Hypoglycemic evaluation of a new triterpene and other compounds isolated from Euclea undulata Thunb. var. myrtina (Ebenaceae) root bark

Aim of the study: Investigate the hypoglycaemic activity of the four isolated compounds from a crude acetone extract of the root bark of Euclea undulata var. myrtina, which is used by traditional healers in the Venda area, Limpopo Province in the treatment of diabetes. Material and methods: The hypoglycaemic activity of the four compounds isolated from Euclea undulata was determined by in vitro screening of glucose utilization by C2C12 myocytes at a concentration of 25 mu g/ml or 50 mu g/ml. The inhibition of alpha-glucosidase was also tested at concentrations ranging from 0.02 to 200.00 mu g/ml. Results: Assay-guided isolation of the crude acetone extract of the root bark of Euclea undulata var. myrtina afforded a new triterpene, alpha-amyrin-3O-beta-(5-hydroxy) ferulic acid (1), in addition to three known compounds; betulin (2), lupeol (3) and epicatechin (4). The in vitro results on C2C12 myocytes suggest that compound 4 may have some effect to lowers blood glucose levels, whereas compound 1 has the ability to inhibit alpha-glucosidase at a concentration of 200.0 mu g/ml with an IC50 value of 4.79 that correlates with that of the positive control acarbose IC50 value 4.75. Conclusion: The results suggest that 4 may have some ability to lower blood glucose levels, whereas 1 has the ability to inhibit alpha-glucosidase. Ethnopharmacological relevance: These findings corroborate the ethnomedicinal use of Euclea undulata by traditional healers for the treatment of diabetes as two substances was isolated from the acetone plant extract that exhibit hypoglycaemic activity. (C) 2010 Elsevier Ireland Ltd. All rights reserved.