Design, synthesis, spectral characterization, photo‐cleavage, and in vitro evaluation of anticancer activities of new transition metal complexes of piperazine based Schiff base‐oxime ligand

Abstract

The newly synthesized Schiff base‐oxime ligand, namely, (2Z,3E)‐3‐((3‐(4‐(3‐(((2E,3E)‐3‐(hydroxyimino)butan‐2‐ylidene)amino)propyl)piperazin‐1‐yl)propyl)imino)butan‐2‐one oxime (H2L) and its Co (II), Cu (II), and Zn (II) complexes were reported. The characterization was accomplished with the aid of CHN‐EA, mass, fourier transform infrared spectroscopy (FT‐IR), electronic spectra, magnetic moment, molar conductance and TGA. According to the spectroscopic approaches, the synthesized ligand (H2L) may act as a tetradentate or hexadentate (bis‐tridentate) coordinating ligand through the azomethine nitrogen, piperazinyl nitrogens, and oximato‐nitrogens affording distorted square planar mononuclear Co (II) complex or tetrahedrally distorted square planar binuclear Cu (II) and Zn (II) complexes whereas the coordination mode varies according to the nature of the metal ion. The microbial resistance of all the synthesized compounds was evaluated and reported. Findings showed that the Cu (II) complex has mostly the highest inhibitory effects against all tested microbial strains. Besides, the anticancer nature of the studied compounds was also evaluated against a panel of three different human cancer cells, including (HCT‐116), (MDA‐MB‐231), (HepG2) in addition to the (WI‐38) used as a healthy cells. In general, the Cu (II) complex displayed the best cytotoxic profiles against the tested cells than the Co (II) and Zn (II) complexes with negligible toxicity towards the (WI‐38) normal cells. The DNA cleavage activities of all tested compounds were assayed against pBR322 plasmid DNA. Whereas, the Cu (II) complex showed the highest DNA cleavage propensity, which proceeds predominantly via the oxidative mechanism. Additionally, flow cytometric analysis dictates that the Cu (II) complex induces cell cycle arrest in S‐phase and apoptotic cell death on HCT‐116 cells. The morphological transformations distinguished in HCT‐116 cells treated with Cu (II) complex have been depicted with the aid of scanning electron microscopy (SEM). The docking results indicate that the Cu (II) complex strongly interacts with human colon cancer (6GUE), Escherichia coli (3T88), Klebsiella pneumoniae (4HL2), and Staphylococcus aureus (3WQU) proteins, through different modes of interactions that harmonize successfully with the experimental results.