Dioscorealide B suppresses LPS-induced nitric oxide production and inflammatory cytokine expression in RAW 264.7 macrophages: The inhibition of NF-kappaB and ERK1/2 activation.
Dioscorealide B (DB), a naphthofuranoxepin has been purified from an ethanolic extract of the rhizome of Dioscorea membranacea Pierre ex Prain & Burkill which has been used to treat inflammation and cancer in Thai Traditional Medicine. Previously, DB has been reported to have anti-inflammatory activities through reducing nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production in lipopolysaccharides (LPS)-induced RAW 264.7 macrophage cells. In this study, the mechanisms of DB on LPS-induced NO production and cytokine expression through the activation of nuclear factor-kappaB (NF-kappaB) and ERK1/2 are demonstrated in RAW 264.7 cells. Through measurement with Griess's reagent, DB reduced NO level with an IC(50) value of 2.85 +/- 0.62 microM that was due to the significant suppression of LPS-induced iNOS mRNA expression as well as IL-1beta, IL-6, and IL-10 mRNA at a concentration of 6 microM. At the signal transduction level, DB significantly inhibited NF-kappaB binding activity, as determined using pNFkappaB-Luciferase reporter system, which action resulted from the prevention of IkappaBalpha degradation. In addition, DB in the range of 1.5-6 microM significantly suppressed the activation of the ERK1/2 protein. In conclusion, the molecular mechanisms of DB on the inhibition of NO production and mRNA expression of iNOS, IL-1beta, IL-6, and IL-10 were due to the inhibition of the upstream kinases activation, which further alleviated the NF-kappaB and MAPK/ERK signaling pathway in LPS-induced RAW264.7 macrophage cells.
Faculty of Medicine, Department of Biomedical Sciences, Prince of Songkla University, Hat-Yai, Songkhla 90110, Thailand. webspider_13@hotmail.com
Poonsit
P
Hiransai
Suvina
S
Ratanachaiyavong
Arunporn
A
Itharat
Potchanapond
P
Graidist
Prasit
P
Ruengrairatanaroj
Juntipa
J
Purintrapiban
D000818:Animals; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000494:pharmacology*; D020672:I-kappa B Proteins / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008156:Luciferases / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D016207:Cytokines; D006576:Heterocyclic Compounds, 4 or More Rings; D020672:I-kappa B Proteins; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D012333:RNA, Messenger; C516706:dioscorealide B; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide; D008156:Luciferases; D052247:Nitric Oxide Synthase Type II; D048049:Extracellular Signal-Regulated MAP Kinases