Hypoglycemic Effects of Ethanolic Extract of Curcuma longa Rhizome in Alloxan-Induced Diabetic Wistar Rats

Abstract

The present study evaluated the antidiabetic activity of the ethanolic extract of Curcuma longa rhizome in alloxan-induced diabetic Wistar rats, using both acute (4 h) and sub-acute (14 days) experimental models. Five groups of rats (n = 5 per group) were treated as follows: normal control, diabetic control, glibenclamide (3 mg/kg), extract (400 mg/kg), and extract (800 mg/kg). In the acute study, the diabetic control group showed a progressive rise in blood glucose from 457.5 ± 23.7 mg/dl post-induction to 518.8 ± 34.4 mg/dl at 4 h, confirming persistent hyperglycemia. Glibenclamide significantly reduced glucose levels from 367.3 ± 20.4 mg/dl to 174.8 ± 6.6 mg/dl, corresponding to a 52.4% fall (p < 0.001). The extract produced a dose-dependent reduction, with the 400 mg/kg group showing a 25.1% fall (478.0 ± 53.6 → 357.8 ± 36.9 mg/dl) and the 800 mg/kg group a 29.2% fall (366.8 ± 22.1 to 259.8 ± 10.7 mg/dl) within 4 h. In the sub-acute study, after 14 days, the diabetic control group continued to worsen, reaching 558.3 ± 19.8 mg/dl. In contrast, glibenclamide-treated rats recorded a 66.6% reduction (367.3 ± 20.4 to 122.5 ± 3.4 mg/dl, p < 0.001). The extract at 400 mg/kg and 800 mg/kg produced sustained glucose-lowering effects of 60.0% (478.0 ± 53.6 → 191.3 ± 6.6 mg/dl) and 60.5% (366.8 ± 22.1 to 144.8 ± 5.8 mg/dl), respectively, both highly significant compared to the diabetic control (p < 0.001). Two-way ANOVA revealed significant main effects of treatment (F(4,75) = 241.56, p < 0.000001), time (F(4,75) = 28.04, p < 0.000001), and treatment × time interaction (F(16,75) = 10.53, p < 0.000001), confirming time- and dose-dependent responses. The extract demonstrated both rapid and sustained antihyperglycemic activity, comparable to glibenclamide in sub-acute treatment. Its effects are likely mediated by preservation of pancreatic β-cell function, enhancement of insulin sensitivity, and attenuation of oxidative stress. These findings support the potential of Curcuma longa as a natural adjunct in diabetes management and justify further mechanistic and clinical investigations.