3.8.3. Ferric Reducing/Antioxidant Power (FRAP) Assay

The FRAP assay was conducted according to the procedure reported with slight modifications [19]. The FRAP reagent was freshly prepared with 300 mM acetate buffer (pH 3.6), 10 mM TPTZ (2,4,6-tripyridyl-s-triazine), and 20 mM FeCl₃-6H₂O (10:1:1, v/v)]. A 0.5 mL of each sample (100 μg/mL) was mixed with 4.5 mL freshly prepared FRAP reagent. Then, the reaction mixture was incubated at 37 °C in the dark for 10 min. The absorbance of the mixture was recorded at 593 nm against a blank that was prepared using distilled water. Trolox was used as a control. The FRAP values were expressed as nmol Trolox equivalent (TE) per mg of extract (nmol TE/mg extract).