摘要：The antioxidant properties of Choto-san and its related constituents such as Chotoko and Choto-san without Chotoko, and phenolic compounds contained in Chotoko such as epicatechin, caffeic, acid and quercetin were evaluated. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay, the scavenging activity of Chotoko (IC50 14.3 μg/ml) was found to be higher than that of Choto-san (IC50 206.2 μg/ml) and Choto-san without Chotoko (IC50 244.3 μg/ml). Epicatechin (IC50 10.4 μ M ), caffeic acid (IC50 13.8 μ M ), and quercetin (IC50 7.1 μ M ) also revealed scavenging activity against DPPH radicals. Choto-san (IC50 67.7 μg/ml) exhibited stronger inhibitory activity against superoxide anion formation than Choto-san without Chotoko (IC50 92.4 μg/ml) but weaker activity than Chotoko (IC50 18.3 μg/ml). The generation of superoxide anion was also inhibited by epicatechin (IC50 175.2 μ M ), caffeic acid (IC50 141.7 μ M ), and quercetin (IC50 18.7 μ M ). In a hydroxyl radical-scavenging experiment, Choto-san (IC50 2.4 mg/ml), Chotoko (IC50 2.2 mg/ml), Choto-san without Chotoko (IC50 2.8 mg/ml), epicatechin (IC50 3.9 m M ), caffeic acid (IC50 3.6 m M ), and quercetin (IC50 1.9 m M ) exhibited activity. In NG108-15 cells, when added simultaneously with H2O2 (500 μ M ), Choto-san (250 μg/ml), Chotoko (250 μg/ml), Choto-san without Chotoko (500 μg/ml), epicatechin (200 μ M ), caffeic acid (200 μ M ), and quercetin (200 μ M ) effectively protected cells from oxidative damage. In conclusion, the present results provide evidence that Choto-san acts as an antioxidant and cytoprotective agent against oxidative damage, which is due at least partly to the phenolic compounds contained in Chotoko.
