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). Saponification and Z-to-E isomerization of the product followed by crystallization gave a mixture of (3 R)-β-cryptoxanthin as the major product. Similarly, acid-catalyzed hydrogenation of unesterified (3 R,3'R,6'R)-lutein with Pt/alumina in ethyl acetate gave a mixture of (3 R,6'R)-α-cryptoxanthin acetate (minor) in a one-pot reaction. Alkaline hydrolysis and Z-to-E isomerization of the mixture followed by crystallization provided (3 R)-β-cryptoxanthin.