a Department of Medicine and the Western Australian Heart Research Institute, University of Western Australia , Perth , Western Australia.
Redox Rep. 1996 Feb;2(1):25-34. doi: 10.1080/13510002.1996.11747023.
Cholesterol oxidation products have been demonstrated to possess a wide variety of biological properties and have been implicated in playing an important role in the development of atherosclerosis. We have developed an analytical method using capillary gas chromatography-mass spectrometry (GC-MS) for the analysis of cholesterol oxidation products in low-density lipoprotein (LDL). The method uses programmed multiple selected ion monitoring (SIM), providing enhanced sensitivity and accuracy of peak detection over full-scan mass spectra. The major oxidation products of cholesterol in oxidized LDL were identified as 7β-hydroxy-cholesterol and 7-keto-cholesterol. Minor products included 4β-hydroxy-cholesterol, 6β-hydroxy-cholesterol and cholesterol-5α,6α-epoxide. Native LDL contains 7-lathosterol, which is a biosynthetic precursor of cholesterol, as well as low levels of 7β-hydroxy-cholesterol and 7-keto-cholesterol. 7-Lathosterol was not detected in oxidized LDL. A time course oxidation of native LDL with 8 μM CuCl2 demonstrated a rapid increase in 7β-hydroxy-cholesterol and 7-keto-cholesterol over the first 4 h. Cholesterol-5α,6α-epoxide, and β4-hydroxy- and 6β-hydroxy-cholesterol levels increased gradually, while 7-lathosterol decreased over the same period. This method was used to measure the levels of 7-lathosterol and cholesterol oxides in the LDL of 20 healthy subjects in order to establish the mean concentration and a reference range. This method can be used for the characterization and quantitation of oxysterols in native and oxidized LDL and may afford an additional index of oxidative modification of plasma lipoproteins.
胆固醇氧化产物具有广泛的生物学特性，并被认为在动脉粥样硬化的发展中起着重要作用。我们开发了一种使用毛细管气相色谱-质谱联用（GC-MS）分析低密度脂蛋白（LDL）中胆固醇氧化产物的分析方法。该方法使用程序多次选择离子监测（SIM），与全扫描质谱相比，提高了峰检测的灵敏度和准确性。氧化 LDL 中胆固醇的主要氧化产物被鉴定为 7β-羟基胆固醇和 7-酮胆固醇。次要产物包括 4β-羟基胆固醇、6β-羟基胆固醇和胆固醇-5α，6α-环氧化物。天然 LDL 中含有胆固醇的生物合成前体 7-羊毛甾醇，以及低水平的 7β-羟基胆固醇和 7-酮胆固醇。氧化 LDL 中未检测到 7-羊毛甾醇。用 8 μM CuCl2对天然 LDL 进行时间过程氧化，在最初的 4 小时内，7β-羟基胆固醇和 7-酮胆固醇迅速增加。胆固醇-5α，6α-环氧化物以及β4-羟基和 6β-羟基胆固醇的水平逐渐增加，而 7-羊毛甾醇在此期间减少。该方法用于测量 20 名健康受试者 LDL 中的 7-羊毛甾醇和胆固醇氧化物的水平，以确定平均值和参考范围。该方法可用于天然和氧化 LDL 中氧化固醇的特征和定量，并可能提供血浆脂蛋白氧化修饰的附加指标。
