Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Nakayama, Tatsushi; Uno, Bunji

doi:10.1248/cpb.c15-00447

Cited by 45 publications

(76 citation statements)

References 43 publications

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“…In the present study, we chose to examine the variation of cathodic peak currents at the EC 50 and zero concentrations ( I 50 pc / I 0 pc ). However, it should be highlighted that several of these compounds registered large pre‐peaks in their voltammograms, and were thus exempted from the aforementioned measurements as they are possibly implicated in a sequence of mechanistic processes which are not at present fully understood; although it has been suggested that these might involve a concerted proton‐coupled electron transfer process . Regardless, in these instances, as described by René et al., an approximate classification was instead performed by considering the difference in the potential (ΔE) of the pre‐peak (when its intensity was half that of O 2 reduction) and the peak of the initial O 2 reduction .…”

Section: Resultsmentioning

confidence: 99%

“…In addition, O 2 .− has also been demonstrated to be relatively long‐lived and easily handled in such media, while changes that occur during its reactions (such as consumption of O 2 .− or analyte) may be monitored in situ . For example, there have been a number of studies that have examined the reactions between electrochemically generated O 2 .− and various groups of natural and synthetic compounds such as flavonoids, (poly)phenols, and others . More specifically, by carefully analyzing the changes in the profiles of the voltammograms obtained for O 2 reduction upon the addition of a substrate, such as the anodic and cathodic peak current intensities, a comparison of relative reactivities across different analytes, and the elucidation of general scavenging mechanisms involved can be made …”

Section: Introductionmentioning

confidence: 99%

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Comparing the Relative Reactivities of Food and Vitamin Molecules Toward Electrochemically Generated Superoxide in Dimethylformamide

et al. 2017

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Superoxide (O2.−), an anionic radical of the reactive oxygen species (ROS) family, is continuously produced in the body and can lead to the undesirable modification and damage of important biological molecules. In the present study, the relative reactivities of 18 food and vitamin molecules toward electrochemically generated O2.− were investigated in N,N‐dimethylformamide (DMF) solutions by using cyclic voltammetry (CV). The quenching of O2.− was measured by monitoring the decreases in the anodic currents of the reverse peaks after the one‐electron reduction of molecular oxygen (O2), while systematically increasing the concentration of the test substrates. The reactivity of each compound was then approximated and compared using effective concentration indexes, EC10 and EC50, which represent the amount of compound required to reduce the concentration of the electrochemically generated O2.− by 10 and 50%, respectively, under the present conditions. Where possible, the likely mechanisms that are involved in the scavenging of O2.− are also discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparing the Relative Reactivities of Food and Vitamin Molecules Toward Electrochemically Generated Superoxide in Dimethylformamide

et al. 2017

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“…Natural phenolic compounds such as flavonoids scavenge ROS by proton-coupled electron transfer [42]. By this transfer, the phenolic compounds are oxidized to semiquinones or quinones.…”

Section: Discussionmentioning

confidence: 99%

Pro- and Antioxidant Activity of Three Selected Flavan Type Flavonoids: Catechin, Eriodictyol and Taxifolin

Chobot

Hadaček

Bachmann

et al. 2016

IJMS

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The flavanol (±)-catechin shows an OH group but no 4-keto group on ring C (C3), and no conjugation between ring A and B. The related flavanone (+)-eriodictyol has a keto group on C4 but no 3-OH group on ring C. (+)-Taxifolin, another flavanone, has an OH on C3 and a keto group on C4 of the C ring. Deoxyribose degradation assay systems, with hydrogen peroxide and ascorbic acid either added or omitted, were performed in variants in which Fe(III) was added in a complex with ethylenediaminetetraacetic acid (EDTA). In combination with differential pulse voltammetry (DVP), the specific redox-chemical contributions of the ring A m-dihydroxyl groups could be explored more specifically in addition to those of the traditionally investigated o-dihydroxyl groups of ring B.

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“…From a mechanistic perspective, DPPH•‐scavenging is similar to reactive oxygen species (ROS)‐scavenging. For example, •O 2 − scavenging, a kind of ROS‐scavenging, has been proven to be mediated by the proton‐coupled electron transfer (PCET),, radical adduct formation (RAF), and proton‐transfer pathways. These pathways can also be found in the DPPH•‐scavenging reaction .…”

Section: Figurementioning

confidence: 99%

Comparative Study of 1,1‐Diphenyl‐2‐picryl‐hydrazyl Radical (DPPH•) Scavenging Capacity of the Antioxidant Xanthones Family

2018

ChemistrySelect

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This study compares the antioxidant capacities of the xanthone family and analyzes structure‐activity relationship. Thirty xanthones with various structural features were selected as the references and their antioxidant capacities were determined using the 1,1‐diphenyl‐2‐picryl‐hydrazyl radical (DPPH•) scavenging assay. The results of the assay indicated that these xanthones could scavenge the DPPH• in a dose‐dependent manner. It was found that their Trolox equivalent antioxidant capacity (TEAC) values varied by the presence or absence of hydroquinone (or catechol) group within the molecule. The former 15 xanthones (1‐15, TEAC=2.030‐0.568) with hydroquinone (or catechol) pattern possessed much higher TEAC values than the latter 15 xanthones (16‐30, TEAC=0.019‐0.002) without hydroquinone (or catechol) pattern. It was concluded that the presence of the hydroquinone (or catechol) group governs the antioxidant capacity of xanthone family. Other structural factors, such as isoprenylation, methylation, and glycosidation, play a minor role, unless they remove the hydroquinone (or catechol) pattern. These findings can be used to directly predict the antioxidant capacity of xanthone.

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Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging

Cited by 45 publications

References 43 publications

Comparing the Relative Reactivities of Food and Vitamin Molecules Toward Electrochemically Generated Superoxide in Dimethylformamide

Comparing the Relative Reactivities of Food and Vitamin Molecules Toward Electrochemically Generated Superoxide in Dimethylformamide

Pro- and Antioxidant Activity of Three Selected Flavan Type Flavonoids: Catechin, Eriodictyol and Taxifolin

Comparative Study of 1,1‐Diphenyl‐2‐picryl‐hydrazyl Radical (DPPH•) Scavenging Capacity of the Antioxidant Xanthones Family

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