3.6. Trolox Equivalents Antioxidant Capacity Assay (TEAC)

Trolox equivalents antioxidant capacity (TEAC) assay was employed to measure the antioxidant capacity. ABTS⁺ radical was produced by reacting 7 mM ABTS and 2.45 mM potassium persulfate in the dark at room temperature for 16–24 h before use. The aqueous ABTS⁺ solution was diluted with 200 mM phosphate buffer (pH 7.4) to an absorbance of 0.7 ± 0.02 at 734 nm. Ten microliters of sample (5 different concentrations ranging from 0.25 to 2 mg/mL) and 1 mL of ABTS⁺ solution were mixed in an Eppendorf vial, and 200 µL of the mixture was transferred into a 96-well microplate. The absorbance was measured at 734 nm every 5 min for 45 min in a M200 Microplate Reader (Tecan Infinite, Switzerland). Trolox was used as reference, and results were expressed as TEAC values (mmol of trolox/g the dried weight of sample). The values were obtained from five different concentrations of each tested in the assay giving a linear response between 20% and 80% of the blank absorbance. All analyses were done in triplicate and average values reported.