2.5.1. DPPH Radical Scavenging Ability

The DPPH radical scavenging activity was determined referring to the methods reported previously with minor modifications [14]. Various concentrations of PSP, SeNPs, PSP-SeNPs, and Vc at 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0 mg/mL were prepared. Further, 2 mL of the sample solutions were mixed with an equal volume of freshly prepared DPPH solution (50 mg/L) in ethanol. The mixture was shaken vigorously and incubated in darkness at 33 ◦C for 30 min. The absorbance was measured at 517 nm using a UVvis spectrophotometer. Vc was used as a positive control. The scavenging activity was calculated as follows:

$$\text{DPPH radical savingability} \left(\% \right) = \left(1 - \frac{\text{A}\_{\text{a}} - \text{A}\_{\text{b}}}{\text{A}\_{\text{c}}} \right) \times 100 \tag{1}$$

where Aa is the absorbance of the sample mixed with DPPH solution, Ab is the absorbance of the sample in the absence of the DPPH solution, Ac is the absorbance of the DPPH solution without the sample as a blank control.
