Synthesis and Anti-inflammatory Effect of Chalcones

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Abstract
The process of degranulation of mast cells and neutrophils contributes to inflammatory disorders. Activation of microglial cells and macrophages is believed to be involved in inflammatory, infectious and degenerative diseases of the CNS. Combining the potent inhibition of chemical mediators released by the degranulation of mast cells or neutrophils and from the activated microglial cells or macrophages, would lead to a promising antiinflammatory agent for the treatment of peripheral and central inflammation. A series of chalcone derivatives have been reported to have potent anti-inflammatory activity. In an effort to continually develop potent anti-inflammatory agents, novel series of chalcones, 2′-hydroxy- and 2′,5′-dihydroxychalcones were synthesized and their inhibitory effects on the activation of mast cells, neutrophils, microglial cells and macrophages were evaluated in-vitro. The chalcones were prepared by Claisen-Schmidt condensation of appropriate acetophenones with an appropriate aromatic aldehyde. The alkoxychalcones were prepared with appropriate hydroxychalcones and alkyl iodide and the dihydroxychalcones were prepared by hydrogenation of an appropriate chalcone with Pd/C. Almost all of the hydroxychalcones exhibited potent inhibitory effects on the release of β-glucuronidase and lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB). Of the hydroxychalcones, compound 1 was the most potent inhibitor of the release of β-glucuronidase (IC50=1.6 ± 0.2 μM) and lysozyme (IC50=1.4 ± 0.2 μM) from rat neutrophils stimulated with fMLP/CB. Almost all of the 2′,5′-dialkoxychalcones exhibited potent inhibitory effects on nitric oxide (NO) formation from murine microglial cell lines N9 stimulated with lipopolysaccharide (LPS). Of these, compound 11 showed the greatest effect (IC50=0.7 ± 0.06 μM). The present results demonstrated that most of the chalcone derivatives have an anti-inflammatory effect. The inhibitory effects of dialkoxychalcones, 10–12 on inflammation are probably not due to the inhibition of mast cells and neutrophil degranulation, but are mediated through the suppression of NO formation from N9 cells.