Evaluation of the antioxidant and pro-oxidant effects of tea catechin oxypolymers

Tea catechin oxypolymers (TCOP) were prepared by oxidizing tea catechin (TC, the content of EGCG was >85%) with H2O2. Their antioxidant and pro-oxidant effects were tested using a deoxyribose assay, a photoreduction of NBT assay, a lipoxygenase assay, a POV assay, and animal tests. The scavenging effects of TCOP to both the hydroxyl radical and superoxide radical were stronger than that of TC, and also they had no pro-oxidant effect; the rate constant for reactions of TC and TCOP for hydroxyl radical were 1.0 x 10(10) and (1.4-2.8) x 10(10) M(-1) x S(-1), respectively. TCOP can inhibit lipid peroxidation and lipoxygenase effectively, and it also can activate red cell SOD and reduce the MDA content in serum of mice very significantly. These results suggested that the antioxidant activity of TCOP was not less than or even more notable than that of TC.