title: Nitric oxide (NO) scavenging capacity of natural antioxidants.
abstract: Nitric oxide (NO)-scavenging capacities of several hydrophilic antioxidants were determined by using the PTIO method, a competitive NO-scavenging method with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). Relative NO-scavenging rates of antioxidants were measured with respect to PTIO and the scavenging rate constants were calculated based on PTIO's rate constant. Results indicated that NO-scavenging rate constants of the antioxidants were: uric acid (2.5)>caffeic acid (1.2)>trolox (1.0)>genistein (0.19)>glutathione (0) ≈N-acetylcysteine (0), where the numbers are expressed in trolox equivalent unit. The oxidation potentials of these antioxidants were measured and the order in the magnitude of oxidation potential was in good accordance with NO-scavenging capacity. Based on the results, we have suggested that the primary chemical process of the antioxidant reaction with NO can be characterised with the electron transfer from NO to the antioxidant.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan. Electronic address: ysueishi@cc.okayama-u.ac.jp.
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: 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: Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors.forename: Yashige
authors.initials: Y
authors.lastname: Kotake
keywords: EPR; Hydrophilic antioxidants; Kinetic study; NO-scavenging capacity; Nitric oxide; PTIO