Ascidia nigra Tunichromes

Recently, a reducing blood pigment named tunichrome B-l (10) was isolated from the tunicate Ascidia nigra L. and characterized.351 It has a structure derived from three (3,4,5-trihydroxy)phenylalanine units and the trihydroxyphenyl group is suitable for reducing the metal. 

Examples of tunichromes from Ascidia nigra (suborder Phlebobranchia) (left) and Molgula manhattensis (suborder Stolidobranchia) (right). 

Tunicates are the only marine invertebrates in which alkaloid biosynthesis has been extensively investigated (189). In addition to the eudistomins, described below, the tripeptide tunichromes have been investigated, by Nakanishi and coworkers at Columbia University, in the solitary tunicate Ascidia nigra (191) and shermilamine, a benzo-3,6-phenanthroline alkaloid, has been studied in Cystodytes dellechiajei, by Steffan and coworkers at the University of Munich (192). The origin of the (3-carboline ring system of the eudistomins has been studied, by Baker s group at Florida Tech, in Eudistoma olivaceum (193, 194). 

Vanadium is often taken up as vanadate, in a pathway parallel to phosphate. However, its oxidation state within organisms seems to be highly variable. Unusually high concentrations of vanadium occur in certain ascidians (the specific transport behavior of which will be dealt with later). The workers who first characterized the vanadium-containing compound of the tunicate, Ascidia nigra, coined the name tunichrome. The characterization of the compound as a dicatecholate has been reported. 

Isol. from the tunicate Ascidia nigra. Blood pigment which selectively accumulates vanadium. rZ-Isomer [97689-87-7]. Tunichrome BI C26H25N3O11 M 555.497 Isol. from A. nigra. Dec. in air on warming. 

Tunichrome a green chromogen in the blood cells of tunicates, e.g. Ascidia nigra, Ciona intestinalis, Molgula manhattensis. 

Actual droplet formation is not necessary as long as the mobile phase can pass through the stationary phase without displacing it. As a matter of fact, both aqueous and nonaqueous biphasic systems have been used (51, 332). Recent results reveal that a variety of natural products such as saponins, saturated fatty acids, and biomacromolecules - the latter on a biphasic aqueous polymer system - can be separated (332). Because of its comparatively rapid and non-destructive action, CPC has recently been used in the isolation of the tunichromes, the rather sensitive phenolic peptides from the vanadium-collecting sea squirt Ascidia nigra (53, 54) and of W-cis- and trans-rciindA from a complex photoisomerization mixture (51). 

Bruening R C, Oltz E M, Furukawa J, Nakanishi K, Kustin K 1985 Isolation and structure of tunichrome B-1, a reducing blood pigment from the tunicate Ascidia nigra L. J Am Chem Soc 107 5298-5300... 

Recently, Bruening etal. (717a) isolated tunichrome B-1 (1036), which is derived from three (3,4,5-trihydroxyphenyl)alanine units, from Ascidia nigra. 

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