The outermost layer of the skin, known as the stratum corneum (horny layer), protects a body from damage by external stresses including drying, and maintains moisture in the skin. In keeping moisture in the stratum corneum, keratin fibers inside the corneocytes (horny cells) , ceramides and other lipids between those cells play a key role.
Keratin is a fibrous protein that is a main structural component of the coenocytes of the stratum corneum, accounting for 80% of their protein content. The amorphous domains at the head and tail of the keratin fiber effectively hold moisture. Ceramides and other lipids form lamellar (layered) structures between the cells hold moisture and keep it from freezing even at temperatures as low as -40 degrees C. It was Kao that discovered these natural mechanisms for maintaining the skin's moisture. We have developed our own unique moisture-retention technologies based on these mechanisms and apply them in the formulation of such skin care and cosmetic lines as Sofina and Curel.
Kao also discovered that certain natural moisturizing factor (NMF), such as arginine, enhance the moisture-retention capacity of the skin's keratin fibers. By using knowledge of this mechanism, we developed our own active ingredient, Kerato NMF, which boosts keratin's moisture retention to an even greater degree than NMF.
With natural ceramide as a lead compound, we analyzed the mechanism of structural moisture retention at the molecular level and succeeded in the developing Sphingolipid E, which exhibited moisture-retention properties equal to or greater than those of natural ceramides. In addition, we extended our research to develop emulsifying technology to enhance the efficacy of Sphingolipid E, taking our hint from the composition and structure of the stratum corneum. Recently, we succeeded in developing a preparation that mimics the lamellar structures of the intercellular lipids in the stratum corneum for excellent moisture retention.
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