A chiral binuclear nickel(II) complex with Schiff base ligand: synthesis, crystal structure, DNA/BSA binding interactions and SOD activity

A comprehensive review on the development of chiral Cu, Ni, and Zn complexes as pharmaceutical agents over the past decades: Synthesis, molecular structure and biological activity

Chirality is a fundamental and widespread geometric structural property in living organisms that most biomacromolecules including nucleic acids, proteins and enzymes, possess. Consequently, the development of chiral drugs capable of binding specific targets have gradually gained wide attention in recent decades due to their selective effects on a broad spectrum of biological events ranging from cell metabolism to cell fate. In this context, the synthesis of chiral compounds as promising therapeutic candidates has assumed a major role in drug discovery. Among them, chiral metal complexes have attracted considerable interest due to their unique and intriguing structural features that could enable overcoming side effects and drug-resistance phenomena of metal-based drugs currently in the market such as cisplatin. In the current scenario, an in-depth overview of non-platinum chiral complexes needs to be presented and carried forward. Therefore, in this perspective article, an update of the scientific development of bioactive chiral copper, zinc and nickel complexes have been reported since they have not been thoroughly reviewed so far. Specifically, we focused the article mainly on metal complexes containing chiral ligands (type 2 chirality) as in literature they are more numerous than those with chirality at the metal center (type 1 chirality). Herein, not only their biological activity but also their mechanism of action is summarized. Furthermore, in the final section of the article we have highlighted copper-based complexes as those with a superior biological activity profile and greater prospects for development as a drug.

In vitro study of the pro-apoptotic mechanism of amino acid Schiff base copper complexes on anaplastic thyroid cancer

In the endocrine system, anaplastic thyroid cancer (ATC) is extremely aggressive since it inhibits the majority of medications and treatments. Therefore, there is an immediate demand to identify new treatment approaches or drugs to deal with ATC. Recently, amino acid Schiff base copper complexes have received great attention due to their excellent anti-tumor activity. In this research, three copper(II) complexes, [Cu(o-van-D-Trp)(phen)](1), [Cu(o-van-D-Trp)(bipy)](2), [Cu(naph-D-Trp)(bipy)](3), [D-Trp = D-tryptophan; o-van = o-vanillin; naph = 2‑hydroxy-1- naphthaldehyde; phen = 1,10-phenanthroline; bipy = 2,2-biprydine], have been synthesized and investigated as potential anticancer agents. The crystal structure data of the complexes demonstrate that the central copper (II) atom forms a twisted polyhedral environment with nitrogen and oxygen atoms. The MTT results demonstrated that three complexes exhibited superior cytotoxicity against five cell lines of thyroid cancer (Cal-62 cells, ARO cells, KHM-5 m cells, BHP10-3 cells and K1 cells), especially complex 1 with the IC50 values of 0.59±0.05 μM, 2.36±0.47 μM, 1.10±0.87 μM, 0.75±0.09 μM, 1.72±0.06 μM, when cisplatin was used as a control. Research on antitumor mechanisms has demonstrated that complex 1 can significantly reduce the mitochondrial membrane potential, raise autophagy, and produce reactive oxygen species (ROS) in ARO cells in a dose-dependent manner. RNA sequencing study reveals that complex 1 may cause apoptosis in ARO cells and exhibit anticancer efficacy in vitro through ROS-mediated downregulation of Akt and p38 MAPK activation.

Water-soluble nickel (II) Schiff base complexes: Synthesis, structural characterization, DNA binding affinity, DNA cleavage, cytotoxicity, and computational studies

Two water-soluble nickel (II) Schiff base complexes were prepared and their interaction with fish sperm DNA (FS-DNA) was investigated by various methods including UV-vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscometric measurements. Complex 1: [N,N'-bis{5-[(triphenyl phosphonium chloride)-methyl] salicylidine}-3,4-diaminobenzophenone]nickel(II) perchloride dihydrate: [Ni(5-CH₂PPh₃-3,4-salophen)] (ClO₄)₂.2 H₂O was synthesized as a new complex and characterized by elemental analysis, IR, ¹H NMR, thermal gravimetric analysis (TGA) and UV-vis spectroscopy. Complex 2: sodium [(N,N'-bis(5-sulfosalicyliden)-3, 4-diaminobenzophenone)aqua] nickel(II) hydrate: Na₂[Ni (5-SO₃-3,4-salbenz)(H₂O)]. H₂O was already synthesized by our research team, but in this study, its function as a DNA-binding compound was tested, and compared with the results of complex 1-DNA binding. The calculation of different constants using absorption and emission data, all confirmed the stronger binding ability of complex 1 than complex 2 with DNA. Different thermodynamic parameters showed the interactions between DNA and complexes were the type of hydrophobic interaction for complex 1 and electrostatic interaction for complex 2. Also, the negative values of free energy changes proved a spontaneous DNA binding process. Based on cell toxicity assay against two different cell lines including Jurkat and MCF-7, the effect of complex 1 was comparable to cisplatin, and the toxicity mechanism was further justified by bright field microscopy, flow cytometry, and cleavage of DNA in the presence of H₂O₂. Besides, the docking calculations suggested intercalation after measuring the lowest-energy between the complexes and DNA. For both complexes, all analytical, spectroscopic, and molecular modeling methods supported partial intercalation as the main binding mode between the complexes and DNA.