title: 2-O-alpha-D-glucopyranosyl-L-ascorbic acid scavenges 1,1-diphenyl-2-picrylhydrazyl radicals via a covalent adduct formation.
abstract: The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging mechanism of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) was studied. We found two undefined products, named X and Y, in the reaction mixture of AA-2G and the DPPH radical under acidic conditions by HPLC analysis. The reaction mixture was further subjected to LC-MS analysis. X was found to be a covalent adduct of AA-2G and the DPPH radical. On the other hand, Y could not be identified, probably because it was a mixture. A time-course study of the radical-scavenging reaction revealed that one molecule of AA-2G scavenged one molecule of DPPH radical to generate an AA-2G radical, which readily reacted with another molecule of the DPPH radical to form a covalent adduct (X). Subsequently, this adduct slowly quenched a third molecule of the DPPH radical, resulting in reaction products (Y). Therefore, one molecule of AA-2G has only one oxidizable -OH group, but can scavenge three molecules of the DPPH radical. The radical-scavenging mechanism of AA-2G elucidated in this study should be useful in understanding the biological roles of AA-2G per se in the food and cosmetic fields.
authors.affiliation: Department of Immunochemistry, Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Takebayashi
authors.forename: Ryuji
authors.initials: R
authors.lastname: Asano
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nakae
authors.forename: Morio
authors.initials: M
authors.lastname: Saito
authors.forename: Eiichi
authors.initials: E
authors.lastname: Gohda
authors.forename: Itaru
authors.initials: I
authors.lastname: Yamamoto
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tai
mesh_terms: D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D001713:Biphenyl Compounds; D002851:Chromatography, High Pressure Liquid; D016166:Free Radical Scavengers / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; C065378:ascorbic acid 2-O-glucoside; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid