In vitro and in vivo treatments of echinococcus protoscoleces and metacestodes with artemisinin and artemisinin derivatives

Abstract

In vitro treatment of Echinococcus multilocularis and Echinococcus granulosus larval stages with the antimalarials dihydroartemisinin and artesunate (10 to 40 microM) exhibited promising results, while 6 weeks of in vivo treatment of mice infected with E. multilocularis metacestodes (200 mg/kg of body weight/day) had no effect. However, combination treatments of both drugs with albendazole led to a substantial but statistically not significant reduction in parasite weight compared to results with albendazole alone.

FIG. 1.

Protoscolicidal activity of artemisinin derivatives. E. granulosus protoscoleces were cultured in vitro in the presence of artesunate, DHA, and nitazoxanide (NTZ) as a positive control (10 and 40 μM). Note the dose-dependent killing of protoscoleces by both artesunate and DHA. This experiment was repeated three times with virtually identical outcomes. One representative result is shown. DMSO, dimethylsulfoxide.

FIG. 2.

EmAP activity in culture supernatant of drug-treated E. multilocularis metacestodes. Artesunate, DHA, artemisinin, and artemether were applied to in vitro-cultured vesicles at 40 μM, and EmAP activity was measured in culture supernatants at different time points as indicated. Albendazole (ABZ) and corresponding amounts of the solvent dimethylsulfoxide (DMSO) were added as positive and negative controls, respectively.

FIG. 3.

Experimental chemotherapy with E. multilocularis-infected mice. In vivo treatment of E. multilocularis-infected mice was carried out with albendazole (ABZ), artesunate (AS), dihydroartemisinin (DHA), and combinations of ABZ-AS and ABZ-DHA. CMC is the solvent control (0.5% CMC in phosphate-buffered saline). The box plots indicate the distribution of parasite weights in the different treatment groups. Significant reductions in parasite weights in relation to those in the CMC control group were achieved by treatment with ABZ, ABZ-AS, and ABZ-DHA. Although the combination treatments were the most efficient, the reduction in both groups in relation to ABZ alone was not significant (Kruskal-Wallis multiple-comparison z-value test; difference was significant with a z value of >1.96; z value for artesunate-ABZ was 1.89; z value for DHA-ABZ was 1.92).