Isovitexin Alleviates Myocardial Ischemia by Targeting SLC25A4 and Modulating the AMPK/PGC-1<i>α</i> Signaling Pathway

Isovitexin (ISOV) is an active component identified in the traditional Tibetan medicine Tsantan Sumtang, which is commonly used for treating myocardial ischemia. Although previous studies have suggested the protective effect of ISOV on cardiomyocytes, the in vivo anti-ischemic efficacy and underlying mechanisms of ISOV remain unclear. This study aimed to systematically evaluate the therapeutic effects of ISOV on myocardial ischemia in rats and to elucidate its molecular mechanism of action. An acute myocardial infarction model was established in rats by ligating the left anterior descending branch (LADL) of the coronary artery. The protective effects of ISOV were assessed by measuring infarct size, serum cardiac injury biomarkers, and oxidative stress levels. Chemical proteomics using photoaffinity magnetic beads was employed to identify potential target proteins of ISOV. Molecular docking, pull-down western blotting, and cellular thermal shift assay (CETSA) western blotting were applied to validate the interaction between ISOV and target. Knockdown of the target was used to verify the mechanism of ISOV on anti-myocardial ischemia effect. ISOV treatment significantly reduced myocardial infarct size, decreased serum levels of lactate dehydrogenase (LDH), creatine kinase isoenzymes (CK-MB), malondialdehyde (MDA), and enhanced superoxide dismutase (SOD) activity in myocardial ischemia rats. Furthermore, ISOV improved mitochondrial function, as evidenced by increased ATP content and enhanced activities of mitochondrial complexes I and IV. Chemical proteomics and bioinformatic analysis identified SLC25A4 as a direct target of ISOV. Molecular docking revealed a high-affinity binding (binding energy: -8.3 kcal/mol), which was further confirmed by pull-down assays and CETSA. In SLC25A4-knockdown H9c2 cells under hypoxic conditions, ISOV upregulated SLC25A4 expression, promoted the phosphorylation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) and upregulated the expression of proliferator-activated receptor gamma coactivator-1α (PGC-1α). ISOV exerts cardioprotective effects against myocardial ischemia by directly binding to SLC25A4 and activating the AMPK/PGC-1α pathway, highlighting its potential as a therapeutic agent for myocardial ischemia.