Radical‐induced oxidation of metformin

• Published in: European journal of biochemistry Vol. 271; no. 23‐24; pp. 4745 - 4752
• Main Authors: Khouri, H., Collin, F., Bonnefont‐Rousselot, D., Legrand, A., Jore, D., Gardès‐Albert, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.12.2004
• Subjects: antioxidant; hydroxyl radical; Hypoglycemic Agents - metabolism; metformin; Metformin - metabolism; Oxidation-Reduction; radiolysis; Reactive Oxygen Species; Spectrophotometry, Ultraviolet - methods
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1111/j.1432-1033.2004.04438.x

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 ‐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 ≥ 200 µmol·L−1, under our experimental conditions. An estimated value of 107 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.