Influence of the level of cholesteryl sulfate present in stratum corneum lipid liposomes on their stability against Triton X-100

The interaction of Triton X-100 (TX-100) with stratum corneum (SC) lipid li posomes varying the proportion of cholesteryl sulfate (Chol-sulf) was inves tigated. The surfactant/lipid molar ratios and the bilayer/aqueous phase pa rtition coefficients were determined at sublytic level by monitoring the ch anges in the fluorescence intensity of liposomes due to the 5(6) carboxyflu orescein released from the interior of vesicles, The fact that the free sur factant concentration was always lower than the surfactant CMC indicates th at permeability changes were mainly ruled by the action of surfactant monom ers in all cases. The lowest surfactant ability to alter the permeability o f SC liposomes and highest surfactant affinity with these bilayer structure s was reached when the proportion of Chol-sulf in bilayers was 10%. Futherm ore, the highest resistance of SC liposomes to be solubilized by TX-100 (vi a mixed micelle formation) also occurred at this Chol-sulf proportion, whic h corresponds to that existing in the intercellular SC lipids, These surfac tant effects may be related to the reported dependencies between the level of Chol-sulf in the intercellular lipids and the abnormalities in the skin properties as the barrier function. (C) 1999 Academic Press.