Mass spectrometric identification of new minor indigoids in shellfish purple dye from Hexaplex trunculus

Izabella Surowiec, Witold Nowik, Thomas Moritz

12 Citations (Scopus)

Abstract

Analysis of natural dyes in historical objects is important for both conservation purposes and to determine the origin and culture that produced it. Identification of a particular dye is usually made based on the presence of its main components, while consideration of minor components is important for differentiating between dyes originating from closely related species. Tyrian purple is one of the oldest dyes known to man and derives from different species of marine molluscs. In all of these species, indigotin, indirubin and their brominated analogues are the main colouring compounds. Here, we describe the identification of minor indigoids found in extracts of the pigment obtained from one of the Tyrian purple species, Hexaplex trunculus. Identification of these compounds was made based on isotopic patterns and accurate mass measurements of protonated molecular ions and their high collision energy fragments obtained in LC-MS/MS experiments. The unknown compounds appeared to be analogues of indirubin and its mono- and dibrominated derivatives with one CO group in the indirubin backbone substituted by a CNH group. Identification of these compounds facilitates the detection of dyestuffs from H. trunculus in historical objects and increases our knowledge about the dye biosynthesis and technology of Tyrian purple production.

Original languageUndefined/Unknown
JournalDyes and Pigments
Volume94
Issue number2
Pages (from-to)363-369
Number of pages7
ISSN0143-7208
DOIs
Publication statusPublished - Aug 2012
Externally publishedYes

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