Study the anti-inflammatory effect of Rose Bengal in LPS-activated macrophages in dark

Rose Bengal is a water-soluble, anionic xanthin dye. It has been used as a safe compound for many years. But, anti-inflammatory effect of Rose Bengal has not been studied. The aim of this study was to determine the effect of Rose Bengal on nitric oxide production and its inflammatory induced response and inducible nitric oxide synthase expression in LPS-activated J774A.1 macrophages as an inflammatory model in dark. In an experimental study, J774A.1 macrophages cell line was purchased from Pasteur’s institute and the cells were treated with different concentrations of Rose Bengal with or without lipopolysaccharide (LPS) in dark. The effect of different concentrations of Rose Bengal on cell viability was studied using MTT assay. Griess reagent was used to determine production of nitric oxide (micromolar) in test and control groups. Western blotting was applied to evaluate the expression of inducible nitric oxide. Data were analyzed at the significant level of P<0.05 using t student-test. MTT assay showed that cell viability of treated macrophages (1, 10, 50, 100, 200 and 300 micromolar) were 99±0.66, 97±1.2, 90±0.88, 88±0.57, 81±0.88, 80±0.57 percent, respectively. The amount of nitrite oxide concentration (micromolar)±SEM by different concentrations of Rose Bengal (1, 10, 50, 100, 200 and 300 micromolar) were 17.1±0.17, 14.3±0.17, 13.1±0.09, 8.9±0.32, 6.1±0.09 and 0 micromolar respectively and 21.4±0.21 in control group. Expression of iNOS was decreased in a dose dependent manner by Rose Bengal. The obtained results showed that Rose Bengal (below 200 micromolar) decreased nitric oxide production and iNOS expression in inflammatory macrophages without significant decreasing in their viability. Besides, its anti-inflammatory effect is mediated by inhibition of iNOS expression. Thus, Rose Bengal could be a new and safe anti-inflammatory agent for in vivo studies.