PF1022A--a novel anthelmintic cyclooctadepsipeptide. Modification and exchange of the N-methyl leucine residues.

The first structure-activity relationships of the anthelmintic cyclooctadepsipeptide PF1022A have been established via a systematic exchange of the leucine residues by a series of related N-alkylated amino acids. The data presented strongly suggest that (L)-N-methyl-leucine is crucial for high in vivo activity.