Crystal structure of a supramolecular dimer of Co(III) complex and evaluation of the DNA /BSA interaction

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.

Synthesis, characterization, cytotoxicity and DNA/BSA binding of two amino acid palladium(II) complexes derived from alanine and valine

Two novel palladium(II)-amino acid complexes, [Pd(Ala)₂]·H₂O (PA) and [Pd(Val)₂].H₂O (PV) (Ala = alanine; Val = valine) were synthesized and characterized through FTIR, UV/Vis, ¹H-NMR spectroscopies, CHN analysis, X-ray crystallography and molar conductivity measurement. Furthermore, cytotoxicity of Pd(II) complexes against human leukemia cancer cell line, MOLT4 showed promising cancer cell death (CC₅₀ = 0.71 ± 0.046 µM for PA; CC₅₀ = 0.85 ± 0.063 µM for PV) that were less than cisplatin (1.59 ± 0.25 µM). Moreover, the interaction of both the complexes with DNA and BSA was studied using UV-Vis absorption and emission spectroscopic techniques that demonstrated the bindings occurred via van der Waals forces and hydrogen bond. Furthermore, the fluorescence titration showed that static quenching mechanism plays predominate role in binding process. All results showed that both complexes have more binding tendency to DNA in compared to BSA that can be a significant achievement for further medical purposes as a potential antitumor candidate. Finally, molecular docking simulation was performed for PA and PV complexes with DNA and BSA and demonstrated both complexes bind to the groove of DNA mainly by hydrogen bond and interact with site I of BSA via hydrogen bond as well.

Crystal structures and biological properties of aroylhydrazone Ni(II) complexes

Three aroylhydrazone ligands ((Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-2-hydroxybenzohydrazide, HL1; (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-3-hydroxybenzohydrazide, HL2; and (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-4-hydroxybenzohydrazide, HL3) and their complexes with nickel (Ni(L1)₂, 1; Ni(L2)₂, 2; Ni(L3)₂∙DMF, 3) were synthesized and characterized by ESI-MS, NMR, IR, UV-vis and elemental analysis techniques. The molecular structure of ligand (HL2) and complexes 1-3 was confirmed by single crystal X-ray crystallography. The single crystal X-ray structure of complexes 1-3 showed a distorted square planar geometry around the metal center, and the ligands adopt a bidentate chelating mode. The interaction of calf thymus (ctDNA) with nickel(II) complexes was explored using absorption, emission spectrum, viscosity, and circular dichroism methods. These complexes exhibited moderate affinity for ctDNA through groove binding modes. The most efficient DNA binder was complex 2. The interaction of the complexes with DNA has also been supported by molecular docking study and molecular dynamics simulation. An in vitro cytotoxicity study of the complexes found low activity against human cervical (Hela) and breast (MCF-7) cancer cell lines, with the best results for complex 2, where IC50 values are 86 μM and 92 μM respectively.