Essential oil from Korean Chamaecyparis obtusa leaf ameliorates respiratory activity in Sprague‑Dawley rats and exhibits protection from NF-κB-induced inflammation in WI38 fibroblast cells.

To date, Korean hinoki cypress (Chamaecyparis obtusa), has been widely used for household and commercial purposes. Although the medicinal efficacy of hinoki cypress essential oil has been observed, that of the essential oil‑derived terpenes, which exhibit a mechanism that acts against lung inflammation, remains to be fully elucidated. The present study investigated the anti‑inflammatory effect of hinoki cypress leaf extracted essential oil on lipopolysaccharide (LPS)‑stimulated WI38 fibroblast cells by inhibiting the nuclear factor κ‑light‑chain‑enhancer of activated B cells (NF‑κB) pathway, which exhibited lung tissue protection through the olfactory administration of essential oil in Sprague‑Dawley rats. GC/MS analysis derived 24 terpenes from the essential oil. The morphological observations revealed that, upon LPS stimulation of WI38 fibroblast cells, inflammation was induced, whereas the condition of the cells reverted to normal in the essential oil extract pre‑treated group. The results of western blot analysis revealed the inhibition of inducible nitric oxide synthase, activation of cyclooxygnase‑2, and the degradation of cytosolic p65 and inhibitor of NF‑κB‑α in the LPS‑stimulated group. Additionally, confocal imaging of nuclei revealed the translocation of phosphorylated p65, which was recovered in the cytosol in the phytoncide essential oil pre‑treated group. Histopathological observation revealed that the alveolar capacity was enhanced in the essential oil olfactory administered rat group, compared with that in the normal rat group. These findings suggest that terpenes in essential oil from the Chamaecyparis obtusa leaf have therapeutic potential against respiratory inflammation‑related disease.