Potent anti-inflammatory effects of denbinobin mediated by dual inhibition of expression of inducible no synthase and cyclooxygenase 2.
Inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) have been suggested to play important roles in various inflammatory diseases. We explored the anti-inflammatory potential of a natural compound, denbinobin (5-hydroxy-3,7-dimethoxy-1,4-phenanthraquinone), by examining its effects on the expression and activity of iNOS and COX-2 in LPS-activated macrophages. Denbinobin markedly decreased the LPS (1 μg/mL)-induced increase in iNOS and COX-2 gene and protein expression, as well as levels of the downstream products NO and prostaglandin E2, in a concentration-dependent manner (0.3-3 μM). In clarifying the mechanisms involved, denbinobin was found not only to inhibit LPS-induced nuclear factor κB (NF-κB) activation, an effect highly correlated with its inhibitory effect on LPS-induced inhibitory κB kinase activation, inhibitory κB degradation, NF-κB phosphorylation, and binding of NF-κB to the κB motif of the iNOS and COX-2 promoters, but also suppressed phosphorylation of mitogen-activated protein kinases. Reporter gene assays and Western blotting revealed that denbinobin significantly suppressed NF-κB activation. Furthermore, denbinobin also downregulated the LPS-mediated CD14/toll-like receptor 4 complex level and TNF-α, IL-1β, and IL-10 mRNA expression. Our results demonstrate that denbinobin exerts potent anti-inflammatory activity, suggesting that it might provide a new therapeutic approach to inflammatory diseases.
Liu
Hsiang-Erh
HE
School of Pharmacy, Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Chang
Anita Shin-Yuan
AS
Teng
Che-Ming
CM
Chen
Chien-Chih
CC
Tsai
An-Chi
AC
Yang
Chia-Ron
CR
D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D016207:Cytokines / Q000096:biosynthesis; D015232:Dinoprostone / Q000096:biosynthesis; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007249:Inflammation / Q000188:drug therapy / Q000201:enzymology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis*; D010616:Phenanthrenes / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D020218:Response Elements
D000880:Anthraquinones; D000893:Anti-Inflammatory Agents; D016207:Cytokines; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010616:Phenanthrenes; C436544:denbinobin; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D015232:Dinoprostone