| Abstract
| - Two new metabolites, named halipeptins A and B, have been isolated from the marine spongeHaliclona sp. Their structures were determined by extensive use of one- and two-dimensional NMR experiments,mass spectrometry, and UV and IR spectroscopy. Halipeptin A is a novel 17-membered cyclic depsipeptide,consisting of five residues including two alanines (with l stereochemistry) and three new residues that appearto be previously undescribed from natural sources: 1,2-oxazetidine-4-methyl-4-carboxylic acid, 3-hydroxy-2,2,4-trimethyl-7-methoxydecanoic acid (HTMMD), and N-methyl-δ-hydroxyisoleucine. The HTMMD residueis substituted with 3-hydroxy-2,2,4-trimethyl-7-hydroxydecanoic acid in halipeptin B. Halipeptin A was foundto possess very potent anti-inflammatory activity in vivo, causing about 60% inhibition of edema in mice atthe dose of 300 μg/kg (i.p.).
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