Bone R A, Landrum J T, Hime G W, Cains A, Zamor J
Department of Physics, Florida International University, Miami 33199.
Invest Ophthalmol Vis Sci. 1993 May;34(6):2033-40.
To complete identification of the major components of the human macular pigment.
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.
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.
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.
完成对人黄斑色素主要成分的鉴定。
获取黄斑色素成分的化学电离质谱，并与玉米黄质和叶黄素标准品的质谱进行比较。还使用了手性柱高效液相色谱法进行比较，该方法能够分离这些类胡萝卜素的各个立体异构体。对人血浆中的玉米黄质和叶黄素进行了类似分析。
质谱数据支持了早期的研究工作，早期研究通过高效液相色谱法、紫外可见光谱法和化学修饰表明，黄斑色素由两种与玉米黄质和叶黄素性质相同的类胡萝卜素组成。手性柱色谱法表明，“玉米黄质”部分是两种立体异构体的混合物，即玉米黄质本身[（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，仅发现了玉米黄质和叶黄素。
结果有力地表明，内消旋玉米黄质是视网膜内化学过程的产物。注意到血浆中叶黄素含量超过玉米黄质，但视网膜中玉米黄质立体异构体的总量超过叶黄素，因此考虑内消旋玉米黄质可能是视网膜中叶黄素的转化产物。在非生理条件下，作者证明叶黄素经碱催化转化为玉米黄质仅产生内消旋-（3R，3′S）立体异构体。
