| Registro completo |
| Provedor de dados: |
Biol. Res.
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| País: |
Chile
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| Título: |
Antioxidant Mechanisms of Polyphenolic Caffeic Acid Oligomers, Constituents of Salvia officinalis
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| Autores: |
BORS,WOLF
CHRISTA,MICHEL
STETTMAIER,KURT
YINRONG,LU
L. YEAP,FOO
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| Data: |
2004-01-01
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| Ano: |
2004
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| Palavras-chave: |
Caffeic acid oligomer
Catechol semiquinone
Electron paramagnetic resonance
Hydroxyl radical
Kinetic modeling
Pulse radiolysis
Salvia officinalis
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| Resumo: |
Caffeic 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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| Tipo: |
Journal article
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| Idioma: |
Inglês
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| Identificador: |
http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000200017
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| Editor: |
Sociedad de Biología de Chile
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| Formato: |
text/html
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| Fonte: |
Biological Research v.37 n.2 2004
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