Neolitsea Sericea Essential Oil Attenuates LPS-induced Inflammation in RAW 264.7 Macrophages by Suppressing NF-κB and MAPK Activation
The chemical composition and antiinflammatory activities of hydrodistilled essential oil from Neolitsea sericea leaves (NSE) have been investigated for the first time. The chemical constituents of NSE were analysed by GC-MS and found to include sericenine (32.3%), sabinene (21.0%), trans-β-ocimene (13.3%), β-caryophyllene (4.8%), and 4-terpineol (4.2%). The effects of NSE on nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages were also examined. Pro-inflammatory cytokine and mediator tests indicated that NSE has excellent dose-dependent inhibitory activities. To further examine the mechanism responsible for the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression by NSE, we examined the effect of NSE on nuclear factor-κB (NF-κB) activation and the phosphorylation of mitogen-activated protein kinases (MAPK). NSE inhibited NF-κB activation by LPS, and this was associated with the abrogation of IκB-α phosphorylation and subsequent decreases in nuclear p50 and p65 protein levels. Further, the phosphorylation of p38, ERK and JNK was suppressed by NSE in a concentration-dependent manner. These results suggest that NSE exerts antiinflammatory effects in LPS-stimulated RAW 264.7 macrophages by inhibition of NF-κB activation and MAPK phosphorylation, and, therefore, may be useful for treatment of inflammatory diseases.