Resveratrol Radical Repair by Vitamin C at the Micelle-Water Interface: Unexpected Reaction Rates Explained by Ion-Dipole Interactions

Abstract

AbstractRepair reactions of lipophilic phenoxy radicals by hydrophilic co‐antioxidants at model membranes are important for understanding the factors that govern the interactions between radical scavengers in biological systems. By using near‐UV photoionization, we have selectively generated the phenoxy radical of the famous antioxidant resveratrol inside anionic (SDS), cationic (DTAC), or neutral (TX‐100) micelles, as well as in homogeneous aqueous solution, and have compared its repairs in these media by the water‐soluble co‐antioxidants ascorbic acid and ascorbate monoanion. With all surfactants, these reactions are dynamic processes at the micelle–water interface. Whereas for the combinations ascorbate monoanion/ ionic micelle the repair rates can be rationalized by the Coulombic interactions, unexpected effects were observed with the neutral ascorbic acid and the charged micelles: for the anionic micelles, this repair is three times faster than in homogeneous solution, and two orders of magnitude faster than for the cationic micelles. Given that the repair by a concerted proton–electron transfer demands a coplanar arrangement of the resveratrol phenoxy centre sticking out into the Stern layer and the co‐antioxidant hydroxy moiety approaching from the aqueous bulk, we explain these results by ion–dipole interactions: only at a negatively charged micellar surface does the direction of the large dipole moment of ascorbic acid lead to an orientation favourable for the repair.

Autoren

Christoph Kerzig
Matthias Hoffmann
Martin Goez

DOI

10.1002/chem.201705635

eISSN

1521-3765

ISSN

0947-6539

Ausgabe der Veröffentlichung

12

Zeitschrift

Chemistry – A European Journal

Sprache

en

Online publication date

2018

Paginierung

3038 - 3044

Datum der Veröffentlichung

2018

Status

Published

Herausgeber

Wiley

Herausgeber URL

http://dx.doi.org/10.1002/chem.201705635

Datum der Datenerfassung

2023

Titel

Resveratrol Radical Repair by Vitamin C at the Micelle–Water Interface: Unexpected Reaction Rates Explained by Ion–Dipole Interactions

Ausgabe der Zeitschrift

24

Datenquelle: Crossref

Abstract

Repair reactions of lipophilic phenoxy radicals by hydrophilic co-antioxidants at model membranes are important for understanding the factors that govern the interactions between radical scavengers in biological systems. By using near-UV photoionization, we have selectively generated the phenoxy radical of the famous antioxidant resveratrol inside anionic (SDS), cationic (DTAC), or neutral (TX-100) micelles, as well as in homogeneous aqueous solution, and have compared its repairs in these media by the water-soluble co-antioxidants ascorbic acid and ascorbate monoanion. With all surfactants, these reactions are dynamic processes at the micelle-water interface. Whereas for the combinations ascorbate monoanion/ ionic micelle the repair rates can be rationalized by the Coulombic interactions, unexpected effects were observed with the neutral ascorbic acid and the charged micelles: for the anionic micelles, this repair is three times faster than in homogeneous solution, and two orders of magnitude faster than for the cationic micelles. Given that the repair by a concerted proton-electron transfer demands a coplanar arrangement of the resveratrol phenoxy centre sticking out into the Stern layer and the co-antioxidant hydroxy moiety approaching from the aqueous bulk, we explain these results by ion-dipole interactions: only at a negatively charged micellar surface does the direction of the large dipole moment of ascorbic acid lead to an orientation favourable for the repair.

Addresses

Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120, Halle (Saale), Germany.

Autoren

Christoph Kerzig
Matthias Hoffmann
Martin Goez

DOI

10.1002/chem.201705635

eISSN

1521-3765

Externe Identifier

PubMed Identifier: 29314459

Open access

false

ISSN

0947-6539

Ausgabe der Veröffentlichung

12

Zeitschrift

Chemistry (Weinheim an der Bergstrasse, Germany)

Schlüsselwörter

Water
Polyethylene Glycols
Ascorbic Acid
Stilbenes
Antioxidants
Surface-Active Agents
Micelles
Resveratrol

Sprache

eng

Medium

Print-Electronic

Online publication date

2018

Paginierung

3038 - 3044

Datum der Veröffentlichung

2018

Status

Published

Datum der Datenerfassung

2018

Titel

Resveratrol Radical Repair by Vitamin C at the Micelle-Water Interface: Unexpected Reaction Rates Explained by Ion-Dipole Interactions.

Sub types

Journal Article

Ausgabe der Zeitschrift

24

Datenquelle: Europe PubMed Central

Abstract

Repair reactions of lipophilic phenoxy radicals by hydrophilic co-antioxidants at model membranes are important for understanding the factors that govern the interactions between radical scavengers in biological systems. By using near-UV photoionization, we have selectively generated the phenoxy radical of the famous antioxidant resveratrol inside anionic (SDS), cationic (DTAC), or neutral (TX-100) micelles, as well as in homogeneous aqueous solution, and have compared its repairs in these media by the water-soluble co-antioxidants ascorbic acid and ascorbate monoanion. With all surfactants, these reactions are dynamic processes at the micelle-water interface. Whereas for the combinations ascorbate monoanion/ ionic micelle the repair rates can be rationalized by the Coulombic interactions, unexpected effects were observed with the neutral ascorbic acid and the charged micelles: for the anionic micelles, this repair is three times faster than in homogeneous solution, and two orders of magnitude faster than for the cationic micelles. Given that the repair by a concerted proton-electron transfer demands a coplanar arrangement of the resveratrol phenoxy centre sticking out into the Stern layer and the co-antioxidant hydroxy moiety approaching from the aqueous bulk, we explain these results by ion-dipole interactions: only at a negatively charged micellar surface does the direction of the large dipole moment of ascorbic acid lead to an orientation favourable for the repair.

Autoren

Christoph Kerzig
Matthias Hoffmann
Martin Goez

Autoren-URL

https://www.ncbi.nlm.nih.gov/pubmed/29314459

DOI

10.1002/chem.201705635

eISSN

1521-3765

Ausgabe der Veröffentlichung

12

Zeitschrift

Chemistry

Schlüsselwörter

antioxidants
laser chemistry
photoionization
radicals
resveratrol
Antioxidants
Ascorbic Acid
Micelles
Polyethylene Glycols
Resveratrol
Stilbenes
Surface-Active Agents
Water

Sprache

eng

Country

Germany

Paginierung

3038 - 3044

Datum der Veröffentlichung

2018

Status

Published

Datum, an dem der Datensatz öffentlich gemacht wurde

2018

Titel

Resveratrol Radical Repair by Vitamin C at the Micelle-Water Interface: Unexpected Reaction Rates Explained by Ion-Dipole Interactions.

Sub types

Journal Article

Ausgabe der Zeitschrift

24

Datenquelle: PubMed

Resveratrol Radical Repair by Vitamin C at the Micelle-Water Interface: Unexpected Reaction Rates Explained by Ion-Dipole Interactions

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