title: Citral, a component of lemongrass oil, activates PPARα and γ and suppresses COX-2 expression.
abstract: Lemongrass is a widely used herb as a food flavoring, as a perfume, and for its analgesic and anti-inflammatory purposes; however, the molecular mechanisms of these effects have not been elucidated. Previously, we identified carvacrol from the essential oil of thyme as a suppressor of cyclooxygenase (COX)-2, a key enzyme for prostaglandin synthesis, and also an activator of peroxisome proliferator-activated receptor (PPAR), a molecular target for "lifestyle-related" diseases. In this study, we evaluated the essential oil of lemongrass using our established assays for COX-2 and PPARs. We found that COX-2 promoter activity was suppressed by lemongrass oil in cell-based transfection assays, and we identified citral as a major component in the suppression of COX-2 expression and as an activator of PPARα and γ. PPARγ-dependent suppression of COX-2 promoter activity was observed in response to citral treatment. In human macrophage-like U937 cells, citral suppressed both LPS-induced COX-2 mRNA and protein expression, dose-dependently. Moreover, citral induced the mRNA expression of the PPARα-responsive carnitine palmitoyltransferase 1 gene and the PPARγ-responsive fatty acid binding protein 4 gene, suggesting that citral activates PPARα and γ, and regulates COX-2 expression. These results are important for understanding the anti-inflammatory and anti-lifestyle-related disease properties of lemongrass.
authors.affiliation: Department of Food Science and Nutrition, Nara Women's University, Kitauoyanishi-machi, Nara-City, Nara, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Katsukawa
authors.forename: Rieko
authors.initials: R
authors.lastname: Nakata
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Takizawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hori
authors.forename: Saori
authors.initials: S
authors.lastname: Takahashi
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D002417:Cattle; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D006801:Humans; D008024:Ligands; D008956:Models, Chemical; D039821:Monoterpenes / Q000494:pharmacology*; D047493:PPAR alpha / Q000378:metabolism*; D047495:PPAR gamma / Q000378:metabolism*; D010938:Plant Oils / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D013729:Terpenes / Q000737:chemistry*; D020298:U937 Cells
chemical_list: D000080462:Acyclic Monoterpenes; D016861:Cyclooxygenase Inhibitors; D008024:Ligands; D039821:Monoterpenes; D047493:PPAR alpha; D047495:PPAR gamma; D010938:Plant Oils; D012333:RNA, Messenger; D013729:Terpenes; C052901:lemongrass oil; D051546:Cyclooxygenase 2; C007076:citral