Kaempferol alleviates myocardial ischemia-reperfusion injury by activating the Nrf2/GPX4 signaling pathway to inhibit ferroptosis.
Myocardial ischemia-reperfusion injury (MIRI) remains a major cause of myocardial dysfunction after reperfusion therapy, and effective pharmacological interventions are still limited. Ferroptosis plays a pivotal role in MIRI pathogenesis. This study investigated whether kaempferol, a natural flavonoid, protects against MIRI by activating nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4)-mediated ferroptosis defense. In male C57BL/6 mice subjected to left anterior descending coronary artery ligation/reperfusion, kaempferol reduced myocardial infarct size, preserved cardiac contractile function, decreased serum cardiac injury markers, and attenuated myocardial fibrosis and apoptosis. In H9c2 cardiomyocytes exposed to hypoxia/reoxygenation (HR), kaempferol improved cell viability and reduced the expression of cleaved caspase-3 and cleaved PARP. Mechanistically, kaempferol restored antioxidant capacity, alleviated lipid peroxidation and iron overload, and preserved mitochondrial membrane potential. Non-targeted metabolomics revealed that kaempferol modulated glutamate/glutamine metabolism, glycerophospholipid metabolism, and glutathione-related pathways. Furthermore, kaempferol was able to reverse MIRI/HR-induced suppression of Nrf2, solute carrier family 7 member 11 (SLC7A11), and GPX4, inhibit RAS-selective lethal 3 (RSL3)-induced ferroptosis, and increase phosphorylation of Nrf2 at Ser40. Molecular docking analysis suggested that kaempferol may interact with the Nrf2-binding pocket of its repressor protein, implying a potential upstream mechanism for Nrf2 activation. Importantly, the Nrf2 inhibitor ML385 markedly weakened the protective and anti-ferroptotic effects of kaempferol. Collectively, these findings demonstrate that kaempferol ameliorates MIRI by activating Nrf2/GPX4-related antioxidant signaling, thereby inhibiting ferroptosis, attenuating apoptosis, reducing myocardial structural damage, and ultimately preserving cardiac function.