View source for Zeaxanthin

'''Zeaxanthin''' is one of the two [[carotenoid]]s contained within the 
[[retina]].  

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} | Zeaxanthin <!-- replace if not identical with the article name -->
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:Zeaxanthin.svg|300px|Zeaxanthin]] <!-- replace if not identical with the pagename -->
|-
! {{chembox header}} | General
|- 
| [[IUPAC nomenclature|Systematic name]]
| 4-[18-(4-hydroxy-2,6,6-trimethyl-1-cyclohexenyl)-<BR>3,7,12,16-tetramethyl-octadeca-<BR>1,3,5,7,9,11,13,15,17-nonaenyl]-<BR>3,5,5-trimethyl-cyclohex-3-en-1-ol
| 
|-
| Other names
| zeaxanthin; ß,ß-carotene-3,3'-diol
|-
| [[Chemical formula|Molecular formula]]
| C<sub>40</sub>H<sub>56</sub>O<sub>2</sub>
|-
|{{chembox SMILES|value=CC1CC(O)CC(C)(C)C=1C=CC(C)=CC=CC(C)=CC=<br>CC=C(C)C=CC=C(C)C=CC2=C(C)CC(O)CC2(C)C}}
|-
| [[Molar mass]]
| 568.88 g/mol
|-
| Appearance
| orange-red
|-
| [[CAS registry number|CAS number]]
| 144-68-3
|-
{{PubChem Row|91445}}
|-
{{EINECS Row|205-636-4}}
|-
! {{chembox header}} | Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| ? g/cm³, ? <!-- ? g/cm³, solid / ? g/ml, liquid / ? g/l, gas -->
|-
| [[Soluble|Solubility]] in [[Water (molecule)|water]]
| insol. <!--  at least put miscible with, not soluble in -->
|-
<!-- | Other solvents e.g. [[ethanol]], [[acetone]] -->
<!-- | solubility info on other solvents -->
<!-- |- -->
| [[Melting point]]
| 215.5 °C (488.7 K) <!-- (mention any decomposition) -->
|-
| [[Boiling point]]
| ? °C (? K)
|-
| [[Acid dissociation constant|Acidity]] (p''K''<sub>a</sub>) <!-- omit if not an acid or a base.  If several values, be clear -->
| ?
|-
| [[Acid dissociation constant|Basicity]] (p''K''<sub>b</sub>) <!-- omit if not a base. If several values, be clear -->
| ?
|-
| [[Specific rotation|Chiral rotation <nowiki>[α]</nowiki><sub>D</sub>]] <!-- (Only include this for chiral compounds, indicate direction/enantiomer combo if known) -->
| ?°
|-
| [[Viscosity]]
| ? [[Poise|cP]] at ? °C <!-- Liquids only, omit if data unavailable. You may use [[Pascal second|Pa.s]] if you prefer -->
|-
! {{chembox header}} | Hazards <!--  Summary only- MSDS entry provides more complete information -->
|-
| [[Material safety data sheet|MSDS]]
| [[Zeaxanthin (data page)#Material Safety Data Sheet|External MSDS]] <!-- please replace with proper link-->
|-
| Main [[Worker safety and health|hazard]]s
| ? <!-- e.g. highly toxic, explosive, flammable, corrosive -->
|-
| [[NFPA 704]]
| <!-- {{nfpa|4|4 ox|4}} These are set on "very dangerous" as default- adjust according to actual values -->
|-
| [[Flash point]]
| ? °C
|-
| [[Risk and Safety Statements|R/S statement]]
| [[List of R-phrases|R]]: ? <br> [[List of S-phrases|S]]: ?
|-
| [[RTECS]] number
| ?
|-
! {{chembox header}} | [[Zeaxanthin (data page)|Supplementary data page]]
|-
| [[Zeaxanthin (data page)#Structure and properties|Structure and<br/>properties]] 
| [[Refractive index|''n'']], [[Dielectric constant|ε<sub>r</sub>]], etc. 
|-
| [[Zeaxanthin (data page)#Thermodynamic properties|Thermodynamic<br/>data]] 
| Phase behaviour<br>Solid, liquid, gas 
|-
| [[Zeaxanthin (data page)#Spectral data|Spectral data]]
| [[UV/VIS spectroscopy|UV]], [[Infrared spectroscopy|IR]], [[NMR spectroscopy|NMR]], [[Mass spectrometry|MS]]
|-
! {{chembox header}} | Related compounds
|-
| Other [[Ion|anion]]s <!-- please omit if not applicable -->
| ? <!-- Put in related anions e.g, iron(II) fluoride & iron(II) bromide if compound is iron(II) chloride -->
|-
| Other [[Ion|cation]]s <!-- please omit if not applicable -->
| ? <!-- Put in other oxidn states of same element e.g. [[iron(III) chloride]], also for related metals such as [[manganese(II) chloride]], [[cobalt(II) chloride]], ruthenium(III) chloride-->
|-
| Related [[?]] <!-- PLEASE INSERT FUNCTIONAL GROUP (e.g. [[aldehyde]]) FOR ORGANICS, please omit if not applicable -->
| ? <!-- Insert related organics e.g. on formaldehyde page put [[acetaldehyde]] -->
|-
| Related compounds 
| [[lutein]]<br>[[xanthophyll]]
|-
| {{chembox header}} | <small>Except where noted otherwise, data are given for<br> materials in their [[standard state|standard state (at 25 °C, 100 kPa)]]<br/>[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>
|-
|}

Within the central [[macula]], zeaxanthin is the dominant component,
whereas in the peripheral retina, [[lutein]] predominates.

Lutein and zeaxanthin have identical chemical formulas and are [[isomer]]s, but 
they are not [[stereoisomer]]s.
The main difference between them is in the location of a [[double bond]] in one of the end rings.
This difference gives lutein three [[chirality (chemistry)|chiral]] centers whereas zeaxanthin has two.

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

==Isomers==
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 [[epidemiology|epidemiological]] evidence of a relationship between low [[blood plasma|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.

On September 10, 2007,  in a 6-year study, [[researchers]], led by 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 [[United States|Americans]], mostly after age 65. Lutein and zeaxanthin reduce the risk of [[AMD]] ([[journal]] [[Archives of Ophthalmology]]). Foods considered good sources of the nutrients also include [[kale]], [[turnip]] [[greens]], [[collard]] greens, [[romaine lettuce]], [[broccoli]], [[zucchini]], [[corn]], [[garden]] [[peas]] and [[Brussels sprouts]].<ref>[http://news.yahoo.com/s/nm/20070910/hl_nm/eyesight_nutrients_dc;_ylt=AhJwo077jBEbQvMoRIMIxV2s0NUE  Yahoo.com, Study finds spinach, eggs ward off cause of blindness]</ref> 


==Natural occurrence==
Zeaxanthin is one of the most common carotenoid alcohols found in nature. It is the pigment that gives [[maize|corn]], [[saffron]], and many other plants their characteristic color.  Zeaxanthin breaks down to form [[picrocrocin]] and [[safranal]], which are responsible for the taste and aroma of saffron.

==External links==
* [http://biocyc.org/META/new-image?type=COMPOUND-IN-PATHWAY&object=CPD1F-130 BioCyc]


==References==
<div class="references-small">
{{reflist|2}}
</div>


{{Carotenoids}}
[[Category:Food colorings]]
[[Category:Carotenoids]]

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[[de:Zeaxanthin]]
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[[nl:Citranaxanthine]]
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