Xanthophyll

This xanthophyll occurs in green leaves and in egg yolk. 

This xanthophyll is the major carotene of paprika peppers. 

Astaxanthin is present in crab and lobster shells and lobsters, the red astaxanthin is released from and, in combination with proteins, provides three a green carotenoid-protein complex. Astaxanthin blue hues (a-, 3- and y-crustacyanin) and one usually occurs in lobster shell as an ester, e. g., diyellow pigment. During the cooking of crabs palmitic ester. 

Violaxanthin is present in orange juice (cf. Table 3.57) and it also occurs in green leaves. 

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The most common of the xanthophyll pigments, it is present in all green leaves, in blossoms and in various animal sources. It crystallizes in violet prisms with one molecule of methanol m.p. I93 C, soluble in organic solvents giving yellow solutions, li is related to a-carolene in the same way as zeaxanlhin is to /1-carolene. 

One of the xanthophyll pigments present in various leaves, seeds and fruits, and in yolk of egg. It is often present in company with lutein, of which it is an isomer. It bears the same relation to -carotene as lutein does to a-caro tene. 

A chromatographic column filled in three sections with ground sugar, chalk, and alumina. When a petroleum extract of spinach leaves is run onto the top of the column, ihe extract spreads down the column, but not uniformly bands of green chlorophylls stop near the top. yellow xanthophyll further down, and red carotene near the bottom. 

C.3 The compound xanthophyll is a yellow compound found in bird feathers and flowers. Xanthophyll contains atoms of carbon, hydrogen, and oxygen in the ratio 20 28 1. Its molecules each have six oxygen atoms. Write the chemical formula of xanthophyll. 

Hager, A. (1980). The reversible, light-induced conversion of xanthophylls in the chloroplast. In Pigments in Plants, ed. F.C. Czygan, pp. 57-79. Stuttgart Gustav Fischer-Verlag. 

The relationship between serum and tissue concentrations of lutein and zeaxanthin was recently studied by Johnson et al, (2000). Dietary intake of xanthophyll-rich vegetables (for example, spinach and com) resulted in significant increases in lutein concentration in serum, adipose tissue and buccal cells, and this correlated with changes in MP density. However, P-carotene and lycopene are normally the major carotenoids detected in buccal cells (Peng et al, 1994). 

Although there are well over 500 different carotenoids in nature (Straub, 1987), all are based on seven different end groups of which only four (P, e, K, /) are foimd in higher plant carotenoids (Fig. 13.1). Cyclisation of the carbon skeleton occurs at one or both ends of the molecule, whilst xanthophylls... 

The oxidation of carotenes results in the formation of a diverse array of xanthophylls (Fig. 13.7). Zeaxanthin is synthesised from P-carotene by the hydroxylation of C-3 and C-3 of the P-rings via the mono-hydroxylated intermediate P-cryptoxanthin, a process requiring molecular oxygen in a mixed-function oxidase reaction. The gene encoding P-carotene hydroxylase (crtZ) has been cloned from a number of non-photosynthetic prokaryotes (reviewed by Armstrong, 1994) and from Arabidopsis (Sun et al, 1996). Zeaxanthin is converted to violaxanthin by zeaxanthin epoxidase which epoxidises both P-rings of zeaxanthin at the 5,6 positions (Fig. 13.7). The... 

BOUVIER F, D HARLINGUE A, HUGUENEY P, MARIN E, MARION-POLL A and CAMARA B (1996) Xanthophyll biosynthesis cloning, expression, functional reconstitution and regulation of 3-cyclohexenyl carotenoid epoxidase from pepper Capsicum annuum) , J Biol Chem, 271, 28861-7. 

BOUVIER F, KELLER Y, d harlingue A and CAMARA B (1998) Xanthophyll biosynthesis molecular and functional characterisation of carotenoid hydroxylases from pepper fruits Capsicum annuum L.) , Biochim Biophys Acta, 1391, 320-28. 

DHARMAPURI S, ROSATI C, PALLARA P, AQUILANI R, BOUVIER F, CAMARA B and GIULIANO G (2002) Metabolic engineering of xanthophyll content in tomato fruits , FEBSLett, 519, 30-34. 

FIGURE 2.2.1 Structures of common carotenoids (I. Main carotenes. II. Xanthophylls. III. Animal carotenoids). 

There are basically two types of carotenoids those that contain one or more oxygen atoms are known as xanthophylls those that contain hydrocarbons are known as carotenes. Common oxygen substituents are the hydroxy (as in p-cryptoxanthin), keto (as in canthaxanthin), epoxy (as in violaxanthin), and aldehyde (as in p-citraurin) groups. Both types of carotenoids may be acyclic (no ring, e.g., lycopene), monocyclic (one ring, e.g., y-carotene), or dicyclic (two rings, e.g., a- and p-carotene). In nature, carotenoids exist primarily in the more stable all-trans (or all-E) forms, but small amounts of cis (or Z) isomers do occur. - ... 

The maximum spectrometric absorption of lutein (C40H56O2, mol wt 568.9, xanthophyll, (3R,3.S,6.R)-p,8-carotene-3,3.-diol) is found between 453 and 481 nm. Its solubihty in ethanol is greater than that of the carotenoids. It is somewhat less sensitive to oxidation and heat degradation than P-carotene. It contributes yellow color." ... 

Zeaxanthin is the abundant xanthophyll in only a small number of food sources and is the dominant xanthophyll in orange peppers and Gou Zi Qi or lycium mill (Lycium chinense) berries, probably the richest sources. - ... 

Carrots were also the main sonrces of a-carotene, whereas tomatoes and tomato prodncts were the major sources of lycopene. Lutein was mainly provided by peas in the Republic of Ireland and United Kingdom. Spinach was found to serve as the major source in other countries. Lutein and zeaxanthin xanthophylls are found in a wide variety of fruits and vegetables, particularly green leafy vegetables, but also in some animal products such as egg yolks. In all countries, P-cryptoxanthin was obtained primarily from citrus fruits. 

Wisniewska, A. and Subczynski, W.K., Accumulation of macular xanthophylls in unsaturated membrane domains. Free Radio. Biol. Med., 40, 1820, 2006. 

In contrast with the hydrocarbon carotenes primarily located in the cores of the CM particles, xanthophylls are present at the surfaces of the CM particles, making their exchanges with other plasma lipoproteins easier." Therefore, if some exchanges occur between lipoproteins, AUC (or absorption) values of the newly absorbed compound in the TRL fraction will be underestimated. Based on all these considerations, the present approach is more appropriate to determine the relative bioavailability of a compound derived from various treatments within one snbject and/or within one study. 

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