Artemisia iwayomogi (Dowijigi) inhibits lipopolysaccharide-induced inflammation in RAW264.7 macrophages by suppressing the NF-κB signaling pathway

Inflammatory diseases are an important health concern and have a growing incidence worldwide. Thus, developing novel and safe drugs to treat these disorders remains an important pursuit. Artemisia iwayomogi, locally known as Dowijigi (DJ), is a perennial herb found primarily in Korea and is used to treat various diseases such as hepatitis, inflammation and immune disorders. In the present study, the anti-inflammatory effects of a polyphenolic extract from the DJ flower (PDJ) in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells were investigated. Cell cytotoxicity was assessed using the MTT assay. The production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) was measured by Griess and ELISA analysis, respectively. The expression levels of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX2) were examined by western blot analysis. Reverse transcription-quantitative PCR was performed to detect the mRNA expression levels of pro-inflammatory cytokines, including tumor necrosis factor α (TNFα), interleukin (IL)-6 and IL-1β, as well as COX2 and iNOS. The production of NO and PGE₂ was significantly decreased following treatment with PDJ. The mRNA expression levels of TNFα, IL-6, IL-1β, COX2 and iNOS were significantly decreased in LPS-induced PDJ co-treated cells compared with the group treated with LPS alone. Western blot analysis indicated that PDJ downregulated the LPS-induced expression of iNOS and COX2, as well as the expression of NF-κB proteins. In conclusion, the present study demonstrated that PDJ exerted anti-inflammatory effects in LPS-induced macrophage cells by suppressing the NF-κB signaling pathway. Therefore, PDJ may be used as a potential therapeutic agent in inflammation.