Binding studies of (N-(methylpyridin-2-yl)-amidino-O-methylurea)copper(II) complexes to four nitrogenous bases and 5′-GMP

• (N-(methylpyridin-2-yl)-amidino-O-methylurea)copper chloride and perchlorate show the same DNA-binding ability.
• The type of anions do not affect on their binding properties, but slightly impact on their antibacterial activities.
• The perchlorate compound exhibits a slightly better antibacterial activity than the chloride one.

Two copper(II) complexes of N-(methylpyridin-2-yl)-amidino-O-methylurea (L) containing different anions, Cl− (1) and ClO4− (2), were prepared and investigated the nucleobase-binding ability toward adenine (A), cytosine (C), guanine (G) and thymine (T). Eight bound adducts were characterized by elemental analysis, spectroscopic methods (infrared, electrospray ionization mass, diffuse reflectance, UV–Vis and electron spin resonance) and thermal analysis. Results have shown the coordination of one or two nucleobase molecules to the copper(II) center of 1 and 2 through the N(7) adenine, N(3) cytosine, N(7) guanine and O(4) thymine by the replacement of anion ligands. Further investigation on the binding potential of 1 and 2 was carried out towards 5′-guanosine monophosphate (5′-GMP), a DNA model, and have found that the N(7) atom of 5′-GMP can bind to their copper(II) center. These two coordination compounds, which display the similar base-binding capability, exhibit the antibacterial activity against the three bacteria involved in human-food poisoning (Salmonella, Escherichia coli and Campylobacter) with the most potent toward Campylobacter for 1 and Salmonella and E. coli for 2. Such a behavior suggests that differences in the anionic ligands on 1 and 2 slightly influence on their antibacterial properties.

Various spectroscopic methods have been used to investigate the anion effect on the DNA-binding potential of two copper(II) complexes of N-(methylpyridin-2-yl)-amidino-O-methylurea containing chlorides and perchlorates. Further study of their antibacterial activities against the three bacteria involved in human-food poisoning (Salmonella, Escherichia coli and Campylobacter) have also undertaken.Figure optionsDownload as PowerPoint slide