title: Carotenoid radical anions and their protonated derivatives.
abstract: In this study, we report the protonation reactions for astaxanthin and canthaxanthin radical anions in methanol, alkaline methanol, and aqueous 2% Triton X-100 at different pH values. The pKa values for the corresponding alpha-hydroxy radical derivatives of astaxanthin, canthaxanthin, and beta-apo-8'-carotenal were estimated in 2% Triton X-100. Also, the effects of the microenvironment and the structure of the carotenoids on the protonation rate constant are discussed.
authors.affiliation: School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK. a.a.g.el-agamey@chem.keele.ac.uk
authors.forename: Ali
authors.initials: A
authors.lastname: El-Agamey
authors.forename: Ruth
authors.initials: R
authors.lastname: Edge
authors.forename: Suppiah
authors.initials: S
authors.lastname: Navaratnam
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Land
authors.forename: T George
authors.initials: TG
authors.lastname: Truscott
mesh_terms: D000838:Anions; D002338:Carotenoids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017830:Octoxynol; D011522:Protons
chemical_list: D000838:Anions; D011522:Protons; D002338:Carotenoids; D017830:Octoxynol