Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/45143
DC FieldValueLanguage
dc.contributor.authorTeixeira, Susana-
dc.contributor.authorSiquet, Christophe-
dc.contributor.authorAlves, Carla-
dc.contributor.authorBoal, Isabel-
dc.contributor.authorMarques, M. Paula-
dc.contributor.authorBorges, Fernanda-
dc.contributor.authorLima, José L. F. C.-
dc.contributor.authorReis, Salette-
dc.date.accessioned2017-12-15T18:43:41Z-
dc.date.available2017-12-15T18:43:41Z-
dc.date.issued2005-
dc.identifier.urihttp://hdl.handle.net/10316/45143-
dc.description.abstractThe screening of natural flavonoids for their bioactivity as antioxidants is usually carried out by determinination of their profile as chain-breaking antioxidants, by the evaluation of their direct free radical-scavenging activity as hydrogen- or electron-donating compounds. Since this may not be the only mechanism underlying the antioxidant activity it is important to check the ability of these compounds to act as chelators of transition metal ions. Accordingly, in the present study the acidity constants of catechin and taxifolin, as well as the formation constants of the corresponding copper (II) complexes, were investigated by potentiometry and/or spectrophotometry. Moreover, a detailed quantitative examination of the coordination species formed is presented. In addition, the partition coefficients of both catechin and taxifolin in a biomimetic system (micelles) were determined, since these properties may also contribute to the antioxidant behavior of this type of compound. The log P values determined depend on the electrostatic interactions of the compounds with the differently charged micelles (the highest values were obtained for zwitterionic and cationic micelles). The prooxidant behavior of the compounds was assessed through the oxidation of 2'-deoxyguanosine, induced by a Fenton reaction, catalyzed by copper. The data obtained reveal that the flavonoids under study did not present prooxidant activity, in this particular system. The results obtained are evidence of a clear difference among the pKa, the complexation properties, and the lipophilicity of the flavonoids studied, which can partially explain their distinct antioxidant activity. The most stable geometries of the free compounds were determined by theoretical (ab initio) methods, in order to properly account for the electron correlation effects which occur in these systems, thus allowing a better interpretation of the experimental data.por
dc.language.isoengpor
dc.rightsopenAccesspor
dc.subjectAntioxidantspor
dc.subjectCatechinpor
dc.subjectDeoxyguanosinepor
dc.subjectFlavonoidspor
dc.subjectFlavonolspor
dc.subjectOxidation-Reductionpor
dc.subjectQuercetinpor
dc.subjectSpectrophotometry, Ultravioletpor
dc.subjectStructure-Activity Relationshippor
dc.subjectDietpor
dc.titleStructure–property studies on the antioxidant activity of flavonoids present in dietpor
dc.typearticle-
degois.publication.firstPage1099por
degois.publication.lastPage1108por
degois.publication.issue8por
degois.publication.titleFree Radical Biology and Medicinepor
dc.peerreviewedyespor
dc.identifier.doi10.1016/j.freeradbiomed.2005.05.028por
dc.identifier.doi10.1016/j.freeradbiomed.2005.05.028-
degois.publication.volume39por
item.languageiso639-1en-
item.fulltextCom Texto completo-
item.grantfulltextopen-
crisitem.author.deptFaculty of Sciences and Technology-
crisitem.author.parentdeptUniversity of Coimbra-
crisitem.author.researchunitQFM-UC – Molecular Physical-Chemistry R&D Unit-
crisitem.author.orcid0000-0002-8391-0055-
Appears in Collections:I&D QFM-UC - Artigos em Revistas Internacionais
FCTUC Ciências da Vida - Artigos em Revistas Internacionais
Files in This Item:
File Description SizeFormat
FRBM_05_39.pdf364.27 kBAdobe PDFView/Open
Show simple item record

SCOPUSTM   
Citations

129
checked on May 29, 2020

WEB OF SCIENCETM
Citations 1

126
checked on Nov 2, 2021

Page view(s)

223
checked on Nov 25, 2021

Download(s) 50

533
checked on Nov 25, 2021

Google ScholarTM

Check

Altmetric

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.