Natural dyes from Rubia tinctorum L., used in tapestries

Plants and insects had been used for a long time in the ancient period as source for dyes for art materials. On many tapestries, there is a widespread state of decay in charge of the colour of many yarns. This phenomenon may be due to presence of alteration products or total destruction of dye molecules. If we consider madder root, for example, contains a large number of compounds characterized by anthraquinone structures, thought as the main chromophores [1]. However, it is worth to notice that the analyses of madder’s extract, obtained in the same condition of dyeing bath [2], reveal also the presence of other types of molecules (not necessarily anthraquinones), present in the matrix. Some of them can be fixed on the yarn and, probably, these are involved in the degradation processes. During this work, it has carried out extraction of dyes from R.tinctorum L. and analysed by HPTLC (Fig. 1), 1H-NMR (Fig. 2). and ESI-MS With ESI-MS/MS, in both positive and negative mode, it has been possible to draw a structural profile of the compounds. These compounds are compared to those extracted by yarns [3] [4], dyed following the ancient recipes [2], in order to evaluate which molecules are fixed on the textile .