The inhibitory effects of
Chinonin, a natural
antioxidant extracted from a Chinese medicine, on apoptotic and necrotic cell death of cardiomyocytes in
hypoxia-reoxygenation process were observed in this study. The possible mechanisms of
Chinonin on scavenging
reactive oxygen species and regulating apoptotic related genes bcl-2 and p53 were also investigated. Neonatal rat cardiomyocytes were subjected to 24-h
hypoxia and 4-h reoxygenation. Cell death was evaluated by
DNA electrophoresis on
agarose gel, cell death ELISA and
annexin-V-
FLUOS/
propidium iodide (PI) double staining cytometry.
Hypoxia caused the increase of apoptotic rates and the release of
lactate dehydrogenase (LDH), while reoxygenation not only further increased the apoptotic rates and leakage of LDH, but also induced
necrosis of cardiomyocytes. In addition,
hypoxia increased the levels of NO(2)(-)/NO(3)(-) and
thiobarbituric acid reacted substances (
TBARS), while reoxygenation decreased NO(2)(-)/NO(3)(-), but further increased
TBARS in the cultured media. Moreover,
hypoxia up-regulated the expression levels of bcl-2 and p53
proteins, while reoxygenation down-regulated bcl-2 and further up-regulated p53.
Chinonin significantly decreased the rates of apoptotic and necrotic cardiomyocytes, and inhibited the leakage of LDH. It also diminished NO(2)(-)/NO(3)(-) and
TBARS, down-regulated the expression level of p53
protein, and up-regulated bcl-2
protein, respectively. The results suggest that
Chinonin has preventive effects against apoptotic and necrotic cell death and its protective mechanisms are related to the
antioxidant properties of scavenging
nitric oxide and
oxygen free radicals, and the modulating effects on the expression levels of bcl-2 and p53
proteins.