Xiao Qing Long Tang essential oil exhibits inhibitory effects on the release of pro-inflammatory mediators by suppressing NF-κB, AP-1, and IRF3 signalling in the lipopolysaccharide-stimulated RAW264.7 cells

steam distillation and characterized by GC-MS analysis. MTT and Griess assays were used to measure cell viability and NO production, respectively. The mRNA expression and the production of LPS-induced pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, and IL-10) and chemokines (MCP-1, Rantes, and MIP-1α) were determined by real-time PCR and enzyme-linked immunosorbent assay, respectively. Furthermore, we determined the protein levels of the components of NF-κB, AP-1 and IRF3 signalling by Western blotting. Immunofluorescence assay was used to estimate the nuclear translocation of NF-κB, AP-1 and IRF3. The results showed that XQEO inhibited the secretion of NO and PGE2 and down-regulated the mRNA and protein levels of iNOS and COX-2. We also found that XQEO suppressed the LPS-induced overproduction of pro-inflammatory mediators. Moreover, XQEO inhibited the phosphorylation of NF-κB/p65, AP-1/c-Jun, and IRF3 by suppressing their upstream kinases, such as MAPKs, TBK1, Akt, IKKα/β, and IκB, reducing the LPS-induced NF-κB, AP-1 and IRF3 translocation to the nucleus. These findings suggest that XQEO effectively suppresses the production of pro-inflammatory mediators possibly through the inhibition of NF-κB, AP-1, and IRF3 signalling in the LPS-stimulated RAW264.7 cells.