Fig. 3.

Effects of amount of burdock root tea (BRT) on antioxidant activities. In order to examine the effect of concentration, BRT was prepared by boiling burdock roots roasted six times at various concentrations (0.10, 0.25, 0.50, and 1.00 mg/mL) for 60 min. Total antioxidant capacities of BRT were tested based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (A), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity (B), ferric reducing capacity (C), copper chelating activity (D), total polyphenol contents (E), and flavonoid contents (F). Data are expressed as the mean±standard deviation (n=6). Mean sharing the same letter (a–d) are not significantly different at the 5% level. AA, ascorbic acid equivalent; TE, Trolox equivalents; GAE, gallic acid equivalents; CE, catechin equivalents.