title: Nitric oxide scavenging rates of solubilized resveratrol and flavonoids.
abstract: Relative nitric oxide scavenging rates of water-insoluble lipophilic antioxidants, such as resveratrol and flavonoids were determined using a β-cyclodextrin analog, DM-β-CD (heptakis(2,6-di-O-methyl)-β-cyclodextrin) as a solubilizer. Antioxidant-mediated decrease of NO concentration was measured with the electron spin resonance-based PTIO (2-phenyl-4,4,5,5-methylimidazoline-1-oxyl 3-oxide) method, from which scavenging rates were calculated. Because both the antioxidant and PTIO form inclusion complex with DM-β-CD, a kinetic treatment was necessary to calculate the scavenging rates. Resveratrol showed the highest NO scavenging rate among the tested antioxidants. The magnitudes of scavenging rates were in the order of: resveratrol>catechin≈myricetin>epicatechin>epigallocatechin gallate>kaempferol. This order is not in agreement with the oxygen radical scavenging rates: i.e., myricetin>epigallocatechin gallate>catechin≈epicatechin>resveratrol>kaempferol. The tested antioxidants showed lower scavenging rates than hydrophilic antioxidants such as uric acid and caffeic acids. Previous redox potential measurement of antioxidants revealed that NO scavenging occurs through non-free radical mechanism, indicating that the scavenging capacity is dependent on the nature of the scavenging reaction.
authors.affiliation: Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan. ysueishi@okayama-u.ac.jp
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Sueishi
authors.forename: Masashi
authors.initials: M
authors.lastname: Hori
mesh_terms: D005419:Flavonoids / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry*; D000077185:Resveratrol; D012995:Solubility; D013267:Stilbenes / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D016166:Free Radical Scavengers; D013267:Stilbenes; D009569:Nitric Oxide; D000077185:Resveratrol