DNA/BSA binding study of mononuclear gold(III) complex with azaconazole

Nitrogen-containing aromatic heterocycles have garnered significant interest as essential scaffolds in the synthesis of bioactive compounds, owing to their broad applications in various pharmacological fields, including vitamins, herbicides, antifungal, antibacterial, and anticancer agents. Their unique structural and electronic properties allow them to interact effectively with biological targets, making them attractive ligands in the design of metal-based therapeutic agents. In the present study, azaconazole (acz) was employed for the synthesis of a mononuclear gold(III) complex, [AuCl₃(acz)]. The complex was obtained by reacting equimolar amounts of potassium tetrachloridoaurate(III) and the acz ligand under reflux conditions for 3 h. In this complex, azaconazole coordinates monodentately to the Au(III) ion, while the remaining coordination sites in the square-planar geometry are occupied by chloride ions. The interaction between the synthesized gold(III) complex and calf thymus DNA (ct-DNA) was investigated using fluorescence emission spectroscopy in the presence of the intercalative agent ethidium bromide (EthBr) and the minor groove binder Hoechst 33258 (Hoe). Additionally, fluorescence competition experiments were performed using specific site markers, including eosin Y, ibuprofen, and digitoxin, to gain deeper insight into the binding sites on BSA. Eosin Y is known as a marker for site I (subdomain IIA), ibuprofen for site II (subdomain IIIA), and digitoxin for site III (subdomain IB).