Effect of Treatment with ‘ Nishamalaki ’ Powder on Glycemic Control and Markers of Erythrocyte Oxidative Stress in Diabetic Rats Compared to Troglitazone

The 1:1 (w/w) mixture of powdered rhizome of Curcuma longa (turmeric) and the dried fruits of Emblica officinalis (Indian gooseberry) known as ‘nishamalaki’, described in traditional Indian medicine as a therapeutic agent in diabetes mellitus was studied for its effect on glycemic control and erythrocyte parameters of oxidative stress in rats with streptozotocin-induced diabetes mellitus in comparison with troglitazone, a thiazolidinedione compound known to possess antioxidant properties and the sulfonylurea drug, glyburide. Streptozotocin-induced diabetic rats were divided into the following treatment groups; nishamalaki powder treated (0.9 g/kg, NT group, n=12), troglitazone treated (36 mg/kg, TT group, n=12) and glyburide treated (4 mg/kg, GT group, n=12). The animals received the respective treatments for 30 days, at the end of which plasma glucose, glycated hemoglobin and erythrocyte parameters of oxidative stress were measured in all animals and the results compared with those of the untreated diabetic control (DC, n=12) and normal control (NC, n=12) rats. Nishamalaki treatment resulted in significant lowering of plasma glucose and glycated hemoglobin in diabetic rats (p<0.001 NT vs DC) comparable to that of the GT and TT groups. Erythrocyte membrane lipid peroxidation was lowered to a comparable extent by the three drugs (p<0.001 vs DC). NT rats showed greater improvement in erythrocyte reduced glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity (both p<0.001 vs DC) than GT rats (p>0.05 vs DC for GSH and p<0.05 vs DC for GSH-Px) and this was comparable to the results of TT rats. Erythrocyte superoxide dismutase (SOD) activity was restored to a similar extent by the three drugs (p<0.01 vs DC). Glycemic control exerted by nishamalaki powder in diabetic rats is comparable to that of glyburide and troglitazone. Antioxidant protection offered by this preparation compares favourably with troglitazone and is greater than glyburide suggesting a role for this preparation in the management of diabetes mellitus.