Activity of Benzimidazole Derivatives and their N-Heterocyclic Carbene Silver Complexes Against Leishmania major Promastigotes and Amastigotes

Little progress was conducted concerning discovering new efficient antileishmanial drugs for many years. Hence, the disease has become a global health problem meanwhile. Benzimidazole derivatives and heavy metal complexes have shown potent antiparasitic activities. The present work is intended to evaluate fourteen synthetic benzimidazolium salts and N-heterocyclic silver carbene complexes against Leishmania major. Promastigotes and amastigotes of L. major were cultured in vitro to evaluate compound-induced inhibitory effects, and isolated mouse macrophages were used for cytotoxicity evaluation. Reactive oxygen species (ROS) formation was detected for all compounds as a possible mode of action. The silver complexes 3d and 3e revealed significant activity against L. major promastigotes with IC50 values of 6.4 and 5.5 µg mL-1, and SI of 1.77 and 2.02, respectively. Both complexes showed higher ROS production in promastigotes than in macrophages. Further in vivo and enzyme inhibition studies are recommended to evaluate the potential of these compounds as new antileishmanial.