The effect of tocopherol on the structure and permeability of phosphatidylcholine liposomes
The effect of tocopherol on the structure and permeability of phosphatidylcholine liposomes
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DOI：
10.1016/j.jconrel.2011.12.029
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发表时间：
2012-06-10
影响因子：
10.8
通讯作者：
Quinn, Peter J.
中科院分区：
文献类型：
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作者：
Quinn, Peter J.
有许多将α - 生育酚作为稳定剂的磷脂配方，但关于α - 生育酚对磷脂结构和双层膜通透性影响的研究却很少。本研究采用同步辐射X射线粉末衍射方法来探究α - 生育酚如何改变二硬脂酰磷脂酰胆碱双层膜的结构。α - 生育酚的比例增加至20摩尔%时，会在双层膜中诱导出波纹结构。产生了两种类型的波纹结构，在冷冻断裂复型的电子显微照片中可以看到，其周期性分别为16纳米和12纳米。在37℃时，波纹结构中磷脂与α - 生育酚的化学计量比为8∶1。α - 生育酚的存在往往会使凝胶相磷脂的烃链相对于双层膜法线在20℃时的倾斜角从约34°减小到更垂直的方向。α - 生育酚比例的增加会逐渐降低磷脂从凝胶相到液晶相转变的温度。在1 - 棕榈酰 - 2 - 油酰 - 磷脂酰胆碱中，高达20摩尔%的α - 生育酚的存在会抑制酚红染料从脂质体中泄漏。将7摩尔%的α - 生育酚对泄漏的影响与含有50摩尔%胆固醇的磷脂脂质体进行了比较。含胆固醇的脂质体比含有α - 生育酚的囊泡对泄漏的抑制程度更大，但α - 生育酚在等摩尔比例下的效果与胆固醇相当。（C）2012爱思唯尔B.V. 保留所有权利。
There are numerous phospholipid formulations that incorporate alpha-tocopherol as a stabilizing agent but there are few studies of the effect of alpha-tocopherol on phospholipid structure and bilayer permeability. This study uses synchrotron X-ray powder diffraction methods to investigate how alpha-tocopherol changes the structure of distearoylphosphatidylcholines bilayers. Increasing proportions of alpha-tocopherol up to 20 mol% induces ripple structures in the bilayers. Two types of ripple structure are produced which are seen in electron micrographs of freeze-fracture replicas with periodicities of 16 and 12 nm, respectively. The stoichiometry of phospholipid: alpha-tocopherol in the ripple structures at 37 degrees C is 8:1. The presence of alpha-tocopherol tends to reduce the angle of tilt of the hydrocarbon chains of the phospholipid in the gel phase from about 34 to the bilayer normal at 20 degrees C into a more vertical orientation. Increasing proportions of alpha-tocopherol progressively decrease the temperature of the gel to liquid-crystal phase transition of the phospholipid. The presence of up to 20 mol% alpha-tocopherol in 1-palmitoyl-2-oleoyl-phosphocholine inhibits leakage of phenol red dye from liposomes. The effect of 7 mol% alpha-tocopherol on leakage was compared with phospholipid liposomes containing 50 mol% cholesterol. The cholesterol-containing liposomes inhibited leakage to a greater extent than the vesicles incorporating alpha-tocopherol but the effect of alpha-tocopherol at equivalent molar proportions was comparable to cholesterol. (C) 2012 Elsevier B. V. All rights reserved.