Industrially viable processes for synthesis of biologically active hydroxycarotenoids commonly found in fruits and vegetables

Human plasma and tissues contain in excess of 12 dietary carotenoids and several metabolites that originate from consumption of fruits and vegetables. The major hydroxycarotenoids absorbed by humans are: (3R,3′R,6′R)-lutein (1), (3R,3′R)-zeaxanthin (2), (3R,6′R)-α-cryptoxanthin (3), and (3R)-β-cryptoxanthin (4) and their E/Z-stereoisomers. In addition, several hydroxycarotenoids that result from metabolic transformation of 1 have also been identified in human plasma and ocular tissues. Epidemiological and experimental evidence to date suggest hydroxycarotenoids may protect against chronic diseases such as cancer, cardiovascular disease and age-related macular degeneration (AMD). Therefore, supplementation with these carotenoids in individuals with a low dietary intake of fruits and vegetables is essential. However, with the exception of 1 and 2, industrial production of 3 and 4 have not yet materialized. A relatively straightforward semisynthetic process has been developed that transform 1 into a mixture of 3 (12%) and 4 (80%). Hydroxycarotenoid 3 can also be directly prepared from allylic deoxygenation of 1 in a single step in an excellent yield. These two processes provide an easy access to optically active 3 and 4 that are normally prepared by numerous synthetic steps.