Anti-inflammatory effect of essential oil extracted from Pinus densiflora (Sieb. et Zucc.) wood on RBL-2H3 cells

The aim of this study is to identify the active compounds of the essential oil extracted from the Pinus densiflora (Sieb. et Zucc.) wood using the hydrodistillation method and evaluate their anti-inflammatory activity. The chemical composition of the oil was identified by GC–MS analysis, and its anti-inflammatory activity was assessed by investigating its effect on the expression of interleukin-4 (IL-4), interleukin-13 (IL-13), and β-hexosaminidase in lipopolysaccharide (LPS)-stimulated RBL-2H3 cells. Treatment of the LPS-stimulated RBL-2H3 cells with the oil and its fractions downregulated the production of pro-inflammatory cytokines such as IL-4 and IL-13 and further attenuated the secretion of β-hexosaminidase out of the cells to a significant level. Among the five obtained fractions, fraction E exhibited the best anti-inflammatory activity, and its main constituent, longifolene, was considered as the active compound. Moreover, the inhibitory effect of longifolene on the expression levels of IL-4 and IL-13 and the β-hexosaminidase secretion was similar to that of the P. densiflora wood oil, indicating longifolene as the active constituent of the P. densiflora wood oil with immunosuppressive effects on inflammation.