Stereochemistry of the human macular carotenoids.
Stereochemistry of the human macular carotenoids.
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DOI：
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发表时间：
1993
影响因子：
4.4
通讯作者：
R. Bone;J. Landrum;Hime Gw;A. Cains;J. Zamor
中科院分区：
文献类型：
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作者：
R. Bone;J. Landrum;Hime Gw;A. Cains;J. Zamor
目的鉴定人黄斑色素的主要成分。方法获得黄斑色素组分的化学电离质谱，并与玉米黄质和叶黄素标准品进行比较。使用手性柱高效液相色谱法，这是能够解决这些类胡萝卜素的个别立体异构体的比较。类似地分析来自人血浆的玉米黄质和叶黄素。结果质谱数据支持早期的工作，其中高效液相色谱，紫外-可见光谱和化学修饰表明，黄斑色素包括两个类胡萝卜素的性质相同的玉米黄质和叶黄素。手性柱色谱法显示“玉米黄质”级分是两种立体异构体的混合物，玉米黄质本身[（3R，3 ′ R）-β，β-胡萝卜素-3，3 ′-二醇]和内消旋-玉米黄质[（3R，3 ′ S）-β，β-胡萝卜素-3，3 ′-二醇]。另一部分是单一的立体异构体叶黄素[（3R，3 'R，6' R）-β，ε-胡萝卜素-3，3 '-二醇]。在人血浆中，只有玉米黄质和叶黄素被发现。结论结果强烈表明，中-玉米黄质的结果从视网膜内的化学过程。注意到血浆中的叶黄素超过玉米黄质，但组合的玉米黄质立体异构体超过视网膜中的叶黄素，认为内消旋玉米黄质可能是衍生自视网膜叶黄素的转化产物。在非生理条件下，作者证明了叶黄素到玉米黄质的碱催化转化仅产生内消旋-（3R，3'S）立体异构体。
PURPOSE To complete identification of the major components of the human macular pigment. METHODS Chemical ionization mass spectra of the macular pigment components were obtained and compared with those of zeaxanthin and lutein standards. A comparison was also made using chiral column high-performance liquid chromatography, which is capable of resolving individual stereoisomers of these carotenoids. Zeaxanthin and lutein from human blood plasma were similarly analyzed. RESULTS The mass spectrometry data supported earlier work in which high-performance liquid chromatography, UV-visible spectrometry and chemical modification showed that the macular pigment comprises two carotenoids with identical properties to those of zeaxanthin and lutein. Chiral column chromatography showed that the "zeaxanthin" fraction is a mixture of two stereoisomers, zeaxanthin itself [(3R,3'R)-beta,beta-Carotene-3,3'-diol] and meso-zeaxanthin [(3R,3'S)-beta,beta-Carotene-3,3'-diol]. The other fraction is the single stereoisomer, lutein [(3R,3'R,6'R)-beta,epsilon-Carotene-3,3'-diol]. In human blood plasma, only zeaxanthin and lutein were found. CONCLUSIONS The results strongly suggest that meso-zeaxanthin results from chemical processes within the retina. Noting that lutein exceeds zeaxanthin in plasma but that the combined zeaxanthin stereoisomers exceed lutein in the retina, the possibility was considered that meso-zeaxanthin is a conversion product derived from retinal lutein. Under nonphysiologic conditions, the authors demonstrate that a base-catalyzed conversion of lutein to zeaxanthin yields only the meso-(3R,3'S) stereoisomer.