A Frequent Drinking of Green Tea Lowers the Levels of Endogenous Oxidative Stress in Small Intestines, Erythrocytes and Kidneys in Rats

摘要

Endogenous antioxidative potential was examined in rats given green tea as daily drinking water for 4 weeks. Rats ingested 196 μmol/kg body weight/day of catechins (sum total of 8 kinds of catechins), and plasma levels were around 0.24 μM. The green tea also contained 2.1 mM ascorbic acid, but the plasma level was similar to that in control rats drinking water, about 30 μM. The tea-drinking rats had significantly lower levels of lipid peroxidation in the small intestines and kidneys, 30% and 40% lower, respectively, than the controls, and their erythrocytes showed significant resistance to aqueous peroxyl radicals generated from azo initiator. Then, the effects of 8 catechins were examined on the antioxidative potency of ascorbic acid in in vitro . Catechins suppressed the oxidation of deoxyguanosine after the immediate exhaustion of ascorbic acid. Thus, frequent daily drinking of green tea improved the antioxidative potential of ascorbic acid.