Ferric reducing antioxidant power (FRAP) Assay

In the FRAP assay, the reducing capacity of the tested compounds to reduce Fe³⁺ to Fe²⁺ was measured, which is considered to be an important parameter for antioxidant function. This method has been widely used for a rapid assessment of the antioxidant potential of various compounds, beverages and natural products [22]

Total antioxidant activity was measured according to [23]. In brief, the FRAP solution was freshly prepared. Different concentrations of kinetin (1, 3.2,10,32,100,500, 1000 and 10000 nM) were mixed with 600 μL of the FRAP solution and the volume was completed to 800 μl with water. Absorbance was measured at 595 nm after 6 min of incubation at room temperature by a spectrophotometer (Bio-Tek, Model Uvikon XL) against a blank of distilled water. 50 μM Tempol was used as a positive control. FRAP values were obtained by comparing the absorbance change at 595 nm in test reaction mixtures with those containing ferrous ions in known concentrations.