Antioxidant Activity of Extracts of Pu-erh Tea and Its Material

In this study, we reported an experimental study on the in vi tro antioxidant activity of various extracts of pu-erh tea as we ll as its fermented mat erials (Camellia sinensis (L.) var. assamica (Masters) Kitamura). The antioxidant activity of the tea extracts were measured using in vi tro assays including the reducing power assay and the assay evaluating the free radical scave nging capacity such as the hyd roxyl, 1,1−diphenyl−2−picrylhydrazyl (DPPH), the superoxide, and the nitrogen dioxide radic al. All tea extracts showed a dose dependent scavenging radical capacity as well as the reducing power activity. Particularly, the ethanol precipitation and water extract of pu-erh tea as well as the ethanol precipitation and ethyl acetate extract of pu-erh tea material, with the IC 50 value of 3.5 μg/mL, 27.9 μg/mL, 13.5 μg/mL and 18.1 μg/mL, respectively, showed the highest antioxidant capability against all four free radicals studied here. The experimental results also revealed that there existed a significant difference in in vitro antioxidant capability among the tea extracts, and there was a strong correlation between the antioxidant capacity and the antioxidant species. Particularly, not only the content of the total catechins but the content of the total phenolics, the thear ubigins, the theabrownins, and the tea polysaccharide contributed to the tea extract antioxidant activity. In addition, the ferric reducing/antioxidant power assay was used to measure the total antioxidant activity of eight tea extracts from fresh infusions. The ethyl acetate extract from pu-erh tea as well as its showed a relative high reducing power. The experimental re sults repor ted here sug gested that pu-erh tea could be an imp ortant dietary antioxidant source.