title: Characterisation of carotenoid radical cations in liposomal environments: interaction with vitamin C.
abstract: Pulse radiolysis was used to generate the radical cations of beta-carotene and two xanthophylls, zeaxanthin and lutein, in unilamellar vesicles of dipalmitoylphosphatidyl choline. The rate constants for the reaction (repair) of these carotenoid radical cations with the water-soluble vitamin C were found to be similar (approximately 1x10(7) M(-1) s(-1)) for beta-carotene and zeaxanthin and somewhat lower (approximately 0.5x10(7) M(-1) s(-1)) for lutein. The results are discussed in terms of the microenvironment of the carotenoids and suggest that for beta-carotene, a hydrocarbon carotenoid, the radical cation is able to interact with a water-soluble species even though the parent hydrocarbon carotenoid is probably entirely in the non-polar region of the liposome.
authors.affiliation: School of Chemistry and Physics, Lennard-Jones Laboratories, Keele University, Staffordshire, UK.
authors.forename: M
authors.initials: M
authors.lastname: Burke
authors.forename: R
authors.initials: R
authors.lastname: Edge
authors.forename: E J
authors.initials: EJ
authors.lastname: Land
authors.forename: T G
authors.initials: TG
authors.lastname: Truscott
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry*; D002412:Cations; D005609:Free Radicals / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D014975:Lutein / Q000737:chemistry*; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives / Q000737:chemistry*
chemical_list: D002412:Cations; D005609:Free Radicals; D008081:Liposomes; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D015060:1,2-Dipalmitoylphosphatidylcholine; D001205:Ascorbic Acid; D014975:Lutein