Quantitation of In Vivo Human Lutein Metabolism

描述（由申请人提供）：叶黄素是一种含氧类胡萝卜素（叶黄素），存在于深绿色叶菜中。膳食叶黄素和玉米黄质积累在视网膜的黄斑区，并被假设为保护黄斑作为抗氧化剂和光学过滤器，可以降低年龄相关性黄斑变性的风险。尽管存在这些关系，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叶黄素代谢的动态和动力学行为在一小部分健康男性和女性谁消费正常饮食，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），并给予溶于橄榄油（0.5 g/kg体重）并掺入香蕉奶昔中的单剂量14 C-叶黄素（70 mcg，36 nCi）。将在即将给药前采集基线血样（10 mL），并以不同的间隔持续至给药后100天，以确保14 C标记的叶黄素完全平衡至最慢的转化叶黄素库中，这可能影响研究后期的血浆动力学。将在单次超离心中从血浆中分离五种脂蛋白。将采集尿液和粪便，直至给药后21天。将在Lawrence Livermore国家实验室（Livermore，CA）的加速器质谱分析中心（AMS）测量每个生物样品的14 C含量。血浆和血浆脂蛋白样品中14 C的化学特性也将通过使用非放射性标准品在一个实施方案中测定，母体化合物（14 C-叶黄素）和两种代谢物（3-羟基-β-胡萝卜素-3 '-酮和3'-肾上腺素）。 HPLC-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用一名正常成年女性证明了我们的方法的可行性。我们在给药后相对较长的时间内使用了高血浆采样密度，以在稳态条件下获得比科学文献中现有的任何数据集更详细/完整的数据集。然后，如果可以规定叶黄素的特定代谢功能，则可以确定叶黄素的最低摄入量以维持这些关键功能，例如维持最佳黄斑色素光密度和最小化黄斑变性的风险。公共卫生相关性：叶黄素是一种脂溶性化合物，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菜中。叶黄素可以保护黄斑，视网膜的一个区域，作为抗氧化剂和光学过滤器，可以降低年龄相关性黄斑变性的风险。 尽管存在这些关系，但人们对叶黄素代谢的定量方面知之甚少，因为它发生在人体内。以前的试点研究表明，需要更好地了解从饮食中吸收和代谢叶黄素，以及它在体内的积累，以了解叶黄素如何帮助改善视力。因此，本研究的目的是确定人体如何使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.