Lanthanide complexes containing 5-methyl-1,2,4-triazolo(1,5-a) pyrimidin-7(4H)-one and their therapeutic potential to fight leishmaniasis and Chagas disease☆

Abstract In the last years, numerous and significant advances in lanthanide coordination chemistry have been achieved. The unique chemical nature of these metal ions which is conferred by their f -electrons has led to a wide range of coordination compounds with interesting structural, physical and also biological properties. Consequently, lanthanide complexes have found applications mainly in catalysis, gas adsorption, photochemistry and as diagnostic tools. However, research on their therapeutic potential and the understanding of their mechanism of action is still taking its first steps, and there is a distinct lack of research in the parasitology field. In the present work, we describe the synthesis and physical properties of seven new lanthanide complexes with the anionic form of the bioactive ligand 5-methyl-1,2,4-triazolo[1,5- a ]pyrimidin-7(4 H )-one ( HmtpO ), namely [Ln(mtpO) 3 (H 2 O) 6 ]·9H 2 O (Ln = La(III), Nd(III), Eu(III), Gd(III), Tb(III), Dy(III) and Er(III)). In addition, results on the in vitro antiproliferative activity against Leishmania spp. and Trypanosoma cruzi are described. The high activity of the new compounds against parasite proliferation and their low cytotoxicity against reference host cell lines show a great potential of this type of compounds to become a new generation of highly effective and non-toxic antiparasitic agents to fight the so considered neglected diseases leishmaniasis and Chagas disease.