Exogenously incorporated ketocarotenoids in large unilamellar vesicles. Protective activity against peroxidation

The ability of astaxanthin and canthaxanthin as chain-breaking antioxidants was studied in Cu2+-initiated peroxidation of phosphatidylcholine large unilamellar vesicles (LUVs). Both carotenoids increased the lag period that precedes the maximum rate of lipid peroxidation, though astaxanthin showed stronger activity. For these experiments, different amounts of xanthophylls were exogenously added to previously made LUVs, non-incorporated pigment being afterwards removed. Differential scanning calorimetry assays with L-beta,gamma-dimyristoyl-alpha-phosphatidylcholine LUVs demonstrated that xanthophylls incorporated as described interact with the lipid matrix becoming interspersed among the phospholipid molecules. (C) 2000 Elsevier Science B.V. All rights reserved.