High amounts of reactive oxygen species (ROS) play a key role in human diseases like cancers. Nevertheless several antioxidants enzymes such as superoxide dismutase, catalase, and glutathione peroxidase act to influence oxidative stress. In this group of enzymes such as Glutathione peroxidase (GPx) is an essential antioxidant enzyme that catalyzes the reduction of hydrogen peroxide, by reduced glutathione (GSH) and as same as other antioxidant enzymes such as catalase and superoxide dismutase, protects the cell from oxidative damage. In this study, we examined the activity of glutathione peroxidase in cultured cells treated with various concentration of WG-9 peptide (15, 30, 45, 60 µg/ml) for 24 h. Here we used UV/visible spectrophotometer to determine the absorption of NADPH that reduced during the glutathione peroxidase system. Our results show that with increasing concentrations of the WG-9 peptide the enzyme activity raises. The cytotoxicity effect of viable cells was evaluated in A549 cell line was measured through the MTT assay. The results show that there was significant correlation between cytotoxicity of different concentrations of the peptide on cultured cancer cells.

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