Increased antioxidant reactivity of vitamin C at low pH in model membranes

J Am Chem Soc. 2002 Sep 25;124(38):11252-3. doi: 10.1021/ja026927b.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / chemistry*
  • Antioxidants / pharmacology
  • Ascorbic Acid / chemistry*
  • Ascorbic Acid / pharmacology
  • Bridged Bicyclo Compounds, Heterocyclic / chemistry
  • Fluorescence
  • Fluorescent Dyes / chemistry
  • Hydrogen-Ion Concentration
  • Kinetics
  • Liposomes / chemistry*
  • Membranes / chemistry
  • Micelles
  • Microscopy, Fluorescence
  • Octoxynol / chemistry
  • Phosphatidylcholines / chemistry
  • Sodium Dodecyl Sulfate / chemistry


  • Antioxidants
  • Bridged Bicyclo Compounds, Heterocyclic
  • Fluorescent Dyes
  • Liposomes
  • Micelles
  • Phosphatidylcholines
  • fluorazophore-P
  • Sodium Dodecyl Sulfate
  • Octoxynol
  • Ascorbic Acid
  • 1-palmitoyl-2-oleoylphosphatidylcholine