New Ni(II) complexes involving symmetrical bidentate N,O-donor Schiff base ligands: synthesis at ambient temperature, crystal structures, electrochemical study, antioxidant and cytotoxic activities

Synthesis, crystal structure, thermal stability and biological study of bis{(2-methoxy-6-[(E)-(propylimino)methyl]phenolato}nickel(II) complex

A Schiff base complex of nickel, bis{(2-methoxy-6-[(E)-(propylimino)methyl]phenolato}nickel(II) was synthesised by condensing bis(2-hydroxy-3-methoxybenzaldehyde) nickel (II) and n-propylamine in methanolic medium. Single crystal X-ray diffraction analysis of the complex revealed it to possess planar geometry with a monoclinic crystal system. The non-isothermal TG/DTA runs on this complex in a high purity (99.99 %) nitrogen environment at atmospheric pressure confirmed the absence of any coordinated water. A sharp endotherm in its DTA shows a melting temperature range of 168-171 °C. It is thermally stable up to 243 °C and decomposes in two steps, yielding NiO and carbon as residue. In addition to the methoxy group (-OCH3), infrared analysis (IR) confirmed the presence of the characteristic azomethine group (-C[bond, double bond]N-) which is also responsible for the biological action. It was further analysed by elemental analyser (C, H, N), 1H and 13C NMR as well as mass spectrometry. It showed considerable antibacterial activity towards Escherichia coli and Staphylococcus aureus when the concentration exceeds 200 μg/ml. The antifungal study shows significant inhibition with the antifungal drug imidazole as a positive control (PC). Small values of MIC, MBC/MIC indicate a lesser quantity of complex is required to inhibit the growth of micro-organisms.

Induction of Cell Cycle Arrest in MKN45 Cells after Schiff Base Oxovanadium Complex Treatment Using Changes in Gene Expression of CdC25 and P53

Compounds containing heavy metals such as vanadium, nickel, and cobalt may be useful for the treatment of various diseases. Multiple studies have been carried out on the anticancer effects of vanadium-contained compounds on different cell types. This study aimed to evaluate the role of schiff base oxovanadium complex ([N,N'-bis(3-methoxy-salicylidene)-1,2-phenylenediamine]Vanadium(IV) Oxide Complex) on cell cycle arrest and different cell cycle phases in MKN45 cell of gastric cancer. Schiff base oxovanadium complex was used to assessthe amount of cytotoxicity via cell viability test. PI color and flow cytometry technique were applied to evaluate the effects of vanadium synthetic compounds on cell cycle phases; subsequently, we analyzed the change rates of gene expression in P53, GADD45, and CDC25 genes, which are involved in cell division phases. The findings indicated that the vital activities of time-dependent and concentration-dependent MKN45 cells with schiff base oxovanadium complex were significantly reduced; therefore, this complex is able to inhibit the migration of cancer cells and metastatic activities in a time-dependent mode. Cell cycle arrest was obtained after 48 h of treatment in phase G2/M at 1 microgram/milliliter (μg/ml) concentration. This is probably attributed to the increased gene expression of P53 and GADD45 genes and reduced gene expression of CDC25 gene. Compounds containing such heavy metals as vanadium decrease the growth, proliferation, and migration of MKN45 cells. They arrest cell cycle in phase G2/M via changing the controllers of cell division phases activated due to DNA damage.

Hadadd H, H. Jaaz B. Novel Nickel (II), Copper (II) and Cobalt (II) Complexes of Schiff Bases A, D and E: Preparation, Identification, Analytical and Electrochemical Survey

A novel set of Cobalt(II), Copper(II) and Nickel(II) complexes of ligands, (E)-2-(((2,5-difluorophenyl)imino) methyl)phenol (A), (E)-2,4-dibromo-1-((2-hydroxybenzylidene) amino)anthracene-9,10-dione (D) & (Z)-1-((1-([1,1'-biphenyl]-4-yl)-2-bromoethylidene) amino)-2,4-dibromo anthracene-9,10-dione (E) were synthesized and characterized. Their structures were investigated on the basis of CHN, conductance measurements and spectral studies (H1-NMR & C13-NMR,FT-infrared and Electronic spectroscopies), cyclic voltammetry. It has observed from spectral and analytical studies that metal complexes have the composition of (ML2.X2) and one mole of ligand behaves as bidentate chelating agents around the corresponding metal ion. From solubility test, we obtained that metal complexes of ligands A, D and E had no ionic properties and dissolve partially in polar and slightly in nonpolar solvents. These results confirmed the behavior of metal complexes as weak electrolyte from their low value of molar conductivity. Conductance data and solubility test of the complexes enhanced them to be (1:2 M:L ratio). All data confirmed an octahedral geometry of these complexes and their structures as {[M (A, D or E)2(CH3COO)2], when M= Co or Ni} and {[Cu (A, D or E)2 Cl2]}. Cyclic voltammetry measurements were accomplished of Cobalt(II), Copper(II) and Nickel(II) complexes using Pt wire as counter electrode and Ag/AgNO3 as reference electrode and (Bu4N+PF6+) as supporting electrolyte. The result exhibit the irreversible process showing single one electron transfer process of Cobalt(II) and Nickel(II) complexes and unique quasi-reversible redox couple is attributed to Cu(II) complexes.