Algal fucoidan is a marine polysaccharide containing sulfur with a wide variety of biological activities
including anti-inflammatory and anti-thrombotic effects. Although antioxidants can inhibit inflammatory
signals through inhibiting activator protein-1 and/or nuclear factor-kappaB activation, it is obscure whether fucoidan
directly scavenges oxy-radicals or indirectly regulates oxidant production and/or antioxidant defense
system The antioxidant activities of fucoidan against peroxyl radicals, peroxynitrites and hydroxyl radicals
were determined by the total oxy-radical scavenging capacity (TOSC) assay. The specific TOSC values of
fucoidan against peroxyl radicals, peroxynitrites or hydroxyl radicals were 282?0, 43? or 40? TOSC/
mg/mL, respectively. These specific TOSC values against peroxyl radicals, peroxynitrites or hydroxyl radicals
are 23, 12, or 13% of the specific TOSC values of glutathione, a positive control, respectively. These results
suggest that fucoidan has direct oxy-radical scavenging capacity, which may be related with anti-inflammatory
effect of fucoidan.