Lonicera Japonioa Inhibits the Production of NO through the Suppression of NF-kB Activity in LPS-stimulated Mouse Peritoneal Macrophages

The flowers of Lonicera japonica Thunb. (Caprifoliaceae) has been used as anti-inflammatory drug in the folk medicine recipe and been proved its anti-inflammatory effect in the oriental medicine. However, the action mechanism of Lonicera japonica that exhibits anti-inflammatory effects has not been determined. Since nitric oxide (NO) is one of the major inflammatory parameter, we studied the effect of aqueous extracts of Lonicera japonica (AELJ) on NO production in lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages. NO and inducible NO synthase (iNOS) level were significantly reduced in LPS-stimulated macrophages by AELJ compared to those without Electrophoretic mobility shift assay (EMSA) indicated that AELJ blocked the activation of nuclear factor kappa B (NF-kB), which was considered to be a potential transcription factor for the iNOS expression. AELJ also blocked the phosphorylation and degradation of inhibitor of kappa B-alpha (IkB-${\alpha}$). Furthermore, IkB kinase alpha (IKK${\alpha}$), which is known to phosphorylate serine residues of IkB directly, is inhibited by AELJ in vivo and in vitro. These results suggest that AELJ could exert its anti-inflammatory actions by suppressing the synthesis of NO through inhibition of NF-kB activity.