Abstract
Citrus peel has been used as a Traditional medicine in Asia to treat coughs, asthma and bronchial disorders. Therefore, the anti‑inflammatory effects of 3,5,6,7,3',4'‑hexamethoxyflavone (quercetogetin, QUE) isolated from Citrus unshiu peel were investigated in lipopolysaccharide (LPS)‑induced RAW 264.7 macrophage cells. The results showed that QUE repressed the production of prostaglandin E2 and nitric oxide by suppressing LPS‑induced expression of cyclooxygenase‑2 and inducible nitric oxide synthase. It also suppressed the production of interleukin (IL)‑6, IL‑1β, and tumor necrosis factor‑α cytokines, and decreased the nuclear translocation of NF‑κB by interrupting the phosphorylation of NF‑κB inhibitor α in macrophage cells. Based on the finding that QUE inhibited the phosphorylation of ERK protein expression in LPS‑induced RAW264.7 cells, it was confirmed that inhibition of inflammatory responses by QUE was mediated via the ERK pathway. Therefore, this study suggests that QUE has strong anti‑inflammatory effects, making it a promising compound for use as a therapeutic agent in treating inflammatory lung diseases, such as emphysema.