Thermotropic behavior of stratum corneum lipids containing a pseudo‐ceramide

Abstract

The mechanism of the self-assembly of the lamellar structure of natural stratum corneum lipids (SCL) has been a subject of considerable interest. We have examined this question by using a synthetic pseudo-ceramide (sphingolipid E, SLE) which was analogous to the naturally occurring ceramide type 2. The thermotropic properties and the structural characteristics of SLE, together with other main components of SCL, fatty acids, and cholesterol, were investigated by differential scanning calorimetry and X-ray analysis. A mixture of SLE and stearic acid was in a stable alpha-form having a lamellar structure, which is very similar to that of natural SCL. However, lipid mixtures in which stearic acid were replaced by oleic acid did not form lamellar structures, and existed in the crystalline states. This indicates that the stable bilayer formation of the natural SCL is strongly dependent on the molecular fatty acid structure. Moreover, incorporation of cholesterol (0-50%) into equimolar mixtures of SLE/stearic acid and of SLE/oleic acid caused a marked decrease of melting entropies, while the aggregation states of both systems were not changed. This effect of cholesterol can be attributed to the disorder of the molecular packing. These results suggest that the hydrophobic interactions between the SCL are important for bilayer formation as are the hydrophilic interactions between the polar groups.

Thermal-history-dependent Phase Behavior of Ceramide Molecular Assembly in a UV-curable Acrylic Adhesive Resin

“…We concluded that the rapid cooling treatment induces the formation of a metastable amorphous-like phase in pure CER. For naturally occurring ceramides 14,29 and a synthetic pseudo-ceramide 30 , an exothermic peak has been distinctly observed. Hence, the appearance of the exothermic peak in the thermogram of the melt-quenched in-resin CER sample is not mainly caused by a specific interaction between the acResin ® and the CER, but it is due to the intrinsic nature of CER.…”

Intermolecular Interaction between a Synthetic Pseudoceramide and a Sterol-Combined Fatty Acid

“…1B). This diffuse reflection shows that there is a liquid-like packing of the hydrocarbon chains (22,23). Consequently, the hexagonal and liquid-like packing coexist in the SLE/stearic acid/cholesterol system, which is a simplified model for natural SCL (23).…”

“…lar structures were successfully prepared from SLE and long- as measured by high performance liquid chromatographic analysis. The cholesterol ester of 2-octadecenylsuccinic acid, cholesteryl hydrogen 2(3)-(2-octadecenyl)succinate (CEOS), was synthesized from 2-octadecenylsuccinic anhydride and cholesterol by the same procedure reported earlier (24). CEOS was obtained as a pair of two regioisomers having a 2-octadecenyl group in different positions of substitution in a weight ratio of about 1:1 (Scheme 1, 2a, and 2b).…”

“…However, lipid mixtures whose saturated fatty acid drous lipid mixtures were checked by Karl Fischer's method had been replaced by other lipids, such as oleic acid, cholesand were proven to be less than 0.1%. The samples were terol, or cholesteryl esters, failed to form bilayers and were then cooled to 25ЊC and maintained at that temperature for in rigid crystalline states (20,22).…”

“…In addition, we determined by extrapolation to the base line of the most have shown that incorporation of cholesterol into both the rapid rise in the excess heat capacity curve as a function of anhydrous and hydrated equimolar mixture of SLE and steatemperature. The melting enthalpy (DH m ) was determined ric acid caused an enhancement of the mobility of hydrocarby integrating the area under the curve from a plot of the bon chains of lipids (22,23).…”