Anti-inflammatory Activity of Essential Oil from Leaves of Blumea balsamifera (L.) DC through Inhibiting TLR4/NF-kB Signaling Pathways and NLRP3 Inflammasome Activation in LPS-induced RAW264.7 Macrophage Cells

Abstract

The essential oil (EO) separated from leaves of Blumea balsamifera (L.) DC is extensively applied as conventional medicine by the Miao, Zhuang, and Li nationalities in China to drive skin healing of trauma or burn. Recently, a lot of evidence has proved that EO possesses anti-inflammatory activity. Nevertheless, the underlying molecular mechanisms are still unknown. This research aims to examine the underlying mechanisms of EO in the wound healing areas of skin through evaluating the anti-inflammatory activity, especially two major concerns, the variations of relative proteins in TLR4-NF-κB signaling pathway and NLRP3 inflammasome in LPS-induced RAW264.7 cells. A total of 39 compounds from EO were determined and interpreted by gas chromatography/mass spectrometry (GC/MS). It was observed that the main compounds of EO are (-)-borneol (25.382 %), trans-caryophyllene (24.439 %), camphor (8.991 %), caryophyllene oxide (5.843 %), xanthoxylin (3.968 %), and alloaromadendrene (3.321 %). The anti-inflammation activity and underlying mechanisms are assessed by ELISA, qRT-PCR, and Western blotting in Lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The outcomes reveal that EO can significantly reduce the LPS-induced pro-inflammatory elements TNF-α, IL-1β, IL-6, and inflammatory mediator COX-2 in RAW264.7 cells (P<0.01). Additionally, EO can significantly inhibit the expression of proteins in the NF-κB signaling pathway, such as CD14, TLR4, MyD88, TAK-1, p-IκBα, and NLRP3 inflammasome (P<0.05, P<0.01). These outcomes show anti-inflammatory roles of EO in LPS-induced RAW264.7 cells by decreasing activity of TLR4-NF-κB signaling pathway and inhibiting NLRP3 inflammasome activation, suggesting that EO can be adopted as a hopeful natural commodity preventing and treating inflammatory diseases.