Synthesis, structure, anticancer, and antioxidant activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag(I) N-heterocyclic carbene complexes (Part-II)

The article describes synthesis, characterization (NMR, FT-IR, microanalysis, X-ray crystallography), in vitro anticancer, and antioxidant 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 cells (HCT 116) and DPPH antioxidant evaluation. According to cell viability measurements using MTT assay, all the tested compounds showed dose-dependent cytotoxic activity against HCT 116 cells. The tested compounds demonstrated significant activity with IC₅₀ values range 0.29–3.30 μM for HCT 116 and % age inhibition 6.37–21.00 for DPPH antioxidant study. 5-Fluorouracil was used as standard drug (IC₅₀ 19.2 μM for HCT 116) whereas for DPPH analysis, Gallic acid was used as positive control (% age inhibition 77.68). All the compounds showed potential anticancer activity against human colorectal cancer whereas antioxidant activity was not significant. We found that as the size of N-alkyl substitution on benzimidazolium salt increases its cytotoxicity against cancer decreases whereas a reverse occurs in case of respective complexes.