Formation of Stable Lamellar Structures with Pseudo-Ceramide

One of the functions of the intercellular lipids of the stratum corneum is to control the permeation of molecules. Their main component being ceramides, the pseudo-ceramide sphingolipid E (SLE), which is similar in structure to natural ceramide type II, is considered a potential drug carrier. Therefore, the internal structure of SLE was investigated. SLE by itself forms a meta-stable lamellar structure that gradually crystallizes out as confirmed by X-ray analysis. With reference to naturally occurring lamellar structures of intercellular lipids, stearic acid was found to be able to stabilize the lamellar structure of SLE, when added within a defined concentration range. It was further demonstrated that both the hydrophobic and the hydrophilic portions of the stearic acid molecule contribute to the stability. Short-chained fatty acids lacking a long hydrophobic chain resulted in unstable structures. Likewise, the addition of less polar derivatives of stearic acid (stearic alcohol and hexadecane, reps.) could not maintain a lamellar structure. Only the strong hydrogen bonds between the carboxy group of stearic acid and the amido-carbonyl group of SLE produced a stable lamellar structure as was confirmed by FT-IR analysis.