Coordination ability and biological activity of a naringenin thiosemicarbazone

The present work is devoted to reveal physicochemical properties and several biological actions of a new thiosemicarbazone (NTSC) derived from naringenin, a natural flavanone, and its Cu-complexes formed in mixed solvent solutions. Equilibrium solution studies were carried out on the NTSC and Cu-NTSC complexes in DMSO/water mixture. The proton-dissociation constants of the ligand, the stability constants and the coordination modes of the metal complex species were determined by means of pH-potentiometric, UV–vis and EPR methods. Mono- and bis-ligand complexes in different protonation states were identified. Circular dichroism, fluorimetric and gel electrophoresis studies demonstrated that both NTSC and copper complex interact with CT DNA and plasmid pEGFP-C1. Fluorimetric experiments allowed to confirm that both NTSC and its Cu(II)-complex bind to human serum albumin (HSA), the Cu-NTSC giving a stronger quenching effect than NTSC at similar molar ratios. Investigations of antibacterial and antifungal properties were carried out on selected strains of bacteria and fungi. The cytotoxic effects were studied on the cancer A2780 and the non-cancer HEK cells, both compounds being found non-toxic. The synthesized thiosemicarbazone of naringenin (NTSC) behaves as a tridentate chelator for Cu2+ ions. Both NTSC and Cu-NTSC bind to DNA and human serum albumin, and complexation protects DNA from the cleaving action of Cu2+ ions. The antibacterial effectiveness of NTSC and CuNTSC depend on bacteria physiology. [Display omitted] •Naringenin thiosemicarbazone (NTSC) acts as strong tridentate chelator of Cu(II) ions•CuNTSC reveals stronger interactions with both DNA and human serum albumin than NTSC•Complexation with NTSC protects DNA from the cleaving action of Cu2+ ions•Antibacterial effectiveness of NTSC or CuNTSC depends on bacteria physiology•Both NTSC and CuNTSC are not cytotoxic towards the A2780 and HEK cell lines