The comparison of effect of catechins and green tea extract on oxidative modification of LDL in vitro.

PURPOSE Green tea due to its content of catechins reveals strong antioxidative activity, which is manifested among others by its ability to inhibit free radical generation, scavenge free radicals as well as chelate transition metal ions that catalyse free radical reactions. The influence of green tea extract, epicatechin (EC), epicatechin galate (ECG) as well as epigallocatechin galate (EGCG) on oxidative modifications of LDL of human blood serum has been examined in the present study. MATERIALS AND METHODS This influence has been evaluated by measurement of the concentration of first products of lipid peroxidation--conjugated dienes and lipid hydroperoxides as well as by determining tryptophan and dityrosine content-- the markers of protein oxidative modification. RESULTS Catechins and green tea abilities to protect lipophilic antioxidant--alpha-tocopherol against oxidation have been also examined. The results reveal that peroxidation of LDL is markedly prevented by green tea extract and in a slightly weaker way by catechins (EGCG in particular), which is manifested by a decrease in concentration of conjugated dienes, lipid hydroperoxides, MDA, dityrosine and by an increase in tryptophan content. Both green tea as well as catechins (EGCG in particular) have been also revealed to prevent decrease in concentration of alpha-tocopherol in oxidating conditions. CONCLUSIONS It can be assumed that green tea and to a lesser degree catechins, protecting the basic antioxidant of LDL-alpha-tocopherol, prevent oxidative modification of LDL.