Synthesis and Antiprotozoal Activity of Cationic 1,4-Diphenyl-1H-1,2,3-triazoles

Novel dicationic triazoles 1−60 were synthesized by the Pinner method from the corresponding dinitriles, prepared via the copper(I)-catalyzed azide−alkyne cycloaddition (CuAAC). The type and the placement of cationic moieties as well as the nature of aromatic substituents influenced in vitro antiprotozoal activities of compounds 1−60 against Trypanosoma brucei rhodesiense, Plasmodium falciparum, and Leishmania donovani and their cytotoxicity for mammalian cells. Eight congeners displayed antitrypanosomal IC50 values below 10 nM. Thirty-nine dications were more potent against P. falciparum than pentamidine (IC50 = 58 nM), and eight analogues were more active than artemisinin (IC50 = 6 nM). Diimidazoline 60 exhibited antiplasmodial IC50 value of 0.6 nM. Seven congeners administered at 4 × 5 mg/kg by the intraperitoneal route cured at least three out of four animals in the acute mouse model of African trypanosomiasis. At 4 × 1 mg/kg, diamidine 46 displayed better antitrypanosomal efficacy than melarsoprol, curing all infected mice.