- The pro-inflammatory vasoconstrictor Angiotensin II can cause endothelial dysfunction and is considered to be one of the mediators of atherosclerosis. Our former results demonstrated that polysaccharides derived from the red alga Porphyridium sp. attenuate inflammatory processes by interfering with tumor necrosis factor-alpha-induced inflammation, in human coronary artery endothelial cells. However, the anti-inflammatory effect of these polysaccharides on inflammation processes occurring under Angiotensin II stimulation is yet unknown. Herein, we studied the polysaccharide's anti-inflammatory effect by quantification of inflammatory markers in Angiotensin II- stimulated Human Coronary Artery Endothelial Cells following pre-treatment with polysaccharides. Inflammatory atherosclerotic pathways up-regulated by Angiotensin II, including adhesion molecule expression and nuclear factor kappa-light-chain-enhancer of activated B cells translocation, were significantly attenuated or diminished in cells pre-treated with the polysaccharides. In addition, the polysaccharides increased the antioxidant response elements activity through the nuclear factor-E2-related factor 2- antioxidant protection system. These polysaccharide's promising abilities may be considered as a basis for future use as a therapeutic agent aimed at improving vascular health by attenuation of the inflammatory atherosclerotic process.