Kuromoji (Lindera umbellata) essential oil inhibits LPS-induced inflammation in RAW 264.7 cells.

Kuromoji (Lindera umbellata) essential oil (KEO) has long been used in Japan as a traditional medicine. It contains linalool (C10H18O), a naturally occurring small terpenoid. For this study, we investigated the anti-inflammatory effect of KEO in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Mouse macrophage-like RAW 264.7 cells were stimulated with LPS. Then they were treated with 25 or 50 µg/mL of KEO for 24 h. KEO suppressed LPS-induced pro-inflammatory cytokine production such as that of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in a dose-dependent manner. In addition, inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA expression and protein levels were suppressed by treatment with KEO cells. In addition, by treatment with 25 or 50 µg/mL of linalool showed the same anti-inflammatory effect. The results suggest that KEO and linalool can be regarded as a natural resource for use in anti-inflammatory therapeutic products.