Abstract
The formation mechanism of multilamellar emulsions of artificial stratum corneum lipids containing synthetic pseudo-ceramide and their physiological effects on dry and scaly skin, lacking the function of stratum corneum lipids, have been investigated. A pseudo-ceramide being the analogous molecular structure to the natural occurring ceramide was synthesized according to the molecular design. The highly selective reaction of the synthesis enabled the industrial production of this synthetic ceramide. Then the artificial stratum corneum lipids, possessing self-organizing lamellar structure, were prepared by using the synthetic pseudo-ceramide in combination with amphiphilic molecules. It was confirmed that these amphiphilic molecules stabilized the lamellar association structure by intermolecular interactions thus enhancing the bound water content. Using these artificial stratum corneum lipids as the oil phase, we obtained multilamellar emulsion in which each emulsion droplet possesses a concentric lamellar structure. The multilamellar emulsion recovered the water-retaining ability of stratum corneum, which was not recovered solely by the treatment of an ordinary emulsion, and improved the scaling to restore the fine texture of the skin. It is concluded that we could succeed in developing a highly functional skin protection cosmetic, a multilamellar emulsion, which recovers water-retaining ability and adhesion of corneocytes in the identical mechanism with intercellular stratum corneum lipids.
