title: Kinetic study of the quenching reaction of singlet oxygen by α-, β-, γ-, δ-tocotrienols, and palm oil and soybean extracts in solution.
abstract: Measurements of the singlet oxygen ((1)O2) quenching rates (kQ (S)) and the relative singlet oxygen absorption capacity (SOAC) values were performed for 11 antioxidants (AOs) (eight vitamin E homologues (α-, β-, γ-, and δ-tocopherols and -tocotrienols (-Tocs and -Toc-3s)), two vitamin E metabolites (α- and γ-carboxyethyl-6-hydroxychroman), and trolox) in ethanol/chloroform/D2O (50:50:1, v/v/v) and ethanol solutions at 35 °C. Similar measurements were performed for five palm oil extracts 1-5 and one soybean extract 6, which included different concentrations of Tocs, Toc-3s, and carotenoids. Furthermore, the concentrations (wt%) of Tocs, Toc-3s, and carotenoids included in extracts 1-6 were determined. From the results, it has been clarified that the (1)O2-quenching rates (kQ (S)) (that is, the relative SOAC value) obtained for extracts 1-6 may be explained as the sum of the product {Σ kQ(AO-i) (S) [AO-i]/100} of the rate constant (kQ(AO-i) (S)) and the concentration ([AO-i]/100) of AO-i (Tocs, Toc-3s, and carotenoid) included.
authors.affiliation: a Faculty of Science, Department of Chemistry , Ehime University , Matsuyama , Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mukai
authors.forename: Eri
authors.initials: E
authors.lastname: Ishikawa
authors.forename: Aya
authors.initials: A
authors.lastname: Ouchi
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Nagaoka
authors.forename: Tomomi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Izumisawa
authors.forename: Taisuke
authors.initials: T
authors.lastname: Koike
mesh_terms: D002338:Carotenoids / Q000737:chemistry; D002839:Chromans / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry; D007700:Kinetics; D000073878:Palm Oil; D010936:Plant Extracts / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry*; D012996:Solutions; D013025:Glycine max / Q000737:chemistry*; D024505:Tocopherols / Q000737:chemistry; D024508:Tocotrienols / Q000737:chemistry*; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D002839:Chromans; D016166:Free Radical Scavengers; D010936:Plant Extracts; D010938:Plant Oils; D012996:Solutions; D024508:Tocotrienols; D014810:Vitamin E; D026082:Singlet Oxygen; C082097:tocotrienol, delta; D002338:Carotenoids; C013649:plastochromanol 8; C082089:tocotrienol, beta; D000073878:Palm Oil; C082032:tocotrienol, alpha; D024505:Tocopherols; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid
keywords: SOAC value; palm oil; quenching rate; singlet oxygen; tocotrienols