METABOLISM OF CAROTENOIDS IN SEA-URCHIN PSEUDOCENTROTUS-DEPRESSUS

1. Feeding experiments with beta,beta-carotene, canthaxanthin and astaxanthin on the sea urchin Pseudocentrotus depressus were investigated. 2. In the case of beta,beta-carotene group, beta-carotene was accumulated, beta-isocryptoxanthin appeared and beta-echinenone increased 6.8 times as much as the control group. On the other hand, in canthaxanthin and astaxanthin groups, canthaxanthin and astaxanthin increased significantly, respectively. The metabolic products of these carotenoids could not be found. 3. It was concluded that beta,beta-carotene was bioconverted to beta-echinenone via beta-isocryptoxanthin in P. depressus and could not be oxidatively metabolized beyond beta-echinenone.