Cells through antioxidant enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase prevent or repair the damages caused by reactive oxygen species. Catalase converts the hydrogen peroxide to the harmless product water. There are several methods for measuring the activity of antioxidant enzymes in cultured cells, such as assay enzyme activity on gels, or western blots. In this study, we measured the activity of catalase in A549 cell line treated by various concentrations of Brevinin-2R (6, 9, 12, 15, and 25 µg/ml), through studying the changes in H2O2 absorption by UV/visible spectrophotometer. Results demonstrated that catalase had its most activity in treated cells at 12 µg/ml of the peptide for 24 h. The cytotoxic effect of the peptide was determined by MTT assays. Results showed that there was a linear correlation between various concentrations of brevinin-2R peptide and its cytotoxicity effect on A549 the cultured cells.

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