Plant sterols have attracted increasing attention due to their excellent cholesterol-lowering activity. However, free plant sterols have some characteristics of low oil solubility, water insolubility, high melting point, and low bioavailability, which greatly limit their application in foods. Numerous studies have been undertaken to modify their chemical structures to improve their chemical and physical properties in meeting the needs of various applications. The present review is to summarize the literature and update the progress on structural modifications of plant sterols in the following aspects: (i) synthesis of plant sterol esters by esterification and transesterification with hydrophobic fatty acids and triacylglycerols to improve their oil solubility, (ii) synthesis of plant sterol derivatives by coupling with various hydrophilic moieties to enhance their water solubility, and (iii) mechanisms by which plant sterols reduce plasma cholesterol and the effect of structural modifications on plasma cholesterol-lowering activity of plant sterols.

中文翻译：

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植物甾醇：化学和酶结构修饰及其对降低胆固醇活性的影响

植物甾醇由于其出色的降胆固醇活性而引起了越来越多的关注。然而，游离植物固醇具有低油溶性，水不溶性，高熔点和低生物利用度的一些特征，这极大地限制了它们在食品中的应用。为了满足各种应用的需要，已经进行了许多研究来改变其化学结构以改善其化学和物理性质。本综述旨在总结文献，并在以下方面更新植物甾醇的结构修饰进展：（i）通过与疏水性脂肪酸和三酰基甘油酯化和酯交换反应合成植物甾醇酯，以改善其油溶性，