Aldehyde inhibition of antioxidant enzymes in the blood of diabetic patients

Abstract

BACKGROUND: The aim of the present study was to examine the effect of aldehyde modification on antioxidant enzyme activity in diabetic patients. METHODS: The activity of commercially available antioxidant enzymes (catalase, glutathione peroxidase [GPx], and Cu,Zn-superoxide dismutase [SOD]) was determined in vitro prior to and after aldehyde modification. The activity of erythrocyte Cu,Zn-SOD was assayed in blood drawn from healthy donors, diabetic patients with decompensated carbohydrate metabolism, and diabetic patients after glucose-lowering therapy. RESULTS: In vitro aldehyde modification had no effect on catalase activity, but diminished GPx and Cu,Zn-SOD activity. In diabetic patients with decompensated carbohydrate metabolism, glucose-lowering therapy significantly increased Cu,Zn-SOD activity, the effect being especially pronounced after administration of metformin. CONCLUSIONS: It is likely that metformin antagonizes the aldehyde-induced inhibition of erythrocyte Cu,Zn-SOD in diabetic patients more effectively than sulfonylurea drugs.