Xanthophyll

Like other carotenoids, xanthophylls are found in highest quantity in the leaves of most green plants, where they act to modulate light energy and perhaps serve as a non-photochemical quenching agent to deal with triplet chlorophyll (an excited form of chlorophyll),[citation needed] which is overproduced at high light levels in photosynthesis.

Their physical arrangement in the macula lutea is believed to be the cause of Haidinger's brush, an entoptic phenomenon that enables perception of polarizing light.

The group of xanthophylls includes (among many other compounds) lutein, zeaxanthin, neoxanthin, violaxanthin, flavoxanthin, and α- and β-cryptoxanthin.

[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 anti-oxidant and by stimulating non-photochemical quenching within light-harvesting proteins.

Examples of other rich sources include papaya, peaches, prunes, and squash, which contain lutein diesters.

The characteristic color of egg yolk results from the presence of a xanthophyll pigment typical in color of lutein or zeaxanthin of the xanthophylls, a division of the carotenoids group.
The chemical structure of cryptoxanthin . Xanthophylls typically present oxygen as a hydroxyl group .
Thin layer chromatography is used to separate components of a plant extract, illustrating the experiment with plant pigments that gave chromatography its name. Plant xanthophylls form the bright yellow band next to the green.
The xanthophyll cycle