N-trans-feruloyltyramine inhibits LPS-induced NO and PGE2 production in RAW 264.7 macrophages: Involvement of AP-1 and MAP kinase signalling pathways

• FLA inhibited NO and PGE2 release in a dose-dependent manner.
• Treatment of RAW 264.7 cells with FLA reduced the expression of iNOS and COX-2.
• FLA decreased c-Jun nuclear translocation and AP-1 mediated luciferase activity.
• FLA strongly suppressed JNK phosphorylation.

Mitogen-activated protein kinase (MAPK) signalling pathway can regulate inflammatory and immune responses. N-trans-feruloyltyramine (FLA) is an active phenylpropanoid compound. It possesses antioxidant, antimicrobial, anti-melanogenesis, and anticancer activities. However, the precise molecular mechanisms underlying FLA modulation of cytokine expression in LPS-stimulated RAW 264.7 macrophages have not been fully investigated. In this study, we examined the mechanisms underlying the immunomodulative effects of FLA isolated from Arcangelisia gusanlung. FLA strongly suppressed mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), but not tumor necrosis factor (TNF)-α, thereby inhibiting the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Furthermore, FLA also inhibited nuclear translocation of activation protein (AP)-1, and simultaneously decreased the expression and phosphorylation of the c-Jun N-terminal kinase (JNK) protein. These results suggest that the anti-inflammatory effects of FLA might be attributed to downregulation of COX-2 and iNOS via suppression of AP-1 and the JNK signalling pathway in RAW 264.7 macrophages.