title: Studies on the singlet oxygen scavenging mechanism of human macular pigment.
abstract: It is thought that direct quenching of singlet oxygen and scavenging free radicals by macular pigment carotenoids is a major mechanism for their beneficial effects against light-induced oxidative stress. Corresponding data from human tissue remains unavailable, however. In the studies reported here, electron paramagnetic resonance (EPR) spectroscopy was used to measure light-induced singlet oxygen generation in post-mortem human macula and retinal pigment epithelium/choroid (RPE/choroid). Under white-light illumination, production of singlet oxygen was detected in RPE/choroid but not in macular tissue, and we show that exogenously added macular carotenoids can quench RPE/choroid singlet oxygen. When the singlet oxygen quenching ability of the macular carotenoids was investigated in solution, it was shown that a mixture of meso-zeaxanthin, zeaxanthin, and lutein in a ratio of 1:1:1 can quench more singlet oxygen than the individual carotenoids at the same total concentration.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
authors.forename: Binxing
authors.initials: B
authors.lastname: Li
authors.forename: Faisal
authors.initials: F
authors.lastname: Ahmed
authors.forename: Paul S
authors.initials: PS
authors.lastname: Bernstein
mesh_terms: D000328:Adult; D002338:Carotenoids / Q000172:deficiency / Q000378:metabolism; D002829:Choroid / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism*; D006801:Humans; D008266:Macula Lutea / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010860:Pigments, Biological / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*
chemical_list: D016166:Free Radical Scavengers; D010860:Pigments, Biological; D026082:Singlet Oxygen; D002338:Carotenoids