Diplosoma virens

The virenamides A-C (180-182), thiazole-containing cytotoxic linear peptides, were isolated from the colonial ascidian Diplosoma virens collected on the Great Barrier Reef, Australia. Their structures were... 

Thiazole-containing linear peptides have also been isolated from tunicates. Virenamides A-E (412-416) were obtained from the didemnid tunicate Diplosoma virens, which contains symbiotic prokaryotic algae in its cloacal cavity. The structures of virenamides A-C were determined by HPLC analysis using Marfey s procedure [323] while the absolute stereochemistry of virenamide E (416) was proven by its synthesis from virenamide A (412) [324], Compounds 412-416 showed modest cytotoxicity toward a panel of cultured cells and 412 also exhibited topoisomerase II inhibitory activity. 

Carroll, A. R., Feng, Y., Bowden, B. F., and Coll, J. C., Studies of Australian ascidians. 5. Virenamides A-C, new cytotoxic linear peptides from the colonial didemnid ascidian Diplosoma virens, J. Org. Chem., 61, 4059, 1996. 

The Other modified linear peptides reported are virenamides A-E (43-47) from the didemnid ascidian Diplosoma virens [40,41]. Strictly speaking, these metabolites are apparently derived from 4 amino acids so should be regarded as tetrapeptides, but are more conveniently regarded as carboxy-protected tripeptides (where the carboxyl group has been... 

Another species of Didemnidae from the Great Barrier Reef Diplosoma virens, contains prenylated peptides with a thiazole nucleus, which is particularly common in cydic peptides and depsipeptides. Virenamides A-E are only weakly cytotoxic in vitro (Carroll et al, 1996a Feng and Bowden, 1997) and, like caledonin, these peptides may act as natural antifouling agents (Davis and Bremner, 1999). 

Ogi, T., Taira, J., Margiastuti, P., and Ueda, K. (2008) Cytotoxic metabolites from the Okinawan asddian Diplosoma virens. Molecules, 13, 565-602. 

Remember that this species, which can be regarded as fixed, was discovered through the symbiotic relationship that it maintains with ascidians of the family Didemnidae, in particular Diplosoma similis and D. virens, Lissoclinum patella and I. voeltzkowi, Trididemnum cyclops and, more recentiy, the genus Polysyncraton (Duclaux, Lafargue, and Wahl, 1998). These relations have considerable importance insofar as the Didemnidae frequently contain antiviral and antitumor substances whose true origin is probably Prochloron. In our current state of knowledge, it has not yet been possible to cultivate in vitro-isolated... 

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