Abstract
Nuclear factor-κB (NF-κB) and the signaling pathways that regulate its activity have become a focal point for intense drug discovery and development efforts. NF-κB regulates the transcription of a large number of genes, particularly those involved in immune, inflammatory, and antiapoptotic responses. In our search for NF-κB inhibitors from natural resources, we identified cardamomin, 2′,4′-dihydroxy-6′-methoxychalcone, as an inhibitor of NF-κB activation from Alpinia conchigera Griff (Zingiberaceae). In present study, we demonstrated the effect of cardamomin on NF-κB activation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and LPS-induced mortality. This compound significantly inhibited the induced expression of NF-κB reporter gene by LPS or tumor necrosis factor (TNF)-α in a dose-dependent manner. LPS-induced production of TNF-α and NO as well as expression of inducible nitric-oxide synthase and cyclooxygenase-2 was significantly suppressed by the treatment of cardamomin in RAW264.7 cells. Also, cardamomin inhibited not only LPS-induced degradation and phosphorylation of inhibitor κBα (IκBα) but also activation of inhibitor κB (IκB) kinases and nuclear translocation of NF-κB. Further analyses revealed that cardamomin did not directly inhibit IκB kinases, but it significantly suppressed LPS-induced activation of Akt. Moreover, cardamomin suppressed transcriptional activity and phosphorylation of Ser536 of RelA/p65 subunit of NF-κB. However, this compound did not inhibit LPS-induced activation of extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun NH2-terminal kinase, but significantly impaired activation of p38 mitogen-activated protein kinase. We also demonstrated that pretreatment of cardamomin rescued C57BL/6 mice from LPS-induced mortality in conjunction with decreased serum level of TNF-α. Together, cardamomin could be valuable candidate for the intervention of NF-κB-dependent pathological condition such as inflammation.
Footnotes
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This study was partially supported by a grant from Plant Diversity Research Center of 21st Century Frontier Research Program and Korea Research Institute of Bioscience and Biotechnology Research Initiative Program funded by Ministry of Science and Technology of Korean government
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.105.092486.
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ABBREVIATIONS: NF-κB, nuclear factor κB; IκBα, inhibitor of κBα; IκB, inhibitor of κB; IKK, IκB kinase; COX, cyclooxygenase; iNOS, inducible nitric-oxide synthase; LPS, lipopolysaccharide; TNF, tumor necrosis factor; ERK, extracellular signal-regulated kinase; SAPK/JNK, stress-activated protein kinase/c-Jun NH2-terminal kinase; EMSA, electrophoretic mobility shift assay; DTT, dithiothreitol; AP-1, activator protein-1; MAP, mitogen-activated protein; PI3K, phosphatidylinositol 3-kinase.
- Received July 11, 2005.
- Accepted September 21, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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