Cited by 187Free Radicals and AntioxidantsPhytochemicals and Antioxidant ActivitiesAntioxidant Activity and Oxidative Stress

Interaction of flavonoids with ascorbate and determination of their univalent redox potentials: A pulse radiolysis study

Bors, Wolf, Michel, Christa, Schikora, Sébastien·1995·Free Radical Biology and Medicine

Abstract

Concurrent pulse-radiolytic generation of flavonoid aroxyl radicals and ascorbyl radicals causes a complex kinetic interplay of competing and parallel reactions. Evaluation by "kinetic modelling," that is, taking into account all possible reactions by a set of differential equations, allowed us to determine equilibria constants for the univalent steps by a novel method. From these kinetic data we were able to calculate the redox potentials for dihydroquercetin, quercetin, rutin (a quercetin 3-glycoside), kaempferol, fisetin, and luteolin. Despite the limited number of substances, two structural criteria became apparent: all substances containing the B-ring catechol group and the 2,3-double bond have a higher redox potential than ascorbate and are consequently able to oxidize it to the ascorbyl radical. With fisetin and kaempferol having values very similar to ascorbate, only the flavanone dihydro-quercetin was capable of reducing the ascorbyl radical, thus fulfilling the so-called "ascorbate-protective" function, originally proposed by Szent-Györgyi. While flavonoids are effective radical scavengers, these rather high redox potentials for most flavonols may explain their occasional prooxidative behavior.

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Crossref · 10.1016/0891-5849(95)00011-l

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Authors
Bors, W., Michel, C., & Schikora, S.
Affiliations
Helmholtz Munich (DE)
Corresponding author
Bors, Wolf
Venue
Free Radical Biology and Medicine
Publisher
Elsevier BV
Published
1995-07
Volume
19
Issue
1
Pages
45-52
ISSN
0891-5849 (ISSN-L)
OpenAlex
W2033670414
Cited by
187
References
41
Citations by year
2026: 1 · 2025: 3 · 2024: 5 · 2023: 2 · 2022: 2 · 2021: 3 · 2020: 6 · 2019: 4 · 2018: 2 · 2017: 1 · 2016: 3 · 2015: 4 · 2014: 4 · 2013: 5 · 2012: 10
FWCI
7.59
Type
journal article
Language
en
Open access
closed
Locations
  • Free Radical Biology and Medicine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Chemistry › Organic Chemistry › Free Radicals and Antioxidants
  • Health Sciences › Medicine › Biochemistry › Phytochemicals and Antioxidant Activities
  • Health Sciences › Medicine › Biochemistry › Antioxidant Activity and Oxidative Stress
Keywords
flavonoids, vitamin C, ascorbyl radical, kinetic modeling, taxifolin, quercetin, rutin, kaempferol, fisetin, luteolin, catechol groups, free radical scavenging, pro-oxidant activity
MeSH terms
Ascorbic Acid, Flavonoids, Hydrogen-Ion Concentration, Kinetics, Oxidation-Reduction, Pulse Radiolysis, Quercetin, Rutin, Molecular Structure, Flavonols, Kaempferols, Luteolin

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