79 ホヤの新血液色素 : チュニクローム類について

概要

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The hematology of tunicates, a class of common marine organisms with the ability to selectively accumulate metals such as V, Fe, Mo, Nb, has puzzled scientists for over 70 years. The black tunicate Ascidia nigra (Linnaeus) sequesters vanadium as the pentavalent vanadate, concentrates it by 10^6-fold, and stores the metal in its reduced V(III) or V(IV) states at physiological pH (ca. 7.2), possibly as a hexaaquo or other complex. The apparent contradiction that V(III) is unstable in aqueous media at pH above 2.5 can be overcome by assuming the presence of a strong reductant that also serves as a good complexing agent. We believe that this role is fulfilled by the tunichromes, the bright yellow blood pigments of A. nigra and various other tunicates. Tunichromes, especially in the crude state, are extremely labile and have thus far eluded all isolation attempts. We report here the isolation and structure determination of tunichrome B-1 (1), the first member of a new group of natural reducing agents; the new technique of centrifugal counter-current chromatography played a crucial roll in this first successful isolation of underivatized tunichrome.
天然有機化合物討論会の論文
1985-09-07