title: Evaluation of the total peroxyl radical-scavenging capacity of flavonoids: structure-activity relationships.
abstract: The antioxidant activity of a series of flavonoids against peroxyl radicals generated from thermal homolysis of 2, 2'-azobis-amidinopropane was determined by the Total Oxyradical Scavenging Capacity (TOSC) assay. Seven flavonoids with hydroxy and/or methoxy substitution were analyzed and compared to the water-soluble vitamin E analogue Trolox. The most active compound was the flavonol quercetin, followed by its 3-glycoside derivative rutin; these were 7 and 5 times, respectively, better scavengers of peroxyl radical than Trolox. Among the flavones with both hydroxy and methoxy substitution, the most active against peroxyl radicals was the 5,6,4'-trihydroxy-7,8,3'-trimethoxyflavone (thymonin), with a TOSC value 1.5 times greater than that of Trolox. The activity of the remaining flavones was in the following relative order: 5, 4'-dihydroxy-6,7,8,3'-tetramethoxyflavone > 5-hydroxy-3,6,7,3', 4'-pentamethoxyflavone (artemetin) > 5,4'-dihydroxy-3,6, 7-trimethoxyflavone > 5,6,7,8,2',3',4',5'-octamethoxyflavone (agehoustin A). The data suggest a potential role for dietary intake of flavonoid-containing foods in lowering the risk of certain pathophysiologies that have been associated with free-radical-mediated events.
authors.affiliation: Department of Toxicology, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Dugas
authors.forename: J
authors.initials: J
authors.lastname: Castañeda-Acosta
authors.forename: G C
authors.initials: GC
authors.lastname: Bonin
authors.forename: K L
authors.initials: KL
authors.lastname: Price
authors.forename: N H
authors.initials: NH
authors.lastname: Fischer
authors.forename: G W
authors.initials: GW
authors.lastname: Winston
mesh_terms: D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D010545:Peroxides; D013329:Structure-Activity Relationship
chemical_list: D005419:Flavonoids; D010545:Peroxides; C049375:perhydroxyl radical