Carotenoid Uptake and Protection in Cultured RPE - Carotenoids: Physical, Chemical, and Biological Functions and Properties - page 310

Lycopene (γ,γ-carotene)

β,β-Carotene (β,β-carotene)

HO

β-Cryptoxanthin ((3R)-β,β-carotenen-3-ol)

OH

HO

Zeaxanthin ((3 R ,3' R )-β,β-carotene-3,3'-diol)

OH

HO

Lutein ((3 R ,3' R ,6' R )-β,ε-carotene-3,3'-diol)

OH

HO

Meso-Zeaxanthin((3 R ,3' S )-β,β-carotene-3,3'-diol)

OH

HO

3'-Epilutein ((3 R ,3' S ,6' R )-β,ε-carotene-3,3'-diol)

O

HO

O

3'-Oxolutein (3-hydroxy-β,ε-carotene-3'-one)

OH

HO

Astaxanthin ((3 S ,3' S )-3,3'dihydroxy-β,β carotene-4,4'-dione)

O

O

Cantaxanthin (β,β-carotene-4,4'-dione)

O

FIGURE 15.1 Structures of carotenoids important for vision. Oxygen-containing carotenoids belong to a
subclass of carotenoids known as xanthophylls.

the area with the highest density of photoreceptors, fovea centralis , responsible for acute vision.
Due to the high optical density of accumulated carotenoids, this area can be visible as a yellow
spot, macula lutea , and therefore lutein and zeaxanthin are often referred to as the macular pig-
ment (Berendschot and van Norren, 2006; Bernstein et al., 2001; Bone et al., 1988, 1993, 1997;
Snodderly et al., 1984a,b). About 25% of total retinal lutein and zeaxanthin is present in the outer