In the DPPH assay, the natural and synthetic antioxidants were able to reduce the stable radical DPPHradical dot to the yellow-coloured DPPH. This method is based on the reduction of DPPHradical dot in alcoholic solution in the presence of a hydrogen-donating antioxidant due to the formation of the non-radical form DPPH-H in the reaction. The use of DPPHradical dot provides an easy way to evaluate antioxidant activity (Oyaizu, 1986). The antioxidant activity of these extracts was measured on basis of their electron-donating ability (EDA) of the stable DPPHradical dot as previously described (Chu, Chang, & Hsu, 2000) with slight modification. Different concentrations (10–500 μg/ml) of black chokeberry and blueberry were prepared. Then, 1 ml of ethanolic DPPHradical dot solution (4 × 10−4 M) was added to the samples. These samples were vortexed and incubated in the dark for 10 min at room temperature. DPPH radical-scavenging activities were measured by spectrophotometer at 490 nm and were calculated and expressed as a percentage using the following formula: