2.4.5. ABTS Assay

ABTS, or 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt assay, was performed following the Sigma manufacturer's instructions (Sigma-Aldrich, Missouri USA). Briefly, 0.0016 g potassium persulphate was dissolved in 25 mL of water and 0.096 g ABTS was dissolved in potassium persulfate. The solution was allowed to stabilize 12 h, stored at dark and room temperature. Then, 0.0064 g Trolox was dissolved in 25 mL methanol, stored at 5 ◦C during the working day. Samples were weighted, extracted with water, and solutions were centrifuged at 2500× *g* for 5 min. ABTS solution was added to the blank, Trolox, and samples. The calibration curve was obtained by di fferent concentrations of Trolox. Results were referred to the Trolox standard curve and are expressed as μmol of Trolox equivalent per gram of extract.
