Mazibuko S.E.,University of Zululand |
Joubert E.,Stellenbosch University |
Johnson R.,Diabetes Discovery Platform South African Medical Research Council Tygerberg South Africa |
Louw J.,Diabetes Discovery Platform South African Medical Research Council Tygerberg South Africa |
And 2 more authors.
Molecular Nutrition and Food Research | Year: 2015
Scope: Saturated-free fatty acids, such as palmitate, are associated with insulin resistance. This study aimed to establish if an aspalathin-enriched green rooibos extract (GRE) and, its major flavanoid, aspalathin (ASP) could contribute significantly to the amelioration of experimentally induced insulin resistance in 3T3-L1 adipocytes. Methods and results: 3T3-L1 adipocytes were cultured in DMEM containing 0.75 mM palmitate for 16 h to induce insulin resistance before treatment for 3 h with GRE (10 μg/mL) or ASP (10 μM). GRE and ASP reversed the palmitate-induced insulin resistance. At a protein level GRE and ASP suppressed nuclear factor kappa beta (NF-κB), insulin receptor substrate one (serine 307) (IRS1 (Ser 307)) and AMP-activated protein kinase phosphorylation and increased serine/threonine kinase AKT (AKT) activation, while only GRE increased glucose transporter four (Glut4) protein expression. Peroxisome proliferator-activated receptor alpha and gamma (PPARα and γ), and carnitine palmitoyltransferase one (CPT1) expression were increased by ASP alone. Conclusion: Together these effects offer a plausible explanation for the ameliorative effect of GRE and ASP on insulin-resistance, an underlying cause for obesity and type 2 diabetes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.