Singlet oxygen quenching and the redox properties of hydroxycinnamic acids.

2.50
Hdl Handle:
http://hdl.handle.net/10541/91352
Title:
Singlet oxygen quenching and the redox properties of hydroxycinnamic acids.
Authors:
Foley, Sarah; Navaratnam, Suppiah; McGarvey, David J; Land, Edward J; Truscott, T G; Rice-Evans, Catherine A
Abstract:
The singlet oxygen quenching rate constants (kq) for a range of hydroxycinnamic acids in acetonitrile and D2O solutions were measured using time resolved near infrared phosphorescence in order to establish their antioxidant activity. The magnitude of kq observed depends on both the nature of the substituent groups and solvent polarity. The variations in kq depend on the energy of the hydroxycinnamic acid/molecular oxygen charge transfer states, (O2delta- ...HCAdelta+). In D2O the values of kq range from 4x10(7) M(-1) s(-1) to 4x10(6) M(-1) s(-1) for caffeic acid and o-coumaric acid respectively. In acetonitrile, the charge transfer energy levels are raised and this is reflected in lower singlet oxygen quenching rate constants with a kq value of 5x10(6) M(-1) s(-1) for caffeic acid. The phenoxyl radical spectra derived from the hydroxycinnamic acids were determined using pulse radiolysis of aqueous solutions and the reduction potentials were found to range from 534 to 596 mV. A linear correlation is observed between reduction potential, and hence free energy for electron transfer, and log kq. These correlations suggest a charge transfer mechanism for the quenching of singlet oxygen by the hydroxycinnamic acids.
Affiliation:
Department of Chemistry, Keele University, Staffordshire, UK.
Citation:
Singlet oxygen quenching and the redox properties of hydroxycinnamic acids. 1999, 26 (9-10):1202-8 Free Radic. Biol. Med.
Journal:
Free Radical Biology & Medicine
Issue Date:
May-1999
URI:
http://hdl.handle.net/10541/91352
DOI:
10.1016/S0891-5849(98)00313-X
PubMed ID:
10381191
Type:
Article
Language:
en
ISSN:
0891-5849
Appears in Collections:
All Paterson Institute for Cancer Research

Full metadata record

DC FieldValue Language
dc.contributor.authorFoley, Sarahen
dc.contributor.authorNavaratnam, Suppiahen
dc.contributor.authorMcGarvey, David Jen
dc.contributor.authorLand, Edward Jen
dc.contributor.authorTruscott, T Gen
dc.contributor.authorRice-Evans, Catherine Aen
dc.date.accessioned2010-02-08T11:23:16Z-
dc.date.available2010-02-08T11:23:16Z-
dc.date.issued1999-05-
dc.identifier.citationSinglet oxygen quenching and the redox properties of hydroxycinnamic acids. 1999, 26 (9-10):1202-8 Free Radic. Biol. Med.en
dc.identifier.issn0891-5849-
dc.identifier.pmid10381191-
dc.identifier.doi10.1016/S0891-5849(98)00313-X-
dc.identifier.urihttp://hdl.handle.net/10541/91352-
dc.description.abstractThe singlet oxygen quenching rate constants (kq) for a range of hydroxycinnamic acids in acetonitrile and D2O solutions were measured using time resolved near infrared phosphorescence in order to establish their antioxidant activity. The magnitude of kq observed depends on both the nature of the substituent groups and solvent polarity. The variations in kq depend on the energy of the hydroxycinnamic acid/molecular oxygen charge transfer states, (O2delta- ...HCAdelta+). In D2O the values of kq range from 4x10(7) M(-1) s(-1) to 4x10(6) M(-1) s(-1) for caffeic acid and o-coumaric acid respectively. In acetonitrile, the charge transfer energy levels are raised and this is reflected in lower singlet oxygen quenching rate constants with a kq value of 5x10(6) M(-1) s(-1) for caffeic acid. The phenoxyl radical spectra derived from the hydroxycinnamic acids were determined using pulse radiolysis of aqueous solutions and the reduction potentials were found to range from 534 to 596 mV. A linear correlation is observed between reduction potential, and hence free energy for electron transfer, and log kq. These correlations suggest a charge transfer mechanism for the quenching of singlet oxygen by the hydroxycinnamic acids.en
dc.language.isoenen
dc.subject.meshAntioxidants-
dc.subject.meshCoumaric Acids-
dc.subject.meshElectron Transport-
dc.subject.meshFree Radicals-
dc.subject.meshKinetics-
dc.subject.meshOxidation-Reduction-
dc.subject.meshOxygen-
dc.subject.meshPhenols-
dc.subject.meshSinglet Oxygen-
dc.subject.meshSpectrophotometry-
dc.titleSinglet oxygen quenching and the redox properties of hydroxycinnamic acids.en
dc.typeArticleen
dc.contributor.departmentDepartment of Chemistry, Keele University, Staffordshire, UK.en
dc.identifier.journalFree Radical Biology & Medicineen

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