Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that plays a pivotal role in regulating inflammatory gene expression. The purpose of this study was to investigate the effects of coffee extract, 3-methyl-1,2-cyclopentanedione (3-MCP) on PPARs in vitro. Western blotting and luciferase assays using the PPAR response element (PPRE) construct revealed that 3-MCP induced PPARgamma-selective activation in YPEN-1 cells and that treatment with the PPARgamma selective antagonist, GW9662, was associated with a decrease in 3-MCP-induced PPARgamma activity. The 3-MCP also was shown to suppress reactive species generation and pro-inflammatory transcription factor NF-kappaB activity through PPARgamma activation. Theses results indicate that 3-MCP is a novel PPARgamma agonist and suggests that this agent may have a potential to minimize inflammation.