Quantitation of In Vivo Human Lutein Metabolism

描述(申请人提供)：叶黄素是一种含氧类胡萝卜素(叶黄素)，存在于深绿色叶类蔬菜中。膳食中的叶黄素和玉米黄质积累在视网膜的黄斑区域，并被认为通过作为抗氧化剂和光学过滤器来保护黄斑，从而降低与年龄相关的黄斑退化的风险。尽管有这些关系，但人们对人体内叶黄素和玉米黄质代谢的定量方面知之甚少。拟议项目的总体目标是描述一小部分健康男性和女性中叶黄素代谢的动态和动力学行为，这些健康男性和女性食用正常饮食，不使用补充剂。为此，将招募12名志愿者，6名女性和6名男性，并将14C-叶黄素(70微克，36 NCI)溶解于橄榄油(0.5g/kg体重)并加入香蕉奶昔中。在给药前将采集基线血样(10毫升)，并持续不同的时间间隔，直到给药后100天，以确保14C标记的叶黄素完全平衡到最慢的翻转叶黄素池中，这可能会影响研究后期的血浆动力学。这五种脂蛋白将在一次超速离心中从血浆中分离出来。尿液和粪便将被收集，直到服药后21天。每个生物样本的14C含量将在位于加州利弗莫尔的劳伦斯·利弗莫尔国家实验室的加速器质谱学(AMS)中心进行测量。血浆和血浆脂蛋白样品中的14C的化学同一性也将通过使用非放射性标准来确定，包括母体化合物(14C-叶黄素)和两种代谢产物(3-羟基-b-e-胡萝卜素-3‘-酮和3’-胡萝卜素)。 高效液相-光电二极管阵列检测器系统。利用该数据集，我们将构建一个人体叶黄素代谢的动力学模型。我们已经使用我们在本申请中描述的方案在一名正常成年妇女身上证明了我们的方法的可行性。自给药以来，我们在相当长的时间内使用了较高的血浆采样密度，以获得比科学文献中已有的任何数据更详细/完整的稳态数据集。然后，如果能够规定叶黄素的特定代谢功能，就有可能确定维持这些关键功能的叶黄素的最低摄入量，例如，保持最佳的黄斑色素光密度，将黄斑变性的风险降至最低。与公众健康相关：叶黄素是一种脂溶化合物，与β-胡萝卜素属于同一家族。叶黄素天然存在于许多食物中，但主要存在于深绿色叶类蔬菜中。叶黄素可以通过作为抗氧化剂和滤光片来保护黄斑，这是视网膜的一个区域，可以降低老年性黄斑变性的风险。尽管有这些关系，但人们对人体内发生的叶黄素代谢的定量方面知之甚少。以前的试点研究表明，需要更好地了解叶黄素从饮食中的吸收和代谢，以及它在体内的积累，才能了解叶黄素是如何工作的，以帮助改善视力。因此，这项研究的目的是确定人体如何利用叶黄素和其他相关化合物。

DESCRIPTION (provided by applicant): Lutein is an oxygenated carotenoid (xanthophyll) found in dark green leafy vegetables. Dietary lutein and zeaxanthin accumulate in the macula region of the retina and are hypothesized to protect the macula by acting as antioxidant and optical filters that may lower the risk of age related macular degeneration. Despite these relationships little is known about the quantitative aspects of lutein and zeaxanthin metabolism as it occurs in vivo in humans. The overall objective of the proposed project is to describe the dynamic and kinetic behavior of lutein metabolism in a small population of healthy men and women who consume a normal diet and do not use supplements. For this purpose 12 volunteers, 6 women and 6 men, will be recruited and administered a single dose of 14C-lutein (70 mcg with 36 nCi) dissolved into olive oil (0.5 g/kg body weight) and incorporated in a banana milk shake. A baseline blood sample (10 mL) will be taken just before the dose is administered and continued at various intervals until 100 days post dose to ensure that the 14C labeled lutein is fully equilibrated into the slowest turning over lutein pool that can affect the plasma kinetics late in a study. The five lipoprotein classes will be separated from plasma in a single ultracentrifugation. Urine and feces will be collected until 21 days post dose. The 14C content of each biological sample will be measured at the Center for the Accelerator Mass Spectrometry (AMS) at Lawrence Livermore National Laboratory (Livermore, CA). The chemical identity of the 14C in plasma and plasma lipoprotein samples will also be determined, parent compound (14C-lutein) and two metabolites (3-hydroxy-b-e-caroten-3'-one and 3'-epilutein) by using non-radioactive standards in an HPLC-photodiode array detector system. Using the dataset, we will construct a kinetic model of human lutein metabolism. We have already demonstrated the feasibility of our approach with one normal adult woman using the protocol we describe in the present application. We used a high sampling density of plasma over a relatively long time since dosing to acquire a much more detailed/complete dataset under steady state conditions than any already existing in the scientific literature. Then if specific metabolic functions for lutein can be stipulated, it will be possible to determine a minimum intake of lutein to sustain these critical functions, such as, maintaining optimum macular pigment optical density and minimizing the risk of macular degeneration. PUBLIC HEALTH RELEVANCE: Lutein is a fat-soluble compound that belongs to the same family as the beta-carotene. Lutein occurs naturally in many foods, but primarily in dark green leafy vegetables. Lutein may protect the macula, a region of the retina, by acting as antioxidant and optical filters which may lower the risk of age related macular degeneration. Despite these relationships little is known about the quantitative aspects of lutein metabolism as it occurs in vivo in humans. Previous pilot studies have shown that a better understanding of the absorption and metabolism of lutein from the diet, and its accumulation in the body is needed to understanding how lutein works to help better vision. Therefore, the purpose of this study is to determine how the human body uses lutein and other related compounds.