2.3.3. Reducing power by FeCl3
The reducing property of the extracts was determined by assessing the ability of the extracts to reduce FeCl3 solution.A 2.5 ml aliquot was mixed with 2.5 ml of 200 mmol/l sodium phosphate buffer (pH 6.6) and 2.5 ml of 1% potassium ferricyanide. The mixture was incubated at 50 °C for 20 min and then 2.5 ml of 10% TCA was added. The mixture was centrifuged at 650 rpm for 10 min. 5 ml of the supernatant was mixed with an equal volume of water and 1 ml of 0.1% ferric chloride. The ability of the extracts to reduce the ferric–ferricyanide complex to the ferrous–ferricyanide complex to Prussian blue was determined by recording the absorbance at 700 nm (Fig. 1). The ferric reducing antioxidant property was subsequently calculated using ascorbic acid as standard (Fig. 2).