DRUG-RESISTANCE IN SCHISTOSOMES

Drug resistance in schistosomes is confined essentially to compounds o f the hycanthone/oxamniquine family, since no documented case of resis tance has so far been reported for the widely used drug praziquantel, The availability of strains of Schistosoma mansoni that are resistant to hycanthone and oxamniquine has permitted o detailed genetic and bio chemical study of the mechanism of action of these compounds, Drugs mu st be activated by enzymatic esterification and this ultimately result s in the production of an electrophilic moiety capable of alkylating D NA and other parasite macromolecules, As reviewed here by Donato Cioli , Livia Pica-Mattoccia and Sydney Archer, resistance is due to the los s of a drug-activating enzyme that is present in sensitive schistosome s and absent in resistant worms and in the mammalian hosts. Further st udy of this enzyme may yield valuable clues for drug design and for a basic understanding of parasite metabolism.