title: Radical-induced oxidation of metformin.
abstract: Metformin (1,1-dimethylbiguanide) is an antihyperglycaemic drug used to normalize glucose concentrations in type 2 diabetes. Furthermore, antioxidant benefits have been reported in diabetic patients treated with metformin. This work was aimed at studying the scavenging capacity of this drug against reactive oxygen species (ROS) like *OH and (O2*-)-free radicals. ROS were produced by gamma radiolysis of water. The irradiated solutions of metformin were analyzed by UV/visible absorption spectrophotometry. It has been shown that hydroxyl free radicals react with metformin in a concentration-dependent way. The maximum scavenging activity was obtained for concentrations of metformin > or = 200 micromol.L(-1), under our experimental conditions. An estimated value of 10(7) L.mol(-1).s(-1) has been determined for the second order rate constant k(*OH + metformin). Superoxide free radicals and hydrogen peroxide do not initiate any oxidation on metformin in our in vitro experiments.
authors.affiliation: Laboratoire de Chimie Physique UMR 8601-CNRS, Université Paris 5, France. hania.khouri@univ-paris5.fr
authors.forename: H
authors.initials: H
authors.lastname: Khouri
authors.forename: F
authors.initials: F
authors.lastname: Collin
authors.forename: D
authors.initials: D
authors.lastname: Bonnefont-Rousselot
authors.forename: A
authors.initials: A
authors.lastname: Legrand
authors.forename: D
authors.initials: D
authors.lastname: Jore
authors.forename: M
authors.initials: M
authors.lastname: Gardès-Albert
mesh_terms: D007004:Hypoglycemic Agents / Q000378:metabolism*; D008687:Metformin / Q000378:metabolism*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D007004:Hypoglycemic Agents; D017382:Reactive Oxygen Species; D008687:Metformin