title: A 1H-NMR study of the permeation of glycolic acid through phospholipid membranes.
abstract: The transmembrane permeability coefficient of the alpha-hydroxyacid, glycolic acid, has been measured for egg phosphatidylcholine large unilamellar vesicles. The determination of the vesicle concentration independent first-order rate constant for membrane transport and the permeability coefficient were made using an NMR technique employing shift agents. Both the temperature dependence and the dependence on cholesterol content were investigated. The activation energy and the Arrhenius pre-exponential factor were found to be dependent on the cholesterol content. A marked increase in both parameters was observed up to 20 mol% cholesterol, with a further, small increase up to 50%. The pH dependence of permeability was also investigated. An increase in permeability is observed with a decrease in pH, providing a possible explanation for the effectiveness of glycolic acid in skin treatment.
authors.affiliation: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.
authors.forename: R G
authors.initials: RG
authors.lastname: Males
authors.forename: F G
authors.initials: FG
authors.lastname: Herring
mesh_terms: D002784:Cholesterol; D004058:Diffusion; D006016:Glycolates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D010539:Permeability; D010713:Phosphatidylcholines / Q000737:chemistry; D013696:Temperature
chemical_list: D006016:Glycolates; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; C031149:glycolic acid; D002784:Cholesterol