Radical-induced oxidation of metformin

Eur J Biochem. 2004 Dec;271(23-24):4745-52. 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 (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.

MeSH terms

  • Hypoglycemic Agents / metabolism*
  • Metformin / metabolism*
  • Oxidation-Reduction
  • Reactive Oxygen Species*
  • Spectrophotometry, Ultraviolet / methods*


  • Hypoglycemic Agents
  • Reactive Oxygen Species
  • Metformin