Novel copper nano-complex based on tetraazamacrocyclic backbone: Template synthesis, structural elucidation, cytotoxic, DNA binding and molecular docking studies

Abstract

Bioactive binuclear Cu(II) nanocomplex of 1,8-dihydro-6-13-di(2-hydroxybenzoyl)-dibenzo[b,i]-1,4,8,11-tetra-azacycloretradeca-4,6,11,13-tetraene) (H4L) derived from 3-formylchromone and o-phenylenediamine in molar ratio 2:2:2 has been designed via template methodology. The structure of macrocyclic ligand (H4L) has been determined by elemental analysis and FT-IR and 1HNMR spectroscopy. As well, the new complex with general formula: [Cu2(H2L)(NO3)2]; was characterized using elemental and thermal analyses, molar conductivity, magnetic susceptibility measurements, UV–Vis, FT-IR, EPR and mass spectroscopy. The crystallinity and morphology of the complex were analyzed by XRD and TEM measurements. On the basis of the spectroscopic data, the ligand behaves as a dianionic bis(tridentate) ligand through OON donor sites forming tetrahedral complex. Transmission electron microscope (TEM) analysis reveals that Cu(II) nanocomplex has high dispersed nanospherical morphology (2 nm). In order to gain some insight into the structure–activity relationship; the binding of H4L and its Cu(II) nanocomplex with DNA was studied theoretically and by spectral titration. Absorption spectroscopic and docking investigation suggest that the H4L and Cu(II) complex bind to groove of DNA. The intrinsic binding constants (Kb) of H4L and Cu(II) complex with DNA are 0.69 × 104 and 0.90 × 104M−1, respectively. The antioxidant activities of prepared compounds were studied. Also, the cytotoxicity assay indicates that Cu(II) nanocomplex exhibited significant inhibitory activity toward HepG-2 cell line, with the lowest IC50 value with respect to H4L and standard drugs.