Synchrotron X-ray diffraction study of the structure of oral stratum corneum model lipid membranes

Membranes modeling the lipid fraction of the mucous membrane of the human oral cavity have been studied by X-ray synchrotron diffraction. Ternary systems, composed of a mixture of sphingomyelin, dipalmitoylphosphatidylcholine, and dipalmitoylphosphatidylethanolamine with component weight ratios of 1: 2: 2 and 1: 2: 1, have lamellar structures in the gel phase at the physiological temperature (37A degrees C). An inverted hexagonal phase is formed in the system with 40% dipalmitoylphosphatidylethanolamine in the temperature range of 60-70A degrees C. This phase coexists with the liquid-crystalline lamellar phase in a narrow temperature range and completely surpresses the lamellar phase with an increase in temperature to 80A degrees C. Multi-component oral stratum corneum membranes are characterized by several lamellar phases at 20-37A degrees C and the coexistence of one or several lamellar phases with inverted hexagonal phase at 80-90A degrees C.