Effect of cholesterol on miscibility and phase behavior in binary mixtures with synthetic ceramide 2 and octadecanoic acid. Infrared studies.
Effect of cholesterol on miscibility and phase behavior in binary mixtures with synthetic ceramide 2 and octadecanoic acid. Infrared studies.
复制标题
胆固醇对合成神经酰胺 2 和十八烷酸二元混合物中混溶性和相行为的影响。
DOI：
10.1016/s0005-2736(01)00339-x
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Moore,DJ
中科院分区：
文献类型：
--
作者：
Chen,H;Mendelsohn,R;Rerek,ME;Moore,DJ
角质层的三种主要脂质成分，即神经酰胺、游离脂肪酸和胆固醇，在维持皮肤屏障中起着重要作用。目前的研究旨在了解这些脂质的可溶解性和分子间相互作用。为此，傅立叶变换红外光谱研究的三种可能的等摩尔二元混合物的胆固醇，一种合成的非羟基化脂肪酸N-酰基鞘氨醇与C18链长（N-硬脂酰鞘氨醇，接近人类神经酰胺2），和硬脂酸进行。亚甲基伸缩振动和剪切振动的热致响应分别用于评价链构象和堆积。选择性perdeuteration，无论是硬脂酸或神经酰胺酸链，允许单独和同时评价的构象顺序和包装性能的鞘氨醇链，酰胺连接的脂肪酸链和/或硬脂酸链。胆固醇在生理温度下与神经酰胺混合良好，而硬脂酸仅在相对较高的温度下与胆固醇混溶，其中脂肪酸是无序的。硬脂酸和神经酰胺之间的复杂的相互作用被检测到。一个单独的富含脂肪酸的相持续到至少50°C，而在更高的温度下，组分似乎是相当混溶的。然而，表明脂肪酸与神经酰胺基链的优先缔合。研究的二元系统都没有表现出类似于这些物质的三元混合物中的相容性和相互作用，这些物质被广泛用于模拟角质层。胆固醇在控制三元体系的溶解特性中的作用是明显的。
The three main lipid components of the stratum corneum, namely ceramides, free fatty acids and cholesterol, play a fundamental role in the maintenance of the skin barrier. The current investigation is aimed toward understanding the miscibility and intermolecular interactions of these lipids. Toward this end, Fourier transform infrared spectroscopic studies of the three possible equimolar binary mixtures of cholesterol, a synthetic non-hydroxylated fatty acid N-acyl sphingosine with a C18 chain length (N-stearoylsphingosine, approximating human ceramide 2), and stearic acid were undertaken. The thermotropic responses of the methylene stretching and scissoring vibrations were used to evaluate chain conformation and packing respectively. Selective perdeuteration, of either the stearic acid or the ceramide acid chains, permitted separate and simultaneous evaluation of the conformational order and packing properties of the sphingosine chain, the amide linked fatty acid chains and/or the stearic acid chain. Whereas cholesterol mixed well with ceramide at physiological temperatures, the stearic acid was miscible with the cholesterol only at relatively high temperatures where the fatty acid is disordered. A complex interaction between stearic acid and ceramide was detected. A separate fatty acid-rich phase persisted until at least 50°C, whereas at higher temperatures the components appear to be quite miscible. However, a preferential association of the fatty acid with the ceramide base chain is indicated. None of the binary systems studied exhibit miscibility and interactions resembling those in the ternary mixtures of these substances, which is widely used to model stratum corneum. The role of cholesterol in controlling the miscibility characteristics in the ternary system is evident.