Ursolic acid is a PPAR-α agonist that regulates hepatic lipid metabolism

In this study, we confirmed that ursolic acid, a plant triterpenoid, activates peroxisome proliferator-activated receptor (PPAR)-alpha in vitro. Surface plasmon resonance and time-resolved fluorescence resonance energy transfer analyses do not show direct binding of ursolic acid to the ligand-binding domain of PPAR-alpha; however, ursolic acid enhances the binding of PPAR-alpha to the peroxisome proliferator response element in PPAR-alpha-responsive genes, alters the expression of key genes in lipid metabolism, significantly reducing intracellular triglyceride and cholesterol concentrations in hepatocytes. Thus, ursolic acid is a PPAR-alpha agonist that regulates the expression of lipid metabolism genes, but it is not a direct ligand of PPAR-alpha. (C) 2011 Elsevier Ltd. All rights reserved.