2.5. Antioxidant activity by free radical-scavenging activity using ABTS radical

Antioxidant activity was determined by the ABTS (2, 2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid) free radical decolorization assay method developed by Re et al. [27]. The ABTS radical cation was regenerated by mixing ABTS stock solution (7 mM) with potassium persulfate (2.45 mM) (final concentration) and incubating for 12–16 h in the dark at room temperature until the reaction was completed and the absorbance was stable. The absorbance of the ABTS solution was equilibrated to 0.70 (±0.02) by diluting with water at room temperature, then 100 μL of this solution was mixed with 50 μL of the test sample and the absorbance was measured at 734 nm after 6 min. Untreated seed extracts were used as the control sample. All experiments were repeated thrice. The radical scavenging activities of samples were calculated by the following equation: