Abstract
The effect of oxidative stress on the alterations of different antioxidant enzyme activities was investigated in human skin melanoma cell line (SK-MEL-2). Oxidative stress was induced by the exposure to hydrogen peroxide ($H_2O$$_2$). SK-MEL-2 cells were treated with antioxidants such as vitamin E and selenomethionine in combination with $H_2O$$_2$. SK-MEL-$_2$ cells were exposed to various concentrations of $H_2O$$_2$ and measured the time course of changes in cell viability and antioxidant enzyme activities for 24 hr. Oxidative stress was induced by the exposure to 2.5mM hydrogen peroxide ($H_2O$$_2$) resulted in declining significantly for 24 hr. GPX and CAT activities peaked at 3 hr and returned to control levels by 24 hr. On the contrary, SOD activity was inactive before 6 hr but recovered at 24 hr. In case vitamin E (Vit E) and selenomethionine (Se-Met) were used at nontoxic concentrations (25$\mu$M Vit E/500$\mu$M Se-Met) to oxidative stress was induced by the exposure to hydrogen peroxide ($H_2O$$_2$) led to a 3- and 5-fold increase on the viability comparing to control and caused an increase in GPX activity respectively.
