Casuarinin protects cultured MDCK cells from hydrogen peroxide-induced oxidative stress and DNA oxidative damage

Casuarinin has been shown to be an antioxidant in acellular experiments. This study was designed to assess the ability of casuarinin, extracted from Terminalia arjuna, to protect cultured Madin-Darby canine kidney (MDCK) cells against H2O2-mediated oxidative stress. A comparison with trolox, a hydrosoluble vitamin E analogue was performed. MDCK cells were pretreated with casuarinin or trolox for 1 h, then exposed to H2O2. After incubation with 0.8 mM H2O2 for 1 h, casuarinin caused a decrease in intracellular peroxide production as shown by dichlorofluorescein (DCF) fluorescence in a concentration-dependent manner. After 3 h exposure to 8 mM H2O2, the percentage of intracellular glutathione (GSH)-negative cells was reduced in the casuarinin-treated group. Addition of 32mM H2O2 to MDCK cells for 3 h induced an increase in the percentage of cells containing 8-oxoguanine but the level of such cells declined in casuarinin-treated cells. These results show that casuarinin is more effective against H2O2-induced oxidative damage than trolox. The data suggest that casuarinin attenuates H2O2-induced oxidative stress, decreases DNA oxidative damage and prevents the depletion of intracellular GSH in MDCK cells.