Dysidenin from the Marine Sponge Citronia sp. Affects the Motility and Morphology of Haemonchus contortus Larvae In Vitro.

High-throughput screening of the NatureBank marine extract library ( n = 7616) using a phenotypic assay for the parasitic nematode Haemonchus contortus identified an active extract derived from the Australian marine sponge Citronia sp. Bioassay-guided fractionation of the CH 2 Cl 2 /MeOH extract from Citronia sp. resulted in the purification of two known hexachlorinated peptides, dysidenin ( 1 ) and dysideathiazole ( 2 ). Compound 1 inhibited the growth/development of H. contortus larvae and induced multiple phenotypic changes, including a lethal evisceration ( Evi ) phenotype and/or somatic cell and tissue destruction. This is the first report of anthelmintic activity for these rare and unique polychlorinated peptides.