title: A new structural theme in the imidazole-containing alkaloids from a calcareous Leucetta sponge.
abstract: Further study of the Fijian sponge Leucetta sp., a source of (+)-calcaridine A (4) and (-)-spirocalcaridines A (5) and B (6), has yielded (-)-spiroleucettadine (8), the first natural product to contain a fused 2-aminoimidazole oxalane ring along with the known compounds N,N-dimethylnaamidine D (3) and isonaamine B (7). NMR analysis allowed the unambiguous 2D structural assignment of 8, and its relative stereochemistry was determined by ROESY data. Good antibacterial activity was observed for 8 against Enterococcus durans with an MIC of less than 6.25 microg/mL.
authors.affiliation: Department of Chemistry and Biochemistry and Institute of Marine Sciences, University of California, Santa Cruz, California 95064, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Ralifo
authors.forename: Phillip
authors.initials: P
authors.lastname: Crews
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000494:pharmacology; D000818:Animals; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D011161:Porifera / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*
chemical_list: D000470:Alkaloids; D007093:Imidazoles; D013141:Spiro Compounds; C534159:spiroleucettadine