phosphate buffer (0.2 M, pH 6.6) and 2.5 mL of potassium ferricyanide (1%).
The mixtures were incubated at 50°C for 20 min, and after that TCA (10%,
2.5 mL) was added. The mixtures were centrifuged at 650 g for 10 min. The
supernatant (2.5 mL) was mixed with 2.5 mL of distilled water and 0.5 mL of
ferric chloride and the absorbance was measured at 700 nm in a Jenwey (6405
UV/Vis) spectrophotometer. Higher absorbance of the reaction mixture indicates
greater reducing power.
IC50 value (mg/mL) is the effective concentration at which the absorbance
was 0.5 for reducing power and was obtained by interpolation from linear regression
analysis.
BHT was used as control.