Efficient radical trapping at the surface and inside the phospholipid membrane is responsible for highly potent antiperoxidative activity of the carotenoid astaxanthin

The effects of the carotenoids beta -carotene and astaxanthin on the peroxi dation of liposomes induced by ADP and Fe2+ were examined. Both compounds i nhibited production of lipid peroxides, astaxanthin being about 2-fold more effective than beta -carotene. The difference in the modes of destruction of the conjugated polyene chain between beta -carotene and astaxanthin sugg ested that the conjugated polyene moiety and terminal ring moieties of the more potent astaxanthin trapped radicals in the membrane and both at the me mbrane surface and in the membrane, respectively, whereas only the conjugat ed polyene chain of beta -carotene was responsible for radical trapping nea r the membrane surface and in the interior of the membrane. The efficient a ntioxidant activity of astaxanthin is suggested to be due to the unique str ucture of the terminal ring moiety. (C) 2001 Elsevier Science B.V. All righ ts reserved.