Kaempferol Attenuates Myocardial Ischemia–Reperfusion Injury by Suppressing Ferroptosis via the <scp>KEAP1</scp> –Nrf2– <scp>GPX4</scp> Axis

Myocardial ischemia/reperfusion (I/R) injury is characterized by cardiomyocyte death, excessive oxidative stress, inflammation, and ferroptosis, which collectively limit the efficacy of reperfusion therapy. In this study, we investigated whether kaempferol (KAE), a natural flavonol with antioxidative and antiinflammatory properties, could protect against myocardial I/R injury by modulating the KEAP1-Nrf2-GPX4 signaling pathway. Using hypoxia/reoxygenation (H/R)-injured AC16 cardiomyocytes and a mouse myocardial I/R model, we observed that KAE significantly enhanced cardiomyocyte viability, promoted Nrf2 nuclear translocation, and upregulated downstream antioxidant and antiferroptotic proteins, including HO-1, NQO1, GPX4, and SLC7A11, while reducing KEAP1 and ACSL4 expression. KAE also markedly attenuated lipid peroxidation, iron accumulation, reactive oxygen species generation, apoptosis, and inflammatory responses in vitro and in vivo. These protective effects were partially abolished by Nrf2 knockdown and were replicated by the ferroptosis inhibitor ferrostatin-1 (Fer-1), indicating a ferroptosis-dependent mechanism. Consistently, KAE pretreatment attenuated myocardial injury, preserved cardiac histology, restored GPX4 and SLC7A11 expression, and lowered serum cTnI, CK-MB, TNF-α, and IL-6 levels in I/R mice. Taken together, these results demonstrate that KAE alleviates myocardial I/R injury by activating the KEAP1-Nrf2-GPX4 axis and suppressing ferroptosis and oxidative stress, highlighting its potential as a therapeutic agent in ischemic heart disease.