Khachik Frederick, de Moura Fabiana F, Zhao Da-You, Aebischer Claude-Pierre, Bernstein Paul S
Department of Chemistry and Biochemistry, Joint Institute for Food Safety and Applied Nutrition (JIFSAN), University of Maryland, College Park, Maryland 20742, USA.
Invest Ophthalmol Vis Sci. 2002 Nov;43(11):3383-92.
To determine the stereochemistry of carotenoids in human ocular tissues in comparison with plasma and liver and to elucidate the possible transformations of dietary (3R,3'R,6'R)-lutein and (3R,3'R)-zeaxanthin in the eye. Similarly, to characterize the carotenoid profiles in the eye tissues, plasma, and liver of quails and frogs to determine whether these can serve as appropriate nonprimate animal models for metabolic studies.
Configurational isomers of carotenoids and their nondietary by-products from pooled human plasma, liver, retinal pigment epithelium (RPE-choroid), ciliary body, iris, and lens were characterized and quantified by high-performance liquid chromatography (HPLC) on a chiral column. Carotenoids and their nondietary by-products in pooled extracts from quail and frog plasma, liver, retina, RPE-choroid, iris, and lens were similarly characterized and quantified.
(3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, (3R,3'S; meso)-zeaxanthin, (3R,3'S,6'R)-lutein (3'-epilutein), 3-hydroxy-beta, epsilon -carotene-3'-one, and 5Z- and all-E-lycopene were detected in nearly all human ocular tissues examined. (3R,3'S; meso)-zeaxanthin was not detected in the human plasma and liver but was present in human macula, retina, and RPE-choroid. (3S,3'S)-zeaxanthin was detected in human macula in minute quantities. The carotenoid profiles in quail and frog ocular tissues were somewhat similar to those in humans, with the exception that lycopene was absent. Frog retina, plasma, and liver revealed the presence of (3S,3'S)-zeaxanthin.
The most likely transformations of carotenoids in the human eye involve a series of oxidation-reduction and double-bond isomerization reactions. Quail and frog appear to possess the appropriate enzymes for conversion of dietary (3R,3'R,6'R)-lutein and (3R,3'R)-zeaxanthin to the same nondietary by-products observed in humans and thus may serve as excellent nonprimate animal models for metabolic studies.
与血浆和肝脏相比，确定类胡萝卜素在人体眼部组织中的立体化学结构，并阐明膳食中（3R,3'R,6'R）-叶黄素和（3R,3'R）-玉米黄质在眼中可能发生的转化。同样，对鹌鹑和青蛙的眼部组织、血浆和肝脏中的类胡萝卜素谱进行表征，以确定它们是否可作为代谢研究的合适非灵长类动物模型。
通过手性柱高效液相色谱法（HPLC）对来自人血浆、肝脏、视网膜色素上皮（RPE-脉络膜）、睫状体、虹膜和晶状体的类胡萝卜素构型异构体及其非膳食副产物进行表征和定量。对来自鹌鹑和青蛙血浆、肝脏、视网膜、RPE-脉络膜、虹膜和晶状体的合并提取物中的类胡萝卜素及其非膳食副产物进行类似的表征和定量。
在几乎所有检测的人体眼部组织中均检测到（3R,3'R,6'R）-叶黄素、（3R,3'R）-玉米黄质、（3R,3'S；内消旋）-玉米黄质、（3R,3'S,6'R）-叶黄素（3'-表叶黄素）、3-羟基-β,ε-胡萝卜素-3'-酮以及5Z-和全反式番茄红素。在人血浆和肝脏中未检测到（3R,3'S；内消旋）-玉米黄质，但在人黄斑、视网膜和RPE-脉络膜中存在。在人黄斑中检测到少量的（3S,3'S）-玉米黄质。鹌鹑和青蛙眼部组织中的类胡萝卜素谱与人类的有些相似，但番茄红素不存在。青蛙视网膜、血浆和肝脏中显示存在（3S,3'S）-玉米黄质。
类胡萝卜素在人眼中最可能的转化涉及一系列氧化还原和双键异构化反应。鹌鹑和青蛙似乎拥有将膳食中（3R,3'R,6'R）-叶黄素和（3R,3'R）-玉米黄质转化为在人类中观察到的相同非膳食副产物的合适酶，因此可作为代谢研究的优秀非灵长类动物模型。
