Lutein: Separation, Antioxidant Activity, and Potential Health Benefits

Lutein is an oxygen-containing carotenoid found in many food plants. Although it is not a vitamin A precursor, many health beneficial effects have been associated with high dietary intake of this phytochemical. Lutein, along with its isomer zeaxanthin, may be the most important xanthophylls for human, as they have been found to play important roles in protecting human from many chronic diseases. In particular, lutein has been found in recent years to protect against age-related macular degeneration (AMD), a leading cause of irreversible vision loss in the elderly population. Lutein is also found to enhance immune function, to prevent cancer, coronary heart disease, and to protect skin from damages caused by ultraviolet light. Our recent study also showed a protective role of lutein against mutagens. Lutein is a strong antioxidant, which may help explain its above physiological functions. However, currently accumulated knowledge on lutein requires further studies on several aspects including the mechanisms of its various bioactivities in the biological system, and how it is absorbed and transported to the site of action. All these require good separation, quantification and detection methods for low concentrations of lutein. Samples containing trace amount of lutein in biological tissues resulting from animal and human clinical trials are particularly challenging. High performance liquid chromatography (HPLC) couple with photodiode array and mass spectrometric detector (LC-DAD-MS) will continue to play an important role in quantification and identification of lutein. Preparative high-speed counter-current chromatography may be a good tool for high quality lutein standard for the various bioassays and trials. This chapter is therefore to briefly review the chemistry and biochemistry of lutein, with an emphasis on its occurrence, distribution, separation and bioactivities, and discuss about its possible adverse effect.