4.5.2. Hydrogen Peroxide Scavenging (H2O2) Assay

The antioxidant activity of EPSR4 was evaluated by assessing its ability to scavenge hydrogen peroxide. The assay was performed following the previously reported protocol by Ruch et al. [98]. Briefly, EPSR4 was prepared at different concentrations (200, 400, 600, 800, 1000, and 1500 µg/mL) in 0.1 M phosphate buffer (pH = 7.4). The EPSR4 solutions were treated with a solution of hydrogen peroxide (43 mM in phosphate buffer). The resultant solutions were incubated in the dark at an ambient temperature and the absorption was recorded at 230 nm at different time intervals (15, 30, 45, and 60 min). The ability of EPSR4 to scavenge the hydrogen peroxide free radical was defined following the formula:

where A_C the absorbance of the control sample; A_S the absorbance in the presence of EPSR4.