where A0 is the absorbance of the incubation DPPH solution without addition of the sample or positive controls, A1 is the absorbance of the sample without DPPH solution and A2 is the absorbance of the incubation mixture containing both the test sample and DPPH solution. The concentration of sample producing a 50% reduction of the radical absorbance (IC50) was used as an index to compare the antioxidant activity.