COMPARATIVE ABSORPTION AND METABOLISM OF CAROTENOIDS

类胡萝卜素色素目前被用来防止糖尿病的发展 与红细胞生成性原卟啉相关的光敏感性和某些 其他皮肤病。类胡萝卜素类色素也被证明是 在动物模型和一些流行病学研究中的抗癌作用。这个 具有维生素A活性的类胡萝卜素也发挥着重要作用，如 维生素A的饮食来源，特别是在发展中国家， 获得合成维生素A的机会有限。出于这些原因，它是 重要的是要了解新陈代谢和功能的各种 类胡萝卜素。目前，人们对人体内的命运知之甚少 那些没有维生素A活性的色素。 因此，我们计划研究两种物质的吸收、运输和代谢。 没有维生素A活性的类胡萝卜素--番茄红素是主要的类胡萝卜素 番茄，是血液中类胡萝卜素含量的重要组成部分 和角黄素，一种用于食品色素的色素，它是 用于治疗光敏性皮肤病，已被证明 在动物模型中具有抗癌活性。吸收和吸收 还将研究β-胡萝卜素的新陈代谢，将其与 另外两种颜料。这些研究将利用C14标记的类胡萝卜素 用于研究大鼠和猴子的吸收、血液运输、细胞 和细胞内色素的位置，以及C13标记的类胡萝卜素 人体在体内的吸收、转运和排泄研究 天哪。我们还计划研究分解β-胡萝卜素的酶， 类胡萝卜素15，15‘双加氧酶测定其在不同组织中的分布 大鼠和猴的器官，研究其对完整的特异性 类胡萝卜素，以及研究人类酶的性质 取自手术切除的小肠标本。 众所周知，使用标有重物的化合物 碳的同位素(13C)是无害的：同位素是天然存在的(天然的 丰度-1-3%)。

Carotenoid pigments are presently used to prevent the development of light-sensitivity associated with erythropoietic protoporphyria and certain other skin diseases. Carotenoid pigments have also been shown to be anticarcinogenic in animal models and in some epidemiological studies. The carotenoids which have vitamin A activity also play a significant role as dietary sources of vitamin A, especially in developing countries, where access to synthetic vitamin A is limited. For these reasons it is important to understand the metabolism and functions of the various carotenoids. At present, not much is known about the fate in the body of those pigments with no vitamin A activity. We thus plan to study the absorption, transport and metabolism of two carotenoids with no vitamin A activity - lycopene the principal carotenoid of the tomato, and an important component of the blood carotenoid content of Americans, and canthaxanthin, a pigment used in food coloring, which is used in the treatment of light-sensitive skin diseases and has been shown in animal models to have anti-cancer activity. The absorption and metabolism of beta-carotene will also be studied, to compare it to that of the other two pigments. These studies will utilize C14 labeled carotenoids for studies in rats and monkeys of absorption, blood transport, cellular and intracellular location of pigments, and C13 labeled carotenoids to human volunteers for studies of absorption, transport and excretion in man. We plan also to study the enzyme which cleaves beta-carotene, carotenoid 15, 15' dioxygenase, to determine its distribution in various organs of the rat and monkey, to study its specificity for intact carotenoids, as well as to study the properties of the human enzyme obtained from operative specimens of small intestine. It is well established that the use of compounds labeled with the heavy isotope of carbon (13C) is harmless: the isotope occurs naturally (natural abundance - 1-3%).