Anti-inflammatory Effects of Eriodictyol in Lipopolysaccharide-stimulated Raw 264.7 Murine Macrophages

Flavonoids have biological activities including anti-allergic, anti-inflammatory, antimicrobial and anticancer activities shown from in vitro studies. Of these biological activities, the anti-inflammatory capacity of flavonoids has long been emphasized in Chinese medicine. In this study, I investigated that what flavonoid can be applied to the suppression of lipopolysaccharide (LPS)-induced inflammatory responses in macrophages among the four similar structure flavonoids. Eriodictyol was found to reduce nitric oxide (NO) production from LPS-stimulated Raw 264.7 cells in non-cytotoxic concentrations. Moreover, eriodictyol strongly suppressed the phagocytic activity of activated macrophages. Pre-treatment of Raw 264.7 cells with eriodictyol reduced the expression of mRNA and the secretion of pro-inflammatory cytokines. These inhibitory effects were found to be caused by blockage of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappa B) activation and phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases 1 and 2 (ERK1/2) and c-Jun N-terminal kinase (JNK).