Carvacrol, a component of thyme oil, activates PPAR alpha and gamma and suppresses COX-2 expression

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme in prostaglandin biosynthesis, plays a key role in inflammation and circulatory homeostasis. Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors belonging to the nuclear receptor superfamily and are involved in the control of COX-2 expression, and vice versa. Here, we show that COX-2 promoter activity was suppressed by essential oils derived from thyme, clove, rose, eucalyptus, fennel, and bergamot in cell-based transfection assays using bovine arterial endothelial cells. Moreover, from thyme oil, we identified carvacrol as a major component of the suppressor of COX-2 expression and an activator of PPAR alpha and gamma. PPAR gamma-dependent suppression of COX-2 promoter activity was observed in response to carvacrol treatment. In human macrophage-like U937 cells, carvacrol suppressed lipopolysaccharide-induced COX-2 mRNA and protein expression, suggesting that carvacrol regulates COX-2 expression through its agonistic effect on PPAR alpha. These results may be important in understanding the antiinflammatory and antilifestyle-related disease properties of carvacrol.-Hotta, M., R. Nakata, M. Katsukawa, K. Hori, S. Takahashi, and H. Inoue. Carvacrol, a component of thyme oil, activates PPAR alpha and gamma and suppresses COX-2 expression. J. Lipid Res. 2010. 51: 132-139.