Inability of Legumes to Reverse Diabetic-Induced Nephropathy in Rats Despite Improvement in Blood Glucose and Antioxidant Status

Diabetes mellitus has assumed epidemic proportions in most parts of the world, including developing countries, with vascular and renal complications being the major causes of death. Evidence is emerging that legumes play a beneficial role in diabetes and its associated complications. In connection with the above, four groups of alloxan-induced diabetic rats were fed on four different legume-based (Vigna unguiculata ssp. dekindtiana var. dekindtiana, V. unguiculata ssp. unguiculata, Sphenostylis stenocarpa, and Vigna subterranean) diets. Feeding rats with these diets for 5 weeks resulted in reduction of plasma glucose and changes in biomarkers of oxidative stress-namely, superoxide dismutase (SOD), peroxidase (PER), and thiobarbituric acid-reactive substances (TBARS). None of the legumes reversed the increase in plasma total protein associated with diabetes. The legumes increased PER activity and decreased the level of TBARS in the erythrocytes. A decrease in the activities of PER and SOD was observed in the kidneys of the diabetic rats. Nitric oxide (NO) production in the erythrocytes of the diabetic rats (as an index of diabetic endothelial dysfunction) increased for all the legumes in the following order: V. unguiculata ssp. unguiculata, V. unguiculata ssp. dekindtiana var. dekindtiana, V. subterranean, and S. stenocarpa. There was a significant increase (P<.05) in the uric acid concentration in the kidneys of treated rats. It is concluded that while the legumes have beneficial effects on reduction of hyperglycemia and strengthening the antioxidant status of the diabetic animals, the increased kidney uric acid concentration should be of concern.