title: Bistellettazines A-C and bistellettazole A: new terpenyl-pyrrolizidine and terpenyl-imidazole alkaloids from a southern Australian marine sponge, Stelletta sp.
abstract: Four new alkaloids have been isolated during chemical investigations into a southern Australian marine sponge, Stelletta sp. Detailed spectroscopic analysis, supported by chemical degradation and partial synthesis, permitted structure elucidation of bistellettazines A-C ( 1- 3), the first reported examples of terpenyl-pyrrolizidine conjugates, and bistellettazole A ( 4), a unique cyclic terpenyl-imidazole conjugate. The alkaloids 1- 4 feature unprecedented carbon skeletons that are proposed to share a common convergent biosynthetic origin, arising via the biogenic equivalent of a Diels-Alder addition between two hypothetical polyenyl norsesquiterpene precursors.
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: Andrew M
authors.initials: AM
authors.lastname: Piggott
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Capon
mesh_terms: D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001315:Australia; D007093:Imidazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D011161:Porifera / Q000737:chemistry* / Q000378:metabolism; D011763:Pyrrolizidine Alkaloids / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000577:Amides; D007093:Imidazoles; D011763:Pyrrolizidine Alkaloids; C532766:bistellettazine A; C532767:bistellettazine B; C532768:bistellettazine C; C532769:bistellettazole A; C029899:imidazole