Carotenoids neoxanthin

BOUVIER F, d harlingue A, BACKHAUs R A, KUMAGAi H and CAMARA B (2000) Identification of neoxanthin synthase as a carotenoid cyclase pmalog , FEBSLetters, 267, 6346-52. BRAMLEY P M (1993) Inhibition of carotenoid biosynthesis , in Yoimg A J and Britton G, Carotenoids in Photosynthesis, London, Chapman and HaU, 127-59. 

Most of this amount is in the form of fucoxanthin in various algae and in the three main carotenoids of green leaves lutein, violaxanthin, and neoxanthin. Others produced in much smaller amounts but found widely are p-carotene and zeaxanthin. The other pigments found in certain plants are lycopene and capsanthin (Figure 2.2.1). Colorant preparations have been made from all of these compounds and obviously the composition of a colorant extract reflects the profile of the starting material. Carotenoids are probably the best known of the food colorants derived from natural sources. ... 

Typically several different carotenoids occur in plant tissues containing this class of pigments. Carotenoids are accumulated in chloroplasts of all green plants as mixtures of a- and P-carotene, P-cryptoxanthin, lutein, zeaxanthin, violaxanthin, and neoxanthin. These pigments are found as complexes formed by noncovalent bonding with proteins. In green leaves, carotenoids are free, nonesterified, and their compositions depend on the plant and developmental conditions. In reproductive... 

Dunaliella natural P-carotene is distributed widely in many different markets under three categories p-carotene extracts, Dunaliella powder for human use, dried Dunaliella for feed use. Extracted purified P-carotene is sold mostly in vegetable oil in bulk concentrations from 1 to 20% to color various food products and for personal use in soft gels usually containing 5 mg P-carotene per gel. Purified natural p-carotene is generally accompanied by the other Dunaliella carotenoids, primarily lutein, neoxanthin, zeaxan-thin, violaxanthin, cryptoxanthin, and a-carotene for a total of approximately 15% of carotene concentration. This compound is marketed as carotenoids mix. ... 

Carotenoids are present at low levels in tea leaf.60 Neoxanthin, violaxanthin, lutein, and B-carotene are the major components of this group. They enter into reactions that lead to aroma formation.61... 

Fucoxanthin, lutein, neoxanthin, violaxanthin, and zeaxanthin are the most common xanthophylls on our planet. They are found in the photosynthetic machinery of algae (fucoxanthin) and higher plants (Figure 7.1). Interestingly, lutein and zeaxanthin have also been found in the retina of humans and some primates (Khachik et al., 1997 Landrum and Bone, 2001). It is likely that these carotenoids possess some universal photophysical properties essential for both photosynthesis and vision (Britton, 1995). 

Snyder, A.M., Clark, B.M., Robert, B., Ruban, A.V., and Bungard, R.A. 2004. Carotenoid specificity of light-harvesting complex II binding sites Occurrence of 9-cis violaxanthin in the neoxanthin-binding site in the parasitic angiosperm cuscuta reflexa. J. Biol. Chem. 279 5162-5168. 

The substrate specificity of these enzymes is not stringent for example, CCD1 from tomato was also shown to cleave at the 9,10- and 9, 10 -positions of (1-carotene, zeaxanthin, lutein, violaxan-thin and neoxanthin all of which have different ionone ring modifications. Unlike NCEDs, CCD1 enzymes have no plastid-targeting sequences and are localized in the cytosol. It is postulated that they access the carotenoids in the plastids through a monotopic membrane association (Kloer et al. 

The involvement of mitochondria in the pro-apoptotic effects of carotenoids has been clearly demonstrated by the fact that P-carotene induces the release of cytochrome c from mitochondria and alters the mitochondrial membrane potential (Aym) in different tumor cells (Palozza et al., 2003a). Moreover, the highly polar xanthophyll neoxanthin has been reported to induce apoptosis in colon cancer cells by a mechanism that involves its accumulation into the mitochondria and a consequent loss of mitochondrial transmembrane potential and releas of cytochrome c and apoptosis-inducing factor (Terasaki et al., 2007). 

Fresh tomato fruit contains about 0.72 to 20 mg of lycopene per 100 g of fresh weight, which accounts for about 30% of the total carotenoids in plasma (Stahl and Sies 1996). In contrast to other pigments such as (3-carotene, lutein, violaxanthin, auroxanthin, neoxanthin, and chlorophylls a and b, which accumulate in inner pulp and in the outer region of the pericarp, lycopene appears only at the end of the maturation period and almost exclusively in the external part of the fruit (Laval-Martin and others 1975). Other tomato components that can contribute to health include flavonoids, folic acid, and vitamin E (Dorais and others 2001a,b). 

Carotenoids are probably the best known of the colorants and certainly the largest group of pigments produced in nature with an annual production estimated at 100,000,000 tons. Most of this is fucoxanthin produced by algae in the ocean and the three main pigments, lutein, violaxanthin and neoxanthin in green leaves.10 Over 600 carotenoid compounds have been reported. 

Fig. 2.9. Separation of carotenoid pigments by reversed-phase (I) and normal-phase (II) HPLC. The relative areas of carotenoids (retention time) are shown for latoxanthin (9.7), capsorubin (11.4), neoxanthin...

Fig. 2.17. Saponified carotenoids in orange juice. Chromatographic conditions are given in text. Chromatograms from absorbance monitoring at 430, 486 and 350 nm, respectively, are shown, all at identical attenuation. Peak identification 1, 3, 5, 8, 26 and 29 = unidentified peaks 4 = valen-ciaxanthin 6 = neochrome 7 = trollichrome 9 = antherxanthin 11 = c/s-anthexanthin 12 = neoxanthin 19 = auoxanthin B 20 = c/s-violaxanthin 22 = leutoxanthin 23 = mutatoxan-thin A 24 = mutatoxanthin B 25 = lutein 27 = zeaxanthin 28 = isolutein 31 = a-cryptoxanthin 33 = /J-cryptoxanthin 34 = phytofluene 35 = a-carotene 36 = ae-carotene 37 = / -carotene. Reprinted with permission from R. Rouseff et al. [41].

The carotenes and carotenoids are very important accessory pigments (Fig. 23-22). The major component in most green plants is (3-carotene. Green sulfur bacteria contain y-carotene in which one end of the molecule has not undergone cyclization and resembles lycopene (Fig. 22-5). Chloroplasts also contain a large variety of oxygenated carotenoids (xanthophylls). Of these, neoxanthin, violaxanthin... 

The percentage composition of carotenoids in plants depends on growing conditions. The average weight percent ranges are /3-carotene, 25-40% lutein, 40-60% violaxanthin, 10-20% and neoxanthin, 5-13%. Carotenoids are biosynthesized by condensation of acetyl CoA through the mevalonic acid pathway and the Porter-Lincoln pathway. 

Structures of major carotenoids /3-carotene, lutein, violaxanthin, and neoxanthin. 

Visible absorption spectra for four carotenoids 3-carotene (—), lutein (- -), violaxanthin and neoxanthin (.. . ). 

The complete separation from I-carotene to violaxanthin requires 35 min. Figure F2.3.4 illustrates the separation of carotenoids in a mixed food extract using this LC system. The hydrocarbon carotenes ( -carotene, a-carotene, lycopene) elute together at the solvent front. The elution order is fi-cryptoxanthin, u-cryptoxanthin, lutein, cis-lutein, zeaxanthin, cis-zeaxanthin, neoxanthin, and violaxanthin. 

Figure F4.3.2 Absorption spectra of the major carotenoids of the photosynthetic biomembranes of green leaves of higher plants in diethyl ether (pure solvent). The carotenoids were freshly isolated from a pigment extract by TLC following Lichtenthaler and Pfister (1978) and Lichtenthaler (1987). P-C, p-carotene Lut, lutein Neo, neoxanthin Viola, violaxanthin.

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