title: Mirabilins revisited: polyketide alkaloids from a southern Australian marine sponge, Clathria sp.
abstract: Chemical investigation of a southern Australian marine sponge, Clathria sp., yielded the known mirabilins C, F and G, together with three new analogues, mirabilins H-J. For the first time mirabilins C and F are documented as the underivatized natural products, and a complete absolute stereochemistry is assigned to mirabilin F. Mirabilin I represents the first member of this structure class to incorporate a trans-fused ring junction. Structures for all mirabilins are assigned on the basis of detailed spectroscopic analysis. A plausible polyketide origin is proposed, linking all mirabilins and related sponge alkaloids. Mirabilin cytotoxicity against several human cancer cell lines is discussed.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Queensland, 4072, Australia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El-Naggar
authors.forename: Melissa
authors.initials: M
authors.lastname: Conte
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Capon
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D001315:Australia; D045744:Cell Line, Tumor; D006801:Humans; D020128:Inhibitory Concentration 50; D018942:Macrolides / Q000737:chemistry*; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011161:Porifera / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D013057:Spectrum Analysis
chemical_list: D000470:Alkaloids; D018942:Macrolides; D012503:Saponins; C105644:mirabilin; D009828:Oleanolic Acid