Evidence that Oleic Acid Exists in a Separate Phase Within Stratum Corneum Lipids
- 1 January 1991
- journal article
- Published by Springer Science and Business Media LLC in Pharmaceutical Research
- Vol. 8 (3), 350-354
- https://doi.org/10.1023/a:1015845632280
Abstract
Oleic acid is known to be a penetration enhancer for polar to moderately polar molecules. A mechanism related to lipid phase separation has been previously proposed by this laboratory to explain the increases in skin transport. In the studies presented here, Fourier transform infrared spectroscopy (FT-IR) was utilized to investigate whether or not oleic acid exists in a separate phase within stratum corneum (SC) lipids. Per-deuterated oleic acid was employed allowing the conformational phase behavior of the exogenously added fatty acid and the endogenous SC lipids to be monitored independently of each other. The results indicated that oleic acid exerts a significant effect on the SC lipids, lowering the lipid transition temperature (Tm) in addition to increasing the conformational freedom or flexibility of the endogenous lipid alkyl chains above their Tm. At temperatures lower than Tm, however, oleic acid did not significantly change the chain disorder of the SC lipids. Similar results were obtained with lipids isolated from the SC by chloroform:methanol extraction. Oleic acid, itself, was almost fully disordered at temperatures both above and below the endogenous lipid Tm in the intact SC and extracted lipid samples. This finding suggested that oleic acid does exist as a liquid within the SC lipids. The coexistence of fluid oleic acid and ordered SC lipids, at physiological temperatures, is consistent with the previously proposed phase-separation transport mechanism for enhanced diffusion. In this mechanism, the enhanced transport of polar molecules across the SC can be explained by the formation of permeable interfacial defects within the SC lipid bilayers which effectively decrease either the diffusional path length or the resistance, without necessarily invoking the formation of frank pores.Keywords
This publication has 15 references indexed in Scilit:
- Lipid content and lipid type as determinants of the epidermal permeability barrier.Journal of Lipid Research, 1989
- Structure of lamellar lipid domains and corneocyte envelopes of murine stratum corneum. An x-ray diffraction studyBiochemistry, 1988
- A differential scanning calorimetry study of the interaction of free fatty acids with phospholipid membranesChemistry and Physics of Lipids, 1987
- Covalently bound ω-hydroxyacylsphingosine in the stratum corneumBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1987
- Role of Stratum Corneum Lipid Fluidity in Transdermal Drug FluxJournal of Pharmaceutical Sciences, 1987
- Interactions of cholesterol and cholesterol sulfate with free fatty acids: Possible relevance for the pathogenesis of recessive X-linked ichthyosisArchiv für dermatologische Forschung, 1986
- Raman and Fourier transform infrared spectroscopic studies of the interaction between glycophorin and dimyristoylphosphatidylcholineBiochemistry, 1981
- The effect of chain length and lipid phase transitions on the selective permeability properties of liposomesBiochimica et Biophysica Acta (BBA) - Biomembranes, 1975
- Dynamic structure of fatty acyl chains in a phospholipid bilayer measured by deuterium magnetic resonanceBiochemistry, 1974
- Phase transitions in phospholipid vesicles Fluorescence polarization and permeability measurements concerning the effect of temperature and cholesterolBiochimica et Biophysica Acta (BBA) - Biomembranes, 1973