Synthesis and biological evaluation of Au-NHC complexes

Abstract

New seven Au-N-heterocyclic carbene (NHC) complexes have been synthesized via transmetalation from Ag-NHC complexes. NHC salts, Ag-NHC, and Au-NHC complexes were fully characterized by widely used spectroscopic techniques. The molecular and crystal structures of 3b and 3f Au-NHC complexes were clarified through the single-crystal X-ray diffraction method. According to X-ray diffraction analysis results, the coordination geometry around Au(I) atoms in the complexes are revealed to be almost linear with C-Au-Cl angle. Anticancer activity, DNA binding, xanthine oxidase (XO) inhibitory activity studies, and molecular docking studies were evaluated for all Au-NHC complexes to explore the binding mechanism at the active site. The IC50 value of Au-NHC complexes against human colorectal cancer (Caco-2) and breast cancer (MCF-7) cell lines was defined by MTT assay. The IC50 values for MCF-7 in the range of 5.2 +/- 2 to 152.4 +/- 1 mu M and Caco-2 5.2 +/- 1 to 152.7 +/- 2 mu M showed that 3a, 3b, 3c, 3d, and 3g have better anticancer activity than Cisplatin incredibly complex 3a against both cancer cell line. All Au-NHC complexes showed excellent antimicrobial activity against different bacteria and fungi. 3a was the complex that exhibited the best antimicrobial activity here as well. The XO inhibitory activity experimental results indicated that all gold complexes showed remarkable inhibition activity against XO compared to the generally used standard, allopurinol. The range of IC50 value was determined from 0.407 to 2.681 mu M. 3d complex showed the lowest IC50 value at 0.407 mu M. DNA binding experiments were performed using agarose gel electrophoresis to observe the ability of synthesized Au-NHC complexes to interact with the supercoiled pUC19 plasmid DNA. Molecular docking studies were performed to determine the binding mode of all active compounds against the XO enzyme, antibacterial, antifungal, and MCF-7 cell lines.