Practical syntheses of D-erythro and L-threo-ceramide [NDS] and difference in contribution of each isomer in microstructure of stratum corneum intercellular lipids

The aims of this study were to develop the efficient synthetic procedure of optically active ceramide and to investigate contribution of stereochemistry of ceramide in stratum corneum of the skin. For the stereoselective asymmetric syntheses of both D-erythro and L-threo-CER [NDS], the practical synthetic routes, utilizing chiral ruthenium catalyzed dynamic kinetic resolution (DKR), were accomplished without any expensive reagents and no chromatographic purification was required for any of intermediates. From the physicochemical investigation of CER [NDS] isomers on the intercellular lipids in the stratum corneum, using simple synthetic lipid model composed of CER [NDS],CHOL and PA, it was clarified that optically active CER [NDS] play a critical role in intercellular lipid model of stratum corneum to form lamellar structure of which essential to barrier function of the mammalian skin.