Studies on the singlet oxygen scavenging mechanism of human macular pigment | October 2010
Macular pigment (MP) was first described as a ‘‘yellow spot”
centered on the fovea of the human eye in the 18th century, and
it was classified spectroscopically as a xanthophyll carotenoid by
Wald in 1945 [1], but it was not until 1985 that Bone and Landrum
chemically identified that the macular pigment is a mixture of the
carotenoids lutein and zeaxanthin [2]. Macular pigment is diffusely
found in the peripheral retina, but it is highly concentrated (100-
fold) in the foveal region of the macula, often exceeding a peak value
of 1 mM in many humans [3–7]. In addition to spatial specificity,
there is also remarkable chemical specificity of uptake into the
human macula. Despite over a dozen readily detectable carotenoids
found in human serum, only lutein, zeaxanthin, and their
metabolites are found in the retina. In the fovea, the ratio of
(3R,30R,60R)-lutein to (3R,30R)-zeaxanthin to (3R,30S-meso)-zeaxanthin
is 1:1:1, while in the peripheral retina, lutein predominates
over the zeaxanthins by a 3:1:0 ratio [1,6,8].
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