Tectorigenin ameliorates myocardial cell injury caused by hypoxia/reoxygenation by inhibiting autophagy via activation of PI3K/AKT/mTOR pathway

Purpose: To investigate the protective role of tectorigenin in myocardial ischaemia/reperfusion. Methods: Myocardial cells (H9c2) were treated with different concentrations of tectorigenin and exposed to hypoxia/reoxygenation. Cell viability and apoptosis were determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) staining, respectively. Oxidative stress and inflammation were evaluated using enzyme-linked immunosorbent assay (ELISA), while autophagy and the underlying mechanisms of action were evaluated by Western blot. Results: Tectorigenin enhanced the proliferative activity of H9c2 under hypoxia/reoxygenation conditions, and significantly reduced the apoptotic activity (p < 0.001) through decrease in Bax and increase in Bcl-2. Tectorigenin also significantly up-regulated SOD (superoxide dismutase) and GSH (glutathione) levels (p < 0.01), and down-regulated MDA (malondialdehyde) and MPO (myeloperoxidase) in hypoxia/reoxygenation-induced H9c2. TNF-α (tumor necrosis factor-α), IL(interleukin)-1β, and IL-6 levels were also inhibited by tectorigenin by down-regulating p-p65. Hypoxia/reoxygenation-induced increase in p62 and decrease in Beclin-1 and LC3-II/LC3-I were reversed by tectorigenin. Protein expressions of p-mTOR, p-AKT, and p-PI3K in hypoxia/reoxygenation-induced H9c2 were elevated by tectorigenin. Conclusion: Tectorigenin exerts anti-oxidant, anti-inflammatory, and anti-autophagic effects on hypoxia/reoxygenation-induced H9c2 through the activation of PI3K/AKT/mTOR pathway, thus suggesting that it is a potential agent for the management of myocardial ischaemia/reperfusion.