Rubia tinctorum purpurin from

Fig. 2.148. UV (254 nm) profile of an acidic hydrolysate of an aqueous alcoholic extract of Rubia tinctorum (after 30 min). The mass spectra (sinlge MS) obtained with NI-ESI with ammonia added post-column and the UV-Vis spectra of peaks 3 and 4 are depicted, lucidin primeveroside (1), rubery-thic acid (2), lucidin glucoside (3), alizarin glucoside (4), munjistin (6), alizarin (8), and purpurin (9). Reprinted with permission from G. C. H. Derksen et al. [320].

Rubia tinctorum alizarin and purpurin can be clearly identified by the marked spots. Pseudopurpurin has been converted into purpurin by decarboxylation, because the old extraction method (boiling with 10% sulfuric acid, followed by shaking with ethyl acetate) has been used to isolate the dyes from the madder roots. 

Figure 5 shows the comparison of the madder dyes taken from the Adler-dalmatika with samples of Rubia tinctorum, alizarin, and purpurin by TLC. The dye extracted from the sample of the Adlerdalmatika with dilute sulfuric acid is unmistakably madder. 

After the first isolation of alizarin a lot of other anthraquinones were isolated from Rubia tinctorum for example purpurin, munjistin, rubiadin, pseudopurpurin, nordamnacanthal, lucidin, xanthopurpurin and anthra-gallol. 

Some anthraquinones isolated from Rubia tinctorum are believed to be artefacts for example the anthraquinones which show the presence of a 2-methoxymethyl or 2-ethoxymethyl group. These anthraquinones have been formed during the extraction of lucidin with boiling methanol or ethanol [4,68,97]. According to Schweppe the anthraquinones purpurin (1,2,4-trihydroxy anthraquinone) and purpuroxanthin (1,3-dihydroxy-anthaquinone) are formed from respectively pseudopurpurin (3-carboxy-1,2,4-trihydroxyanthraquinone) and munjistin (2-carboxy-l,3-dihydroxy-anthraquinone) during drying of the roots [3]. Some anthraquinones were only isolated once from Rubia tinctorum. It is thus doubtful whether these... 

Alizarin, Pseudopurpurin, Purpurin as well as Lucidin, Morindone, Munjistin and Rubiadin in Madder and other closely related dyestuffs of natural origin from plant species such as Rubia tinctorum L. and other R. species, Odenlandia species, Morinda species and Galium species. 

Another important organic red color that has served since ancient times for dyeing textile materials is madder. This colorant is derived from the roots of Rubia tinctorum and other plants in the Rubiaceae family it consists of a mixture of alizarin, purpurin, and pseudopurpurin, and thus one might expect that the natural product would yield a variety of shades. It was described by Strabo, Dioscorides, Pliny the Elder, and in the Tahnud. It has been identified on Egyptian textiles as early as 1300 BCE and in six paint pots of Greco-Roman origin that are now in the British Museum. In addition, textiles dyed with madder were sold at the St. Denis... 

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