A new heterotrimetallic sandwich‐like CuII–LaIII–CuII (3d–4f–3d) cluster as a model anticancer drug in interaction with FS‐DNA and BSA and as a new artificial catalyst for catecholase activity

Abstract

A new heterotrimetallic sandwich‐like CuII–LaIII–CuII cluster, [(valpn)2Cu2La(NO3)2]NO3(H2O)1.8, (H2valpn = 1,3‐propanediylbis(2‐iminomethylene‐6‐methoxy‐phenol)), was synthesized by the reaction of [Cu(valpn)] with La (NO3)3.6H2O (1:1 M ratio) at room temperature. The resulted cluster was characterized by X‐ray diffraction, UV–Vis and IR spectroscopy, and elemental analysis (CHN). The crystal structure of the cluster revealed that La(III) ion was sandwiched between two [Cu(valpn)] moieties and located in the open compartments of two copper Schiff base complexes and being surrounded by 12 oxygen atoms. This cluster complex, as a model anticancer drug, was investigated in interaction with fish sperm deoxyribonucleic acid (FS‐DNA) using docking study and experimental methods such as fluorescence and UV–Vis spectroscopy, circular dichroism spectroscopy (CD), cyclic voltammetry (CV), viscosity measurements, and agarose gel electrophoresis. These investigations suggested intercalative interaction between the cluster complex and FS‐DNA. Plasma proteins are other targets for the anticancer drugs, so the cluster–bovine serum albumin (BSA) interaction was also investigated. For evaluating the binding, Stern–Volmer constants (KSV) and the number of binding sites (n) were calculated. It was proposed that the electrostatic interaction was the main force in the cluster–BSA binding. Cytotoxic activity was assayed by MTT assay toward LACaP, MCF‐7, and HeLa cancer cell lines. The IC50 values of the cluster for HeLa and LACaP cell lines were lower than for MCF‐7 cell lines. The docking studies were also performed for cluster–BSA and cluster–DNA interactions. The cluster was also investigated as an artificial enzyme in catechol oxidase activity, and kinetics of the oxidation of 3,5‐di‐tert‐butylcatechol catalyzed by the cluster was studied.