Evidence that the anti-inflammatory effect of 4-aryl-4H-chromenes is linked to macrophage repolarization

Abstract

The inflammatory response is a common feature of many pathological conditions, and there is urgent necessity for new substances that minimize the harmful effects of inflammation. Chromenes represent a class of compounds with multiple pharmacological actions that have already been described and may be potential candidates for studies of therapeutic action. This study aimed to test novel 4-aryl-4H-chromene-derived molecules in an in vitro model of inflammation using lipopolysaccharide (LPS)-induced Raw 264.7 cells. Seven compounds derived from 4-aryl-4H-chromene were tested on Raw 264.7 cells to evaluate their cytotoxic effects. Next, the effect of the selected compounds on the pro-inflammatory mediators (tumor necrosis factor-alpha [TNF-α], monocyte chemoattractant protein-1 [MCP-1], interleukin [IL]-6) and on the anti-inflammatory mediators (IL-10 and IL-13) was analyzed, and finally, the effect of the compounds on macrophage apoptosis and expression of surface receptors (toll-like receptor 4 [TLR-4] and mannose) was evaluated. The results of this study demonstrated that changes in the molecular structure of 4-aryl-4H-chromene altered its cytotoxic profile. Therefore, derivatives that showed safe results were selected for further analyses (named compounds: 4-6). In these experiments, the compounds were able to decrease nitric oxide (NO) levels and production of MCP-1, IL-6, IL-10, and IL-13. Furthermore, these derivatives were effective in reducing macrophage apoptosis and the expression of surface receptors, as TLR-4/CD284. Moreover, compounds 5 and 6 also were effective in increasing mannose receptor (CD206) expression. The results indicate, for the first time to our knowledge, that the anti-inflammatory effect produced by chromenes is linked to macrophage repolarization (M1 to M2).

Keywords: LPS; Raw 264.7; chromenes; inflammation; macrophage polarization.