The superoxide radical scavenging abilities of the sample wereassessed by the method of Robak and Gryglewski , with aminor modification. Samples were firstly dissolved in distilled water at different concentrations. Then, 0.1 mL of sample solution,1 mL of 16 mM Tris-HCl (pH 8.0) containing 557 M NADH, 1 mLof 16 mM Tris-HCl (pH 8.0) containing 45 M PMS, and 1 mL of16 mM Tris-HCl (pH 8.0) containing 108 M NBT were mixed.