2.3. DPPH radical scavenging assay

DPPH-Radical scavenging capacity was determined according to the method reported by [22]. 1000 μg/ml PBEA stock solution was prepared by dissolving extractive yield of PBEA (10 mg) in methanol (10 ml). PBEA stock solution was series diluted into 10, 25, 50, 100, 200 and 500 μg/ml with methanol. In each concentration, 1 ml of PBEA solutions and methanol (Blank) were mixed with 1.5 ml of DPPH (0.25 mM). The reaction mixture was shaken vigorously for 2 min and incubates at room temperature for 30 min in dark place. Ascorbic acid, Quercetin, α-tocopherol and Curcumin were used as standard and for the blank, sample was substituted by methanol. Disappearance of DPPH color was determined by measuring the absorbance at 517 nm against methanol with a spectrophotometer (Shimadzu - 1800). The DPPH radicals scavenging activity was determine by the following equation: Scavenging activity = [A₀-A₁/A₀] × 100 where A₀ is the absorbance of the blank (without extract) and A₁ is the absorbance of the sample (extract or standard).