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 spong es, a carotenoid produced by a marine bacterium, Pseudomonas sp. strai n number KK10206C, which was associated with a marine sponge, Halichon dra akadai, was investigated. A visible absorption spectrum-guided iso lation procedure led to the isolation of a novel C-50-carotenoid, okad axanthin. Its structure, roxy-2-methyl-2-butenyl)-epsilon,epsilon-caro tene, was elucidated mainly by spectroscopic methods. Okadexanthin tur ned out to be a potent singlet oxygen quencher, approximately 10 times as strong as alpha-tocopherol.