植物甾醇己二酸单酯对胆固醇胶束的沉淀作用

Enzymatic Synthesis of Phytosterol Adipates Monoesters and Their Precipitation Effecton Model Cholesterol Micelles

植物甾醇因优良的降胆固醇活性,以及预防心血管疾病的作用而受到广泛关注。植物甾醇二元酸单酯是游离植物甾醇结构修饰的重要中间体,通常使用化学方法获得。本研究旨在探究一种酶法制备植物甾醇二元酸单酯的技术,并探讨其体外降胆固醇的可能机制。以叔丁醇为反应溶剂,在脂肪酶Lipozyme TL IM催化下,β-谷甾醇己二酸乙烯酯水解为β-谷甾醇己二酸单酯,水解率在99%以上。与β-谷甾醇相比,β-谷甾醇己二酸单酯的结晶度降低,润湿性增强(接触角从131.4°降至98.6°),这有利于提高β-谷甾醇己二酸单酯掺入胆固醇模型胶束的能力,增大其胶束溶解度,扩大胶束疏水核尺寸。通过观察胶束相和沉淀相的微观结构,进一步确定β-谷甾醇己二酸单酯的体外降胆固醇活性主要体现在其对模型胶束的沉淀作用。本研究对开发植物甾醇膳食营养补充剂具有一定的社会价值和现实意义。

Phytosterols have received an extensive attention owing to their excellent cholesterol-lowering activity and the role in cardiovascular diseases prevention.Phytosterol diacid monoesters,the important intermediates in the structural modification of free phytosterols,were often obtained by chemical method with catalyst.The aim of this research was to provide a synthesis technology of phytosterol adipate monoesters and explore the possible mechanism on reducing cholesterol level in vitro.β-Sitosterol vinyl adipate was hydrolyzed toβ-sitosterol adipate monester in the presence of Lipozyme TL IM and tert-butanol,and the maximum hydrolysis rate was more than 99%.Compared with freeβ-sitosterol,β-sitosterol adipate monester possessed lower crystallinity and improved wetting properties.The contact angle was decreased from 131.4°to 98.6°.That was beneficial to dissolve in model cholesterol mixed micelles and swell micellar hydrophobic core.The microstructure of micellar and precipitation phase was observed and found further thatβ-sitosterol adipate monester kept the cholesterol-lowering activity in vitro due to its precipitation effect on model mixed micelles.This study has certain social value and practical significance to develop phytosterol dietary nutritional supplement.