Document Detail


Black tea represents a major source of dietary phenolics among regular tea drinkers.
MedLine Citation:
PMID:  12516885     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.
Authors:
A R Rechner; E Wagner; L Van Buren; F Van De Put; S Wiseman; C A Rice-Evans
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Free radical research     Volume:  36     ISSN:  1071-5762     ISO Abbreviation:  Free Radic. Res.     Publication Date:  2002 Oct 
Date Detail:
Created Date:  2003-01-08     Completed Date:  2003-04-14     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9423872     Medline TA:  Free Radic Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  1127-35     Citation Subset:  IM    
Affiliation:
Centre for Age-Related Diseases, Guy's, King's and St Thomas's School of Biomedical Sciences, King's College London, Guy's Campus, Hodgkin Building-3rd floor, London SE1 9RT, UK.
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MeSH Terms
Descriptor/Qualifier:
Antioxidants / analysis*
Biflavonoids*
Camellia sinensis / chemistry*
Catechin / analogs & derivatives*,  analysis,  metabolism
Coumaric Acids / analysis
Diet*
Flavonoids / analysis
Flavonols
Gallic Acid / analysis
Gastric Juice / metabolism
Humans
Phenols / analysis*,  metabolism
Plant Leaves / chemistry
Polymers / analysis
Tea / chemistry*
Chemical
Reg. No./Substance:
0/Antioxidants; 0/Biflavonoids; 0/Coumaric Acids; 0/Flavonoids; 0/Flavonols; 0/Phenols; 0/Polymers; 0/Tea; 12698-96-3/thearubigin; 149-91-7/Gallic Acid; 154-23-4/Catechin; 4670-05-7/theaflavin; 989-51-5/epigallocatechin gallate

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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