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 Marfey's LC-MS analysis.