title: Scavenging rate constants of hydrophilic antioxidants against multiple reactive oxygen species.
abstract: Scavenging rate constants of eight hydrophilic antioxidants, including caffeic acid, chlorogenic acid, genistein, glutathione, N-acetylcysteine, rutin, trolox, and uric acid against multiple ROS, namely superoxide anion, hydroxyl radical, singlet oxygen, and alkoxyl radical were determined with the electron spin resonance method. Direct flash photolysis measurement of the second-order rate constant in the reaction of alkoxyl radical plus the spin trap 5,5-dimethyl-pyrroline N-oxide made it possible to evaluate scavenging rate constants in antioxidants. The magnitudes of scavenging rate constants were notably dependent on the character of each ROS and the overall rate constants were highest in hydroxyl radical scavenging and the lowest in superoxide anion. The highest scavenging rate constant against superoxide anion was obtained by chlorogenic acid (2.9 × 10(5) M(-1) s(-1)) and the lowest was by N-acetylcysteine (5.0 × 10(2) M(-1) s(-1)). For singlet oxygen, the highest was by glutathione (9.4 × 10(8) M(-1) s(-1)) and the lowest was by uric acid (2.3 × 10(6) M(-1) s(-1)). All other numbers are listed and illustrated. Redox potential measurements of the antioxidants indicated that the antioxidants are likely to react with superoxide anion and singlet oxygen through electron transfer processes.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sueishi
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hori
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Misa
authors.initials: M
authors.lastname: Ishikawa
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Matsu-Ura
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Erisa
authors.initials: E
authors.lastname: Kamogawa
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Honda
authors.affiliation: Graduate School of Education, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kita
authors.affiliation: Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Ohara
keywords: hydrophilic antioxidant; radical scavenging; reactive oxygen species (ROS); redox potential; spin trapping