Oxidation of Zeaxanthin and characterization of 3'-Alkyl Lutein ethers

• Main Author: Chi, Jie
• Format: Others
• Published: FIU Digital Commons 2001
• Subjects: Chemistry
• Online Access: http://digitalcommons.fiu.edu/etd/2161; http://digitalcommons.fiu.edu/cgi/viewcontent.cgi?article=3415&context=etd

One purpose of this study was to understand the oxidation metabolites of zeaxanthin, another was to prepare, purify, and characterize a series of 3'-alkyl lutein ethers for use as internal standards. Studies have proven that lutein and zeaxanthin are two of the principal carotenoids in human serum and the only carotenoids found in the retina, but their metabolism and transport in the human body are still only poorly understood. In vitro oxidation of zeaxanthin with MnO2 produced three components. They were characterized by HPLC, UV/Vis, MS, NMR and identified as all-trans rhodoxanthin and its cis-isomers. 3'-alkyl lutein ethers have been utilized as internal standards for carotenoid analysis in human serum and macular tissue. Nine 3'-alkyl lutein ethers were prepared by reaction of lutein with the corresponding acidified alcohols. The purified products were characterized by HPLC, UV/Vis, MS for the first time, and the resulting lutein ethers showed similar properties to lutein with increasing retention times as the alkyl chain lengthened. This provides us alternatives in selecting internal standards.