2.7.1. ABTS Assay

The ABTS assay was performed according to a previously described method [1]. A solution of 5 mL of ABTS (7 mM) and 88 μL of potassium persulfate (140 mM) was prepared. This solution (ABTS reagent) was incubated for 16 h in the dark at RT. The stock solution was diluted with ethanol to obtain an absorbance at 734 nm. Then, 50 μL of each sample (10 mg/mL) was added to 1 mL of ABTS reagent. After 3 min, the absorbance was measured at 734 nm. The ABTS value was calculated as follows:

ABTS radical-scavenging activity (%) = [1 − (A₁/A₀)] × 100, where A₀ is the absorbance of the blank, and A₁ is the absorbance of the sample.