[structure: see text] Laboratory cultures of an undescribed streptomycete obtained from the surface of a British Columbia lichen produce uncialamycin (1), a new enediyne antibiotic. The structure of uncialamycin (1) has been elucidated by analysis of spectroscopic data. Uncialamycin (1) exhibits potent in vitro antibacterial activity against gram-positive and gram-negative human pathogens, including Burkholderia cepacia, a major cause of morbidity and mortality in patients with cystic fibrosis.

Five new alkaloids, dictyodendrins A-E (1-5), were isolated from the Japanese marine sponge Dictyodendrilla verongiformis as telomerase inhibitors. Their structures were elucidated by spectroscopic and chemical methods. Dictyodendrins are tyramine-based pyrrolocarbazole derivatives containing three or four p-hydroxybenzene groups. They inhibited telomerase completely at a concentration of 50 microg/mL.

The sequence positions of d and l Leu and Lys residues in bogorol A (1) have been defined by a simple and novel approach that utilizes small amounts of sample and focuses on detecting the order in which amino acids are liberated from the parent peptide during acid-catalyzed hydrolysis. This technique builds on a previously established relationship between the steric and electronic features of amino acids and their predilection for acidic liberation from polypeptides via dipeptides. The results, which complete the structure of bogorol A, have been confirmed by traditional degradation experiments. Utilizing the knowledge of the structure of bogorol A (1) as a template, we rapidly elucidated the structures of bogorols B-E (2-5) via analysis of ESI-MS and ESI-MS/MS data and GC analysis of degradation products. The bogorol cationic peptide antibiotics contain a number of unusual structural features, which include the reduction of the C-terminal residue to valinol, an N-terminal residue of 2-hydroxy-3-methylpentanoic acid, the incorporation of four d amino acids, and the presence of a dehydroamino acid. Bogorols show selective and relatively potent activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus spp., as well as moderate activity against Escherichia coli.

No abstract

The new macrolide spirastrellolide B (5) has been isolated from extracts of the marine sponge Spirastrella coccinea collected in Dominica. Chemical transformations of spirastrellolide B have converted it to a bromine-containing crystalline derivative 8 that has a truncated side chain. Single-crystal X-ray diffraction analysis of the derivative 8 has revealed the absolute configuration of the macrolide core of spirstrellolide B to be 3R,7S,9S,11S,13R,14S,17S,20S,21R, 22S,23S,24S,27R,29S,31R,34S,35R,37S,38S.