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- Title
β-Carotene autoxidation: oxygen copolymerization, non-vitamin A products, and immunological activity.
- Authors
Burton, Graham W.; Daroszewski, Janusz; Nickerson, James G.; Johnston, James B.; Mogg, Trevor J.; Nikiforov, Grigory B.
- Abstract
Carotenoids are reported to have immunological effects independent of vitamin A activity. Although antioxidant activity has been suggested as a basis of action, the ability of carotenoids to autoxidize to numerous non-vitamin A products with immunological activity is an alternative yet to be fully explored. We have undertaken a systematic study of β-carotene autoxidation and tested the product mixture for immunological activity. Autoxidation proceeds predominantly by oxygen copolymerization, leading to a defined, reproducible product corresponding to net uptake of almost 8 molar equivalents of oxygen. The product, termed OxC-beta, empirical formula C40H60O15 versus C40H56 for β-carotene, contains more than 30% oxygen ( w/ w) and 85% β-carotene oxygen copolymers ( w/ w) as well as minor amounts of many C8−C18 norisoprenoid compounds. No vitamin A or higher molecular weight norisoprenoids are present. The predominance of polymeric products has not been reported previously. The polymer appears to be a less polymerized form of sporopollenin, a biopolymer found in exines of spores and pollen. Autoxidations of lycopene and canthaxanthin show a similar predominance of polymeric products. OxC-beta exhibits immunological activity in a PCR gene expression array, indicating that carotenoid oxidation produces non-vitamin A products with immunomodulatory potential.
- Subjects
CAROTENES; OXIDATION; OXYGEN; COPOLYMERIZATION; VITAMIN A; IMMUNOLOGY; ANTIOXIDANTS
- Publication
Canadian Journal of Chemistry, 2014, Vol 92, Issue 4, p305
- ISSN
0008-4042
- Publication type
Article
- DOI
10.1139/cjc-2013-0494