Natural Red

C-Glycosyl compounds have a carbon atom ia place of the exocycHc oxygen atom of the acetal group and, therefore, are branched cycHc ethers. An example is the naturally occurring anthroquiaone dye, carminic acid [1260-17-9] (Cl Natural Red 4). 

Cochineal Extract. Cochineal extract (Cl Natural Red 4, Cl No. 75470 EEC No. E 120) is the concentrated solution obtained after removing the alcohol from an aqueous-alcohoHc extract of cochineal, which is the dried bodies of the female insect Coccus cacti Dactylopius coccus costd) a variety of field louse. The coloring principle of the extract is beHeved to be carminic acid [1260-17-9] (40), an hydroxyanthraquinone linked to a glucose unit, comprising approximately 10% of cochineal and 2—4% of its extract. 

Anthraquinone Dyes. This second most important class of dyes also iacludes some of the oldest dyes they have been found ia the wrappiags of mummies dating back over 4000 years. In contrast to the a2o dyes, which have no natural counterparts, all the important natural red dyes were anthraquiaones (see Dyes, natural). However, the importance of anthraquiaone dyes is declining due to their low cost-effectiveness. 

Alizarin. There is only one significant plant anthraquinone dye, alizariu [72-48-0] (Cl Natural Red 6, 8, 9,10, 11, and 12 Cl 75330). In ancient times, alizaria was the preferred red dye. Cloth dyed with it has been found in Egyptian tombs dating 6000 years ago. The dye is found in the madder plant, a member of the Rubiaceae family. In 1944 about 35 species of this plant were known (1), but the use of more sophisticated analytical methods led to the detection of many more species by 1984 the number had increased to 50 (2). Of these, tinctorum and R peregrina yield the greatest amount of dye,... 

Kermisic Acid. Many accounts claim that kermisic acid [476-35-7] (Cl Natural Red 3 Cl 75460) is the oldest dyestuff ever recorded (23). The name kermes is derived from an Armenian word meaning Httle worm for which the later Latin equivalent was vermiculus, the basis of the Knglish word Vermillion. The dye was obtained from an oriental shield louse, K. ilicis which infest the holm o5kQuercus ilex and the shmb oak. coccifera. The dye produces a brilliant scarlet color with an alum mordant. Although expensive, it was cheaper than its rival Tyrian Purple. It was in great demand until the sixteenth century when it was displaced by carminic acid. 

Sardaryan, E. et al., Arpink Red meet a new natural red food colourant of microbial origin, in Pigments in Pood More Than Colors, Dufosse, L., Ed., Universite de Bretagne Occidentale, Quimper, 2004, 207. 

A systematic study was carried out using in parallel 50 standard solutions for each concentration of three natural colorants (curcumin, carminic acid, and caramel as yellow, red, and brown, respectively). No false positive results for synthetics were obtained up to concentrations of 15 and 20 ng/ml for natural red and yellow colorants, respectively, or 110 ng/ml for natural brown colorant. The concentrations have to be high enough to prove that the screening method is able to accurately discriminate natural and synthetic colorants. To make a clear interpretation of the quantitative UV-Vis spectrum, linear regression analysis was used. Quantitative UV-Vis analysis of a dye ° can be calculated according to the following formula ... 

The use of the mordanting process with the natural red dye alizarin to form the metal complex dye Turkey Red (so-called because the color was like that found on a turkey s neck), was one of the first examples of the preparation and use of a metal complex colorant. 

M.A. Ackacha, K. Polec Pawlak and M. Jarosz, Identification of anthraquinone coloring matters in natural red dyestuffs by high performance liquid chromatography with ultraviolet and electrospray mass spectrometric detection, J. Sep. Sci., 26, 1028 1034 (2003). 

A further important application of these pigments is in paints. The natural red iron oxides are also used in primers for steel structures and cars, for marine coatings and for anti-fouling paints. In the USA, the metallic browns are used for these purposes. The level of soluble salts in the latter pigments is low and this reduces corrosion problems. The metallic browns are also used in heat resistant enamels. 

Some natural dyes are coming back into use and amongst these is one called Dragon s Blood (C.I. Natural Red) which consists of the flavenes dracorhodin (134) and dracorubin (135). 

The flavonoids, derivatives of flavone (353) and of isoflavone (354), are widely distributed among plants of many kinds. They provide colour (from pale yellow to orange) in flowers and their potential as dyes is being revived now that awareness of the toxicity of some synthetic dyes is increasing, for example morin (355 CI. Natural Red) is one of many... 

Murai, K. and D. Wilkins "Natural Red Color Derived from Red Cabbage," food Technology, 131 ljune 1990). 

The structure of kermisic acid is l,3,4,5-tetrahydroxy-7-carboxy-8-mcrhylanthraquinone. Carminic acid (Cl Natural Red 4 Cl 75470). is a red dye occurring as a glycoside in the body of the cochineal insect Dactylopius coccus of the order Homoptera. family Coecidae, Until the advent of synthetic dyes, the principal use for carminic acid was for dyeing tin-mordanted wool or silk. Its aluminum lake, carmine, finds use in Lhe coloring of foods. The structural formula of carminic acid is (2). 

Laccaic acid has been designated (Cl Natural Red 25 Cl 75450). Lac dye ranks as ihe most ancient of animal dyes. It is found in lac. the resinous secretion of a eery small insect. Coccus laccae. found growing in India and Southeast Asia. Lac dye is actually a mixture of acids derived front 2-phenylanthraquinonc... 

Alkannin. shikonin. and shikalkin are grouped together because the first two are enantiomers and the last one is their racemate. Alkannin (Cl Natural Red 20 Cl 75530) [Anchu.sa tinctoria or ttlkanua tinctoria) is a member uf the Boraginaceae family. It is found in the roots of alkanet, a perennial shrub native to Southern Eurupe. 

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