Capacity of fucoxanthin for scavenging peroxyl radicals and inhibition of lipid peroxidation in model systems.

Carotenoids act as physiological antioxidant by scavenging reactive-free radicals as well as quenching singlet oxygen. Fucoxanthin is one of the abundant carotenoids found in edible brown seaweeds. The assessment of radical scavenging capacity of carotenoids has been the subject of extensive studies, which, however, gave inconsistent results. In the present study, the capacity of fucoxanthin for scavenging peroxyl radicals, chain carrying species of lipid peroxidation, was assessed quantitatively by measuring the effect of alpha-tocopherol on the decay of fucoxanthin induced by peroxyl radicals. It was found that alpha-tocopherol was 7.1 times more reactive than fucoxanthin in heptane solution, but interestingly fucoxanthin exerted 1.6 times higher reactivity than alpha-tocopherol in methanol solution. In SDS micelles, the relative reactivity of fucoxanthin and alpha-tocopherol depended on the site of peroxyl radical formation. The efficacy of lipid peroxidation inhibition by fucoxanthin was much less than that of alpha-tocopherol.