Neolitsea sericea essential oil attenuates LPS-induced inflammation in RAW 264.7 macrophages by suppressing NF-kappaB and MAPK activation

The chemical composition and anti-inflammatory 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-beta-ocimene (13.3%), beta-caryophyllene (4.8%), and 4-terpineol (4.2%). The effects of NSE on nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, 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-kappaB (NF-kappaB) activation and the phosphorylation of mitogen-activated protein kinases (MAPK). NSE inhibited NF-kappaB activation by LPS, and this was associated with the abrogation of IkappaB-alpha 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 anti-inflammatory effects in LPS-stimulated RAW 264.7 macrophages by inhibition of NF-kappaB activation and MAPK phosphorylation, and, therefore, may be useful for treatment of inflammatory diseases.