Anti-arthritic effects of magnolol in human interleukin 1ß-stimulated fibroblast-like synoviocytes and in a rat arthritis model.

Fibroblast-like synoviocytes (FLS) play an important role in the pathologic processes of destructive arthritis by producing a number of catabolic cytokines and metalloproteinases (MMPs). The expression of these mediators is controlled at the transcriptional level. The purposes of this study were to evaluate the anti-arthritic effects of magnolol (5,5'-Diallyl-biphenyl-2,2'-diol), the major bioactive component of the bark of Magnolia officinalis, by examining its inhibitory effects on inflammatory mediator secretion and the NF-κB and AP-1 activation pathways and to investigate its therapeutic effects on the development of arthritis in a rat model. The in vitro anti-arthritic activity of magnolol was tested on interleukin (IL)-1ß-stimulated FLS by measuring levels of IL-6, cyclooxygenase-2, prostaglandin E(2), and matrix metalloproteinases (MMPs) by ELISA and RT-PCR. Further studies on how magnolol inhibits IL-1ß-stimulated cytokine expression were performed using Western blots, reporter gene assay, electrophoretic mobility shift assay, and confocal microscope analysis. The in vivo anti-arthritic effects of magnolol were evaluated in a Mycobacterium butyricum-induced arthritis model in rats. Magnolol markedly inhibited IL-1ß (10 ng/mL)-induced cytokine expression in a concentration-dependent manner (2.5-25 µg/mL). In clarifying the mechanisms involved, magnolol was found to inhibit the IL-1ß-induced activation of the IKK/IκB/NF-κB and MAPKs pathways by suppressing the nuclear translocation and DNA binding activity of both transcription factors. In the animal model, magnolol (100 mg/kg) significantly inhibited paw swelling and reduced serum cytokine levels. Our results demonstrate that magnolol inhibits the development of arthritis, suggesting that it might provide a new therapeutic approach to inflammatory arthritis diseases.

Aciculatin inhibits lipopolysaccharide-mediated inducible nitric oxide synthase and cyclooxygenase-2 expression via suppressing NF-κB and JNK/p38 MAPK activation pathways.

OBJECTIVES: Natural products have played a significant role in drug discovery and development. Inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) have been suggested to connect with various inflammatory diseases. In this study, we explored the anti-inflammatory potential of aciculatin (8-((2R,4S,5S,6R)-tetrahydro-4,5-dihydroxy-6-methyl-2H-pyran-2-yl)-5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one), one of main components of Chrysopogon aciculatis, by examining its effects on the expression and activity of iNOS and COX-2 in lipopolysaccharide (LPS)-activated macrophages. METHODS: We used nitrate and prostaglandin E2 (PGE2) assays to examine inhibitory effect of aciculatin on nitric oxide (NO) and PGE2 levels in LPS-activated mouse RAW264.7 macrophages and further investigated the mechanisms of aciculatin suppressed LPS-mediated iNOS/COX-2 expression by western blot, RT-PCR, reporter gene assay and confocal microscope analysis. RESULTS: Aciculatin remarkably decreased the LPS (1 µg/mL)-induced mRNA and protein expression of iNOS and COX-2 as well as their downstream products, NO and PGE2 respectively, in a concentration-dependent manner (1-10 µM). Such inhibition was found, via immunoblot analyses, reporter gene assays, and confocal microscope observations that aciculatin not only acts through significant suppression of LPS-induced NF-κB activation, an effect highly correlated with its inhibitory effect on LPS-induced IκB kinase (IKK) activation, IκB degradation, NF-κB phosphorylation, nuclear translocation and binding of NF-κB to the κB motif of the iNOS and COX-2 promoters, but also suppressed phosphorylation of JNK/p38 mitogen-activated protein kinases (MAPKs). CONCLUSION: Our results demonstrated that aciculatin exerts potent anti-inflammatory activity through its dual inhibitory effects on iNOS and COX-2 by regulating NF-κB and JNK/p38 MAPK pathways.

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-1ß, 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.