The carotenoid pigments of the holothurian Psolus Fabrichii (Düben and Koren)

The carotenoid content of the body wall of the subarctic holothurian Psolus fabrichii (Düben and Koren) has been investigated. -- The carotenoids were extracted by cold acetone, taken into petroleum ether, and after concentration of this solution were separated by thin layer chromatography on a silica gel H layer, using 10% acetone in petroleum ether as the developing solvent. The ten carotenoids separated were further purified by thin layer chromatography. -- As far as possible each carotenoid has been identified by measurement of its light absorption properties, its partition ratio between hexane and 95% methanol, and by investigation of the effects of potassium hydroxide, sodium borohydride, and acidic methanol on the compound. -- The direct effect of dietary carotenoids on the carotenoid content of echinoderms has previously been emphasised. It has generally been accepted that the herbivorous diet of holothurians provides mainly carotenes and less polar xanthophylls, arid these carotenoids are therefore predominant in the tissues. -- The results of this investigation indicate that, though a small part of the dietary carotenoid is stored in the tissues of Psolus fabrichii, the food does not contain measurable amounts of the more abundant body wall carotenoids. -- It is proposed that the highly oxidised carotenoids, which compose about 80% of the total carotenoid content might be the intermediates and product of a sequential pathway responsible for the oxidation of dietary β-carotene (and possibly some of its hydroxy derivatives) to astaxanthin, the predominant carotenoid in the organism