Investigation of Active Anti-Inflammatory Constituents of Essential Oil from Pinus koraiensis (Sieb. et Zucc.) Wood in LPS-Stimulated RBL-2H3 Cells

In a previous study, we demonstrated the anti-inflammatory activity of the essential oil extracted from Korean pine (Pinus koraiensis, Sieb. et Zucc.) wood. This study aims to investigate the active anti-inflammatory constituents of P. koraiensis oil. The essential oil was extracted from P. koraiensis wood by hydrodistillation and was divided into six fractions (A–F) through fractional distillation. Then, the anti-inflammatory activities of the fractions (A–F) were determined. Fractions A and F markedly downregulated the production of pro-inflammatory cytokines as well as the secretion of β-hexosaminidase in lipopolysaccharide (LPS)-stimulated RBL-2H3 cells. The main constituents of the active anti-inflammatory A and F fractions were (+)-α-pinene, (−)-β-pinene, (+)-α-terpineol, 3-carene, (+)-limonene, and longifolene. These six single compounds decreased the expression of inflammatory-related genes (i.e., IL-4 and IL-13) as well as the secretion of β-hexosaminidase in LPS-stimulated RBL-2H3 cells. (+)-α-Pinene, (−)-β-pinene, (+)-α-terpineol, and longifolene exhibited the strongest effects
these effects were comparable to those of the positive control (i.e., dexamethasone). The findings indicate that the interactions between these components exhibit potential for the management and/or treatment of inflammatory conditions as well as base structures for the development of novel anti-inflammatory drugs.