Effects of ethanol extract of propolis (EEP) and its flavones on inducible gene expression in J774A.1 macrophages

Propolis, a bee-hive product, has been used in folk medicine for centuries, and recently in modern medicine as an anti-inflammatory and immunomodulatory agent. These activities would be mainly due to phenolic compounds such as flavonoids, especially flavone derivatives. The present study examined the effect of ethanol extract of propolis (EEP) and selected flavone derivatives (chrysin, galangin, kaempferol and quercetin) on interleukin-1beta (IL-1beta) and inducible nitric oxide synthase (iNOS) gene expression in lipopolysaccharide (LPS)-induced J774A.1 macrophages. Treatment of cells with EEP significantly suppressed both IL-1beta mRNA (P<0.02) and iNOS mRNA (P<0.001) expression. The concentrations of cytokine in cell culture supernatants and cell lysates and nitric oxide (NO) generation were reduced in a dose-dependent manner. The tested phenolic compounds significantly decreased the IL-1beta mRNA level and IL-1beta protein concentration (P<0.05) (excluding galangin), iNOS mRNA level and NO production (P<0.001). The most potent inhibitor of the IL-1beta synthesis and NO generation was chrysin. These results indicate that EEP exerts its inhibitory effect on the IL-1beta and iNOS gene expression in J774A.1 macrophages at the transcriptional level. Tested flavone derivatives contribute to the anti-inflammatory activity of propolis.