Phase behaviors and structures of pseudoceramide-cholesterol-linoleic acid mixtures for cosmetic application

Abstract

Gemini type synthetic ceramides, 1,3-bis(N-(2-hydroxyethyl)-palmitoylamino)-2-hydroxy-propane(HEPHP) and 1,3-bis(N-(2-hydroxyethyl)-tocophenylamino)-2-hydroxy -propane(HETHP) enhanced with vitamin E(tocopherol) on the ceramide HEPHP, were investigated for a potent restorative effect of the damaged human skin. These synthetic materials were considered to overcome the crystallizing problem of ceramides. The interaction between the polar groups of surfactants(C16EO20, CholEO20) and ceramide HEPHP(trade name: PC(Pacific ceramide) 104) prevents from crystallizing out, while water molecules play a key role for the strong interaction between hydrophilic part of ceramide PC104 and polyoxyethylene. A ceramide HETHP(trade name: tocomide (tocopherol+ceramide)) mixture was considered as a model system of an artificial stratum corneum lipid complex(ASCLC), which was composed of cholesterol, linoleic acid, and tocomide like as the constitution of the natural skin. The physical properties and phase behaviors of tocomide were more intensively examined in order to figure out a thermodynamically stable lamellar phase region. To be able to use intercellular lipids as a drug carrier(i.e. as liposome and/or emulsion), a stable lamellar structure had to be developed with cholesterol and fatty acids. In the range of concentration that it is observed, the internal structures of tocomide and lipid complex with tocomide(LCT) 415 are optically clear and stable. The model liquid layer is particularly susceptible to inhibit transepidermal water loss and oxidative damage and a 2-dimensional Langmuir film was studied for the partial miscibility of lipids at the air-water interface. The structural properties of tocomide structure were also investigated. From the X-ray diffraction(XRD) results and polarized microscopic images, pure tocomide formed a liquid crystal at room temperature with lamellar periodicity to be 36.7Å (2Θ=2.41˚). Transepidermal water loss(TEWL) and antioxidation experimenta...