The superoxide anion radical scavenging activity was measured
by the method of Yang, Zhao, Prasad, Jiang, and Jiang (2010), with
some modifications. Briefly, 1 ml of various concentrations of the
phenolics in ethanol was added to reaction solution. The reaction
solution contained 0.5 ml of phosphate buffer (pH 7.5), 0.3 ml of
50 lM riboflavin, 0.25 ml of 20 mM methionine and 1 ml of
510 lM NBT and 1.95 ml deionized water.