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Equally Effective Antioxidants:Theaflavins&Catechins

Theaflavins in Black Tea and Catechins in Green Tea Are Equally Effective Antioxidants1

Lai Kwok Leung, Yalun Su, Ruoyun Chen, Zesheng Zhang, Yu Huang* and Zhen-Yu Chen2

Department of Biochemistry and * Department of Physiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, The People’s Republic of China and Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, The People’s Republic of China

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 (TF2A), 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 TF2B TF2A > TF1 EC > EGC.

Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu+2-mediated LDL oxidation at concentrations of 5–40 µmol/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.

(Journal of Nutrition. 2001;131:2248-2251.) © 2001 The American Society for Nutritional Sciences

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