Novel diamidines with activity against Babesia divergens in vitro and Babesia microti in vivo.

Dicationic diamidines, such as diminazene and pentamidine, are well-studied chemotherapeutic agents with significant activity against parasitic diseases. The in vitro activities of novel diamidine compounds against the Babesia divergens strains 1903B and 4201 were investigated. The most potent compound, a diphenyl furan, had a 50% inhibitory concentration (IC(50)) of 1.5 ng/ml. In a murine model, several test compounds were effective enough to cure mice infected with Babesia microti at a dose of 12.5 and/or 25 mg/kg of body weight given by the subcutaneous route for 4 days. The best antibabesial properties were exhibited by terphenyls, benzimidazoles, diphenyl furans, pentamidine, and pentamidine analogues.