Title: Xanthophyll
CAS Registry Number: 127-40-2
CAS Name: b,e-Carotene-3,3¢-diol
Additional Names: lutein; vegetable lutein; vegetable luteol
Trademarks: Bo-Xan
Molecular Formula: C40H56O2
Molecular Weight: 568.87
Percent Composition: C 84.45%, H 9.92%, O 5.62%
Literature References: One of the most widespread carotenoid alcohols in nature. Originally isolated from egg yolk, also isolated by chromatography from nettles, algae, and petals of many yellow flowers. Occurs also in colored feathers of birds: Volker, Z. Physiol. Chem. 288, 20 (1951). Extraction from petals of Tagetes patula L., Compositae: Karrer et al., Helv. Chim. Acta 30, 531 (1947). Occurs together with zeaxanthin, q.v. Dipalmitate occurs in Helenium autumnale L., Compositae and other flowers: Kuhn, Winterstein, Naturwissenschaften 18, 754 (1930). Conversion to zeaxanthin with sodium alcoholate: Karrer, Jucker, ibid. 266. Does not possess vitamin A potency: Schumacher et al., Poult. Sci. 23, 529 (1944). Stereochemistry: Zechmeister, Chem. Rev. 34, 267 (1944). Structure: Karrer, Helv. Chim. Acta 34, 2160 (1951). Abs config: Goodfellow et al., Chem. Commun. 1970, 1578; Buchecker et al., Chimia 25, 192 (1971); eidem, Helv. Chim. Acta 57, 631 (1974). Synthesis: H. Mayer, A. Rüttimann, ibid. 63, 1451 (1980). Sepn and determn of configurational isomers: A. Rüttiman et al., J. High Resolut. Chromatogr. Chromatogr. Commun. 6, 612 (1983). Reviews: Zechmeister, Carotinoide (Berlin, 1934); Mayer, The Chemistry of Natural Coloring Matters (New York, 1943); Karrer, Jucker, Carotenoids (New York, 1950).
Properties: Yellow prisms with metallic luster from ether + methanol, mp 190° (corr), (a higher mp indicates impure material). Also reported as mp 183° [Buchecker (1974)]. [a]18Cd +165° (c = 0.7 in benzene). Absorption max (dioxane): 481, 453, 429, 333, 268 nm (e 142000, 152000, 100000, 15500, 35000). Insol in water, sol in fats and in fat solvents. More sol in boiling methanol (1:700) than zeaxanthin.
Melting point: Yellow prisms with metallic luster from ether + methanol, mp 190° (corr), (a higher mp indicates impure material); mp 183° [Buchecker (1974)]
Optical Rotation: [a]18Cd +165° (c = 0.7 in benzene)
Absorption maximum: Absorption max (dioxane): 481, 453, 429, 333, 268 nm (e 142000, 152000, 100000, 15500, 35000)
Derivative Type: Dipalmitate
Additional Names: Helenien
Trademarks: Adaptinol (Bayer)
Molecular Formula: C72H116O4
Molecular Weight: 1045.69
Percent Composition: C 82.70%, H 11.18%, O 6.12%
Properties: Red needles from alcohol, mp 92°.
Melting point: mp 92°
Xanthopterin Xanthosine Xanthoxyletin Xanthoxylin Xanthurenic Acid

The chemical structure of cryptoxanthin
The color of an egg yolk is from the xanthophyll carotenoids lutein and zeaxanthin
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

Xanthophylls (originally phylloxanthins) are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos (ξανθός, "yellow")[1] and phyllon (φύλλον, "leaf"),[2] due to their formation of the yellow band seen in early chromatography of leaf pigments. Their molecular structure is similar to carotenes, which form the other major carotenoid group division, but xanthophylls contain oxygen atoms, while carotenes are purely hydrocarbons with no oxygen. Xanthophylls contain their oxygen either as hydroxyl groups and/or as pairs of hydrogen atoms that are substituted by oxygen atoms acting as a bridge (epoxide). For this reason, they are more polar than the purely hydrocarbon carotenes, and it is this difference that allows their separations from carotenes in many types of chromatography. Typically, carotenes are more orange in color than xanthophylls.

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. The xanthophylls found in the bodies of animals, and in dietary animal products, are ultimately derived from plant sources in the diet. For example, the yellow color of chicken egg yolks, fat, and skin comes from ingested xanthophylls (primarily lutein, which is often added to chicken feed for this purpose).

The yellow color of the human macula lutea (literally, yellow spot) in the retina of the eye comes from the lutein and zeaxanthin it contains, both xanthophylls again requiring a source in the human diet to be present in the eye. These function in eye protection from ionizing blue light, which they absorb. These two specific xanthophylls do not function in the mechanism of sight, since they cannot be converted to retinal (also called retinaldehyde or vitamin A aldehyde).

The group of xanthophylls includes (among many other compounds) lutein, zeaxanthin, neoxanthin, violaxanthin, and α- and β-cryptoxanthin. The latter compound is the only known xanthophyll to contain a beta-ionone ring, and thus β-cryptoxanthin is the only xanthophyll that is known to possess pro-vitamin A activity for mammals. Even then, it is a vitamin only for plant-eating mammals that possess the enzyme to make retinal from carotenoids that contain beta-ionone (some carnivores lack this enzyme). In species other than mammals, certain xanthophylls may be converted to hydroxylated retinal-analogues that function directly in vision. For example, with the exception of certain flies, most insects use the xanthophyll derived R-isomer of 3-hydroxyretinal for visual activities, which means that β-cryptoxanthin and other xanthophylls (such as lutein and zeaxanthin) may function as forms of visual "vitamin A" for them, while carotenes (such as beta carotene) do not.