New dinuclear gold(III) complex with 1,5-naphthyridine as bridging ligand: Synthesis, characterization, DNA/BSA binding studies and anticancer activity

Abstract

Abstract With the aim to reveal the antitumor drug which possesses improved activity compared with cisplatin, we synthesized the new dinuclear gold(III) complex with 1,5-naphthyridine as bridging ligand. Further, the newly synthesized complex was characterized by various techniques to confirm the structure. The stability of this complex in water and in PBS buffer was investigated by UV-Vis spectroscopy. DNA binding studies were examined by UV-Vis, fluorescence spectroscopy and viscosity measurements. The competitive studies with EB or HOE were done by fluorescence spectroscopy. The results showed that the dinuclear gold(III) complex interacts with calf-thymus DNA (CT-DNA) via covalently binding mode. Furthermore, the investigated complex shows high value of binding constants for the interaction with bovine serum albumin (BSA) as well as for the interactions in the presence of site markers (eosin Y or ibuprofen). Dinuclear gold(III) complex induced remarkable cytotoxicity on HCT116 and MDA-MB-231 cancer cell lines, 24 and 72 h after treatment. The complex also showed selectivity and induced significantly lower cytotoxic activity on healthy cells compared to cancers. In support of the antitumor activity of this complex, the proapoptotic activity (via increased caspase 9 activity) and low percentages of necrosis were observed. All experimentally obtained results were corroborated by molecular docking simulations.