COMPARATIVE ABSORPTION AND METABOLISM OF CAROTENOIDS

类胡萝卜素色素目前被用于防止 光敏感性与红细胞生成原卟啉症和某些 其他皮肤病。 类胡萝卜素色素也被证明是 在动物模型和一些流行病学研究中的抗癌作用。 的 具有维生素A活性的类胡萝卜素也发挥重要作用， 维生素A的饮食来源，特别是在发展中国家， 合成维生素A的供应有限。 由于这些原因， 重要的是要了解代谢和功能的各种 类胡萝卜素 目前，对这具尸体的命运知之甚少。 这些色素没有维生素A活性。 因此，我们计划研究两种药物的吸收、转运和代谢。 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 是血液中类胡萝卜素含量的重要组成部分 和黄质，一种用于食品着色的色素， 用于治疗光敏感性皮肤病， 在动物模型中具有抗癌活性。 的吸收和 也将研究β-胡萝卜素的代谢，以将其与 另外两种颜料。 这些研究将利用C14标记的类胡萝卜素 用于在大鼠和猴子中研究吸收、血液转运、细胞 和色素的细胞内定位，以及C13标记的类胡萝卜素， 人体志愿者，用于研究 伙计 我们还计划研究切割β-胡萝卜素的酶， 类胡萝卜素15，15'双加氧酶，以确定其在各种 大鼠和猴的器官，以研究其对完整的 类胡萝卜素，以及研究人类酶的特性 从小肠的手术标本中获得。 已经充分确定，使用标记有重金属的化合物是有效的。 碳的同位素（13 C）是无害的：同位素自然存在（天然 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%).