Synthesis of Trioxaquantel® derivatives as potential new antischistosomal drugs

Over the past 20 years, praziquantel, a pyrazinoisoquinoline derivative, has become the mainstay for morbidity control of human and animal schistosomiasis. From early in their lives in vertebrate hosts, schistosomes ingest hemoglobin and aggregate the released heme as a dark pigment very similar to the hemozoin produced by Plasmodium in malaria infection. The antimalarial artemisinin derivatives have real, though low, schistosomicide activity. Because of the complementarity of the two drug classes - praziquantel and arternisinin derivatives - we designed new molecules, named trioxaquantels (R), that combine the 1,2,4-trioxane unit responsible for the activity of artemisinin, and the pyrazinoisoquinoline moiety of praziquantel within a single drug. The synthesis of these new drugs and their preliminary evaluation in mice infected with Schistosoma mansoni is reported here. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).