Cholesterol ester hydroperoxide (CEOOH) is one of the main lipid oxidation products contained in oxidized low-density lipoprotein (LDL). Previous studies suggest that CEOOH in oxidized LDL is closely related to several diseases. Of the oxidation mechanisms of cholesterol ester (CE) in vivo, it has been suggested that enzymatic oxidation induced by lipoxygenase (LOX) plays an important role. Thus, we attempted to develop a method that can evaluate the enzymatic oxidation of CE via the diastereoselective separation of CEOOH bearing 13RS-9Z,11E-hydroperoxy-octadecadienoic acid (13(RS)-HPODE CE). Firstly, we synthesized the standard of 13(RS)-HPODE CE. Using this standard, the screening of analytical conditions (i.e., column, mobile phase, and column temperature) was conducted, and separation of the diastereomers of 13(RS)-HPODE CE was achieved. The diastereoselective separation of 13(RS)-HPODE CE was also confirmed by LC-MS/MS. The developed method (column, CHIRALPAK IB N-3; mobile phase, hexane:ethanol (100:1, v/v); column temperature, 0 °C) can distinguish between enzymatic oxidation and other oxidation mechanisms of CE. Thus, the method can be expected to provide a greater understanding of the biochemical oxidation mechanisms in vivo. Such information will be essential to further elucidate the involvement of CEOOH in various diseases.

中文翻译：

---

使用 LC-MS/MS 直接分离胆固醇酯氢过氧化物的非对映异构体以评估酶促脂质氧化

胆固醇酯氢过氧化物 (CEOOH) 是氧化低密度脂蛋白 (LDL) 中所含的主要脂质氧化产物之一。先前的研究表明，氧化型低密度脂蛋白中的 CEOOH 与多种疾病密切相关。在体内胆固醇酯 (CE) 的氧化机制中，已表明脂氧合酶 (LOX) 诱导的酶促氧化起重要作用。因此，我们尝试开发一种方法，通过非对映选择性分离带有 13RS-9Z,11E-氢过氧-十八碳二烯酸 (13(RS)-HPODE CE) 的 CEOOH 来评估 CE 的酶促氧化。首先，我们合成了 13(RS)-HPODE CE 的标准品。使用该标准进行分析条件（即色谱柱、流动相和柱温）的筛选，实现了13(RS)-HPODE CE的非对映异构体的分离。LC-MS/MS 也证实了 13(RS)-HPODE CE 的非对映选择性分离。开发的方法（色谱柱，CHIRALPAK IB N-3；流动相，己烷:乙醇（100:1，v/v）；柱温，0 °C）可以区分 CE 的酶促氧化和其他氧化机制。因此，该方法有望提供对体内生化氧化机制的更好理解。这些信息对于进一步阐明 CEOOH 在各种疾病中的作用至关重要。该方法有望提供对体内生化氧化机制的更深入了解。这些信息对于进一步阐明 CEOOH 在各种疾病中的作用至关重要。该方法有望提供对体内生化氧化机制的更深入了解。这些信息对于进一步阐明 CEOOH 在各种疾病中的作用至关重要。