An in vitro study of the structure-activity relationships of sulfated polysaccharide from brown algae to its antioxidant effect

In this paper, the structure-activity relationships of chemically modified uronic acid polymer fragments from brown algae with regard to their antioxidant effects on H2O2-damaged lymphocyte were studied. The results indicated that the most potent antioxidant activity was obtained from the sulfated polysaccharide with ratio of mannuronate blocks (M-blocks) to guluronate blocks (G-blocks) of 3 to 1 and carboxyl residue unesterified. The sulfated G-blocks with esterified carboxyl residue also prevented lymphocyte from injury. However, the sulfated G-blocks bearing unesterified carboxyl residue hardly exerted antioxidant activity. These findings suggested that both M-blocks and esterified carboxyl residue were determinant structures in preventing lymphocyte from being oxidized by H2O2, indicating that the existence of M-blocks was more important in scavenging free radicals.