Antidiabetic Activity and Toxicity Evaluation of Aqueous Extracts of Spondias mombin and Costus afer on Wistar Rats

Aims: To evaluate the antidiabetic efficacy of the aqueous extracts of Spondias mombin leaf and Costus afer stem, both individually and in combination ratios, as well as the acute and subchronic toxicities of the most effective antidiabetic combination ratio.
Study Design: Antidiabetic study was carried using diabetic animals grouped into seven of five animals each.
Place and Duration of Study: Department of Pharmacology and Toxicology, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria, between May 2013 and June 2014.
Methodology: Alloxan-induced diabetic rats received 100, 200 and 400 mg/kg of the extracts orally; control groups received glibenclamide (5 mg/kg, oral) and normal saline. Blood glucose was measured 2-hourly for 6 hours and weekly for 28 days. The LD50 of both plants was estimated using the modified Lorke’s method.
Results: The toxicity of the 1:1 mixture on body weight, haematological indices (RBC, WBC, PCV, and haemoglobin), and liver enzymes (AST, ALT, and ALP) were assessed for 60 days. The aqueous extracts of Spondias mombin and Costus afer showed significant (p>0.05) hypoglycaemic effect, with the 1:1 ratio having the best antidiabetic effects among the ratios when co-administered. There were non-significant (p>0.05) variations in weight change, RBC, WBC, PCV, and hemoglobin concentration, as well as in AST, ALT, and ALP levels of the test groups.
Conclusion: This study justifies the antidiabetic activity of the aqueous extracts of Spondias mombin and Costus afer, both individually and as mixtures of various ratios, especially when combined in equal proportions (1:1).