Design, synthesis, and in vitro protective effect evaluation of α-carboline derivatives against HO-induced cardiomyocyte injury.

As one of the most important features of myocardial ischemia reperfusion (MI/R) injury, the overproduction of reactive oxygen species (ROS) overwhelms the intrinsic antioxidant and impairs the function of mitochondria and, finally, leads to cardiomyocyte death. To improve the damage of cardiomyocyte caused by oxidative stress, a series of α-carboline derivatives were designed and synthesized in this study. The biological studies revealed that most of the α-carbolines exhibited obvious protective activities against HO-induced cardiomyocyte injury. Among them, compound 14b significantly increased the cell viability in HO-induced oxidative stress in H9c2 cardiomyoblasts with a concentration-dependent manner, which was more potent than polydatin. Pretreatment of 14b obviously inhibited HO-induced lactate dehydrogenase (LDH) leakage, enhanced the capacity of endogenous antioxidant defenses, including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and reduced the formation of the toxic product of lipid peroxidation (malondialdehyde, MDA). In addition, 14b effectively reduced the overproduction of ROS and restored the mitochondrial membrane potential ΔΨm, better than that of polydatin. Flow cytometry analysis demonstrated that 14b markedly reduced both necrosis and apoptosis in H9c2 cells after the exposure to HO. Further Western blot analysis revealed that 14b obviously decreased the ratio of Bax/Bcl-2 and reduced the expression of cytochrome c. Overall, these results revealed the potential of α-carboline 14b as a promising cardioprotective agent against HO-induced oxidative injury.