Anti-diabetic effects of Korean red pepper via AMPK and PPAR-γ activation in C2C12 myotubes

In the present study, the anti-diabetic properties and mechanisms underlying the actions of Korean red pepper using C2C12 myotube were evaluated. An ethanol (70%) extract of Korean red pepper (Ekrp) markedly increased 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose uptake in a concentration-dependent manner. To examine the mechanism by which Ekrp increased glucose uptake in C2C12 myotube, the phosphorylation levels of AMP-activated protein kinase (AMPK) and Acetyl-CoA carboxylase (ACC), a marker of AMPK activity were investigated using western blot analysis. Ekrp significantly increased AMPK and ACC phosphorylations in a dose dependent manner. Moreover, we also examined whether the transcriptional activity of peroxisome proliferator-activated receptor gamma (PPAR-gamma) was involved in Ekrp-stimulated glucose uptake. Ekrp increased the transactivation of PPAR-gamma in a concentration-dependent manner. The total phenolic compound content of Ekrp was measured (508.97 +/- 24.93 mg/100 g), and several major compounds contents such as capsaicin and dihydrocapsaicin were also measured. Finally, we investigated the anti-obesity properties of Ekrp by using 3T3-L1 adipocyte differentiation systems. Ekrp did not inhibit adipocyte differentiation. These results suggest that Korean red pepper exhibits anti-diabetic effects via activation of PPAR-gamma and AMPK, and that Korean red pepper may be useful for preventing diabetes. (C) 2012 Elsevier Ltd. All rights reserved.