Activity of the isolated polyacetylenes towards the three subtypes of human PPAR (α, β/δ, γ) in a luciferase reporter transactivation assay.

n.d. not detected up to 30 µM.HEK-293 cells transiently co-transfected with the respective PPAR subtype expression plasmids, a luciferase reporter plasmid (tk-PPREx3-luc), and EGFP as internal control were treated with six different concentrations of the polyacetylenes (0.1–30 µM) for 18 h. The luciferase activity was expressed as fold induction above the vehicle control (DMSO, 0.1%) after normalization to the EGFP-derived fluorescence. To verify the specificity of the performed assays, GW7647, GW0742, and pioglitazone were used as a selective agonist for PPARα, PPARβ/δ, and PPARγ, respectively. EC50 and maximal fold activation were determined with a non-linear regression in the GraphPad Prism software version 4.03 (GraphPad Software Inc, USA). The data shown are means of three independent experiments performed in triplicate.