HYPOGLYCEMIC AND ANTIHYPERGLYCEMIC EFFECT OF LEAVES EXTRACTS OF PSIDIUM GUAJAVA IN NORMOGLYCEMIC AND STREPTOZOTOCIN-INDUCED DIABETIC MICE

Introduction: Diabetes mellitus is a metabolic disorder of multiple etiologies characterized by chronic hyperglycemia. As morbidity and mortality rate from diabetes is increasing on the one hand and the cost of modern medicine is getting higher on the other in low – and middle – income countries, it is necessary to evaluate medicinal plants for their potential therapeutic effects against diabetes. The present study was, therefore, undertaken to evaluate the hypoglycemic and anti-hyperglycemic activity of the leaf extracts of Psidium guajava in normoglycemic and streptozotocin-induced diabetic mice, respectively. Materials and Methods: The aqueous and ethanol extracts of Psidium guajava leaves were prepared following standard procedures. Swiss albino mice of either sex weighing 20-30 grams were used for the experiments. Normal mice were grouped into eight groups to carry out the hypoglycemic effect of the extracts, whereas mice that were made diabetic were grouped into nine groups to study the antihyperglycemic effect of the extracts. Diabetes was induced by streptozotocin (STZ). Blood glucose levels were measured using the glucose oxidase method. Results: A significant decrease in blood glucose levels (P < 0.05) was observed after administering for 21 days treatment of the aqueous and ethanolic extracts of Psidium guajava leaf to streptozotocin-induced diabetic mice. The aqueous and ethanol extracts of Psidium guajava leaves, however, did not show a hypoglycemic effect on normoglycemic mice. Guava leaf extracts were found to contain alkaloids, phenols, flavonoids, tannins, and saponins which might be responsible for the observed antihyperglycemic effect. It was also observed that the extracts had shown no acute toxicity. Conclusion: The aqueous and ethanol extracts of Psidium guajava leaves are effective in lowering blood glucose level in diabetic mice without causing hypoglycemia. Further studies are warranted to elucidate the possible mechanism(s) of action of the plant material.