Lissoclinum patella ulithiacyclamide from

The heptapeptide ulicyclamide (15) and the octapeptide ulithiacyclamide (16) were the first representatives of a series of cyclic peptides to be isolated from Lissoclinum patella. Their structures were elucidated by interpretation of spectral data [44], A revised structure was later put forward for ulicyclamide (15) as a result of a detailed analysis of the fast atom bombardment (FAB) mass spectrum. The same paper reported the isolation of two more polar cyclic peptides and another, which was present as a minor component. These heptapeptides were called lissoclinamides 1-3 (17-19) [45]. An unidentified tunicate from the Great Barrier Reef contained ulithiacyclamide (16) and ascidiacyclamide (14) [46]. Two syntheses of ulithiacyclamide (16)... 

Two cyclic peptides that were isolated from the marine tunicate Lissoclinum patella,30 named ulicyclamide and ulithiacyclamide, have structures (33) and (34). 

Lissoclinum bistratum contains mostly cyclic hexapepti-des/ but Lissoclinum patella has yielded patellamides A-G (Figure 28.15), which are regarded as octapeptides, as well as ulithiacyclamides A and B and pre-ulithiacydamide these last three peptides are characterized by the presence of an intracyclic disulfide bridge. Lissoclinum patella has also yielded asddiacydamide, which had been isolated in 1983 from an tmdetermined ascidian, and tawicyclamides A and which appear to be currently the only cyclic peptides containing only thiazoles or thiazolines. These... 

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