Pigments of marine animals. IV. The anthraquinoid pigments of the crinoids, Comatula pectinata L. and C. cratera A. H. Clark

Abstract

A review of the literature describing the pigments of the crinoids (phylum Echinodermata) reveals a prevalence of indicator-type pigments which are of unknown nature, except for certain polyhydroxy-meso- naphthodianthrones isolated from a fossilized Jurassic stalked crinoid. The highly coloured free-swimming crinoids, Comatula pectinata L. and C. cratera A. H. Clark, contain mixtures of indicator-type pigments which have been separated by adsorption chromatography on magnesium carbonate to yield three principal constituents, the 6-methyl and the 6,8-dimethyl ethers of rhodocomatulin, and a monomethyl ether of rubrocomatulin. The structure of the rhodocomatulin skeleton is shown to be 4-butyryl-1,3,6,8-tetrahydroxyanthraquinone rather than 2- butyryl-1,3,6,8-tetrahydroxyanthraquinone as previously suggested.¹