Plants pigments from

Discovery Experiment Analysis of Plant Pigments from Various Sources... 

Effect of Solvent Polarity on Efficiency of Separation, p. 186 Analysis of Plant Pigments from Various Sources, p. 186 Analysis of Analgesics by TLC, p. 187... 

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be beneficially used to separate anthocyanins from betalains on an RP-18 solid-phase extraction cartridge (Stintzing, unpublished data). 

Naturally Occurring Acetylene Compounds. XX. A Preliminary Communication on Some Polyacetylenic Pigments from Compositae Plants. Acta Chem. Scand. 8, 1769 (1954). 

Because plants are able to synthesize carotenoids de novo, the carotenoid composition of plant foods is enriched by the presence of small or trace amounts of biosynthetic precursors, along with derivatives of the main components. Although commonly thought of as plant pigments, carotenoids are also encountered in some animal foods. Animals are incapable of carotenoid biosynthesis thus their carotenoids need to be derived from the diet. Selectively or unselectively absorbed, carotenoids accumulate in animal tissues unchanged or slightly modified into typical animal carotenoids. 

The methods used for making pigments from these and other natural dyes were more like recipes than scientific procedures and were probably derived from the work of alchemists and herbalists. The former spent their lives trying to prepare gold by dissolving all kinds of cheap substances in acids and then re-precipitating them (hence their discovery of many precipitants), while the latter sought to extract compounds of medicinal value from plants and some of their extracts must have included natural dyes. 

Mason (30) and Pierpoint (31) have described the involvement of o-diphenols in plants and how they contribute to abnormal plant pigmentation. o-Diphenols are oxidized to o-quinones by enzymes of the phenolase complex (o-diphenol O2 oxidoreductase, E.C. 1.10.3.1) and by peroxidase (E.C. 1.11.1.7). o-Quinones react with amino acids, proteins, amines and thiol groups of proteins to polymerize and from reddish-brown pigments. Concentrations of caffeic acid are doubled in both bean (8) and peanut... 

Shahjahan, M., M. Mosihuzzaman, and A. Mian. Phenolic acids in rice plant (Oryza sativa). J Bangladesh Chem Soc 1992 5(1) 59-63. Nakashima, R., K. Hakamoto, Y. Katagiri, T. Mizutani, N. Ueda, and J. Yamamoto. Structure determination of a pigment from Oryza sativa Linn. (Kurogome). Chem Express 1993 8(6) 393-396. 

Figure 9.38, for example, shows the application of the chemical mass balance approach to the fine particle fraction of particles collected at a location in Philadelphia (Dzubay et at., 1988 Olmez et al., 1988 Gordon, 1988). If the set of equations (II) fitted the data perfectly, the sum of the contributions of the various sources would be 100% for each element. Clearly, from the top frame, this is not the case for a number of elements, and both positive and negative deviations from 100% can be seen. However, the contributions of several sources are clear Si and Fe from soil, Ni, V, and Ca from oil-fired power plants, Ti from a paint pigment plant, La, Ce, and Sm from a catalytic cracker, K, Zn, and Sn from an incinerator, Sb from an antimony roaster, and Pb and Br from motor vehicles. 

Given the co-evolution of plants and animals, it is not smprising that hmnans inherited from their ancestors an acute ability to sense plant pigments—there were rather few non-plant pigments in the hmnan environment rmtil recent centimes. 

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