The reducing antioxidant power of samples were measured
using FRAP assay (Benzie and Strain 1996; Benzie and Szeto, 1999;
Wojdylo et al., 2007) with slight modifications. In brief, the FRAP
reagent was freshly prepared by mixing acetate buffer (0.3 M, pH
3.6), a solution of 10 M TPTZ in 40 M HCl, and 20 M FeCl3 at 10:1:1
(v/v/v). The FRAP reagent(1.0 mL) and appropriately diluted sample
solutions (0.05 mL) were added to each well and mixed thoroughly.
The absorbance was taken at 593 nm after incubation at 37 ◦C for 30 min. All solutions were used on the day of preparation. Standard
curve was prepared using the different Trolox concentrations
(50–1000 mol/L). Results were expressed in terms of mmol TEAC.