Pigments of marine animals. XIV. Polyketide sulfates from the crinoid Comatula pectinata

Abstract

The polyhydroxyanthraquinones known from the crinoid Comatula pectinata are shown to be present largely as (fish repellent) sulfate monoesters. The sodium salt of the 3-O-sulfate of 4-butyryl-1,3-dihydroxy-6,8-dimethoxy-9,10-anthraquinone was isolated by its chromatographic mobility on alumina in aqueous acetone or on sodium bicarbonate in aqueous ethanol. The sulfate hydrolyses readily to the free phenol and is methylated (Me₂SO₄/K₂CO₃ in refluxing acetone) to 4-butyryl-1,3,6,8-tetramethoxyanthraquinone. Methylated in the presence of tertiary alcohols however, the sulfate ester resists cleavage, yielding the 1,6,8-trimethyl ether, hydrolysable to 4-butyryl-3-hydroxy-1,6,8-trimethoxyanthraquinone.