OKADAXANTHIN, A NOVEL C-50-CAROTENOID FROM A BACTERIUM, PSEUDOMONAS SP KK10206C ASSOCIATED WITH MARINE SPONGE, HALICHONDRIA-OKADAI

To study the origins of biologically active substances in marine sponges, a carotenoid produced by a marine bacterium, Pseudomonas sp. strain number KK10206C, which was associated with a marine sponge, Halichondra akadai, was investigated. A visible absorption spectrum-guided isolation procedure led to the isolation of a novel C-50-carotenoid, okadaxanthin. Its structure, 2,2'-bis(4-hydroxy-2-methyl-2-butenyl)-epsilon,epsilon-carotene, was elucidated mainly by spectroscopic methods. Okadexanthin turned out to be a potent singlet oxygen quencher, approximately 10 times as strong as alpha-tocopherol.