Ancient dyes

Only natural dyes were known until the nineteenth century. By trial and error and probably also by chance, humans learned to extract and use a large variety of dyes of vegetable and animal origin. Dyes were extracted from the roots, trunk bark, and branches of trees, the stems, leaves, flowers, and fruits of plants, the bodies of insects and mollusks, and the eggs of insects. All the dyes obtained from natural sources are rather impure, and hence the accurate reproducibility of colors was almost impossible during antiquity. Still, many of the dyes and dyeing techniques used in antiquity were highly developed and remained in use until the discovery of the synthetic dyes in the middle of the nineteenth century (Colombo 1995 Robinson 1969). 

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Another ancient dye is the deep blue indigo [482-89-3], the presence of two bromine atoms at positions gives the dye Tyrian purple [19201 -53-7] once laboriously extracted from certain sea shells and worn by Roman emperors. 

Because of the long overland route used to bring indigotin from India to Europe, and because of the small amount of indigotin that was present in the leaves, about 2—4%, indigotin ranked among the most expensive of the ancient dyes (105). 

Direct and Mordant Dyes. The ancient dyes (see Fig. 77) may be classified into three main groups direct dyes, mordant dyes, and vat dyes (see... 

The most famous halogenated bis-indole is Tyrian purple, the dibromo analog of indigo (1). This colorful mollusc metabolite, which was the major component of the ancient dye, continues to receive attention (1369-1374). Additional studies of Tyrian purple from various molluscs have revealed the presence of 6,6 -dibromoin-dirubin (1441) (1375), 6-bromoindigotin (1442) (1375, 1376), 6-bromoisatin (1443) (1377, 1378), 6-bromoindoxyl (1444) (1378), 1445 (1378), 1446 (1378), 6-bromoindirubin (1447) (1379), and 6 -bromoindirubin (1448) (1379). The bromi-nated indirubins are potent and selective kinase inhibitors (1379). A direct-exposure... 

Steinhart CE (2001) Biology of the Blues The Snail Behind the Ancient Dyes. J Chem Ed 78 1444... 

The most famous dyestuff is probably indigo, an ancient dye that used to be isolated from plants but is now made chemically. It is the colour of blue jeans. More modern dyestuffs can be represented by ICI s benzodifuranones, which give fashionable red colours to synthetic fabrics like polyesters. 

Fig. 1.1 6,6 -Dibromoindigotin and its reduced form. This compound was the basis of the ancient dye Royal Purple, references to which go back to biblical times.

Other well-known indoles that have various natural sources are skatole (3-methylindole) (2), serotonin (3), L-tryptophan (4), tryptamine (5), the plant growth hormones 3-indoleacetic acid (6) and 4-chloro-3-indoleacetic acid (7) [19], the mushroom hallucinogen psilocin (8), and the indole-derived ancient dyes indigo (9) [20] and Tyrian Purple (10) [19] (Scheme 1). 

The ancient dyes berberine, palmatine, and jatrorrhizine were recovered from paper and analyzed on a C[g column (2 = 345 nm). The 40/10/49.5/0.5 ethanenitrile/ methanol/water [50 mM TFA)/sodium lauryl sulfate (no concentration given so assumed by weight) mobile phase gave baseline resolution and excellent peak shapes [1025]. Separation was complete in <15 min and complete resolution of all peaks was obtained. 

Although the chemistry of ancient dyes and mordanting processes was developed empirically, today we understand much of it in terms of modem coordination theory. However, many aspects of color shifts still await investigation. 

Baker, J.T. (1974) Tyrian pmple an ancient dye, a modern problem. Erxdeavour, 33,11-17. 

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