Effect of 5-O-Methylhirsutanonol on Nuclear Factor-kB-Dependent Production of NO and Expression of iNOS in Lipopolysaccharide-lnduced RAW264.7 Cells

摘要

Diarylheptanoids are known to have anti-inflammatory and anti-atherosclerotic activities in various cell types,including macrophages.5-O-Methylhirsutanonol(5-MH)isolated from the leaves of Alnus japonica Steud exhibited the antioxidant activities on Cu~(2+)-and AAPH-mediated low-density lipoprotein(LDL)oxidation in the thiobarbituric acid-reactive substances(TBARS)assay as well as the macrophage-mediated LDL oxidation.In the main study,we examined anti-inflammatory activities of 5-O-methylhirsutanonol(5-MH)on nuclear factor kB(NF-kB)-dependent nitric oxide(NO)production and expression of inducible nitric oxide synthease(iNOS)in lipopolysaccharide(LPS)-induced RAW264.7 macrophages.5-MH inhibited NO production with an IC50 value of 14.5 mu M and expression of both iNOS protein and iNOS mRNA in a parallel dose-response manner.Then,expression of inflammation-associated genes,such as TNF-a,COX-2,and IL-1 beta,was suppressed by 5-MH,as determined by reverse transcriptase polymerase chain reaction analysis.Moreover,5-MH attenuated NF-KB activation by inhibition of hyperphosphorylation of kB-alpha and its subsequent proteolytic degradation and p65 nuclear translocation,as well as preventing DNA-binding ability.In addition,5-MH suppressed the mRNA expression of the gene reactive oxygen species(ROS)concerned in the regulation of NF-KB signaling.