FRAP test

The reducing power of the extracts was determined according to the method reported by Benzie [46]. Firstly, 2.5 ml of each methanolic and/or acetone extract was added to a reaction solution with 2.5 ml of phosphate buffer (0.2 M, pH 6.6) and 2.5 ml of 1% potassium ferricyanide K₃Fe(CN)₆ (freshly prepared). After incubation at 50°C for 20 minutes, the mixture was centrifuged at 6000 rpm for 10 minutes and then 2.5 ml of trichloroacetic acid (10%) was added. An aliquot of 2.5 ml of the supernatant was mixed with 2.5 ml distilled water and 0.5 ml of FeCl₃ (0.1%). The absorbance was measured at 700 nm. The EC₅₀ value (mg/ml) was calculated as the effective concentration at which the reducing capacity is 50% less. Ascorbic acid was used as a reference standard. The solvents used for the extraction were also used as negative controls.