title: Novel cytotoxic compounds from the ascidian Lissoclinum bistratum.
abstract: The isolation and structures of two new cyclic hexapeptides and two new macrocyclic ethers from the aplousobranch ascidian Lissoclinum bistratum are described. Their structures were determined by two-dimensional NMR techniques. The hexapeptides, named bistratamide A and bistratamide B, differ only by the presence or absence of one double bond. They were tested for cytotoxicity toward human fibroblast and tumor cell lines and displayed similar toxicities to the octapeptides called patellamides from Lissoclinum patella. The peptides are found within the obligate algal symbiont Prochloron but clearly differ from peptides isolated from the same Prochloron of L. patella. The macrocyclic ethers isolated from L. bistratum are exceedingly potent in cytotoxicity. They have been named bistratenes A and B, and structures for these compounds are proposed.
authors.affiliation: Department of Biochemistry, University of Queensland, St. Lucia, Australia.
authors.forename: B M
authors.initials: BM
authors.lastname: Degnan
authors.forename: C J
authors.initials: CJ
authors.lastname: Hawkins
authors.forename: M F
authors.initials: MF
authors.lastname: Lavin
authors.forename: E J
authors.initials: EJ
authors.lastname: McCaffrey
authors.forename: D L
authors.initials: DL
authors.lastname: Parry
authors.forename: D J
authors.initials: DJ
authors.lastname: Watters
mesh_terms: D000081:Acetamides; D000818:Animals; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000096:biosynthesis; D004988:Ethers, Cyclic / Q000302:isolation & purification* / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008968:Molecular Conformation; D015394:Molecular Structure; D008970:Molecular Weight; D010456:Peptides, Cyclic / Q000302:isolation & purification* / Q000494:pharmacology; D011714:Pyrans; D013141:Spiro Compounds; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000378:metabolism; D014561:Urochordata / Q000032:analysis*
chemical_list: D000081:Acetamides; D004988:Ethers, Cyclic; D010456:Peptides, Cyclic; D011714:Pyrans; D013141:Spiro Compounds; C059975:bistratene A; C059973:bistratamide A; C059976:bistratene B; C059974:bistratamide B; D004247:DNA