2.4. Determination ofantioxidant capacity
2.4.1. DPPH assay
The DPPH radical-scavenging activity was determined using the method proposed by Wojdylo et al. (2007) with some modifications. The DPPH solution (4.0 mL, absorbance of 0.700 ± 0.02 at 517 nm) was added to 0.1 mL of sample, which was properly diluted and mixed thoroughly. The reaction mixture was stored at room temperature (∼23 ◦C) for 6 h, and absorbance was immediately recorded at 517 nm by using a Shimadzu UV-2550 UV–vis spectrophotometer (Kyoto, Japan). Trolox standard solution (final concentration 50–800 mol/L) was prepared and assayed under the same conditions. Results were expressed in terms of mmol Trolox equivalent antioxidant capacity per 100 g dry weight (TEAC). All determinations were performed in triplicate.