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Zeaxanthin
Zeaxanthin
IUPAC name
Other names β,β-carotene-3,3'-diol
Identifiers
CAS number 144-68-3 Yes check.svgY
Properties
Molecular formula C40H56O2
Molar mass 568.88 g/mol
Appearance orange-red
Melting point

215.5 °C, 489 K, 420 °F

Solubility in water insol.
Related compounds
Related compounds lutein
xanthophyll
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Zeaxanthin is one of the two carotenoids contained within the retina of the eye. Within the central macula, zeaxanthin is the dominant component, whereas in the peripheral retina, lutein predominates.

The name is derived from Zea mays (common yellow maize corn) in which zeaxanthin provides the primary yellow pigment, plus the Greek word for yellow (see xanthophyll)

As a food additive, zeaxanthin is a food dye with E number E161h.

Contents

Isomers

Lutein and zeaxanthin have identical chemical formulas and are isomers, but they are not stereoisomers. The main difference between them is in the location of a double bond in one of the end rings. This difference gives lutein three chiral centers whereas zeaxanthin has two. Because of symmetry, the (3R,3'S) and (3S,3'R) stereoisomers of zeaxanthin are identical. Therefore, zeaxanthin has only three stereoisomeric forms. The (3R,3'S) stereoisomer is called meso-zeaxanthin.

The principal natural form of zeaxanthin is (3R,3'R)-zeaxanthin. The macula mainly contains the (3R,3'R)- and meso-zeaxanthin forms, but it also contains much smaller amounts of the third (3S,3'S) form.

Relationship with diseases of the eye

There is epidemiological evidence of a relationship between low plasma concentrations of lutein and zeaxanthin on the one hand, and the risk of developing age-related macular degeneration (AMD) on the other. Some studies support the view that supplemental lutein and/or zeaxanthin help protect against AMD. There is also epidemiological evidence that increasing lutein and zeaxanthin intake lowers the risk of cataract development.

In 2007, in a 6-year study, John Paul SanGiovanni of the National Eye Institute, Maryland found that lutein and zeaxanthin (nutrients in eggs, spinach and other green vegetables) protect against blindness (macular degeneration), affecting 1.2 million Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD. Foods considered good sources of the nutrients also include goji berry, kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, kiwifruit, corn, garden peas, swiss chard and Brussels sprouts.[1]

Natural occurrence

Zeaxanthin is one of the most common carotenoid alcohols found in nature. It is the pigment that gives paprika (made from bell peppers), corn, saffron, and many other plants their characteristic color.[2] Zeaxanthin breaks down to form picrocrocin and safranal, which are responsible for the taste and aroma of saffron.

External links

References

  1. ^ "Age-Related Eye Disease Study Research Group, SanGiovanni JP, Chew EY, et al.", The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report 125 (22): 1225–1232, 2007, doi:10.1001/archopht.125.9.1225, PMID 17846363  
  2. ^ Spice Science and Technology, K. Hirasa, M. Takamasa, page 15
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