DISTRIBUTION OF LUTEIN AND ZEAXANTHIN STEREOISOMERS IN THE HUMAN RETINA

The distribution of macular pigment stereoisomers in the human retina has been mapped and a pathway to account for the presence of the non-d ietary carotenoid, meso-zeaxanthin, is proposed. Adult neural retinas were cut into three concentric areas centered on the fovea, and the ex tracted carotenoids were analysed and purified by high-performance liq uid chromatography. The dicarbamate or dibenzoate derivatives of the c ollected zeaxanthin fractions for each tissue sample were further anal ysed by HPLC to determine their stereoisomer composition. Whole retina s from infant eyes were similarly analysed. The results show that, rel ative to zeaxanthin, the concentration of lutein in the adult neural r etina increases with radial distance from the fovea while that of meso -zeaxanthin decreases. Infant retinas were found to have more lutein a nd less meso-zeaxanthin, relative to zeaxanthin, than adult retinas. S mall quantities of(3S, 3'S)-zeaxanthin were also found in the adult re tina, particularly in the macula. It is proposed that lutein and zeaxa nthin are transported into an individual's retina in the same proporti ons found in his or her blood serum. Some of the lutein is then conver ted into meso-zeaxanthin, primarily in the macula, by a mechanism whic h is less developed in infants than adults. (C) 1997 Academic Press Li mited.