Publication
The dependence of alpha-tocopheroxyl radical reduction by hydroxy-2,3-diarylxanthones on structure and micro-environment
| dc.contributor.author | Morlière, Patrice | |
| dc.contributor.author | Patterson, Larry K. | |
| dc.contributor.author | Santos, Clementina M.M. | |
| dc.contributor.author | Silva, Artur | |
| dc.contributor.author | Marzière, Jean-Claude | |
| dc.contributor.author | Filipe, Paulo | |
| dc.contributor.author | Gomes, Ana Sara | |
| dc.contributor.author | Fernandes, Eduarda | |
| dc.contributor.author | Garcia, Beatriz | |
| dc.contributor.author | Santus, René | |
| dc.date.accessioned | 2012-05-10T10:52:11Z | |
| dc.date.available | 2012-05-10T10:52:11Z | |
| dc.date.issued | 2012 | |
| dc.description.abstract | The flavonoid quercetin is known to reduce the α-tocopheroxyl radical (˙TocO) and reconstitute α-tocopherol (TocOH). Structurally related polyphenolic compounds, hydroxy-2,3-diarylxanthones (XH), exhibit antioxidant activity which exceeds that of quercetin in biological systems. In the present study repair of ˙TocO by a series of these XH has been evaluated using pulse radiolysis. It has been shown that, among the studied XH, only 2,3-bis(3,4-dihydroxyphenyl)-9H-xanthen-9-one (XH9) reduces ˙TocO, though repair depends strongly on the micro-environment. In cationic cetyltrimethylammonium bromide (CTAB) micelles, 30% of ˙TocO radicals are repaired at a rate constant of ∼7.4 × 106 M−1 s−1 by XH9 compared to 1.7 × 107 M−1 s−1 by ascorbate. Water-soluble Trolox (TrOH) radicals (˙TrO) are restored by XH9 in CTAB (rate constant ∼3 × 104 M−1 s−1) but not in neutral TX100 micelles where only 15% of ˙TocO are repaired (rate constant ∼4.5 × 105 M−1 s−1). In basic aqueous solutions ˙TrO is readily reduced by deprotonated XH9 species leading to ionized XH9 radical species (radical pKa ∼10). An equilibrium is observed (K = 130) yielding an estimate of 130 mV for the reduction potential of the [˙X9,H+/XH9] couple at pH 11, lower than the 250 mV for the [˙TrO,H+/TrOH] couple. A comparable value (100 mV) has been determined by cyclic voltammetry measurements. | por |
| dc.identifier.citation | Morlière, Patrice; Patterson, Larry K.; Santos, Clementina M.M.; Silva, Artur; Marzière, Jean-Claude; Filipe, Paulo; Gomes, Ana; Fernandes, Eduarda; Garcia, Beatriz; Santus, René (2012). The dependence of alpha-tocopheroxyl radical reduction by hydroxy-2,3-diarylxanthones on structure and micro-environment. Organic & Biomolecular Chemistry. ISSN 1477-0539. 10, p. 2068-2076 | por |
| dc.identifier.doi | 10.1039/c2ob06612b | |
| dc.identifier.issn | 1477-0539 | |
| dc.identifier.uri | http://hdl.handle.net/10198/6887 | |
| dc.language.iso | eng | por |
| dc.peerreviewed | yes | por |
| dc.publisher | Royal Society of Chemistry | por |
| dc.subject | Pulse-radiolysis | por |
| dc.subject | Redox potentials | por |
| dc.subject | Vitamin-E | por |
| dc.subject | Electron | por |
| dc.subject | Micelles | por |
| dc.subject | Fluorescence | por |
| dc.title | The dependence of alpha-tocopheroxyl radical reduction by hydroxy-2,3-diarylxanthones on structure and micro-environment | por |
| dc.type | journal article | |
| dspace.entity.type | Publication | |
| oaire.citation.endPage | 2076 | por |
| oaire.citation.startPage | 2068 | por |
| oaire.citation.title | Organic Biomolecular Chemistry | por |
| person.familyName | Santos | |
| person.givenName | Clementina M.M. | |
| person.identifier.ciencia-id | 9018-DB9C-C590 | |
| person.identifier.orcid | 0000-0003-4380-7990 | |
| person.identifier.scopus-author-id | 7201458663 | |
| rcaap.rights | openAccess | por |
| rcaap.type | article | por |
| relation.isAuthorOfPublication | 64f662b6-775d-4ea0-bfd7-f527af0ac1a0 | |
| relation.isAuthorOfPublication.latestForDiscovery | 64f662b6-775d-4ea0-bfd7-f527af0ac1a0 |