Dictionary:
xan·tho·phyll (zăn'thə-fĭl') ![]() |
- A yellow carotenoid pigment, C40H56O2, found with chlorophyll in green plants and identical with lutein.
- Any of various related yellow pigments.
Dictionary:
xan·tho·phyll (zăn'thə-fĭl') ![]() |
| 5min Related Video: xanthophyll |
| Food and Nutrition: xanthophylls |
Yellow-orange hydroxylated carotene derivatives; occur in all green leaves together with the chlorophyll and carotene, also present in egg yolk, Cape gooseberry, rose hips, etc. Most have no vitamin A activity. Include flavoxanthin, lutein, cryptoxanthin, which is converted into vitamin A, rubixanthin, rhodoxanthin, and canthaxanthin.
| Veterinary Dictionary: xanthophyll |
Yellow pigment in plants.
| WordNet: xanthophyll |
The noun has one meaning:
Meaning #1:
yellow carotenoid pigments in plants and animal fats and egg yolks
Synonyms: xanthophyl, lutein
| Wikipedia: Xanthophyll |
Xanthophylls (originally phylloxanthins) are yellow pigments from the carotenoid group. Their molecular structure is based on carotenes; contrary to the carotenes, some hydrogen atoms are substituted by hydroxyl groups and/or some pairs of hydrogen atoms are substituted by oxygen atoms. They are found in the leaves of most plants and are synthesized within the plastids. They are involved in photosynthesis along with green chlorophyll, which typically covers up the yellow except in autumn, when the chlorophyll is denatured by the cold.
In plants, xanthophylls are considered accessory pigments, along with carotenes, and, in red algae and cyanobacteria, phycobilins. Xanthophylls, along with carotenic pigments are seen when leaves turn orange in the autumn season. Anthocyanins, which produce red, blue, and purple colors in leaves, flowers, and other plant parts, do not participate in photosynthesis and so are not accessory pigments.
Animals cannot produce xanthophylls, and thus xanthophylls found in animals (e.g. in the eye) come from their food intake. The yellow color of chicken egg yolks also comes from ingested xanthophylls.
Xanthophylls are oxidized derivatives of carotenes. They contain hydroxyl groups and are more polar than carotenes; therefore, carotenes travel further than xanthophylls in paper chromatography.
The group of xanthophylls includes lutein, zeaxanthin, neoxanthin, violaxanthin, and α- and β-cryptoxanthin.
The xanthophyll cycle involves the enzymatic removal of epoxy groups from xanthophylls (e.g. violaxanthin, antheraxanthin, diadinoxanthin) to create so-called de-epoxidised xanthophylls (e.g. diatoxanthin, zeaxanthin). These enzymatic cycles were found to play a key role in stimulating energy dissipation within light harvesting antenna proteins by non-photochemical quenching- a mechanism to reduce the amount of energy that reaches the photosynthetic reaction centers. Non-photochemical quenching is one of the main ways of protecting against photoinhibition.[1] In higher plants there are three carotenoid pigments that are active in the xanthophyll cycle: violaxanthin, antheraxanthin and zeaxanthin. During light stress violaxanthin is converted to zeaxanthin via the intermediate antheraxanthin, which plays a direct photoprotective role acting as a lipid-protective anti-oxidant and by stimulating non-photochemical quenching within light harvesting proteins. This conversion of violaxanthin to zeaxanthin is done by the enzyme violaxanthin de-epoxidase, while the reverse reaction is performed by zeaxanthin epoxidase[2]
In diatoms and dinoflagellates the xanthophyll cycle consists of the pigment diadinoxanthin, which is transformed into diatoxanthin (diatoms) or dinoxanthin (dinoflagellates), at high light. [3]
|
||||||||||||||
|
|||||||||||||||||
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
| lutein | |
| Xangold | |
| rhodoxanthin (biochemistry) |
| Which is more polar xanthophyll lutein or chlorophyll? Read answer... |
Copyrights:
![]() | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved. Read more | |
![]() | Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved. Read more | |
![]() | Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved. Read more | |
![]() | WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. Read more | |
![]() | Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Xanthophyll". Read more |
Mentioned in