Hypoglycaemic activity of four plant extracts traditionally used in South Africa for diabetes

Aim: To validate plant species for hypoglycaemic activity. Materials and methods: Four plants were investigated for hypoglycaemic activity by evaluating inhibiting effects on carbohydrate-hydrolising enzymes: alpha-glucosidase and alpha-amylase. Acetone plant extracts were screened against C2C12 myocytes, 3T3-L1 preadipocytes and Chang liver cells by measuring glucose uptake. Cytotoxicity was done in preadipocytes and hepatocytes. Results: Extract of Euclea undulata rootbark exhibited highest activity, displaying a glucose uptake of 162.2% by Chang liver cells at 50 mu g/ml. An inhibition concentration of 50% for Euclea undulata was found to be 49.95 mu g/ml for alpha-glucosidase and 2.8 mu g/ml for alpha-amylase. No cytotoxicity was recorded for Euclea undulata, while Schkuhria pinnata and Elaeodendron transvaalense exhibited cytotoxicity at 12.5 mu g/ml. alpha-Glucosidase and alpha-amylase assays showed inhibitory activity on enzymes for three plant extracts. Conclusion: Euclea undulata, Schkuhria pinnata and Elaeodendron transvaalense showed in vitro hypoglycaemic activity. Schkuhria pinnata and Elaeodendron transvaalense indicated cytotoxicity on 3T3-L1 preadipocytes and Chang liver cells. Euclea undulata, Pteronia divaricata and Elaeodendron transvaalense inhibited alpha-glucosidase and alpha-amylase enzymes. Ethnopharmacological relevance: Screening of plant extracts scientifically validated traditional use of Euclea undulata for treatment of diabetes. Cytotoxicity results revealed that acetone extracts of Schkuhria pinnata and Elaeodendrom transvaalense are toxic and raise concern for chronic use. (C) 2009 Elsevier Ireland Ltd. All rights reserved.