Carotenoids and Xanthophylls

Under these conditions, chlorophylls a and b, carotenoids, and xanthophyll esters are transferred to the epiphase (upper phase), as described in German in Lichtenthaler and Pfister (1978) and briefly in English in Lichtenthaler (1987). 

It should be emphasised that carotenoids and xanthophylls are a vast family of materials and three of the most naturally abundant are fucoxanthin, violaxanthln and neoxanthin (ref. 4) although they are not... 

Both carotenoids and xanthophylls have been found in all leaf tissues examined. Cyclic carotenes and xanthophylls from leaf tissues have both P- and e-ring types. Only dicyclic xanthophylls, and particularly those with C-3 or C-3, have been found in the biosynthetic tissues of higher plants. Acyclic carotenoids normally are not present (Young, 1993a). The same four major carotenoids, namely P-carotene (1), lutein (2), violaxanthin (3), and neoxanthin (4), have been found as the major carotenoid constituents of leaf tissues of all plants examined to date (Young, 1993a). Purple and green phototrophic bacteria rarely contain any of the monocyclic... 

Carotenoids have two structural types such as carotenes of arene carotenoids (hydrocarbon carotenoids) and xanthophylls of their oxygenated derivatives (Figure 1). 

Figure 1. Classification of carotenoids carotenes (arene carotenoids) and xanthophylls.

The chlorophylls, carotenoids, and xanthophylls are the best-known fat-soluble pigments and are often referred to as lipochromes. These pigments are found in... 

The red, orange and yellow pigments that we lump together as the carotenoids and xanthophylls have also piqued the interest of many talented chemists, and can therefore count as many Nobel Prizes as can chlorophyll research as the results of research in this field. There are hundreds of these pigments known today, so we must necessarily confine ourselves to the highlights of this field of research. 

Upon presenting the Nobel Prize to Karrer, Wilhelm Palmaer, chair of the prize committee at the time, described him as a scientist with the ability to visualize great and important problems as well as their smaller parts and one who in his own unique way approached problems and pursued new ideas by using his own methods [61] . Karrer s methodology has borne much fruit over the decades. The spinoffs from his work on the carotenoids and xanthophylls is still evolving today intense research on vision, vitamins, hormones, metabolic pathways, and enzymes. 

The true carotenoids and xanthophylls have 40 carbon atoms this corresponds to 8 isoprene residues. Like squalene, they are constructed symmetrically and it is assumed that they arise by head-to-head condensation of two C20 precursors. It has been found that mevalonic acid is one important precursor the appropriate enzyme systems from plants can convert mevalonate to carotenoids. The tetra-... 

Refined flours obtained from durum wheats, although rarely produced. Most flours are yellow pigmented due to carotenoids and xanthophylls. 

Name of the refined milled fraction that has a coarser particle size compared to flour. Most semolinas are yellow pigmented due to carotenoids and xanthophylls. Semolina is obtained from durum wheats and has a range of particle-size distribution of U.S. + 60to+ 100. 

For each class, there are specific carotenoids and xanthophylls (carotenoids containing oxygen), among others, which are common to several classes (see Chapters 8-14). 

The red algae have a complete set of photosynthetic eqrtip-ment, comparable to that of Cyanobacteria, because they possess chlorophylls, phycobiliproteins, carotenoids, and xanthophylls. 

Absorption spectra of pigments of box eledr separated by the paper chromatography (Fig 1) indicate that chlorophyls in diferent tissues are the same, when carotenoids seam to be different. The shifts of absorbtion maxima of carotenoids and xanthophylls could be either caused by different chemical forms or by different concentrations of pigments. Similar results were obtained with pigments of Chlorophytum (Fig. 2). Further more in leaf of this plant (Fig. 3) the distinct pigment with a new absorption maxima is detected. 

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