Ostrowska J, Skrzydlewska E
Department of Analytical Chemistry, Medical University of Białystok, Poland.
Adv Med Sci. 2006;51:298-303.
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.
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.
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.
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.
绿茶因其儿茶素含量而具有强大的抗氧化活性，这尤其表现为它具有抑制自由基生成、清除自由基以及螯合催化自由基反应的过渡金属离子的能力。本研究检测了绿茶提取物、表儿茶素（EC）、表儿茶素没食子酸酯（ECG）以及表没食子儿茶素没食子酸酯（EGCG）对人血清低密度脂蛋白（LDL）氧化修饰的影响。
通过测量脂质过氧化的初级产物——共轭二烯和脂质氢过氧化物的浓度，以及测定色氨酸和二酪氨酸含量（蛋白质氧化修饰的标志物）来评估这种影响。
还研究了儿茶素和绿茶保护亲脂性抗氧化剂——α-生育酚免受氧化的能力。结果显示，绿茶提取物能显著抑制LDL的过氧化，儿茶素（尤其是EGCG）的抑制作用稍弱，这表现为共轭二烯、脂质氢过氧化物、丙二醛（MDA）、二酪氨酸的浓度降低，以及色氨酸含量增加。研究还发现，绿茶以及儿茶素（尤其是EGCG）能防止氧化条件下α-生育酚浓度的降低。
可以认为，绿茶以及程度稍轻的儿茶素，通过保护LDL的基本抗氧化剂——α-生育酚，防止了LDL的氧化修饰。
