title: Effect of l-menthol on the thermotropic behavior of ceramide 2/cholesterol mixtures as a model for the intercellular lipids in stratum corneum.
abstract: The major components of the intercellular lipids in the stratum corneum are ceramides (CERs), cholesterol (CHOL) and free fatty acids. To estimate the effects of l-menthol on the intercellular lipids, we elucidated the thermotropic behavior and lateral structure of a CER2/CHOL mixture. This formed a eutectic mixture at molar fraction of CHOL (Xch) = 0.6, as a lamellar structure with a repeat distance of 3.99 nm, and it showed a hexagonal hydrocarbon chain packing conformation at ambient temperature. In thermograms of the CER2/CHOL mixtures, the addition of l-menthol broadened the transition peaks and reduced the enthalpy of transition. The effect of l-menthol on the change in transition temperature of the eutectic mixture at Xch = 0.6 was weaker than for other molar fractions of CHOL. This suggested that the structure of the eutectic mixture was stable to the effects of l-menthol. Furthermore, l-menthol increased the repeat distance of the lamellar structure and inhibited the formation of hexagonal hydrocarbon chain packing. Therefore, l-menthol induced a disturbance of the lateral structure of the eutectic mixture of CER2/CHOL and the phase transition became unclear. These effects of l-menthol could enhance transdermal drug delivery.
authors.affiliation: Department of Pharmaceutics, Hoshi University, Ebara 2-4-41, Shinagawa-ku, Tokyo, 142-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Obata
authors.forename: Kenya
authors.initials: K
authors.lastname: Ishida
authors.forename: Kozo
authors.initials: K
authors.lastname: Takayama
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D002518:Ceramides / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry*; D004817:Epidermis / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D008610:Menthol / Q000737:chemistry*; D015394:Molecular Structure; D044367:Phase Transition; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D002518:Ceramides; D008051:Lipid Bilayers; D008055:Lipids; D008610:Menthol; D002784:Cholesterol