Methanolic extract of Momordica cymbalaria enhances glucose uptake in L6 myotubes in vitro by up-regulating PPAR-γ and GLUT-4

The present study was undertaken to evaluate the influence of the methanolic fruit extract of Momordica cymbalaria （MFMC） on PPARγ, （Peroxisome Proliferator Activated Receptor gamma） and GLUT-4 （Glucose transporter-4） with respect to glucose transport. Various concentrations of MFMC ranging from 62.5 to 500 μg·mL^-1 were evaluated for glucose uptake activity in vitro using L6 myotubes, rosiglitazone was used as a reference standard. The MFMC showed significant and dose-dependent increase in glucose uptake at the tested concentrations, further, the glucose uptake activity of MFMC （500 μg·mL^-1） was comparable with rosigilitazone. Furthermore, MFMC has shown up-regulation of GLUT-4 and PPARy gene expressions in L6 myotubes. In addition, the MFMC when incubated along with cycloheximide （CHX）, which is a protein synthesis inhibitor, has shown complete blockade of glucose uptake. This indicates that new protein synthesis is required for increased GLUT-4 translocation. In conclusion, these findings suggest that MFMC is enhancing the glucose uptake significantly and dose dependently through the enhanced expression of PPARμ and GLUT-4 in vitro.