Anti-inflammatory effects and action mechanisms of Lindera erythrocarpa essential oil in LPS-stimulated RAW 264.7 cells

Abstract

In this study, the chemical constituents of Lindera erythrocarpa Makino essential oil (LEO) were investigated useding GC–MS. The main constituents of LEO were Nerolidol (18.73%),Caryophyllene (14.41%), α-Caryophyllene(7.73%), Germacrene-D (4.82%) and α- pinene (4.47%). We also investigated the effects of LEO on the production of nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor (TNF)-α, and IL-6, in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Western blotting tests indicated that LEO has suppression effects on pro-inflammatory cytokines and mediators, dose-dependent manner. We investigated the action mechanism by which LEO suppressed NO and PGE2 by examining the level of nuclear factor-κB (NF-κB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation suppressed signal pathway in RAW 264.7 cells. LEO suppressed LPS-induced ERK, JNK, and p38 phosphorylation. Furthermore, LEO inhibited the LPS-induced phosphorylation and degradation of Iκ-B-α, which is required for the nuclear translocations of the p50 and p65 NF-κB subunits in RAW 264.7 cells. Our results suggest that LEO might demonstrate an anti-inflammatory effect by suppressing the expression of pro-inflammatory cytokines. Such an effect is mediated by a blocking of NF-κB activation which accordigly suppress inflammatory mediators in RAW 264.7 cells. In conclusion, LEO is suggested as a potential candidate treating inflammatory diseases.