A 70% Ethanol Extract of Mistletoe Rich in Betulin, Betulinic Acid, and Oleanolic Acid Potentiated β-Cell Function and Mass and Enhanced Hepatic Insulin Sensitivity

Figure 6

PPAR-γ activity of betulin, betulinic acid, and oleanolic acid as determined by luciferase ligands. The cells were transiently transfected with four vectors such as a PPRE-luciferase construct, pSV-SPORT-PPAR-γ expression vector, pSV-SPORT-retinoid X receptor- (RXR-) α vector, and renilla phRL-TK vector with a Lipofectamine PLUS reagent. After 2 h of transfection, the cells were treated with serum-free DMEM containing 0.1% BSA for 40 h and were exposed to betulin, betulinic acid, and oleanolic acid (5 and 50 μM) for 12 hours. At the end of the incubation, the cells were solubilized in 1x passive lysis buffer and assayed for both firefly (PPRE-luciferase) and renilla luciferase activities using the Dual-Luciferase Reporter Assay System. Ratios of firefly luciferase activity and renilla luciferase activity were used for the results. The bars and error bars represent mean ± SD (). Values on the bars with different superscripts were significantly different in a Tukey post hoc test at a significance of .