Halicylindramides A-C, Antifungal and Cytotoxic Depsipeptides from the Marine Sponge Halichondria cylindrata

Halicylindramides A-C (1–3) have been isolated from the Japanese marine sponge Halichondria cylindrata. They are tetradecapeptides with the N-terminus blocked by a formyl group and the C-terminus lactonized with a threonine residue. Their total structures including absolute stereochemistry were determined by a combination of spectral and chemical methods. Halicylindramides A-C were antifungal against Mortierella ramanniana and cytotoxic against P388 murine leukemia cells.