title: Xanthophyll epoxides, unlike beta-carotene monoepoxides, are not detectibly absorbed by humans.
abstract: Increased intake of fruits and vegetables is associated with reduced risk of cancer and other chronic diseases. Epoxycarotenoids are widely distributed in nature and constitute major dietary carotenoids in a number of fruits and vegetables. Previous studies have shown that beta-carotene 5,6-epoxide was absorbed well by humans, and was much more active than beta-carotene in inducing the differentiation of NB4 cells. Xanthophyll epoxides such as neoxanthin, violaxanthin and lutein 5,6-epoxide, are more abundant than epoxy-hydrocarbon carotenes in a number of vegetables and fruits that humans consume. To determine whether xanthophyll epoxides are also absorbed by humans, lutein 5,6-epoxide (taraxanthin) and zeaxanthin 5,6,5'6'-diepoxide (violaxanthin) were chemically prepared, dissolved in corn oil and orally administered to three human subjects. Analysis of plasma for carotenoids within 9 h after a single oral dose of either violaxanthin or taraxanthin failed to show any violaxanthin, taraxanthin or any of their metabolites.
authors.affiliation: Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA 50011, USA. abarua@iastate.edu
authors.forename: A B
authors.initials: AB
authors.lastname: Barua
authors.forename: J A
authors.initials: JA
authors.lastname: Olson
mesh_terms: D000042:Absorption; D002338:Carotenoids / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004852:Epoxy Compounds / Q000493:pharmacokinetics*; D005260:Female; D005638:Fruit; D006801:Humans; D014975:Lutein / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D014675:Vegetables; D024341:Xanthophylls / Q000493:pharmacokinetics*; D065146:Zeaxanthins; D019207:beta Carotene / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*
chemical_list: D004852:Epoxy Compounds; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D002338:Carotenoids; C005613:violaxanthin; D014975:Lutein