Theaflavins in black tea and catechins in green tea are equally effective antioxidants

被引:383
作者
Leung, LK
Su, YL
Chen, RY
Zhang, ZH
Huang, Y
Chen, ZY [1 ]
机构
[1] Chinese Univ Hong Kong, Dept Biochem, Shatin, Hong Kong, Peoples R China
[2] Chinese Univ Hong Kong, Dept Physiol, Shatin, Hong Kong, Peoples R China
[3] Chinese Acad Med Sci, Inst Mat Med, Beijing 100050, Peoples R China
关键词
black tea; catechins; green tea; low density lipoprotein; oxidation; theaflavins;
D O I
10.1093/jn/131.9.2248
中图分类号
R15 [营养卫生、食品卫生]; TS201 [基础科学];
学科分类号
100403 ;
摘要
Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (TF), a mixture of theaflavin (TF1), theaflavin-3-gallate (TF(2)A), theaflavin-3 ' -gallate (TF2B) and theaflavin-3,3 ' -digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin using human LDL oxidation as a model. All catechins and TF tested inhibited Cu+2-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive substances (TBARS) and conjugated dienes produced during LDL oxidation revealed that the antioxidant activity was in the order: TF3 > ECG > EGCG greater than or equal to TF2B greater than or equal to TF(2)A greater than or equal to TF1 greater than or equal to EC > EGC. Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu+2-mediated LDL oxidation at concentrations of 5-40 mu mol/L. These results demonstrate that the TF present in black tea possess at least the same antioxidant potency as catechins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free radical-scavenging activity.
引用
收藏
页码:2248 / 2251
页数:4
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