Xanthophyll
Xanthophylls (originally phylloxanthins) are yellow pigments that occur widely in nature and form one of two major divisions of the carotenoid group; the other division is formed by the carotenes. The name is from Greek: xanthos (ξανθός), meaning "yellow",[1] and phyllon (φύλλον), meaning "leaf"),[2] due to their formation of the yellow band seen in early chromatography of leaf pigments.
Molecular structure
As both are carotenoids, xanthophylls and carotenes are similar in structure, but xanthophylls contain
Occurrence
Like other carotenoids, xanthophylls are found in highest quantity in the
, which is added to chicken feed for this purpose.The yellow color of the
Example compounds
The group of xanthophylls includes (among many other compounds)
Xanthophyll cycle
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.[3] 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, i.e. reduced, to zeaxanthin via the intermediate antheraxanthin, which plays a direct photoprotective role acting as a lipid-protective
In
Wright et al. (Feb 2011) found that, "The increase in zeaxanthin appears to surpass the decrease in violaxanthin in spinach" and commented that the discrepancy could be explained by "a synthesis of zeaxanthin from beta-carotene", however they noted further study is required to explore this hypothesis.[6]
Food sources
Xanthophylls are found in all young leaves and in etiolated leaves. Examples of other rich sources include papaya, peaches, prunes, and squash, which contain lutein diesters.[7][8][9]
References
- Perseus Project
- Perseus Project
- ^ Falkowski, P. G. & J. A. Raven, 1997, Aquatic photosynthesis. Blackwell Science, 375 pp
- ^ Taiz, Lincoln and Eduardo Zeiger. 2006. Plant Physiology. Sunderland, MA: Sinauer Associates, Inc. Publishers, Fourth edition, 764 pp
- ^ Jeffrey, S. W. & M. Vesk, 1997. Introduction to marine phytoplankton and their pigment signatures. In Jeffrey, S. W., R. F. C. Mantoura & S. W. Wright (eds.), Phytoplankton pigments in oceanography, pp 37-84. – UNESCO Publishing, Paris.
- S2CID 8454497.
- ^ Factors That Influence the Bioavailablity of Xanthophylls, Susan Zaripheh, John W. Erdman Jr.
- ^ "UCLA College of Life Sciences, General Botany:Leaf Color: Xanthophylls". Archived from the original on 2016-08-25. Retrieved 2014-08-03.
- ^ Michele Turcotte, MS, RD (January 7, 2016). "Foods That Contain Zeaxanthin". Archived from the original on September 16, 2017.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - PMID 28208784.
- Demmig-Adams, B & W. W. Adams, 2006. Photoprotection in an ecological context: the remarkable complexity of thermal energy dissipation, New Phytologist, 172: 11–21.
External links
- Xanthophylls at the U.S. National Library of Medicine Medical Subject Headings (MeSH)