title: In vitro anti-diabetic activity of Sclerocarya birrea and Ziziphus mucronata.
abstract: Type 2 diabetes mellitus is on the increase worldwide. Current treatments possess undesirable side-effects and therefore investigations into alternative remedies, which may be cost-effective and devoid of such side-effects, are on-going. Aqueous and methanol extracts of the bark of Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro (Anacardiaceae) and Ziziphus mucronata Willd. subsp. mucronata (Rhamnaceae) were subjected to testing in order to assess their in vitro anti-diabetic activity. Total polyphenolic content and antioxidant activity, as well as the effect on alpha-amylase, alpha-glucosidase and cytotoxicity, were measured. Furthermore, glucose uptake was evaluated in C2C12 myotubes, 3T3-L1 adipocytes and HepG2 hepatocarcinoma cells, and insulin secretion in RIN-m5F rat pancreatic beta-cells. The extracts of both plants inhibited the activities of alpha-amylase and alpha-glucosidase in a concentration dependent manner, with results being comparable with the positive control, acarbose. All the extracts contained antioxidant activity, with the methanol extracts of S. birrea displaying the strongest free radical scavenging capacity (IC50 = 2.16 microg/mL). Most of the extracts were not cytotoxic to the cell lines with IC50 values > 100 microg/mL. Extracts of both plants significantly increased glucose uptake in C2C12, 3T3-L1 and HepG2 cells. However, insulin secretion from RIN-m5F cells was not altered. This study provides evidence that the plants possess in vitro anti-diabetic properties.
authors.affiliation: Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, South Africa.
authors.forename: Nuno M H Da Costa
authors.initials: NM
authors.lastname: Mousinho
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: van Tonder
authors.forename: Vanessa
authors.initials: V
authors.lastname: Steenkamp
mesh_terms: D041721:3T3-L1 Cells; D000681:Amylases / Q000037:antagonists & inhibitors; D027926:Anacardiaceae / Q000737:chemistry*; D000818:Animals; D065089:Glycoside Hydrolase Inhibitors; D056945:Hep G2 Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000032:analysis* / Q000494:pharmacology; D051379:Mice; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D031957:Ziziphus / Q000737:chemistry*
chemical_list: D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D000681:Amylases