Potassium persulfate dipotassium peroxidisulfate 6 hydroxy 2 5 7 8 tetramethylchroman 2 carboxylic acid trolox

The antioxidant activity was calculated by the azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) test^{30 (link)}. The ABTS diammonium salt, potassium persulfate (dipotassium peroxidisulfate), 6-hydroxy 2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), and HPLC grade methanol were obtained from Sigma-Aldrich Milano, Italy. Trolox, 2.5 mM in methanol prepared day-to-day, was used as antioxidant stock standard. The ABTS and potassium persulfate were dissolved in distilled water to a final concentration of 7 and 2.45 mM, respectively, and mixed. The mixture was kept in the dark at room temperature for 16 h before its use to produce the ABTS radical (ABTS⁺). The ABTS radical solution was diluted using distilled water to have an absorbance of 1.00 at 734 nm. Samples (final concentrations 0.0001–0.0100 mg/ml) or Trolox standard (final concentration 0–20 mM) were added to the diluted ABTS⁺ solution; the absorbance was read 6 min after mixing by a UV/Vis spectrophotometer (Cary Varian, Palo Alto, CA, USA). Determinations were performed in triplicate and results expressed as the samples μmol Trolox equivalent antioxidant capacity (TEAC) ± SD.

The antioxidant activity was assessed through the 2,2′Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) test (26 (link)). The ABTS diammonium salt, potassium persulfate (dipotassium peroxidisulfate), 6-hydroxy 2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox^®), and LC-grade methanol were purchased by the Sigma–Aldrich Milano, Italy. A measure of 2.5 mM of Trolox^® (methanolic daily preparation) constituted the antioxidant stock standard. First, the ABTS and potassium persulfate were suspended in distilled water (final concentration of 7 and 2.45 mM, respectively), mixed, and kept in the dark at room temperature before its use to produce the ABTS radical (ABTS⁺). Next, the ABTS radical solution was diluted with distilled water to have a final absorbance at λ 734 nm=1.00). Finally, samples (final concentrations 0.0001–0.0100 mg/ml) or Trolox^® standard (final concentration 0–20 mM) were added to the diluted ABTS+ solution; the absorbance was read 6 min after mixing. The average triplicate determinations were expressed as the samples μmol Trolox^® equivalent antioxidant capacity (TEAC) ± SD.