LC/MS of Large Atherogenic Lipid Oxidation Products

说明（由申请人提供）：三酰甘油（TAG）含有不饱和位点，暴露在空气中或加热时易氧化。这些TAG形成多种含有多种官能团的脂肪酸的初级氧化产物，如氢过氧化物、环氧化物、酮类和醇类。脂肪酸氧化产物已被证明具有显著的动脉粥样硬化风险。氧化产物已被证明与刷状边缘细胞结合，然后形成低密度脂蛋白（LDL）。P.I.首创的新分析方法首次直接鉴定了由几个氧化TAG连接而成的大分子量TAG氧化产物（TAGOX）。这些大的低聚TAGOX值得进一步研究，因为它们是典型美国人日常饮食的一部分，但它们以前从未被表征过。我们提出液相色谱联用电喷雾电离质谱法（ESI-MS）对油加热后产生的大型含氧低聚物进行分析。我们将表征包含两个（二聚体），三个（三聚体）或四个（四聚体）共价结合在一起的三酰基甘油的完整低聚物。这些分子含有氧官能团，这些官能团具有反应性，可以使氧化脂肪酸结合到生物组织中，如低密度脂蛋白（LDL）。我们将分析三油酸（橄榄油和菜籽油的主要成分）加热0小时的氧化产物。1小时。3小时。6小时。测定氧化引起的降解的开始和程度。我们将检查用0 ppm、100 ppm和400 ppm α生育酚（维生素E）处理的加热油样品，以证明加入抗氧化剂可以显著减少氧化。本研究首次直接鉴定了高分子量氧化产物的特定分子种类。我们提出用液相色谱/质谱法研究模拟油形成的产物以及在加热油中煎炸的薯片提取的产物。表征这些高分子量氧化低聚物将提供前所未有的洞察机制，通过膳食油被氧化，并使可纳入生物组织。

DESCRIPTION (provided by applicant): Triacylglycerols (TAG) contain sites of unsaturation that are susceptible to oxidation when exposed to air, or when heated. These TAG form a variety of primary oxidation products that contain fatty acids with multiple functional groups, such as hydroperoxides, epoxides, ketones and alcohols. Fatty acid oxidation products have been shown to represent a significant atherosclerotic risk. Oxidation products have been shown to be incorporated into brush border cells, and then into low-density lipoprotein (LDL). New analytical methodologies that the P.I. is pioneering have allowed large, high molecular weight (MW) TAG oxidation products (TAGOX), made from the joining together of several oxidized TAG, to be directly identified for the first time. These large, oligomeric TAGOX deserve further study because they are routinely consumed as part of the typical American diet, yet they have never before been characterized. We propose to use liquid chromatography coupled with electrospray ionization-mass spectrometry (ESI-MS) for analysis of the large oxygen-containing oligomers produced by heated oils. We will characterize intact oligomers containing two (dimers), three (trimers) or four (tetramers) triacylglycerols covalently bonded together. These molecules contain oxygen functional groups that are reactive and could allow oxidized fatty acids to be incorporated into biological tissue, such as low-density lipoprotein (LDL). We will analyze oxidation products from triolein (the major component in olive and canola oils) heated for 0 hr., 1 hr., 3 hr., and 6 hr. to determine the onset and extent of degradation due to oxidation. We will examine heated oil samples treated with 0 ppm, 100 ppm, and 400 ppm alpha tocopherol (vitamin E) to demonstrate that oxidation can be significantly reduced by incorporation of antioxidants. This research will represent the first time that the specific molecular species of high molecular weight oxidation products have been directly identified. We propose to use LC/MS to study the products formed by model oils and also the products extracted from potato chips fried in the heated oils. The characterization of these high molecular weight oxidized oligomers will provide unprecedented insight into the mechanisms by which dietary oils are oxidized and made available for incorporation into biological tissue.