title: Redox reactions of the urate radical/urate couple with the superoxide radical anion, the tryptophan neutral radical and selected flavonoids in neutral aqueous solutions.
abstract: The kinetics of several processes involving the potential antioxidant role of urate in physiological systems have been investigated by pulse radiolysis. While the monoanionic urate radical, .UH-, can be produced directly by oxidation with .Br2- or .OH, it can also be generated by oxidation with the neutral tryptophan radical, .Trp, with a rate constant of 2 x 10(7) M-1s-1. This radical, .UH-, reacts with .O2- with a rate constant of 8 x 10(8) M-1s-1. Also, .UH- is reduced by flavonoids, quercetin and rutin in CTAB micelles at rate constants of 6 x 10(6) M-1s-1 and 1 x 10(6) M-1s-1, respectively. These results can be of value by providing reference data useful in further investigation of the antioxidant character of urate in more complex biological systems.
authors.affiliation: Radiation Laboratory, University of Notre Dame, Notre Dame, In. 46556, USA. santus@mnhn.fr
authors.forename: R
authors.initials: R
authors.lastname: Santus
authors.forename: L K
authors.initials: LK
authors.lastname: Patterson
authors.forename: P
authors.initials: P
authors.lastname: Filipe
authors.forename: P
authors.initials: P
authors.lastname: Morlière
authors.forename: G L
authors.initials: GL
authors.lastname: Hug
authors.forename: A
authors.initials: A
authors.lastname: Fernandes
authors.forename: J C
authors.initials: JC
authors.lastname: Mazière
mesh_terms: D000818:Animals; D002392:Catechin / Q000378:metabolism; D002417:Cattle; D005419:Flavonoids / Q000378:metabolism*; D007700:Kinetics; D008823:Micelles; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D011794:Quercetin / Q000378:metabolism; D012431:Rutin / Q000378:metabolism; D012996:Solutions / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013481:Superoxides / Q000737:chemistry / Q000378:metabolism*; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*; D014527:Uric Acid / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D005419:Flavonoids; D008823:Micelles; D012996:Solutions; D014867:Water; D013481:Superoxides; D014527:Uric Acid; D012431:Rutin; D014364:Tryptophan; D002392:Catechin; D011794:Quercetin