title: Kinetic study of the quenching reaction of singlet oxygen by seven rice bran extracts in ethanol solution. Development of a singlet oxygen absorption capacity (SOAC) assay method.
abstract: Measurements of singlet oxygen ((1)O2) quenching rates (kQ (S)) and the relative singlet oxygen absorption capacity (SOAC) values were performed for seven rice bran extracts 1-7, which contained different concentrations of antioxidants (AOs) (such as α-, β-, γ-, and δ-tocopherols and -tocotrienols, three carotenoids (lutein, β-carotene, and zeaxanthin), and γ-oryzanol), in ethanol at 35 °C using UV-vis spectrophotometry. The concentrations of four tocopherols and four tocotrienols, three carotenoids, and γ-oryzanol contained in the extracts were determined using HPLC-MS/MS, UV-HPLC, and UV-vis absorption spectroscopy, respectively. Furthermore, comparisons of kQ (S) (Obsd.) values observed for the above extracts 1-7 with the sum of the product {[Formula: see text] [AO-i]} of the [Formula: see text] values obtained for each AO-i and the concentration ([AO-i]) of AO-i contained in extracts 1-7 were performed. From the results, it has been ascertained that the SOAC method is applicable to general food extracts to evaluate their (1)O2-quenching activity.
authors.affiliation: a Faculty of Science, Department of Chemistry , Ehime University , Matsuyama , Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mukai
authors.affiliation: a Faculty of Science, Department of Chemistry , Ehime University , Matsuyama , Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Ishikawa
authors.affiliation: b Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science , Tohoku University , Sendai , Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Abe
authors.affiliation: a Faculty of Science, Department of Chemistry , Ehime University , Matsuyama , Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Ouchi
authors.affiliation: a Faculty of Science, Department of Chemistry , Ehime University , Matsuyama , Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Nagaoka
authors.affiliation: c Agricultural Research Institute, Toyama Prefectural Agricultural , Forestry and Fisheries Research Center , Toyama , Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Murata
authors.affiliation: b Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science , Tohoku University , Sendai , Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Miyazawa
authors.affiliation: b Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science , Tohoku University , Sendai , Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Nakagawa
mesh_terms: D065966:Absorption, Physicochemical; D000975:Antioxidants / Q000032:analysis / Q000737:chemistry*; D002338:Carotenoids / Q000032:analysis / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry*; D007700:Kinetics; D012275:Oryza / Q000737:chemistry*; D010666:Phenylpropionates / Q000032:analysis / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013696:Temperature; D014810:Vitamin E / Q000032:analysis / Q000737:chemistry
chemical_list: D000975:Antioxidants; D010666:Phenylpropionates; D010936:Plant Extracts; D012996:Solutions; D014810:Vitamin E; D026082:Singlet Oxygen; D002338:Carotenoids; D000431:Ethanol; C013172:gamma-oryzanol
keywords: antioxidant activity; carotenoid; reaction rate; rice bran extract; singlet oxygen