Sythesis, Characterisation, Anticancer and Antimicrobial Activity of Ag-N-heterocyclic Carbene Complexes Containing Benzimidazole Derivatives

To prepare a novel series of silver(I) complexes, the interaction of benzimidazolium salts having their two nitrogen atoms substituted by bulky groups with Ag2O in DCM has been carried out. Their structures were characterized by elemental analyses, 1H NMR, 13C NMR, elemental analysis, and IR spectroscopy techniques. Further, the antimicrobial and antifungal activities properties of both the salts and their silver(I)-NHC complexes were tested against positive and negative bacteria using the Clinical and Laboratory Standards Institute (CLSI) and the European Committee for Antimicrobial Susceptibility Testing (EUCAST) respectively. The results show that silver complexes are effective against E. coli, P. aeruginosa and S. aureus bacterial species with moderate to high activity, and their minimum inhibitory concentrations ranging from 25 to 400 mu g/Ml. It was also observed that 3b compound, which has the best antifungal properties among the synthesized compounds, showed high antimicrobial activity when all bacterial species were taken into account. In addition, the salts and complexes were then evaluated for their ability to inhibit the proliferation of four different cancer cell lines (A549, MCF-7, HCT116, SH-SY5Y and BEAS-2B cells lines). AlamarBlue assay demonstrated that the salts and complexes exhibited potent cytotoxicity towards all cancer lines. 2c compound showed the highest cytotoxic activity against BEAS-2B, A549 and MCF-7 cell lines. Except for 2c, compounds 3d, 3e and 3f showed cytotoxic activity at the lowest concentrations against MCF7 cell line.The study highlights the importance of N-heterocyclic carbene ligands in the development of silver-based drugs with anticancer properties.