The reducing power was estimated by the following procedure
proposed by Wang et al., 2006 with small modifications.
2.5 mL different concentrations of the samples were placed in
five test tubes, and 2.5 mL phosphate buffer (0.2 mol/L,
pH6.6), 2.5 mL K3[Fe(CN)6] (1%) solution were added to each
test tube, orderly. The test tubes were incubated in a water bath
at 50 C for exactly 20 min, and then cooled to room temperature
rapidly. To this end, 10 mL distilled water and 2 mL FeCl3
(0.1%) solution were added to the five test tubes. Absorbance
was monitored at 700 nm after 10 min. The reducing power of
Ascorbic Acid and control was analyzed at the same conditions.
Each of the experiment was run in duplicate and the experiments
were performed in triplicate to confirm the results.