Color, pigments xanthophylls

In the animal kingdom, carotenoids are incorporated via the diet, and stored in different tissues. The egg yolk owes its yellow color to xanthophylls such as lutein and zeaxanthin, and to traces of 3-carotene. While the presence and distribution of carotenoids in mammals is very limited, other vertebrates, such as birds, fish, reptiles, and amphibians, and, above aU, the invertebrates show a great diversity of carotenoid pigments, and even have the capacity to modify structurally some of the carotenoids ingested in the diet. ... 

Algae are classified according to their colors (1) Chlorophyceae (green), (2) Rhodophyceae (red), (3) Cyanophyceae (bine-green), and (4) Pheophyceae (brown). The major pigments inclnde chlorophylls a, b, and c, P-carotene, phycocyanin, xanthophylls, and phycoerythrin. All these pigments have great potential for applications in foods, pharmacenticals, and cosmetics. 

The yellow coloration in the Monarch as well as the larva of three other species of butterfly from South Florida is exclusively due to the specific accumulation of exceptionally high levels of lutein producing a pigmented epidermis. This active accumulation, reminiscent of the specific accumulation that occurs in the primate macula, indicates that butterfly larva is an excellent animal model for the study of carotenoid transport and binding. As such, elucidation of the mechanism of transport and binding of lutein in the epidermis and other tissues of these butterfly larvae may provide insight into xanthophyll uptake within the human eye (Bhosale et al. 2004). 

Immediately cork the tube filled with nitrogen and then add a drop or two of dichloromethane to dissolve the pigments for TLC analysis. Carry out the analysis without delay by spotting the mixture on a TLC plate about 1 cm from the bottom and 8 mm from the edge. Make one spot concentrated by repeatedly touching the plate, but ensure that the spot is as small as possible—less than 1.0 mm in diameter. The other spot can be of lower concentration. Develop the plate with 70 30 hexane acetone. With other plates try cyclohexane and toluene as eluents and also hexane/ethanol mixtures of various compositions. The container in which the chromatography is carried out should be lined with filter paper that is wet with the solvent so the atmosphere in the container will be saturated with solvent vapor. On completion of elution, mark the solvent front with a pencil and outline the colored spots. Examine the plate under the uv light. Are any new spots seen Report colors and i /values for all of your spots, and identify each as lycopene, carotene, chlorophyll, or xanthophyll. 

Pigments.— These are substances which give color to various plant parts in which they are found. They occur either in special protoplasmic structures, as chloroplasts, chromoplasts or chroma-tophores, or dissolved in tjie cell sap. Of the pigments named the following will be considered Chlorophyll, Xanthophyll, Chromophyll, Etiolin, Anthocyanin, Phycocyanin, Phycophxin, and Phycoerythrin. 

Chromophyll also called xanthophyll and carotin is the yellow or orange pigment found in chromoplastids. By some the term carotin is limited to the orange pigment found in the carrot. Sulphuric acid forms a blue color with chromophyll. 

Carotenoids. Carotenoids are fat-soluble pigments comprised of isoprene units and, in plants, are generally associated with membranes (30). Carotenoids are generally classified as either carotenes, which are structurally related to hydrocarbons, or xanthophylls which are hydroxy, epoxy and oxy derivatives and are frequently esterified. The carotenoids most important in Imparting color to fruits and vegetables are derivatives of a- and -carotenes and lycopene. Carotenoids vary in their stability but, due to their unsaturated nature, they are generally susceptible to oxidation. Carotenes are important to... 

Fig. 1. Separation of leaf carotenes and leaf xanthophylls by chromatographic adsorption, obtained in 1938 by Harold Strain. I. Separation of a carotene from )3-carotene by adsorption of petroleum ether extracts of leaves on a magnesia column. II. Separation of leaf xanthophylls by adsorption of a dichloroethane solution of these pigments on a magnesium column note the separation of violaxanthin, zeaxanthin and lutein, mentioned in the text. The figure is taken from Strain (1938, p. ii, frontispiece). See also Color Plate 1.

C40H56O3, Mr 584.88, deep carmine red crystals (petroleum ether), mp. 175-176°C, uv ax 483 nm, [ajp -70° (CHCI3), well soluble in organic solvents except petroleum ether. A carotinoid belonging to the group of xanthophylls which occurs as red pigment in peppers [Capsicum annuum, Solanaceae). C. is authorized in the EU for use in coloring foods as well as in cosmetics. 

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