Action of pelargonidin on hyperglycemia and oxidative damage in diabetic rats: implication for glycation-induced hemoglobin modification.

Glycation-modified hemoglobin in diabetes mellitus has been suggested to be a source of enhanced catalytic iron and free radicals causing pathological complications. The present study aims to verify this idea in experimental diabetes. Pelargonidin, an anthocyanidin, has been tested for its antidiabetic potential with emphasis on its role against pathological oxidative stress including hemoglobin-mediated free radical reactions. Male wistar rats were grouped as normal control, streptozotocin-induced diabetic control, normal treated with pelargonidin and diabetic treated with pelargonidin. Pelargonidin-treated rats received one time i.p injection of the flavonoid (3 mg/kg bodyweight). Biochemical parameters were assayed in blood samples of different groups of rats. Liver was used for histological examinations. Pelargonidin treatment normalized elevated blood glucose levels and improved serum insulin levels in diabetic rats. Glucose tolerance test appeared normal after treatment. Decreased serum levels of SOD and catalase, and increased levels of malondialdehyde and fructosamine in diabetic rats were reverted to their respective normal values after pelargonidin administration. Extents of hemoglobin glycation, hemoglobin-mediated iron release, iron-mediated free radical reactions and carbonyl formation in hemoglobin were pronounced in diabetic rats, indicating association between hemoglobin glycation and oxidative stress in diabetes. Pelargonidin counteracts hemoglobin glycation, iron release from the heme protein and iron-mediated oxidative damages, confirming glycated hemoglobin-associated oxidative stress in diabetes.