2.13. FRAP (Ferric Reducing Antioxidant Power) Activity Assay

The FRAP assay was brought with a minor alteration for the measurement of reduction power, as previously described by Benzie et al. [30]. In brief, the FRAP reagent included, 10 mM 2,4,6-Tris(2-pyridyl)-s-triazine (TPTZ) solution in HCl (40 mM), ferric chloride solutions (FeCl₃·6H₂O; 20 mM), and acetate buffer (pH 3.5; 300 mM) with a ratio of 1:1:10. A 10 μL aqueous sample was mixed at different concentrations and 990 μL of FRAP mixture and incubated at 37 °C for half an hour. The optical density was assessed at 595 nm. Besides, ascorbic acid as a standard antioxidant compound was also studied.