Synthesis, crystal structures, in vitro anticancer, and in vivo acute oral toxicity studies of bis-imidazolium/benzimidazolium salts and respective dinuclear Ag(I)-N-heterocyclic carbene complexes

Abstract

The synthesis, spectral (FT-IR and NMR), and structural studies of 1,1′-methylene linked 3,3′-2-cyanobenzyl bis-imidazolium salt (L₁) and respective dinuclear Ag(I)-NHC complex (C₁) are reported. The structures of both compounds were established through single-crystal X-ray diffraction. C₁ has a short Ag–Ag separation of 3.16 Å. Both L₁ and C₁ were tested for potential against leukemia (k562) cell line. For comparison, para-xylyl linked bis-benzimidazolium salts (L₂–L₄) and their dinuclear Ag(I)-NHC complexes (C₂–C₄) were synthesized and tested against the same cell line (K562). The IC₅₀ values proved that L₂–L₄ and C₂–C₄ are many fold more active than L₁ and C₁. The mechanism of action and structure activity relationship are discussed. In vivo oral acute toxicity study (sighting study) was carried out which depicts that 2000 mg/kg dose of selected compounds is an appropriate and safe dose for conducting main study on animals.

Keywords:

• Ag(I)-N-heterocyclic carbene
• Anticancer
• K562
• Crystal structure
• Ag–Ag separation
• SAR
• Acute oral toxicity