PF1022A and related cyclodepsipeptides - a novel class of anthelmintics.

Parasitic nematodes are a major cause of morbidity and mortality in man and also cause widespread loss of food production by infection of livestock. A milestone in the chemotherapy of nematode infections, especially in animals, was the discovery of the avermectins and milbemycins during the 1970s. Since the discovery of these highly active macrolides, reports of potent new classes of anthelmintics have been scarce. One of the most outstanding recently reported anthelmintics is the cyclooctadepsipeptide PF1022A, the most active member of a novel class of anthelmintic agents. During the past years several total syntheses of PF1022A and manifold structure-activity relationships have been established. Additionally, the biosynthesis of PF1022A has been elucidated and intensive investigations into the mode of action of this novel anthelmintic are underway. Comprehensive studies including cyclodepsipeptides with smaller ring-sizes, such as the enniatins, proved the PF1022 family and related cyclodepsipeptides to be the most promising follow-up candidates for the avermectins and milbemycins, which suffer from increasing nematode resistance.