2.6. TEAC Assay

The TEAC assay is based on the reduction of the 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical induced by antioxidants. The ABTS radical cation (ABTS^+● was prepared by mixing a 7 mM ABTS solution (Sigma-Aldrich, Milan, Italy) with 2.45 mM potassium persulfate (1:1) and stored for 16 h at room temperature and in dark. To prepare the ABTS reagent, the ABTS^+● was diluted in 5 mM phosphate buffer (pH 7.4) to obtain a stable absorbance of 0.700 (±0.02) at 730 nm. For the assay, 10 µL of BUO extract (at the final concentrations of 0.5, 1.0, 5.0, and 10.0 µg/mL) were added to 140 µL of diluted the ABTS^+●. The microplate was incubated for 30 min at 30 °C and the absorbance was read at 730 nm using a Synergy™ HT-multimode microplate reader (Biotek Instruments, Winooski, VT, USA). The TEAC values were calculated using a Trolox (Sigma-Aldrich, Milan, Italy) calibration curve (60–320 µM) (Figure S1).