Process for synthesis of (3r,3'r)-zeaxanthin and (3r,3′s;meso)-zeaxanthin from (3r,3′r,6′r)-lutein via (3r)-3′,4′-anhydrolutein

Abstract

(3R,3'R,6′R)-Lutein and (3R,3′R)-zeaxanthin are two dietary carotenoids that are present in most fruits and vegetables commonly consumed in the US and accumulate in the human plasma, major organs, and ocular tissues. Another stereoisomer of (3R,3′R)-zeaxanthin that is not of dietary origin but is found in the human ocular tissues is (3R,3′S;meso)-zeaxanthin. There is growing evidence that these carotenoids play an important role in the prevention of age-related macular degeneration (AMD) that is the leading cause of blindness in the U.S. and the Western World. In view of the potential therapeutic application of dietary lutein, (3R,3′R)-zeaxanthin, and (3R,3′S;meso)-zeaxanthin, the industrial production of these carotenoids is of considerable importance. The present invention provides a process for the partial synthesis of (3R,3′R)-zeaxanthin and (3R,3′S;meso)-zeaxanthin from a readily accessible dehydration product of (3R,3′R,6′R)-lutein, namely, (3R)-3′,4′-didehydro-β,β-caroten-3-ol [(3R)-3′,4′-anhydrolutein]. The process involves regioselective hydroboration of (3R)-3′,4′-anhydrolutein to a mixture of (3R,3′R)-zeaxanthin and (3R,3′S;meso)-zeaxanthin followed by separation of these carotenoids by enzyme-mediated acylation.