Hypoglycaemic and Antioxidant Activities of the Stem Bark of Morinda Lucida Benth in Streptozotocin – Induced Diabetic Rats

Abstract

Introduction: This work was conducted in order to investigate the hypoglycaemic and antioxidant activity of the stem bark of Morinda lucida Benth (Rubiaceae), which has traditionally been used in Ghana for the management of diabetes mellitus. Methods: The powdered stem bark was successively Soxhlet-extracted with petroleum ether and 70% v / v ethanol, respectively, and were then evaporated to dryness to produce crude petroleum ether (PML) and ethanolic (EML) extracts. The hypoglycaemic activity of PML and EML were determined in streptozotocin-induced diabetic rats. Five groups of six diabetic rats received oral administrations of 100, 200 and 400 mg per kg body weight of PML and EML once daily for 19 days. Glibenclamide (5 mg per kg body weight) was used as positive control while distilled deionised water (2 ml) acted as the diabetic control. Blood glucose levels were monitored initially for 6 hours and subsequently over the full 20 days. Results: All extracts exhibited statistically significant (P < 0.001) hypoglycaemic and substantial antioxidant activities throughout the study period. While EML demonstrated the strongest hypoglycaemic activity 6 hours after administration, PML exhibited the highest activity 24 hours after administration and throughout the rest of the study period. Again, both extracts showed antioxidant activities, however EML was more effective. Conclusion: The results of our investigation indicate that the stem bark of M. lucida possesses hypoglycaemic constituents that are well distributed in both petroleum ether and 70% v / v ethanol extracts. In addition, both extracts also showed considerable antioxidant activity. These results give credibility towards the traditional use of the stem bark of M. lucida as an antidiabetic agent.