2.6.3. Ferric-Reducing Antioxidant Power (FRAP)

The FRAP assay for different concentrations of the extract was performed according to Kim et al. [28]. The FRAP reagent was prepared fresh daily by 300-mM acetate buffer (pH 3.6), a 10-mM 2, 4, 6-tri (2-pyridyl) -1, 3, 5-triazine (TPTZ) solution in 40-mM HCl, and a 20-mM FeCl3·6H2O solution in proportions of 10:1:1 (v/v), respectively. After preparation, the reagent was warmed to 37 °C in a water bath before use. Then, 0.05 mL of the sample was mixed with distilled water (0.15 mL) and the FRAP reagent (1.5 mL). The reaction mixture was incubated at 37 °C in a water bath for 4 min, and the absorbance was measured at 595 nm.