Plant pigment

M. S. Tswett, the Polish botanist, in 1906 used adsorption columns in his investigations of plant pigments. It was not untU about 1930 that the method was used extensively by chemists. The most startling results have been obtained in the fields of plant pigments and natural products, but... 

Section 26 16 Carotenoids are tetraterpenes They have 40 carbons and numerous dou ble bonds Many of the double bonds are conjugated causing carotenes to absorb visible light and be brightly colored They are often plant pigments... 

Carotenoids (Section 26 16) Naturally occurring tetrater penoid plant pigments... 

Betalaines. In 1968, the term betalaines was used to describe collectively two groups of plant pigments the red betacyanins and the yellow betaxanthins. The red and yellow dyes found in beets. Beta vulgaris, fall into this category. An interesting history has been written about these dyes (133). 

R. Willstatter (Munich) plant pigments, especially chlorophyll. 

Alkenes with many double bonds in a row are colored. Some plant pigments are alkenes of this kind. One example is )S-carotene, which gives carrots their distinctive orange color. Animals break down )S-carotene into vitamin A, which is essential for vision. Xanthin molecules, relatives of j6-carotene that contain oxygen atoms, occur in com, orange juice, and shellfish. The xanthin below makes the flamingo pink. 

COGDELL R (1988) The function of pigments in chloroplasts . In Plant Pigments. T W Goodwin (ed) London, Academic Press. 

GOODWIN T w and britton g (1988) Distribution and analysis of carotenoids , in Goodwin T W, Plant Pigments, London, Academic Press, 61-134. 

Rudiger, W. and Schoch, S., Chlorophylls, in Plant Pigments, Goodwin, T.W., Ed., Academic Press, London, 1988, chap. 1. 

Schoefs, B., Plant pigments properties, analysis, and degradation, Adv. Food Nutr. Res., 49, 41, 2005. 

Betalains are vacuolar plant pigments. Hence their hydrophilic nature is comprehensible. Although they are slightly soluble in ethanol and methanol, water is the best snited solvent both for stability and solnbility reasons. In contrast to the antho-cyanins, the betalains are even more polar as can be demonstrated by shorter retention times in RP-HPLC and lower solubilities in alcoholic solutions. The varying polarities may also be beneficially used to separate anthocyanins from betalains on an RP-18 solid-phase extraction cartridge (Stintzing, unpublished data). 

Jurd, L., Some advances in the chemistry of anthocyanins-type plant pigments, in The Chemistry of Plant Pigments, Chichester, C.O., Ed., Academic Press, New York, 1972, 123. 

Zryd, J.P. and Christinet, L., Betalains, in Plant Pigments and Their Manipulation, Davies, K., Ed., Annual Plant Reviews 14, CRC Press/Blackwell, Oxford, 2004, 185. Gill, M. and Steglich, W., Pigments of fungi (Macromycetes), Progr. Chem. Organic Natural Products, 51, 1, 1987. 

For the sake of study, the biosynthesis of carotenoid plant pigments can be divided into parts involving enzymes and their associated activities as listed in Table 5.3.1 and further detailed in Figure 5.3.1 through Figure 5.3.4. Some of the parts have common enzymatic mechanisms and may also be in distinct subcellular compartments such as cytoplasm, endoplasmic reticulum, or plastid thylakoid. 

Bouvier, R, Dogbo, O., and Camara, B., Biosynthesis of the food and cosmetic plant pigment bixin (annatto). Science 300, 2089, 2003. 

Standard open column and thin-layer chromatographic methods have been gradually replaced by HPLC, which is faster, more reliable, more accurate and highly reproducible for analyzing plant pigments and for opening new perspectives in chlorophyll... 

In recent decades, the synthetic colorant market has dechned, to the benefit of the natural-oriented market and consumers. Excluding FD C Red 40 and Red 28, the synthetic colorants are now as well accepted as they were. In addition to the decreasing enthusiasm for chemicals in food, the high costs of toxicological studies also inhibit the development and approval of new synthetic colorants. The existing technologies used for the extraction, concentration, and purification of natural plant pigments to be used as food colorants still produce lower yields and the final products are still expensive. 

Davis, K.M., in Plant Pigments and Their Manipulation, Davis, K.M., Iid., Blackwell Publishing, Oxford, 2004, chap. 1. 

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