Effects of various terpenoids on the activation of PPAR ligand and chemical structures of active terpenoids. PPAR activity in monkey CV-1 kidney cells was determined by luciferase reporter assay using advanced highly sensitive GAL4/PPAR chimera system described in [40]. After 24 hours of incubation with or without each terpenoid at 50 or 100 M, luciferase activity was measured. The activity of a vehicle control was set at 100% and the relative luciferase activities are presented as fold induction compared with that of the vehicle control. The values are means S.E.M. of 3-4 replicates. B: Chemical structures of active terpenoids.