Wikipedia

Zeaxanthin

Zeaxanthinis one of the most commoncarotenoidsin nature, and is used in thexanthophyll cycle.Synthesized in plants and some micro-organisms, it is the pigment that givespaprika(made from bell peppers),corn,saffron,goji (wolfberries), and many other plants and microbes their characteristic color.[1][2]

Zeaxanthin
Structural formula of zeaxanthin
Space-filling model of the zeaxanthin molecule
Names
IUPAC name
(3R,3′R)-β,β-Carotene-3,3′-diol
Systematic IUPAC name
(1R,1′R)-4,4′-[(1E,3E,5E,7E,9E,11E,13E,15E,17E)-3,7,12,16-Tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaene-1,18-diyl]bis(3,5,5-trimethylcyclohex-3-en-1-ol)
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.005.125Edit this at Wikidata
E number E161h(colours)
UNII
  • InChI=1S/C40H56O2/c1-29(17-13-19-31(3)21-23-37-33(5)25-35(41)27-39(37,7)8)15-11-12-16-30(2)18-14-20-32(4)22-24-38-34(6)26-36(42)28-40(38,9)10/h11-24,35-36,41-42H,25-28H2,1-10H3/b12-11+,17-13+,18-14+,23-21+,24-22+,29-15+,30-16+,31-19+,32-20+/t35-,36-/m1/s1checkY
    Key: JKQXZKUSFCKOGQ-QAYBQHTQSA-NcheckY
  • InChI=1/C40H56O2/c1-29(17-13-19-31(3)21-23-37-33(5)25-35(41)27-39(37,7)8)15-11-12-16-30(2)18-14-20-32(4)22-24-38-34(6)26-36(42)28-40(38,9)10/h11-24,35-36,41-42H,25-28H2,1-10H3/b12-11+,17-13+,18-14+,23-21+,24-22+,29-15+,30-16+,31-19+,32-20+/t35-,36-/m1/s1
    Key: JKQXZKUSFCKOGQ-QAYBQHTQBL
  • CC1=C(C(C[C@@H](C1)O)(C)C)/C=C/C(=C/C=C/C(=C/C=C/C=C(/C=C/C=C(/C=C/C2=C(C[C@H](CC2(C)C)O)C)\C)\C)/C)/C
Properties
C40H56O2
Molar mass 568.88 g/mol
Appearance orange-red
Melting point 215.5 °C (419.9 °F; 488.6 K)
insol.
Related compounds
Related compounds
 lutein
xanthophyll
Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).

The name (pronouncedzee-uh-zan'-thin) is derived fromZea mays(common yellow maize corn, in which zeaxanthin provides the primary yellow pigment), plusxanthos,the Greek word for "yellow" (seexanthophyll).

Xanthophylls such as zeaxanthin are found in highest quantity in theleavesof most greenplants,where they act to modulate light energy and perhaps serve as anon-photochemical quenchingagent to deal with triplet chlorophyll (an excited form of chlorophyll) which is overproduced at high light levels during photosynthesis.[3]Zeaxanthin inguard cellsacts as a blue lightphotoreceptorwhich mediates thestomatalopening.[4]

Animals derive zeaxanthin from a plant diet.[2]Zeaxanthin is one of the two primaryxanthophyllcarotenoidscontained within theretinaof theeye.Zeaxanthin supplements are typically taken on the supposition of supporting eye health. Although there are no reported side effects from taking zeaxanthin supplements, the actual health effects of zeaxanthin andluteinare not proven,[5][6][7]and, as of 2018, there is no regulatory approval in theEuropean Unionor the United States forhealth claimsabout products that contain zeaxanthin.

As afood additive,zeaxanthin is afood dyewithE numberE161h.

Isomers and macular uptake

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Luteinand zeaxanthin have identical chemical formulas and areisomers,but they are notstereoisomers.The only difference between them is in the location of thedouble bondin one of the end rings. This difference gives lutein threechiralcenters 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 calledmeso-zeaxanthin.

The principal natural form of zeaxanthin is (3R,3′R)-zeaxanthin. Themaculamainly contains the (3R,3′R)- and meso-zeaxanthin forms, but it also contains much smaller amounts of the third (3S,3′S) form.[8]Evidence exists that a specific zeaxanthin-binding proteinrecruits circulating zeaxanthin and lutein for uptake within the macula.[9]

Due to the commercial value of carotenoids, theirbiosynthesishas been studied extensively in bothnatural productsand non-natural (heterologous) systems such as the bacteriaEscherichia coliand yeastSaccharomyces cerevisiae.Zeaxanthin biosynthesis proceeds from beta-carotene via the action of a single protein, known as a beta-carotene hydroxylase, that is able to add a hydroxyl group (-OH) to carbon 3 and 3′ of the beta-carotene molecule. Zeaxanthin biosynthesis therefore proceeds from beta-carotene to zeaxanthin (a di-hydroxylated product) via beta-cryptoxanthin (the mono hydroxylated intermediate). Although functionally identical, several distinct beta-carotene hydroxylase proteins are known.

Due to the nature of zeaxanthin, relative toastaxanthin(a carotenoid of significant commercial value) beta-carotene hydroxylase proteins have been studied extensively.[10]

Relationship with diseases of the eye

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Severalobservational studieshave provided preliminary evidence for high dietary intake of foods including lutein and zeaxanthin with lower incidence ofage-related macular degeneration(AMD), most notably theAge-Related Eye Disease Study(AREDS2).[11][12]Because foods high in one of these carotenoids tend to be high in the other, research does not separate effects of one from the other.[13][14]

  • Three subsequent meta-analyses of dietary lutein and zeaxanthin concluded that these carotenoids lower the risk of progression from early stage AMD to late stage AMD.[15][16][17]
  • A 2023 (updated)Cochranereview of 26 studies from several countries, however, concluded thatdietary supplementscontaining zeaxanthin and lutein have little to no influence on the progression of AMD.[18]In general, there remains insufficient evidence to assess the effectiveness of dietary or supplemental zeaxanthin or lutein in treatment or prevention of early AMD.[2][13][18]

As for cataracts, two meta-analyses confirm a correlation between high serum concentrations of lutein and zeaxanthin and a decrease in the risk of nuclear cataract, but not cortical or subcapsular cataract. The reports did not separate a zeaxanthin effect from a lutein effect.[19][20]The AREDS2 trial enrolled subjects at risk for progression to advanced age-related macular degeneration. Overall, the group getting lutein (10 mg) and zeaxanthin (2 mg) did not reduce the need for cataract surgery.[21]Any benefit is more likely to be apparent in subpopulations of individuals exposed to high oxidative stress, such as heavy smokers, alcoholics or those with low dietary intake of carotenoid-rich foods.[22]

In 2005, the USFood and Drug Administrationrejected aQualified Health Claimsapplication by Xangold, citing insufficient evidence supporting the use of a lutein- and zeaxanthin-containing supplement in prevention of AMD.[23]Dietary supplement companies in the U.S. are allowed to sell lutein and lutein plus zeaxanthin products usingdietary supplement,such as "Helps maintain eye health", as long as the FDA disclaimer statement ( "These statements have not been evaluated..." ) is on the label. In Europe, as recently as 2014, theEuropean Food Safety Authorityreviewed and rejected claims that lutein or lutein plus zeaxanthin improved vision.[24]

Natural occurrence

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Zeaxanthin is the pigment that givespaprika,corn,saffron,wolfberries (goji),and many other plants their characteristic colors of red, orange or yellow.[2][18]Spirulinais also a rich source and can serve as a dietary supplement.[25]Zeaxanthin breaks down to formpicrocrocinandsafranal,which are responsible for the taste and aroma of saffron.[26]

Dark greenleaf vegetables,such askale,spinach,turnip greens,collard greens,romaine lettuce,watercress,Swiss chardandmustard greensare rich in lutein[2][27]but contain little to no zeaxanthin, with the exception of scallions cooked in oil.[28]Orange bell peppers (but not green, red, or yellow) are rich in zeaxanthin.[28]

Lutein and zeaxanthin concentrations in fruits and vegetables (μg / 100 g)[28]
Food (100 g) Luteintrans(μg) Zeaxanthintrans(μg)
Spinach, cooked 12,640 0
Spinach, raw 6,603 0
Kale, cooked 8,884 0
Cilantro 7,703 0
Scallions, cooked in oil 2,488
Scallions, raw 782 0
Bell pepper, green 173 0
Bell pepper, orange 208 1,665
Bell pepper, red 0 22
Bell pepper, yellow 139 18
Cornmeal, yellow 1 531
Cornmeal, white 13 13
Corn, cooked from frozen 202 202
Tortilla, corn 276 255

Safety

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Anacceptable daily intakelevel for zeaxanthin was proposed as 0.75 mg/kg of body weight/day, or 53 mg/day for a 70 kg adult.[29]In humans, an intake of 20 mg/day for up to six months had noadverse effects.[29]As of 2016, neither the U.S. Food and Drug Administration nor the European Food Safety Authority had set a Tolerable Upper Intake Level (UL) for lutein or zeaxanthin.

References

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  1. ^Encyclopedia.com."Carotenoids".Retrieved6 May2012.
  2. ^abcde"Lutein + Zeaxanthin Content of Selected Foods".Linus Pauling Institute, Oregon State University, Corvallis. 2014.Retrieved20 May2014.
  3. ^Bassi, Roberto; Dall'Osto, Luca (2021)."Dissipation of Light Energy Absorbed in Excess: The Molecular Mechanisms".Annual Review of Plant Biology.72:47–76.doi:10.1146/annurev-arplant-071720-015522.PMID34143647.S2CID235480018.
  4. ^Kochhar, S. L.; Gujral, Sukhbir Kaur (2020). "Transpiration".Plant Physiology: Theory and Applications(2 ed.). Cambridge University Press. pp. 75–99.doi:10.1017/9781108486392.006.ISBN978-1-108-48639-2.
  5. ^Age-Related Eye Disease Study 2 Research Group (2013)."Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: The Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial".JAMA.309(19): 2005–15.doi:10.1001/jama.2013.4997.PMID23644932.{{cite journal}}:CS1 maint: numeric names: authors list (link)
  6. ^Pinazo-Durán, M. D.; Gómez-Ulla, F; Arias, L; et al. (2014)."Do Nutritional Supplements Have a Role in Age Macular Degeneration Prevention?".Journal of Ophthalmology.2014:1–15.doi:10.1155/2014/901686.PMC3941929.PMID24672708.
  7. ^Koo, E; Neuringer, M; Sangiovanni, J. P. (2014)."Macular xanthophylls, lipoprotein-related genes, and age-related macular degeneration".American Journal of Clinical Nutrition.100(Supplement 1): 336S–346S.doi:10.3945/ajcn.113.071563.PMC4144106.PMID24829491.
  8. ^Nolan, J. M.; Meagher, K; Kashani, S; Beatty, S (2013)."What is meso-zeaxanthin, and where does it come from?".Eye.27(8): 899–905.doi:10.1038/eye.2013.98.PMC3740325.PMID23703634.
  9. ^Li, B; Vachali, P; Bernstein, P. S. (2010)."Human ocular carotenoid-binding proteins".Photochemical & Photobiological Sciences.9(11): 1418–25.doi:10.1039/c0pp00126k.PMC3938892.PMID20820671.
  10. ^Scaife, Mark A.; Ma, Cynthia A.; Ninlayarn, Thanyanun; et al. (22 May 2012). "Comparative Analysis of β-Carotene Hydroxylase Genes for Astaxanthin Biosynthesis".Journal of Natural Products.75(6): 1117–24.doi:10.1021/np300136t.PMID22616944.
  11. ^"NIH study provides clarity on supplements for protection against blinding eye disease".US National Eye Institute, National Institutes of Health, Bethesda, MD. 5 May 2013. Archived fromthe originalon 15 August 2019.Retrieved10 August2017.
  12. ^Bernstein, P. S.; Li, B; Vachali, P. P.; et al. (2015)."Lutein, Zeaxanthin, and meso-Zeaxanthin: The Basic and Clinical Science Underlying Carotenoid-based Nutritional Interventions against Ocular Disease".Progress in Retinal and Eye Research.50:34–66.doi:10.1016/j.preteyeres.2015.10.003.PMC4698241.PMID26541886.
  13. ^abKrishnadev N, Meleth AD, Chew EY (May 2010)."Nutritional supplements for age-related macular degeneration".Current Opinion in Ophthalmology.21(3): 184–9.doi:10.1097/ICU.0b013e32833866ee.PMC2909501.PMID20216418.
  14. ^SanGiovanni JP, Chew EY, Clemons TE, et al. (September 2007). "The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22".Archives of Ophthalmology.125(9): 1225–1232.doi:10.1001/archopht.125.9.1225.PMID17846363.
  15. ^Liu R, Wang T, Zhang B, et al. (2014). "Lutein and zeaxanthin supplementation and association with visual function in age-related macular degeneration".Invest. Ophthalmol. Vis. Sci.56(1): 252–8.doi:10.1167/iovs.14-15553.PMID25515572.
  16. ^Wang X, Jiang C, Zhang Y, et al. (2014). "Role of lutein supplementation in the management of age-related macular degeneration: meta-analysis of randomized controlled trials".Ophthalmic Res.52(4): 198–205.doi:10.1159/000363327.PMID25358528.S2CID5055854.
  17. ^Ma L, Dou HL, Wu YQ, et al. (2012)."Lutein and zeaxanthin intake and the risk of age-related macular degeneration: a systematic review and meta-analysis".Br. J. Nutr.107(3): 350–9.doi:10.1017/S0007114511004260.PMID21899805.
  18. ^abcEvans, Jennifer R.; Lawrenson, John G. (2023-09-13). "Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration".The Cochrane Database of Systematic Reviews.2023(9): CD000254.doi:10.1002/14651858.CD000254.pub5.ISSN1469-493X.PMC10498493.PMID37702300.
  19. ^Liu XH, Yu RB, Liu R, et al. (2014)."Association between lutein and zeaxanthin status and the risk of cataract: a meta-analysis".Nutrients.6(1): 452–65.doi:10.3390/nu6010452.PMC3916871.PMID24451312.
  20. ^Ma L, Hao ZX, Liu RR, et al. (2014). "A dose-response meta-analysis of dietary lutein and zeaxanthin intake in relation to risk of age-related cataract".Graefes Arch. Clin. Exp. Ophthalmol.252(1): 63–70.doi:10.1007/s00417-013-2492-3.PMID24150707.S2CID13634941.
  21. ^Chew EY, SanGiovanni JP, Ferris FL, et al. (2013)."Lutein/zeaxanthin for the treatment of age-related cataract: AREDS2 randomized trial report no. 4".JAMA Ophthalmol.131(7): 843–50.doi:10.1001/jamaophthalmol.2013.4412.PMC6774801.PMID23645227.
  22. ^Fernandez MM, Afshari NA (January 2008). "Nutrition and the prevention of cataracts".Current Opinion in Ophthalmology.19(1): 66–70.doi:10.1097/ICU.0b013e3282f2d7b6.PMID18090901.S2CID25735519.
  23. ^"Letter of Denial - Xangold Lutein Esters, Lutein, or Zeaxanthin and Reduced Risk of Age-related Macular Degeneration or Cataract Formation (Docket No. 2004Q-0180".US FDA, Qualified Health Claims. 19 December 2005.
  24. ^"Scientific Opinion on the substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions pursuant to Article 13(5) of Regulation (EC) No 1924/2006".EFSA Journal.12(7): 3753. 2014.doi:10.2903/j.efsa.2014.3753.ISSN1831-4732.
  25. ^Yu, B.; Wang, J.; Suter, P. M.; et al. (2012)."Spirulina is an effective dietary source of zeaxanthin to humans".British Journal of Nutrition.108(4): 611–619.doi:10.1017/S0007114511005885.PMID22313576.
  26. ^Frusciante, Sarah; Diretto, Gianfranco; Bruno, Mark; et al. (2014-08-19)."Novel carotenoid cleavage dioxygenase catalyzes the first dedicated step in saffron crocin biosynthesis".Proceedings of the National Academy of Sciences.111(33): 12246–12251.Bibcode:2014PNAS..11112246F.doi:10.1073/pnas.1404629111.ISSN0027-8424.PMC4143034.PMID25097262.
  27. ^"Foods highest in lutein-zeaxanthin per 100 grams".Conde Nast for the USDA National Nutrient Database, release SR-21. 2014.Retrieved23 December2015.
  28. ^abcAlisa Perry; Helen Rasmussen; Elizabeth J. Johnson (Feb 2009)."Xanthophyll (lutein, zeaxanthin) content in fruits, vegetables and corn and egg products".Journal of Food Composition and Analysis.22(1): 9–15.doi:10.1016/j.jfca.2008.07.006.Retrieved4 February2024.
  29. ^abEdwards JA (2016)."Zeaxanthin: Review of Toxicological Data and Acceptable Daily Intake".Journal of Ophthalmology.2016:1–15.doi:10.1155/2016/3690140.PMC4738691.PMID26885380.
    • In their evaluation of the safety of synthetic zeaxanthin as a Novel Food, the EFSA NDA Scientific Panel [37] applied a 200-fold safety factor to this NOAEL to define an ADI of 0.75 mg/kg bw/day, or 53 mg/day for a 70 kg adult.
    • Formulated zeaxanthin was not mutagenic or clastogenic in a series of in vitro and in vivo tests for genotoxicity.
    • Information from human intervention studies also supports that an intake higher than 2 mg/day is safe, and an intake level of 20 mg/day for up to 6 months was without adverse effect.
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