Mel'nikov Sergey M, Seijen ten Hoorn Jack W M, Eijkelenboom Astrid P A M
Foods Research Centre, Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands.
Chem Phys Lipids. 2004 Feb;127(2):121-41. doi: 10.1016/j.chemphyslip.2003.09.015.
The effect of a plant sterol, beta-sitosterol (SI), and a plant stanol, sitostanol (SS), on the solubilization of cholesterol (CH) by model dietary mixed micelles was examined under in vitro conditions with the use of gas chromatography, isothermal titration calorimetry, NMR spectroscopy and cryogenic transmission electron microscopy techniques. Free SI and SS were shown to reduce the concentration of CH in dietary mixed micelles via a dynamic competition mechanism. CH, SI and SS affect the microstructure of lipid vesicles and influence the process of amphiphilic self-assembly of nutrients in the gut with the formation of dietary mixed micelles in a similar manner. Therefore, substitution of CH by phytosterols and phytostanols in the diet does not lead to the notable changes in the mechanism of dietary mixed micelle formation and does not affect the process of the intestinal transport of nutrients and drugs via the micellar diffusion mechanism. Our experimental findings demonstrate that the introduction of plant sterols and plant stanols into the diet is clearly beneficial for the reduction of the intestinal uptake of cholesterol. Due to the limited capacity of dietary mixed micelles to embody hydrophobic sterol/stanol molecules, the micellar concentration of cholesterol is reduced and hence, its transport towards the intestinal brush border membrane decreases.
在体外条件下，利用气相色谱、等温滴定量热法、核磁共振光谱和低温透射电子显微镜技术，研究了植物甾醇β-谷甾醇（SI）和植物甾烷醇谷甾烷醇（SS）对模型膳食混合胶束溶解胆固醇（CH）的影响。游离的SI和SS通过动态竞争机制降低了膳食混合胶束中CH的浓度。CH、SI和SS影响脂质囊泡的微观结构，并以类似方式影响肠道中营养物质的两亲性自组装过程以及膳食混合胶束的形成。因此，饮食中用植物甾醇和植物甾烷醇替代CH不会导致膳食混合胶束形成机制发生显著变化，也不会影响营养物质和药物通过胶束扩散机制的肠道运输过程。我们的实验结果表明，在饮食中添加植物甾醇和植物甾烷醇显然有利于减少肠道对胆固醇的吸收。由于膳食混合胶束容纳疏水性甾醇/甾烷醇分子的能力有限，胆固醇的胶束浓度降低，因此其向肠道刷状缘膜的转运减少。
