Stratum corneum molecular mobility in the presence of natural moisturizers
Stratum corneum molecular mobility in the presence of natural moisturizers
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DOI：
10.1039/c4sm00137k
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发表时间：
2014-01-01
期刊：
影响因子：
3.4
通讯作者：
Sparr, Emma
中科院分区：
文献类型：
--
作者：
Bjorklund, Sebastian;Andersson, Jenny Marie;Sparr, Emma
皮肤的最外层，角质层（SC），是一种脂质蛋白膜，在干燥和寒冷的气候中会受到相当大的渗透压。天然保湿因子（NMF）由小分子和极性物质组成，像渗透剂一样可以保护生命系统免受渗透压力。NMF通常被声称可以增加SC中的水含量，从而保护皮肤免受干燥。在这项工作中，我们挑战这一建议的机制，并探讨NMF的脂质和蛋白质组分的影响，在SC。我们采用天然丰度C-13固态NMR方法来研究如何SC分子组分的影响尿素，甘油，吡咯烷酮羧酸（PCA），和尿刊酸（UCA），所有这些都是天然存在于SC的NMF化合物。用完整的SC、分离的角质细胞和模型脂质进行实验。NMR实验的组合提供了关于不同SC脂质和蛋白质组分的动力学的分子分辨定性信息。我们获得了这些NMF化合物与SC脂质和蛋白质相互作用的全新分子信息。我们表明，尿素和甘油，这也是常见的成分，在皮肤护理产品，增加SC脂质和蛋白质的分子流动性在中等相对湿度的SC组件是相当多的刚性在没有这些化合物。这种效应不能归因于SC水含量的增加。PCA没有检测到SC分子流动性的条件下调查的影响。它最终表明，更非极性的化合物，UCA，具体影响的SC脂质区域的流动性。目前的研究结果表明，NMF组分的作用，以保持流动性的SC分子组分在脱水条件下，在这样一种方式，SC的性能基本保持不变相比，更多的水合SC。这些发现提供了一个新的分子洞察如何在NMF和护肤产品中的小极性分子的行为，以保护人类皮肤干燥。
The outermost layer of the skin, the stratum corneum (SC), is a lipid-protein membrane that experiences considerable osmotic stress from a dry and cold climate. The natural moisturizing factor (NMF) comprises small and polar substances, which like osmolytes can protect living systems from osmotic stress. NMF is commonly claimed to increase the water content in the SC and thereby protect the skin from dryness. In this work we challenge this proposed mechanism, and explore the influence of NMF on the lipid and protein components in the SC. We employ natural-abundance C-13 solid-state NMR methods to investigate how the SC molecular components are influenced by urea, glycerol, pyrrolidone carboxylic acid (PCA), and urocanic acid (UCA), all of which are naturally present in the SC as NMF compounds. Experiments are performed with intact SC, isolated corneocytes and model lipids. The combination of NMR experiments provides molecularly resolved qualitative information on the dynamics of different SC lipid and protein components. We obtain completely novel molecular information on the interaction of these NMF compounds with the SC lipids and proteins. We show that urea and glycerol, which are also common ingredients in skin care products, increase the molecular mobility of both SC lipids and proteins at moderate relative humidity where the SC components are considerably more rigid in the absence of these compounds. This effect cannot be attributed to increased SC water content. PCA has no detectable effect on SC molecular mobility under the conditions investigated. It is finally shown that the more apolar compound, UCA, specifically influences the mobility of the SC lipid regions. The present results show that the NMF components act to retain the fluidity of the SC molecular components under dehydrating conditions in such a way that the SC properties remain largely unchanged as compared to more hydrated SC. These findings provide a new molecular insight into how small polar molecules in NMF and skin care products act to protect the human skin from drying.