Free radicals astaxanthin

Bagchi, D., Oxygen free radical scavenging abilities of vitamins C, E, P-carotene, pycnogenol, grape seed proanthocyanidin extract, astaxanthin and BioAstin in vitro, Final Report to Cyanotech Corporation, Creighton University School of Health Sciences, Omaha, NE, 2001. 

Uchiyama, K. et al.. Beneficial effects of astaxanthin in type 2 diabetes model of db/db mouse. Free Radical Biol. Med., 33, S211, 2002. 

Not all carotenoids are vitamin A precursors - they comprise 90% of carotenoids, nevertheless they are excellent free radical scavengers. Examples are lycopene (in tomatoes) and astaxanthin (Fig. 51.2). The latter is enjoying a reputation as a nutriceutical it is pink and found in aquatic animals, e.g. salmon, shrimp and lobster, and in the alga, Haematococcus pluvialis, from which it is commercially extracted. 

Some carotenoids are precursors (provitamins) of vitamin A. Other carotenoids, such as cryptoxanthin, zeaxanthin and lutein, exhibit, by contrast, about half of the activity of provitamins A. Some carotenoids, such as lycopene, astaxanthin and canthaxanthin, are more effective in quenching singlet oxygen than P-carotene. Carotenoids also react with free radicals such as P-carotene. Because of their antioxidative properties, they are used in the prevention of degenerative processes and as anticancer agents. 

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