Tawicyclamides

Solution- and solid-state conformations of tawicyclamides A (57) and B (58), proline-containing cyclic peptides from a Philippines specimen of L. patella, were determined by spectroscopic and X-ray analyses respectively [87]. Patellins 1-6 (50-55), trunkamide A (56) and the tawicyclamides A-B (57-58) all lack the oxazoline ring present in most other cyclic peptides isolated from the Lissoclinum genus [22]. 

The patellins 1-6 (382-387) and trunkamide A (388) [298, 299] along with tawicyclamides A (389) and B (390) [300] represent another variation of the cyclic peptides produced by Lissoclinum species. All of these compounds lack the characteristic oxazoline ring present in most Lissoclinum cyclic peptides. Compounds 382-386 and 388 were inactive in a series of in vitro cytotoxicity assays while 387, 389, and 390 showed modest cytotoxicity, supporting the importance of the presence of the oxazoline ring for cytotoxic activity [298, 300],... 

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... 

McDonald, L.A., Foster, M.P., Phillips, D.R., and Ireland, C.M. (1992) Tawicyclamides A and B, new cyclic peptides from the ascidian Lissodinum patella studies on the solution and solid-state conformation./. Org. Chem., 57, 4616-4624. 

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