Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: September 20, 2009
Publication Date: December 20, 2009
Citation: Wang, X. 2009. Biological activities of carotenoid metabolites. In: Britton, A., Jensen, B., Pfander, D., editors. Carotenoids. 5th edition. Basel, Switzerland: Verlag Press. p.383-408.
Considerable research effort has been expended in an attempt to substantiate and understand the potential roles of carotenoids in human health and disease. Early studies dealt with beta-carotene and other provitamin A carotenoids, but more recent research efforts have focused on the potential roles in health and disease of non-provitamin A carotenoids, such as lycopene and lutein. Carotenoids are lipophilic and the series of conjugated double bonds in the central chain of the molecule makes them susceptible to oxidative cleavage, isomerization between the trans (E) and cis (Z) forms, and the formation of potentially bioactive metabolites. The best known metabolite of carotenoids is vitamin A, as in retinal, retinol and retinoic acid. In recent years, considerable efforts have been made to identify biological properties of carotenoid metabolites other than vitamin A and related retinoids. Better understanding of the molecular details behind the actions of these carotenoid oxidative metabolites may yield insights into both physiological and pathophysiological processes in human health and disease. For provitamin A carotenoids, such as beta-carotene, alpha-carotene, and beta-cryptoxanthin, central cleavage is a major pathway leading to vitamin A and its derivatives. This pathway has been substantiated by the cloning of a central cleavage enzyme, beta-carotene 15, 15'-oxygenase (BCO1), which can cleave carotenoids at their C(15,15') double bond. It has been well demonstrated that retinoids, the most important oxidative products of provitamin A carotenoids, play an essential role in many critical biological processes, including vision, reproduction, metabolism, differentiation, haematopoiesis, bone development, and pattern formation during embryogenesis.