[The association between copper ions and peroxidative reaction in diabetic cataract]

The concentration of copper ions in cataractous lenses was higher than that in clear lenses. The concentration was significantly higher in the diabetic (DM) group than in the non-diabetic (control) group. Compared to Cu4, the concentration of Cu24 was significantly greater in the DM group. The concentration of protein-unconjugated copper ions was higher than that of protein-conjugated copper ions. I assume that in cataractous lenses of the DM group, decrease of the reactivity of copper-containing enzyme, Cu, Zn-SOD (Cu, Zn-superoxide dismutase), and increase of hydrogen peroxide lead to generation of hydroxyl radicals from a Fenton-like reaction. In diabetes, the increase of lenticular glucose induced glycation and the release of copper ions from copper-containing enzyme, followed by the increase of lenticular copper ions. As a result, superoxide scavenging activity was reduced and peroxide lipid was increased. I assume this to be due to hyperactivity of the cascade of peroxidation.