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 IC(50) values below 10 nM. Thirty-nine dications were more potent against P. falciparum than pentamidine (IC(50) = 58 nM), and eight analogues were more active than artemisinin (IC(50) = 6 nM). Diimidazoline 60 exhibited antiplasmodial IC(50) value of 0.6 nM. Seven congeners administered at 4 x 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 x 1 mg/kg, diamidine 46 displayed better antitrypanosomal efficacy than melarsoprol, curing all infected mice.