The reducing power of the extracts was determined by the method of Lin, Wei, and Chou (2006). Briefly, 5.5 ml reaction
mixture containing 0.5 ml of sample solution in 2.5 ml PBS (0.2 M, pH 6.6) was added to 2.5 ml of potassium ferricyanide
(1%, w/v), and the mixture was incubated at 50 °C for 20 min. After 2.5 ml of trichloroacetic acid (10%, w/v) was added, the mixture was centrifuged at 420 g for 10 min and then 2.5 ml of the supernatant was mixed with 0.5 ml of ferric chloride (0.1%, w/v) for 10 min at room temperature. The absorbance was then read at 700 nm against a blank in a spectrophotometer. A higher absorbance of the reaction mixture indicates a higher reducing power.