Synthesis and anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective Ag(I) N-heterocyclic carbene complexes

The article describes synthesis, characterization (NMR, FT-IR, microanalysis, X-ray crystallography), and in vitro anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag-NHC complexes. All the compounds were tested for their cytotoxicity against human colorectal cancer (HCT 116) and promyelocytic leukemia (HL-60) cell lines. According to cell viability measurements using MTT assay, all tested compounds showed dose-dependent cytotoxic activity against both cell lines. The tested compounds demonstrated significant activity with IC50 values range 0.01-18.7 mu M for HCT 116 and 0.7-55.7 mu M for HL-60 cells. 5-Fluorouracil was used as standard drug (IC50 19.2 mu M for HCT 116 and 5.4 mu M for HL-60). We found that as the size of N-alkyl substitution on benzimidazolium salt increases its cytotoxicity decreases whereas a reverse occurred in case of respective complexes.