Isolation and structural elucidation of callipeltins J–M: antifungal peptides from the marine sponge Latrunculia sp.

Continued investigation of the polar extracts of the marine sponge Latrunculia sp. has resulted in the discovery of callipeltins J–M. The new structures were determined by interpretation of their NMR and MS data. The stereochemistry of the unusual 3-methylglutamine residue in callipeltins J and K was secured by stereoselective synthesis and Marfeyʹs LC–MS analysis.