Vaccarin Improves Myocardial Ischemia–Reperfusion Injury by Attenuating Oxidative Stress and Ferroptosis Through Reducing NOX4 ‐Modulated JAK2 / STAT3 Pathway Activation

ABSTRACT Vaccarin is a naturally occurring flavonoid glycoside with cardioprotective properties; however, its involvement in myocardial ischemia–reperfusion (MI/R) injury remains poorly defined. We herein investigated whether vaccarin protects cardiomyocytes from MI/R‐induced dysfunction in vivo and in vitro and examined the associated molecular mechanisms. To explore the protective effects of vaccarin, we established an MI/R injury mouse model and in vitro hypoxia/reoxygenation (H/R) injury model using H9c2 cardiomyocytes. In vivo results showed that vaccarin alleviated MI/R injury. In H9c2 cells, vaccarin partially reversed the H/R‐induced elevation of reactive oxygen species and malondialdehyde levels and restored the reduced activity of superoxide dismutase. Vaccarin also suppressed the H/R‐induced accumulation of Fe 2+ and glutathione disulfide while restoring the levels of glutathione, solute carrier family 7 member 11, and glutathione peroxidase 4. NADPH oxidase 4 (NOX4) was subsequently identified as a putative molecular target of vaccarin. Moreover, vaccarin inhibited H/R‐induced activation of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in cardiomyocytes. NOX4 overexpression counteracted vaccarin‐mediated suppression of JAK2/STAT3 signaling and blocked its antioxidative and antiferroptotic effects in H/R‐treated cardiomyocytes. Collectively, these findings indicate that vaccarin confers cardioprotection against MI/R injury by suppressing oxidative stress and ferroptosis, at least partly through inhibition of NOX4‐driven JAK2/STAT3 signaling. These results suggest that vaccarin may be a promising therapeutic candidate for the treatment of MI/R injury.