RESUMO
In this study, we found that a sulfated polysaccharide isolated from the brown alga Ascophyllum nodosum, ascophyllan, showed suppressive effects on stimulated RAW264.7 cells. Ascophyllan significantly inhibited expression of inducible nitric oxide synthase mRNA and excessive production of nitric oxide (NO) in lipopolysaccharide (LPS)-stimulated RAW264.7 cells in a dose-dependent manner without affecting the viability of RAW264.7 cells. Ascophyllan also reduced the elevated level of intracellular reactive oxygen species (ROS) in LPS-stimulated RAW264.7 cells. Furthermore, preincubation with ascophyllan resulted in concentration-dependent decrease in ROS production in phorbol 12-myristate-13-acetate-stimulated RAW264.7 cells. Our results suggest that ascophyllan can exhibit anti-inflammatory effects on stimulated macrophages mainly through the attenuation of NO and ROS productions.