Green tea catechins partially protect DNA from ·OH radical-induced strand breaks and base damage through fast chemical repair of DNA radicals

Green tea catechins partially protect DNA from ·OH radical-induced strand breaks and base damage... The catechins, (–)-epicatechin (EC), (–)-epigallocatechin (EGC), (–)-epicatechin gallate (ECG) and (–)-epigallocatechin gallate (EGCG) are believed to be active constituents of green tea accounting for the reported chemoprevention of certain cancers. The molecular mechanisms by which the measured low concentrations ( ca . micromolar) of catechins in humans can reduce the incidence of carcinogenesis is not clear. Using an in vitro plasmid DNA system and radiolytically generating reactive oxygen species (ROS) under constant scavenging conditions, we have shown that all four catechins, when present at low concentrations, ameliorate free radical damage sustained by DNA. A reduction in both prompt DNA single-strand breaks and residual damage to the DNA bases, detected by subsequent incubation with the DNA glycosylases formamidopyrimidine (FPG), endonuclease III (EndoIII) and 5′ AP endonuclease exonuclease III (ExoIII), was observed. EGCG was found to be the most active of the catechins, with effects seen at micromolar concentrations. Combined fast-reaction chemistry studies support a mechanism of electron transfer (or H-atom transfer) from catechins to ROS-induced radical sites on the DNA. These results support an antioxidant role for catechins in their direct interaction with DNA radicals. Key words D 0 , the radiation dose required on average to produce one DNA single-strand break E (1), one-electron reduction potiential at pH 7 versus normal hydrogen electrode EC, (−)-epicatechin ECG, (−)-epicatechin gallate EDTA, ethylenediaminetetraacetic acid EGC, (−)-epigallocatechin EGCG, (−)-epigallocatechin gallate EndoIII, endonuclease III Exoll, exonuclease III FPG, formidopyrimidine-DNA glycosylase G (ess), yield of endonuclease-indiced DNA single-stand breaks per absorbed dose (Gy) G (ssb), radiation chemical yield of single-strand breaks per absorbed dose (Gy) G (ssb′), reduction in G (ess) due to the presence of catechins Gy, absorbed radiation dose (J/kg) ROS, reactive oxygen specie TAE, Tris/acetic acid/EDTA buffer Tris, tris(hydroxy-methyl)aminomethane © Oxford University Press « Previous | Next Article » Table of Contents This Article Carcinogenesis (2001) 22 (8): 1189-1193. doi: 10.1093/carcin/22.8.1189 » Abstract Free Full Text (HTML) Free Full Text (PDF) Free Classifications Molecular Epidemiology and Cancer Prevention Services Article metrics Alert me when cited Alert me if corrected Find similar articles Similar articles in Web of Science Similar articles in PubMed Add to my archive Download citation Request Permissions Citing Articles Load citing article information Citing articles via CrossRef Citing articles via Scopus Citing articles via Web of Science Citing articles via Google Scholar Google Scholar Articles by Anderson, R. F. Articles by Packer, J. E. Search for related content PubMed PubMed citation Articles by Anderson, R. F. Articles by Fisher, L. J. Articles by Hara, Y. Articles by Harris, T. Articles by Mak, W. B. Articles by Melton, L. D. Articles by Packer, J. E. Related Content Load related web page information Share Email this article CiteULike Delicious Facebook Google+ Mendeley Twitter What's this? Search this journal: Advanced » Current Issue October 2015 36 (10) Alert me to new issues The Journal About this journal Rights & Permissions Dispatch date of the next issue This journal is a member of the Committee on Publication Ethics (COPE) We are mobile – find out more Journals Career Network Impact factor: 5.334 5-Yr impact factor: 5.698 Editor-in-Chief Dr Curtis C Harris, USA View full editorial board For Authors Instructions to authors Online submission Submit Now! Self archiving policy Open access options for authors - visit Oxford Open This journal enables compliance with the NIH Public Access Policy Alerting Services Email table of contents Email Advance Access CiteTrack XML RSS feed Corporate Services Advertising sales Reprints Supplements var taxonomies = ("MED00710"); Most Most Read Apoptosis in cancer Modulation of E-cadherin expression by K-Ras; involvement of DNA methyltransferase-3b Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead Tumor progression and metastasis Cancer-related inflammation, the seventh hallmark of cancer: links to genetic instability » View all Most Read articles Most Cited Oxyradicals and DNA damage Sensing and repairing DNA double-strand breaks Functional role of estrogen metabolism in target cells: review and perspectives Apoptosis in cancer Nucleotide excision repair and human syndromes » View all Most Cited articles Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department. Online ISSN 1460-2180 - Print ISSN 0143-3334 Copyright © 2015 Oxford University Press Oxford Journals Oxford University Press Site Map Privacy Policy Cookie Policy Legal Notices Frequently Asked Questions Other Oxford University Press sites: Oxford University Press Oxford Journals China Oxford Journals Japan Academic & Professional books Children's & Schools Books Dictionaries & Reference Dictionary of National Biography Digital Reference English Language Teaching Higher Education Textbooks International Education Unit Law Medicine Music Online Products & Publishing Oxford Bibliographies Online Oxford Dictionaries Online Oxford English Dictionary Oxford Language Dictionaries Online Oxford Scholarship Online Reference Rights and Permissions Resources for Retailers & Wholesalers Resources for the Healthcare Industry Very Short Introductions World's Classics function fnc_onDomLoaded() { var query_context = getQueryContext(); PF_initOIUnderbar(query_context,":QS:default","","JRN"); PF_insertOIUnderbar(0); }; if (window.addEventListener) { window.addEventListener('load', fnc_onDomLoaded, false); } else if (window.attachEvent) { window.attachEvent('onload', fnc_onDomLoaded); } var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-189672-16"); pageTracker._setDomainName(".oxfordjournals.org"); pageTracker._trackPageview(); } catch(err) {} http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Carcinogenesis Oxford University Press

Green tea catechins partially protect DNA from ·OH radical-induced strand breaks and base damage through fast chemical repair of DNA radicals

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Publisher
Oxford University Press
Copyright
Copyright © 2015 Oxford University Press
ISSN
0143-3334
eISSN
1460-2180
DOI
10.1093/carcin/22.8.1189
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Abstract

The catechins, (–)-epicatechin (EC), (–)-epigallocatechin (EGC), (–)-epicatechin gallate (ECG) and (–)-epigallocatechin gallate (EGCG) are believed to be active constituents of green tea accounting for the reported chemoprevention of certain cancers. The molecular mechanisms by which the measured low concentrations ( ca . micromolar) of catechins in humans can reduce the incidence of carcinogenesis is not clear. Using an in vitro plasmid DNA system and radiolytically generating reactive oxygen species (ROS) under constant scavenging conditions, we have shown that all four catechins, when present at low concentrations, ameliorate free radical damage sustained by DNA. A reduction in both prompt DNA single-strand breaks and residual damage to the DNA bases, detected by subsequent incubation with the DNA glycosylases formamidopyrimidine (FPG), endonuclease III (EndoIII) and 5′ AP endonuclease exonuclease III (ExoIII), was observed. EGCG was found to be the most active of the catechins, with effects seen at micromolar concentrations. Combined fast-reaction chemistry studies support a mechanism of electron transfer (or H-atom transfer) from catechins to ROS-induced radical sites on the DNA. These results support an antioxidant role for catechins in their direct interaction with DNA radicals. Key words D 0 , the radiation dose required on average to produce one DNA single-strand break E (1), one-electron reduction potiential at pH 7 versus normal hydrogen electrode EC, (−)-epicatechin ECG, (−)-epicatechin gallate EDTA, ethylenediaminetetraacetic acid EGC, (−)-epigallocatechin EGCG, (−)-epigallocatechin gallate EndoIII, endonuclease III Exoll, exonuclease III FPG, formidopyrimidine-DNA glycosylase G (ess), yield of endonuclease-indiced DNA single-stand breaks per absorbed dose (Gy) G (ssb), radiation chemical yield of single-strand breaks per absorbed dose (Gy) G (ssb′), reduction in G (ess) due to the presence of catechins Gy, absorbed radiation dose (J/kg) ROS, reactive oxygen specie TAE, Tris/acetic acid/EDTA buffer Tris, tris(hydroxy-methyl)aminomethane © Oxford University Press « Previous | Next Article » Table of Contents This Article Carcinogenesis (2001) 22 (8): 1189-1193. doi: 10.1093/carcin/22.8.1189 » Abstract Free Full Text (HTML) Free Full Text (PDF) Free Classifications Molecular Epidemiology and Cancer Prevention Services Article metrics Alert me when cited Alert me if corrected Find similar articles Similar articles in Web of Science Similar articles in PubMed Add to my archive Download citation Request Permissions Citing Articles Load citing article information Citing articles via CrossRef Citing articles via Scopus Citing articles via Web of Science Citing articles via Google Scholar Google Scholar Articles by Anderson, R. F. Articles by Packer, J. E. Search for related content PubMed PubMed citation Articles by Anderson, R. F. Articles by Fisher, L. J. Articles by Hara, Y. Articles by Harris, T. Articles by Mak, W. B. Articles by Melton, L. D. Articles by Packer, J. E. Related Content Load related web page information Share Email this article CiteULike Delicious Facebook Google+ Mendeley Twitter What's this? Search this journal: Advanced » Current Issue October 2015 36 (10) Alert me to new issues The Journal About this journal Rights & Permissions Dispatch date of the next issue This journal is a member of the Committee on Publication Ethics (COPE) We are mobile – find out more Journals Career Network Impact factor: 5.334 5-Yr impact factor: 5.698 Editor-in-Chief Dr Curtis C Harris, USA View full editorial board For Authors Instructions to authors Online submission Submit Now! Self archiving policy Open access options for authors - visit Oxford Open This journal enables compliance with the NIH Public Access Policy Alerting Services Email table of contents Email Advance Access CiteTrack XML RSS feed Corporate Services Advertising sales Reprints Supplements var taxonomies = ("MED00710"); Most Most Read Apoptosis in cancer Modulation of E-cadherin expression by K-Ras; involvement of DNA methyltransferase-3b Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead Tumor progression and metastasis Cancer-related inflammation, the seventh hallmark of cancer: links to genetic instability » View all Most Read articles Most Cited Oxyradicals and DNA damage Sensing and repairing DNA double-strand breaks Functional role of estrogen metabolism in target cells: review and perspectives Apoptosis in cancer Nucleotide excision repair and human syndromes » View all Most Cited articles Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department. Online ISSN 1460-2180 - Print ISSN 0143-3334 Copyright © 2015 Oxford University Press Oxford Journals Oxford University Press Site Map Privacy Policy Cookie Policy Legal Notices Frequently Asked Questions Other Oxford University Press sites: Oxford University Press Oxford Journals China Oxford Journals Japan Academic & Professional books Children's & Schools Books Dictionaries & Reference Dictionary of National Biography Digital Reference English Language Teaching Higher Education Textbooks International Education Unit Law Medicine Music Online Products & Publishing Oxford Bibliographies Online Oxford Dictionaries Online Oxford English Dictionary Oxford Language Dictionaries Online Oxford Scholarship Online Reference Rights and Permissions Resources for Retailers & Wholesalers Resources for the Healthcare Industry Very Short Introductions World's Classics function fnc_onDomLoaded() { var query_context = getQueryContext(); PF_initOIUnderbar(query_context,":QS:default","","JRN"); PF_insertOIUnderbar(0); }; if (window.addEventListener) { window.addEventListener('load', fnc_onDomLoaded, false); } else if (window.attachEvent) { window.attachEvent('onload', fnc_onDomLoaded); } var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-189672-16"); pageTracker._setDomainName(".oxfordjournals.org"); pageTracker._trackPageview(); } catch(err) {}

Journal

CarcinogenesisOxford University Press

Published: Aug 1, 2001

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