title: Increased antioxidant reactivity of vitamin C at low pH in model membranes.
abstract: The reactivity of the water-soluble antioxidant vitamin C (l-ascorbic acid) depends on pH. It is generally recognized that the ascorbate monoanion, which predominates at neutral physiological pH, acts as a stronger antioxidant than the protonated form, ascorbic acid. Fluorazophore-L, a long-lived fluorescent probe, was employed as a mimic for lipid peroxyl radicals. The experiments with micellar and bilayer membrane models demonstrate that vitamin C becomes, in fact, a more powerful antioxidant at low pH. This phenomenon may be general for the interception of reactive oxidizing species at the lipid/water interface.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Gramlich
authors.forename: Jiayun
authors.initials: J
authors.lastname: Zhang
authors.forename: Werner M
authors.initials: WM
authors.lastname: Nau
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology; D001205:Ascorbic Acid / Q000737:chemistry* / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry; D008823:Micelles; D008856:Microscopy, Fluorescence; D017830:Octoxynol / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry
chemical_list: D000975:Antioxidants; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005456:Fluorescent Dyes; D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; C467790:fluorazophore-P; D012967:Sodium Dodecyl Sulfate; D017830:Octoxynol; D001205:Ascorbic Acid; C028694:1-palmitoyl-2-oleoylphosphatidylcholine