2-O-alpha-D-glucopyranosyl-L-ascorbic acid scavenges 1,1-diphenyl-2-picrylhydrazyl radicals via a covalent adduct formation.
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.
Takebayashi
Jun
J
Department of Immunochemistry, Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
Asano
Ryuji
R
Nakae
Yoshinori
Y
Saito
Morio
M
Gohda
Eiichi
E
Yamamoto
Itaru
I
Tai
Akihiro
A
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*
D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010851:Picrates; C065378:ascorbic acid 2-O-glucoside; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid