Regulation of Inflammatory Cytokines in Lipopolysaccharide-Stimulated RAW 264.7 Murine Macrophage by 7-O-Methyl-naringenin

7-O-Methylnaringenin, extracted from Rhododendron speciferum, belongs to the flavanone class of polyphenols. In the present study, we investigated the anti-inflammatory effects of 7-O-methylnaringenin on cytokine production by lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages in vitro. The results showed that pretreatment with 10, 20 or 40 mu g/mL of 7-O-methylnaringenin could downregulate tumour necrosis factor (TNF-alpha), interleukin (IL-6) and interleukin (IL-1 beta) in a dose-dependent manner. Furthermore, we investigated the signal transduction mechanisms to determine how 7-O-methylnaringenin affects RAW 264.7 macrophages. The activation of mitogen-activated protein kinases (MAPK) and I kappa B alpha were measured by Western blotting. The data showed that 7-O-methylnaringenin could downregulate LPS-induced levels of phosphorylation of ERK1/2, JNK and I kappa B beta. These observations indicated that 7-O-methylnaringenin modulated inflammatory cytokine responses by blocking NF-kappa B, ERK1/2 and JNK/MAPKs activation.