title: Trikentramides A-D, indole alkaloids from the Australian sponge Trikentrion flabelliforme.
abstract: Chemical investigations of two specimens of Trikentrion flabelliforme collected from Australian waters have resulted in the identification of four new indole alkaloids, trikentramides A-D (9-12). The planar chemical structures for 9-12 were established following analysis of 1D/2D NMR and MS data. The relative configurations for 9-12 were determined following the comparison of (1)H NMR data with data previously reported for related natural products. The application of a quantum mechanical modeling method, density functional theory, confirmed the relative configurations and also validated the downfield carbon chemical shift observed for one of the quaternary carbons (C-5a) in the cyclopenta[g]indole series. The indole-2,3-dione motif present in trikentramides A-C is rare in nature, and this is the first report of these oxidized indole derivatives from a marine sponge.
authors.affiliation: Eskitis Institute, Griffith University , Brisbane, QLD 4111, Australia.
authors.forename: Shahan
authors.initials: S
authors.lastname: Khokhar
authors.forename: Yunjiang
authors.initials: Y
authors.lastname: Feng
authors.forename: Marc R
authors.initials: MR
authors.lastname: Campitelli
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Quinn
authors.forename: John N A
authors.initials: JN
authors.lastname: Hooper
authors.forename: Merrick G
authors.initials: MG
authors.lastname: Ekins
authors.forename: Rohan A
authors.initials: RA
authors.lastname: Davis
mesh_terms: D000818:Animals; D001315:Australia; D026121:Indole Alkaloids / Q000737:chemistry / Q000302:isolation & purification*; D008386:Marine Biology; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D011161:Porifera / Q000737:chemistry*
chemical_list: D026121:Indole Alkaloids; C586134:trikentramide A