Natural pigments flowering plants

Carotenoids are natural pigments characterized by a tail to tail linkage between two C20 units and an extended conjugated system of double bonds They are the most widely dis tributed of the substances that give color to our world and occur m flowers fruits plants insects and animals It has been estimated that biosynthesis from acetate produces approximately a hundred million tons of carotenoids per year The most familiar carotenoids are lycopene and (3 carotene pigments found m numerous plants and easily isolable from npe tomatoes and carrots respectively... 

Dye planta. Term for all wild-growing or cultivated plants whose flowers, fruits, seeds, leaves, stems, woods, roots, and barks contain natural pigments or pigment precursors that are used for dyeing wool, cotton, silk, leather, paper, wood, foods, and cosmetics or serve as pigments of paints. See table for the important dye plants see also madder (see table, p. 197). Lit. Rowe, p. 848. Angew. Bot. 67, 128 (1993). Franke, Nutzpflanzenkunde (5.), Stuttgart Thieme 1992. gen. Ullmann (4.) 11, 99-134. 

Carotenoids are natural pigments synthesized by plants and some microorganisms. Humans and animals are not able to synthesize and need to acquire them by alimentation [1]. These compounds are widely distributed in fruits, flowers, roots, seaweeds, invertebrates, fishes, birds, bacteria, fungi, and yeasts [2-4]. They are responsible for the red, yellow, and orange colors, but green, purple, or blue color could be obtained when carotenoids are botmd with some proteins [1]. Such molecules act as photosynthesis aid and for the photoprotection of their hosts [2-4]. Due to this, it is used in food and feed as colorant, flavoring, and nutritional supplement, being source of provitamin A. 

The carotenoids are the most widespread group of pigments in nature, with an estimated yield of 100 million tonnes per annum. They are present in all photosynthetic organisms and responsible for most of the yellow to red colours of fruits and flowers. The characteristic colours of many birds, insects and marine invertebrates are also due to the presence of carotenoids, which have originated in the diet. Animals are unable to synthesise carotenoids de novo, and so rely upon the diet as the source of these compounds. Carotenoids found in the human diet are primarily derived from crop plants, where the carotenoids are located in roots, leaves, shoots, seeds, fruit and flowers. To a lesser extent, carotenoids are also ingested from eggs, poultry and fish. Commercially, carotenoids are used as food colourants and in nutritional supplements (Table 13.1). Over recent years there has been considerable... 

The functions of phenylpropanoid derivatives are as diverse as their structural variations. Phenylpropanoids serve as phytoalexins, UV protectants, insect repellents, flower pigments, and signal molecules for plant-microbe interactions. They also function as polymeric constituents of support and surface structures such as lignins and suberins [1]. Therefore, biosynthesis of phenylpropanoids has received much interest in relation to these functions. In addition, the biosynthesis of these compounds has been intensively studied because they are often chiral, and naturally occurring samples of these compounds are usually optically active. Elucidation of these enantioselective mechanisms may contribute to the development of novel biomimetic systems for enantioselective organic synthesis. 

Chalcones (l,3-diaryl-2-propen-l-ones) are open-chain fiavonoids that are widely biosynthesized in plants. They are important for the pigmentation of flowers and, hence act as attractants to the pollinators. As fiavonoids, chalcones also play an important role in defending against pathogens and insects. A review of the literature concerning the evaluation of natural chalcones from medicinal plants reveals that many studies into their antimicrobial and antiviral activities have been carried out in recent years. Some of these compounds were isolated by bioassay-guided fractionation, after previously detecting activity on the part of the plants. 

Commonly the target phenotype has been flower color. In addition to the expected white-flower phenotypes, in some species both ordered and erratic pigmentation patterns have been obtained (Table 3.4). Patterning only seems to occur in species that naturally have patterned varieties. Furthermore, some of the patterns show instability, not only within a particular plant but also in their inheritance (see, e.g.. Ref. 331), which may limit the commercial usefulness of some of the more dramatic phenotypes. ... 

Eorkmann, G., Elavonoids as flower pigments the formation of the natural spectrum and its extension by genetic engineering, Plant Breeding, 106, 1, 1991. 

As we begin to unravel the molecular mechanisms of the regulation of anthocyanin biosynthesis, we must remember that evolution and selection had significant opportunities to explore new ways to color plants, flowers, and seeds. Model plant systems such as maize, petunia, and Arabidopsis will continue to provide the framework to understand how pigment accumulation is controlled. However, it is important to investigate how nature has exploited variations in these central prototypes to provide the amazing diversity found today in the type and distribution of anthocyanin pigments. 

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