Abstract

We investigated the effect of freshly prepared aqueous extracts of Psidium guajava,Momordica charantia, Coccinia indica leaves and their combination on blood glucose level and neuropathic pain in hyperglycemic rats. Streptozotocin (STZ; 65 mg/kg, Iv) was injected to albino rats to induce diabetes. Oral administration of freshly prepared aqueous extracts of each of the leaves and their combination were given to STZ-induced diabetic rats until 8 weeks after the STZ injection at a dosage of 500 mg/kg bwt/day. Oral glucose tolerance test to follow the changes in blood glucose and von Frey test to evaluate the tactile allodynia were performed to investigate the antidiabetic effects. Treatment with these freshly prepared leaf aqueous extracts significantly reduced blood glucose in diabetic rats (p < 0.001). Blood glucose lowering effect of the combination treatment was significantly greater than individual treatments (p < 0.01). Oral glucose tolerance test also showed the improvement of glucose tolerance by each extracts (p < 0.001). These effects were significantly greater in the combination treatment group over the individual treatment groups (p < 0.01). STZ-induced loss of body weight was attenuated by the individual and their combination treatment (p < 0.02). Diabetic rats developed stable tactile allodynia measured by von Frey test. Treatment with these freshly prepared leaf aqueous extracts significantly improved tactile allodynia in diabetic rats (p < 0.01). Effect of the combination treatment on tactile allodynia was also significantly greater than individual treatments (p < 0.05). These data suggest beneficial effect of freshly prepared aqueous extracts of P. guajava, M. charantia and C. indica leaves on hyperglycemic and neuropathic pain. Their combination therapy works better againsthyperglycemia and neuropathy of STZ-induced diabetes rats. Therefore, the use of these plants as antidiabetics in folkloric medicine is justified.

Key words: Psidium guajava, Momordica charantia, Coccinia indica, hyperglycemia, neuropathic pain, STZ-induced diabetic rats.