Pigments of marine animals. VI. Anthraquinoid pigments of the crinoids Ptilometra australis Wilton and Tropiometra afra Hartlaub

The crinoid Ptilometra australis Wilton yields to organic solvents a complex mixture of pigments from which the three principal components have been separated by chromatography on magnesium carbonate. These substances have been shown by spectral and chemical examination to be 1,6,8-trihydroxy-3-(1-hydroxypropyl). anthraquinone, 1,6,8-trihydroxy- 3-(2-hydroxypropyl)anthraquinone, and 1,6,8-trihydroxy-3- propylanthraquinone-2-carboxylic acid. The distinct types of crinoidal pigments isolated from Comatula species1 and from Ptilometra australis both conform to the acetate rule and are probably endogenous in origin. Both yellow and black specimens of the crinoid Tropiometra afra Hartlaub also contain the anthraquinonecarboxylic acid isolated from P. australis.