Hypoglycemic and antihyperglycemic activities of the aqueous ethanolic extracts of Gymnema sylvestre (RETZ) R. Br. Ex SCHULT and Sclerocarya birrea (A RICH) HOCHST

Gymnema sylvestre (Retz.) R. Br. ex Schult (Asclepiadaceae) and Sclerocarya birrea (A. Rich) Hochst (Anacardiaceae) are two plants used in Burkina Faso in traditional medicine and in the form of phytomedicine in the treatment of diabetes. This study evaluated the effect of aqueous ethanolic extracts of leaves of Gymnema sylvestre and Sclerocarya birrea on glycemia. A phytochemical screening of the extracts obtained by successive exhaustion after maceration of the leaves was carried out. The effect of these extracts was tested on basal plasma glucose and oral tolerance glucose in mice. Saponosides, tannins, flavonoids, sterol and triterpene glycosides, reducing compounds and coumarinic derivatives were found in the leaves of both plants. Alkaloids were also detected in the leaves of G. sylvestre and anthocyanosides in the leaves of S. birrea. The aqueous ethanolic extracts from leaves of G. sylvestre, S. birrea or both in combination at 100 mg/kg body per weight did not have a significant hypoglycemic effect on basal plasma glucose but significantly reduced (p<0.05; p<0.001) peak of hyperglycemia. The effect of the combination of the aqueous ethanolic extracts of the two plants on hyperglycemia is greater (47% reduction) than the effect of the aqueous ethanolic extracts of G. sylvestre (21% reduction) or S. birrea (36% reduction) alone. These results show that the combined use of G. sylvestre and S. birrea aqueous ethanolic extracts would be an asset in the treatment of diabetes. Key words: Gymnema sylvestre, Sclerocarya birrea, oral glucose tolerance test, hypoglycemia, Antihyperglycemia.