Essential Oil from the Heartwood of Taiwan fir Ameliorates LPS-induced Inflammatory Response by Inhibiting the Activation of Mitogen-activated Protein Kinase

Abstract

The essential oil from the heartwood of Taiwan fir (EOTC) was demonstrated to exhibit anti-inflammatory activity in lipopolysaccharide (LPS)-activated mouse macrophages. EOTC reduced nitrite oxide levels and inducible nitrite oxide synthase expression in, and tumor necrosis factor-α and interleukin-6 secretion by, LPS-activated macrophages without affecting cyclooxygenase-2 expression. EOTC reduced the levels of interleukin-1β precursor induced by LPS and decreased the NLRP3 inflammasome-derived interleukin-1β secretion induced by LPS and adenosine triphosphate. In addition, the phosphorylation levels of ERK1/2, JNK1/2, and p38 in LPS-activated macrophages were reduced by EOTC. Furthermore, EOTC was composed of oxygenated sesquiterpenes (68.4%), sesquiterpene hydrocarbons (28.9%) and diterpenes (0.9%). The major compounds of the oxygenated sesquiterpenes were τ-cadinol (23.9%), α-cadinol (21.1%) and cedrol (16.9%). These findings suggest that EOTC may be a candidate for the development of anti-inflammatory agents for preventing and ameliorating inflammation-related diseases.