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

Citation
Lk. Leung et al., Theaflavins in black tea and catechins in green tea are equally effective antioxidants, J NUTR, 131(9), 2001, pp. 2248-2251
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Food Science/Nutrition","Endocrinology, Nutrition & Metabolism
Journal title
JOURNAL OF NUTRITION
ISSN journal
0022-3166 → ACNP
Volume
131
Issue
9
Year of publication
2001
Pages
2248 - 2251
Database
ISI
SICI code
0022-3166(200109)131:9<2248:TIBTAC>2.0.ZU;2-T
Abstract
Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallat e (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 t heaflavin-3,3 ' -digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin usi ng human LDL oxidation as a model. All catechins and TF tested inhibited Cu +2-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive sub stances (TBARS) and conjugated dienes produced during LDL oxidation reveale d 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 demonst rated 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 p resent in black tea possess at least the same antioxidant potency as catech ins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free r adical-scavenging activity.