Identification of products from canthaxanthin oxidation

Canthaxanthin is a carotenoid that lacks pro-vitamin A activity but is known to have antioxidant activity. The products of its oxidation in oxygen were found to be mainly substituted apo-carotenals and apo-carotenones. The product profile resembles that obtained in the oxidation of beta-carotene, except that with canthaxanthin these products are the 4-oxo-beta-apo-carotenals and 4-oxo-beta-apo-carotenones. Epoxides and diepoxides were clearly identified from beta-carotene oxidation but in contrast, with canthaxanthin, apart from 5,6-epoxy-canthaxanthin, which was detected at the early stage of oxidation and minor quantities of 5,6-epoxy-beta-ionone and 5,6-epoxy-4-oxo-beta-apo-11-carotenal, no other epoxides were detected. The identities of these products lead us to suggest that the mechanism of canthaxanthin oxidation bears significant similarity to that of beta-carotene. (C) 2015 Elsevier Ltd. All rights reserved.