6-Shogaol suppressed lipopolysaccharide-induced up-expression of iNOS and COX-2 in murine macrophages.
Ginger, the rhizome of Zingiber officinale, is a traditional medicine with carminative effect, antinausea, anti-inflammatory, and anticarcinogenic properties. In this study, we investigated the inhibitory effects of 6-shogaol and a related compound, 6-gingerol, on the induction of nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2) in murine RAW 264.7 cells activated with LPS. Western blotting and reverse transcription-PCR analyses demonstrated that 6-shogaol significantly blocked protein and mRNA expression of inducible NOS (iNOS) and COX-2 in LPS-induced macrophages. The in vivo anti-inflammatory activity was evaluated by a topical 12-O-tetradecanoylphorbol 13-acetate (TPA) application to mouse skin. When applied topically onto the shaven backs of mice prior to TPA, 6-shogaol markedly inhibited the expression of iNOS and COX-2 proteins. Treatment with 6-shogaol resulted in the reduction of LPS-induced nuclear translocation of nuclear factor-kappaB (NF kappaB) subunit and the dependent transcriptional activity of NF kappaB by blocking phosphorylation of inhibitor kappaB (I kappaB)alpha and p65 and subsequent degradation of I kappaB alpha. Transient transfection experiments using NF kappaB reporter constructs indicated that 6-shogaol inhibits the transcriptional activity of NF kappaB in LPS-stimulated mouse macrophages. We found that 6-shogaol also inhibited LPS-induced activation of PI3K/Akt and extracellular signal-regulated kinase 1/2, but not p38 mitogen-activated protein kinase (MAPK). Taken together, these results show that 6-shogaol downregulates inflammatory iNOS and COX-2 gene expression in macrophages by inhibiting the activation of NF kappaB by interfering with the activation PI3K/Akt/I kappaB kinases IKK and MAPK.
Pan
Min-Hsiung
MH
Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung, Taiwan. mhpan@mail.nkmu.edu.tw
Hsieh
Min-Chi
MC
Hsu
Ping-Chi
PC
Ho
Sheng-Yow
SY
Lai
Ching-Shu
CS
Wu
Hou
H
Sang
Shengmin
S
Ho
Chi-Tang
CT
D000818:Animals; D002396:Catechols / Q000494:pharmacology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000235:genetics*; D015232:Dinoprostone / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005233:Fatty Alcohols / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D020672:I-kappa B Proteins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D008813:Mice, Inbred ICR; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D012867:Skin / Q000201:enzymology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D002396:Catechols; D005233:Fatty Alcohols; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D000072000:NF-KappaB Inhibitor alpha; C040115:shogaol; C007845:gingerol; D052247:Nitric Oxide Synthase Type II; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone