The superoxide anion radical-scavenging capacities of the sample were tested by the method of
Sakanaka et al. [28]. Briefly, phosphate buffer solution (1.0 mL, 65.0 mM, pH 7.8), xanthine solution
(0.1 mL, 7.5 mM), ydroxylammonium chloride solution (0.1 mL, 10.0 mM), and sample fractions