Investigation of the in vitro effects of benzimidazol-2-ylidene-based silver-N-heterocyclic carbene complexes on Microsporidia and Leishmania major promastigotes

In this study, chloro[1-methallyl-3-(2,3,5,6-tetramethylbenzyl)-5,6-dimethylbenzimidazole-2-ylidene]silver(I) (C24H30AgClN2) (2a), chloro[1-methallyl-3-(2,3,4,5,6-pentamethylbenzyl)-5,6-dimethylbenzimidazole-2ylidene]silver(I) (C25H32AgClN2) (2b), chloro[1-methallyl-3-(naphthylmethyl)benzimidazole-2-ylidene]silver(I) (C24H24AgClN2) (2c) were prepared, and characterized by FT-IR, NMR (1H, 13 C{ 1 H) spectroscopy and elemental analysis. In addition, the structures of 2a and 2b were elucidated by single crystal X-ray diffraction analysis. The study evaluated the cytotoxic potential of benzimidazole-2-ylidene-based silver-NHC complexes in vitro. These complexes were tested for their antimicrosporidial activity using E. intestinalis spores in human renal epithelial cell lines (HEK-293). Similarly, the effect on Leishmania major promastigotes was measured by metabolic activity or cell viability assessed by the tetrazolium reaction. The results of our investigation showed that all the compounds studied exhibited inhibitory effects on the proliferation of both L. major promastigotes and E. intestinalis spores. Complex 2b showed promising potent inhibitory activity to combat microsporidial infections. Complex 2a showed the highest level of activity as a potent anti-Leishmania agent.