title: Influence of retinoids on phosphatidylethanolamine lipid polymorphism.
abstract: The interaction of all-trans-retinoic acid and all-trans-retinol with dielaidoylphosphatidylethanolamine has been studied by differential scanning calorimetry and 31P-NMR spectroscopy. Increasing concentrations of all-trans-retinoic acid up to a mol fraction of 0.09 were found to induce shifts to lower temperatures of both the L beta to L alpha and L alpha to hexagonal-HII phase transitions, with a slight decrease in the enthalpy change of the transitions. At higher concentrations no further effects on the transitions were observed, and this is interpreted as indicative of a limited miscibility of retinoic acid with the phospholipid. 31P-NMR spectroscopy confirmed that the L alpha to hexagonal-HII phase transition was shifted to lower temperatures in the presence of retinoic acid. On the other hand increasing concentrations of all-trans-retinol up to a mol fraction of 0.166, induced a progressive shift of the L beta to L alpha and the L alpha to hexagonal-HII phase transitions to lower temperatures. At higher concentrations the main gel to liquid-crystalline phase transition was further displaced to lower temperatures and the lamellar to hexagonal-HII phase transition was not observed in the thermograms. 31P-NMR spectroscopy indicated that retinol was able of inducing the phospholipid to adopt the hexagonal-HII phase at temperatures even below the main gel to liquid-crystalline phase transition temperature of the pure phospholipid.
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ortiz
authors.forename: F J
authors.initials: FJ
authors.lastname: Aranda
authors.forename: J
authors.initials: J
authors.lastname: Villalaín
authors.forename: J C
authors.initials: JC
authors.lastname: Gómez-Fernández
mesh_terms: D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D012176:Retinoids / Q000494:pharmacology*; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D014212:Tretinoin / Q000494:pharmacology; D014801:Vitamin A / Q000494:pharmacology
chemical_list: D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; D012176:Retinoids; D012996:Solutions; D014801:Vitamin A; D014212:Tretinoin