The influence of glucose on free radical peroxidation of low density lipoproteins in vitro and in vivo

In the range of concentrations 12.5–100 mM glucose stimulated Cu-mediated free radical peroxidation of low density lipoproteins (LDL) from human blood plasma. Based on analysis of kinetic parameters of the LDL peroxidation it was found that intensification of this process is caused by formation of free radical intermediates of glucose autooxidation during generation of reactive oxygen species in the presence of transition metal ions. Normalization of blood glucose in patients with type 2 diabetes during therapy was accompanied by a significant decrease of LDL oxidation. Therapy with the sugar-lowering drug metformin, which utilizes methylglyoxal, caused much higher inhibition of the in vivo LDL peroxidation in blood of patients with diabetes mellitus probably due to the decrease of methylglyoxal-dependent generation of superoxide anion radicals shown by us earlier [Biochemistry (Moscow) 2009, vol. 74, pp. 568–574].