Abstract
Corticosteroids are commonly used anti-inflammatory agents. However, their prolonged use can lead to side effects. Therefore, the development of natural compounds with minimal side effects is necessary. This study was performed to investigate the anti-inflammatory effects and mechanisms of action of Chamaecyparis obtusa (Siebold & Zucc.) Endl. leaf (COL), bioconverted using Ganoderma applanatum (G. applanatum) in lipopolysaccharide (LPS)-induced RAW264.7 cells. The COL 70% EtOH extract fermented by G. applanatum (70COLGA) improved the high cytotoxicity of 70% EtOH extracts (70COL). When RAW264.7 cells were pre-treated with 100 and 200 μg/mL of 70COLGA for 2 h and then treated with LPS for 16 h, LPS induced the production of nitric oxide (NO), and the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) were significantly inhibited. When RAW264.7 cells were pre-treated with 100 and 200 μg/mL of 70COLGA for 2 h and then treated with LPS for 4 h, the phosphorylation of signal transducers and activators of transcription (STAT) was markedly decreased. In addition, 70COLGA markedly suppressed the production of the inflammatory cytokines interleukin (IL)-1β and IL-6 in LPS-induced RAW264.7 cells. Analysis of pro-inflammatory molecules using cytokine arrays showed that macrophage inflammatory protein (MIP)-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF) and IL-27 expressions were also suppressed by 200 μg/mL of 70COLGA in LPS-induced RAW264.7 cells. These results demonstrate that 70COLGA significantly prevented inflammatory responses by inhibiting the secretion of pro-inflammatory molecules in LPS-induced RAW264.7 cells. When RAW264.7 cells were pre-treated with 100 and 200 μg/mL of 70COLGA for 2 h and then treated with LPS-conditioned medium (LPS-CM) for 30 min, 70COLGA directly inhibited STAT activation. In summary, our findings suggest that 70COLGA has therapeutic potential for the treatment of inflammatory diseases.