title: Macular pigments lutein and zeaxanthin as blue light filters studied in liposomes.
abstract: Lutein and zeaxanthin are the predominant carotenoids in the human macula lutea. Epidemiological data suggest that an increased intake of a lutein-rich diet correlates with a diminished risk for age-related macular degeneration, a major cause of impaired vision in the elderly. Filtering of blue light has been proposed as a possible mechanism of protection. Here, the blue light filter efficacy of carotenoids was investigated in unilamellar liposomes loaded in the hydrophilic core space with a fluorescent dye, Lucifer yellow, excitable by blue light. Carotenoids were incorporated into the lipophilic membrane. Fluorescence emission in carotenoid-containing liposomes was lower than in carotenoid-free controls when exposed to blue light, indicating a filter effect. Filter efficacy was in the order lutein > zeaxanthin > beta-carotene > lycopene. Some of the difference in blue light filter efficacy of carotenoids is attributable to differences in extinction coefficients, and a major further contribution is suggested to be related to the orientation of the incorporated molecules in the liposomal membrane.
authors: Institut für Physiologische Chemie I and Biologisch-Medizinisches Forschungszentrum, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, D-40001, Germany.
authors: A
authors: A
authors: Junghans
authors: H
authors: H
authors: Sies
authors: W
authors: W
authors: Stahl
mesh_terms: D005374:Filtration; D006801:Humans; D008027:Light; D008081:Liposomes / Q000378:metabolism*; D014975:Lutein / Q000378:metabolism*; D008266:Macula Lutea / Q000378:metabolism* / Q000528:radiation effects; D013057:Spectrum Analysis; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives / Q000378:metabolism*
chemical_list: D008081:Liposomes; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D014975:Lutein