Transformation of naturally occurring (3R,3'R,6'R)-lutein and its fatty acid esters to (3 R)-β-cryptoxanthin and (3R,6'R)-α-cryptoxanthin.

The objective of this study was to develop straightforward processes that could be applied to the large-scale production of β-cryptoxanthin in an attempt to facilitate investigation of its biological activity. An oleoresin obtained from crude extracts of marigold flowers (Tagetes erecta) with approximately 24% total lutein fatty acid ester content was directly used as starting material for partial synthesis of (3 R)-β-cryptoxanthin under mild reaction conditions at ambient temperature. Therefore, acid-catalyzed deoxygenation of lutein esters from marigold oleoresin followed by hydrogenation in the presence of catalytic amount of platinum (Pt) supported on alumina (5%) at ambient temperature gave a mixture of (3 R)-β-cryptoxanthin fatty acid esters (major) and (3 R,6'R)-α-cryptoxanthin fatty acid esters (minor).

Partial synthesis of serum carotenoids and their metabolites.

Human serum and tissues contain in excess of 12 dietary carotenoids and several metabolites that originate from consumption of fruits and vegetables. Among these are hydroxycarotenoids: (3R,3'R,6'R)-lutein (1), (3R,3'R)-zeaxanthin (2), (3R,6'R)-α-cryptoxanthin (3), and (3R)-β-cryptoxanthin (4). In addition, several dehydration products of 1 have also been identified in human serum, these are: (3R,6'R)-3-hydroxy-3',4'-didehydro-β,γ-carotene (5), (3R,6'R)-3-hydroxy-2',3'-didehydro-β,ε-carotene (6), and (3R)-3-hydroxy-3',4'-didehydro-β,β-carotene (7).

Total synthesis of (3R,3'R,6'R)-lutein and its stereoisomers.

(3R,3'R,6'R)-lutein (1) is a major dietary carotenoid that is abundant in most fruits and vegetables commonly consumed in the U.S. and that accumulates in the human plasma, major organs, and ocular tissues.