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Article: Genoprotection and genotoxicity of green tea (Camellia sinensis): Are they two sides of the same redox coin?

TitleGenoprotection and genotoxicity of green tea (Camellia sinensis): Are they two sides of the same redox coin?
Authors
KeywordsDNA damage
ARE
Green tea
Pro-oxidant
HO-1
Hydrogen peroxide
Oxidative stress
Redox tone
Genoprotection
Issue Date2013
Citation
Redox Report, 2013, v. 18, n. 4, p. 150-154 How to Cite?
AbstractObjectives: Regular intake of green tea associates with lower DNA damage and increased resistance of DNA to oxidant challenge. However, in vitro pro-oxidant effects of green tea have been reported. Both effects could be mediated by hydrogen peroxide (H 2 O 2 ) which is generated by autoxidation of tea catechins. In large amounts, H 2 O 2 is genotoxic, but low concentrations could activate the redox-sensitive antioxidant response element (ARE) via the Keap-1/Nrf2 redox switch, inducing genoprotective adaptations. Our objective was to test this hypothesis. Methods: Peripheral lymphocytes from healthy volunteers were incubated for 30 minutes at 37°C in freshly prepared tea solutions (0.005, 0.01, 0.05%w/v (7, 14, 71 μmol/l total catechins) in phosphate buffered saline (PBS), with PBS as control) in the presence and absence of catalase (CAT). H 2 O 2 in tea was measured colorimetrically. Oxidation-induced DNA lesions were measured by the Fpg-assisted comet assay. Results: H 2 O 2 concentrations in 0.005, 0.01, and 0.05% green tea after 30 minutes at 37°C were, respectively, ~3, ~7, and ~52 μmol/l. Cells incubated in 0.005 and 0.01% tea showed less (P < 0.001) DNA damage compared to control cells. Cells treated with 0.05% green tea showed ~50% (P < 0.001) more DNA damage. The presence of CAT prevented this damage, but did not remove the genoprotective effects of low-dose tea. No significant changes in expression of ARE-associated genes (HMOX1, NRF2, KEAP1, BACH1, and hOGG1) were seen in cells treated with tea or tea + CAT. Conclusion: Genoprotection by low-dose green tea could be due to direct antioxidant protection by green tea polyphenols, or to H 2 O 2 -independent signalling pathways. © W. S. Maney & Son Ltd 2013.
Persistent Identifierhttp://hdl.handle.net/10722/244149
ISSN
2015 Impact Factor: 2.606
2015 SCImago Journal Rankings: 0.694

 

DC FieldValueLanguage
dc.contributor.authorHo, Cyrus K.-
dc.contributor.authorSiu-Wai, Choi-
dc.contributor.authorSiu, Parco M.-
dc.contributor.authorBenzie, Iris F.-
dc.date.accessioned2017-08-31T08:56:11Z-
dc.date.available2017-08-31T08:56:11Z-
dc.date.issued2013-
dc.identifier.citationRedox Report, 2013, v. 18, n. 4, p. 150-154-
dc.identifier.issn1351-0002-
dc.identifier.urihttp://hdl.handle.net/10722/244149-
dc.description.abstractObjectives: Regular intake of green tea associates with lower DNA damage and increased resistance of DNA to oxidant challenge. However, in vitro pro-oxidant effects of green tea have been reported. Both effects could be mediated by hydrogen peroxide (H 2 O 2 ) which is generated by autoxidation of tea catechins. In large amounts, H 2 O 2 is genotoxic, but low concentrations could activate the redox-sensitive antioxidant response element (ARE) via the Keap-1/Nrf2 redox switch, inducing genoprotective adaptations. Our objective was to test this hypothesis. Methods: Peripheral lymphocytes from healthy volunteers were incubated for 30 minutes at 37°C in freshly prepared tea solutions (0.005, 0.01, 0.05%w/v (7, 14, 71 μmol/l total catechins) in phosphate buffered saline (PBS), with PBS as control) in the presence and absence of catalase (CAT). H 2 O 2 in tea was measured colorimetrically. Oxidation-induced DNA lesions were measured by the Fpg-assisted comet assay. Results: H 2 O 2 concentrations in 0.005, 0.01, and 0.05% green tea after 30 minutes at 37°C were, respectively, ~3, ~7, and ~52 μmol/l. Cells incubated in 0.005 and 0.01% tea showed less (P < 0.001) DNA damage compared to control cells. Cells treated with 0.05% green tea showed ~50% (P < 0.001) more DNA damage. The presence of CAT prevented this damage, but did not remove the genoprotective effects of low-dose tea. No significant changes in expression of ARE-associated genes (HMOX1, NRF2, KEAP1, BACH1, and hOGG1) were seen in cells treated with tea or tea + CAT. Conclusion: Genoprotection by low-dose green tea could be due to direct antioxidant protection by green tea polyphenols, or to H 2 O 2 -independent signalling pathways. © W. S. Maney & Son Ltd 2013.-
dc.languageeng-
dc.relation.ispartofRedox Report-
dc.subjectDNA damage-
dc.subjectARE-
dc.subjectGreen tea-
dc.subjectPro-oxidant-
dc.subjectHO-1-
dc.subjectHydrogen peroxide-
dc.subjectOxidative stress-
dc.subjectRedox tone-
dc.subjectGenoprotection-
dc.titleGenoprotection and genotoxicity of green tea (Camellia sinensis): Are they two sides of the same redox coin?-
dc.typeArticle-
dc.description.natureLink_to_subscribed_fulltext-
dc.identifier.doi10.1179/1351000213Y.0000000051-
dc.identifier.pmid23849339-
dc.identifier.scopuseid_2-s2.0-84880395062-
dc.identifier.volume18-
dc.identifier.issue4-
dc.identifier.spage150-
dc.identifier.epage154-
dc.identifier.eissn1743-2928-

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