Anti-inflammatory effects of natural volatile organic compounds from Pinus koraiensis and Larix kaempferi in mouse model

Natural volatile organic compounds (VOCs) extracted from conifers such as P. koraiensis and L. kaempferi have long been studied for their anti-oxidant, anti-proliferative, and anti-inflammatory effects. To evaluate the anti-inflammatory effects of VOCs from P. koraiensis and L. kaempferi, lipopolysaccharide (LPS) was administered to generate a mouse model for inflammation by the nasal route to the lungs and intraperitoneally to the whole body. VOCs of P. koraiensis and L. kaempferi were exposed to the mice by standardized wood panels with closed system. Increased levels of serum IgE and PGE2 were observed after exposure to dexamethasone and VOCs. We further determined the expression levels of inflammatory cytokine mRNA in the LPS-induced inflammation model by the reverse transcription quantitative polymerase chain reaction. Furthermore, the levels of cyclooxygenase-2, tumor necrosis factor-α, interleukin-1β, and interleukin-13 were determined in peripheral blood mononuclear cells. Those inflammatory cytokines and the key enzyme for inflammation cyclooxygenase-2 expression in PBMCs were strongly reversed by dexamethasone and VOCs. Lung tissues after nasal LPS exposure showed increased cytokine mRNA expressions which were suppressed by treatment with dexamethasone and VOCs. Furthermore, the damage induced by LPS was attenuated by dexamethasone and VOCs. In conclusion, the results from the present study indicate that VOCs of P. koraiensis and L. kaempferi have a therapeutic potential in the treatment or prevention of local and systemic inflammation due to their immunosuppressive effects.