Carotenoid Cleavage Dioxygenase and Presence of Apo-Carotenoids in Biological Matrices

Evidence exists demonstrating that carotenoid cleavage dioxygenase enzymes in plants exhibit broad substrate specificity for several carotenoid pigments. Non-specific phase I and phase II metabolism is also suggested to generate carotenoid metabolites in vivo . More recently in animals and humans, specific oxidation products of carotenoids have been identified. These products are hypothesized to possess biological activity similar to retinoids with potential to bind to the retinoid receptors in-vivo. Although oxidative eccentric cleavage mechanisms of carotenoids have been well documented, few reports have unequivocally identified the in-vivo apo-carotenoid and apo-lycopenoid metabolic products. Our laboratory has developed highly selective and sensitive liquid chromatography tandem mass spectrometry methodology to analyze these compounds in foods and biological tissues. In collaboration with other researchers at the Ohio State University, several eccentric cleavage products have been identified in plants and humans by comparison to synthesized authentic compounds, and their potential biological activity demonstrated.