ROS, Fe 2+ ), and antioxidant capacity. Mechanistic validation employed PPARG lentiviral knockdown in H9C2 cardiomyocytes and pharmacological PPARγ antagonism (GW9662) in vivo. GGQL dose-dependently attenuated cardiomyocyte hypertrophy, myocardial fibrosis, and systolic dysfunction, while suppressing ferroptotic markers and restoring GPX4/SLC7A11 expression. Multi-omics profiling converged on PPAR signaling and fatty acid oxidation as dominant therapeutic axes. Network pharmacology identified PPARγ as the central hub target. Formononetin (FMN) exhibited the highest PPARγ binding affinity (-9.3 kcal/mol), and CETSA confirmed direct intracellular target engagement. PPARG silencing and GW9662 co-administration each abolished FMN-mediated cardioprotection and anti-ferroptotic effects. Mechanistically, FMN activated the PI3K/AKT/mTOR signaling axis downstream of PPARγ, and PI3K inhibition reversed GPX4/SLC7A11 upregulation. FMN is a key candidate bioactive constituent of GGQL that attenuates DbCM by suppressing ferroptosis through a PPARγ-PI3K/AKT/mTOR-GPX4/SLC7A11 signaling cascade, providing a mechanistic basis for GGQL's clinical use in diabetic cardiovascular disease.