The ester-linked ω-hydroxy acyl chain linked to a sphingosine base referred to as CER EOS is essential for the skin barrier lipid organization. While the majority of the skin lipids form a dense, crystalline structure, associated with low permeability, the unsaturated moiety of CER EOS, (either the linoleate or the oleate chain) exists in a liquid phase at the skin's physiological temperature. Thus, the relationship between CER EOS and barrier function is not entirely comprehended. We studied the permeability and lipid organization in skin lipid models, gradually increasing in CER EOS concentration, mixed with non-hydroxy sphingosine-based ceramide (CER NS) in an equimolar ratio of CERs, cholesterol, and free fatty acids (FFAs) mimicking the ratio in the native skin. A significant increase in the orthorhombic-hexagonal phase transition temperature was recorded when CER EOS concentration was raised to 70 mol% of the total CER content and higher, rendering a higher fraction of lipids in the orthorhombic phase at the expense of the hexagonal phase at physiological temperature. The model's permeability did not differ when CER EOS concentration ranged between 10 and 30% but increased significantly at 70% and higher. Using CER EOS with a perdeuterated oleate chain, it was shown that the fraction of lipids in a liquid phase increased with CER EOS concentration, while the neighboring CERs and FFAs remained in a crystalline state. The increased fraction of the liquid phase therefore, had a stronger effect on permeability than the increased fraction of lipids forming an orthorhombic phase.

与鞘氨醇碱（称为CER EOS）连接的酯键连接的ω-羟基酰基链对于皮肤屏障脂质的组织至关重要。尽管大多数皮肤脂质形成致密的晶体结构并伴有低渗透性，但CER EOS的不饱和部分（亚油酸酯或油酸酯链）在皮肤的生理温度下呈液相状态。因此，不能完全理解CER EOS与屏障功能之间的关系。我们研究了皮肤脂质模型中的渗透性和脂质组织，其CER EOS浓度逐渐增加，并与非羟基鞘氨醇基神经酰胺（CER NS）混合，以等摩尔比率的CER，胆固醇和游离脂肪酸（FFA）模仿了天然皮肤中的比例。当CER EOS浓度提高到总CER含量的70 mol％或更高时，正交六方相转变温度会显着升高，从而使正交相中的脂质比例更高，而在生理上却损失了六方相温度。当CER EOS浓度在10％到30％之间时，模型的渗透率没有差异，但在70％或更高时显着增加。使用具有氘代油酸酯链的CER EOS，显示液相中的脂质比例随CER EOS浓度的增加而增加，而相邻的CER和FFA仍保持结晶状态。因此，增加的液相部分比形成正交相的脂质的增加部分对渗透性具有更强的影响。