ABSTRACT
Liposomes in which sphingolipids are the building blocks have been termed “sphingosomes”. Among the many factors that contribute to the efficacy of liposomes in cosmetics, the chemical structure of their membrane components is of cardinal importance. The complex and varied chemical structure of sphingolipids sets a serious problem in quality control. For instance, the octyl glucoside/lipid ratio required for the transition of nonionic surfactant vesicles to mixed micelles is three times higher than it is for egg phosphatidyl choline small unilamellar liposomes. Similar adverse effects have been observed with some lipid-soluble nonionic surfactants. The main asset of vesicles for the alleviation of the “dry skin” syndrome is to be found in the emollient properties of their lipid components. Ionic amphiphiles, such as dicetyl phosphate, phosphatidic acid, cholesterol sulfate, cholesterol phosphate, lipoaminoacids and long-chain alkyl-ammonium salts are efficient for this purpose at concentrations less than 10% by weight of the total lipids.
