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dc.creatorBORS,WOLF
dc.creatorCHRISTA,MICHEL
dc.creatorSTETTMAIER,KURT
dc.creatorYINRONG,LU
dc.creatorL. YEAP,FOO
dc.date2004-01-01
dc.date.accessioned2020-02-17T15:34:03Z
dc.date.available2020-02-17T15:34:03Z
dc.identifierhttps://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000200017
dc.identifier.urihttps://revistaschilenas.uchile.cl/handle/2250/131114
dc.descriptionCaffeic acid, rosmarinic acid and oligomers of caffeic acid with multiple catechol groups are all constituents of Salvia officinalis. Their antioxidant potential was investigated with regard to their radical scavenging activity and the stability and structure of the intermediate radicals. Pulse-radiolytic studies revealed very high rate constants with hydroxyl radicals. Evidence from kinetic modeling calculations suggested an unusual complex behavior due to the presence of both O4- and O3-semiquinones and formation and decay of a hydroxyl radical adduct at the vinyl side chain. The radical structures observed by EPR spectroscopy after autoxidation in slightly alkaline solutions were only partially identified due to their instability and generally represented dissociated O4-semiquinones. Hybrid density-functional calculations of the potential radical structures showed distinct differences between the resonance stabilization of the O4- and O3-semiquinones of caffeic and dihydrocaffeic acids, reflected also in the considerably faster decay of the O3-semiquinone observed by pulse radiolysis. No evidence was found for dimerization reactions via Cb radicals typical for lignin biosynthesis
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dc.languageen
dc.publisherSociedad de Biología de Chile
dc.relation10.4067/S0716-97602004000200017
dc.rightsinfo:eu-repo/semantics/openAccess
dc.sourceBiological Research v.37 n.2 2004
dc.subjectCaffeic acid oligomer
dc.subjectcatechol semiquinone
dc.subjectelectron paramagnetic resonance
dc.subjecthydroxyl radical
dc.subjectkinetic modeling
dc.subjectpulse radiolysis
dc.subjectSalvia officinalis
dc.titleAntioxidant Mechanisms of Polyphenolic Caffeic Acid Oligomers, Constituents of Salvia officinalis


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