Effect of flavone derivatives on interleukin-1β (IL-1β) mRNA expression and IL-1β protein synthesis in stimulated RAW 264.7 macrophages

It is known that the redox status of cells affects gene expression. Flavones, as natural antioxidants, efficiently modulate this status and may play a role in the regulation of inducible gene expression of inflammatory mediators. This study was designed to investigate the effect of five flavone derivatives variously substituted with hydroxyl groups (chrysin, galangin, kaempferol, quercetin and myricetin) on interleukin-1β (IL-1β) gene expression in stimulated RAW 264.7 macrophages. The cells were incubated with tested hydroxyflavones and stimulated with lipopolysaccharide (LPS) and interferon-γ (IFN-γ). Then, the following were estimated: the level of IL-1β mRNA in these cells and the concentration of IL-1β protein in cell-culture supernatants and cell lysates. Each of the tested compounds significantly decreased IL-1β mRNA expression. The most potent inhibitor was chrysin (hydroxyflavone with two hydroxyl groups and a weak antioxidant activity). The effects of galangin and kaempferol were similar. Myricetin (hydroxyflavone with a strong antioxidant activity) significantly decreased the level of IL-1β mRNA, but it had no effect on the IL-1β protein synthesis. The results indicated that hydroxyflavones could modulate the IL-1β gene expression in activated RAW 264.7 macrophages via inhibiting gene transcription. This action seems unlikely to be the result of antioxidant properties of tested compounds.