2.2.3. DPPH Assay

The free radical scavenging activity of the extracts was evaluated using DPPH assay according to the method described by Shen et al. [28]. The extracts were diluted in 0.1 mM DMSO to various concentrations from 0 to 200 μg/mL. 0.5 mL of the extracted was added to 1.5 mL of 0.1 mM DPPH which was dissolved completely in methanol. The mixtures were shaken vigorously and incubated in the dark at room temperature for 30 mins. Then, the absorbance was measured at 517 nm using a spectrophotometer. Ascorbic acid was used as a positive control. The capability of scavenging the DPPH radical was calculated using the following formula:

A ₀ is the absorbance of the control reaction and A₁ is the absorbance in the presence of the extracts or positive control.