Synthesis, characterization, in vitro cytotoxicity and anti-inflammatory activity of palladium(II) complexes with tertiary phosphines and heterocyclic thiolates: Crystal structure of [PdC28H19N8PS2]

New Pd(II) complexes of the bisthiocarbohydrazones derived from isatin and disubstituted salicylaldehydes: Synthesis, characterization, crystal structures and inhibitory properties against some metabolic enzymes

Pd(II) complexes (Pd1, Pd2, and Pd3) were synthesized for the first time using asymmetric isatin bisthiocarbohydrazone ligands and PdCl₂(PPh₃)₂. All complexes were characterized by a range of spectroscopic and analytical techniques. The molecular structures of Pd1 and Pd3 have been determined by single-crystal X-ray diffraction analysis. The complexes are diamagnetic and exhibit square planar geometry. The asymmetric isatin bisthiocarbohydrazone ligands coordinate to Pd(II) ion in a tridentate manner, through the phenolic oxygen, imine nitrogen and thiol sulfur, forming five- and six-membered chelate rings within their structures. The fourth coordination site in these complexes is occupied by PPh₃ (triphenylphosphine). The free ligands and their Pd(II) complexes were evaluated for their carbonic anhydrase I, II (hCAs) and acetylcholinesterase (AChE) inhibitor activities. They showed a highly potent inhibition effect on AChE and hCAs. K_i values are in the range of 9 ± 0.6 - 30 ± 5.4 nM for AChE, 7 ± 0.5 - 16 ± 2.2 nM for hCA I and 3 ± 0.3-24 ± 1.9 nM for hCA II isoenzyme. The results clearly demonstrated that the ligands and their Pd(II) complexes effectively inhibited the used enzymes.

Novel P,C-orthopalladated complexes containing histidine and phenylalanine amino acids: synthesis, DNA and BSA interactions, in vitro antitumoral activity and molecular docking approach

Novel [Pd(o-CH₂C₆H₄P(o-tolyl)₂)(histidine)] (1) and [Pd(o-CH₂C₆H₄P(o tolyl)₂)(phenylalanine)] (2) P,C-orthopalladated complexes have been prepared and characterized by elemental analysis, IR and NMR spectroscopy. To study the stability of the compounds in biological media, the complexes were incubated in Tris buffer during 10 days. The absorbance of the compounds remained constant, which confirmed the stability of the complexes in biological media. UV-Vis absorption spectrophotometry, fluorescence spectroscopy and viscosity studies were used to investigate the binding of the complexes with native calf thymus DNA (CT-DNA). These methods along with competitive binding of methylene blue (MB) DNA show that the complexes interact with DNA via groove mode. The UV-Vis absorption spectrophotometry of BSA with complexes has shown an α-helix perturbation induced by a particular interaction between the metal complexes and BSA. In addition, the fluorescence quenching mechanism of BSA with the complexes is a static process, according to the fluorescence spectrometry of bovine serum albumin (BSA). The experimental results of site competitive replacement with specific site markers are clear indications that the complexes bind to site I of BSA. Furthermore, both complexes showed significant selective cytotoxic activity against melanoma B16F0 and colon carcinoma C26 cancer cells as well as normal fibroblast NIH cell line. Ultimately, the binding of Pd(II) complexes to DNA and BSA was verified by molecular docking experiment.Communicated by Ramaswamy H. Sarma.

Synthesis, characterization and anti-cancer properties of water-soluble bis(PYE) pro-ligands and derived palladium(ii) complexes

The two cationic palladium(ii) complexes, [Pd(Len)2][OTf]2 (4) and [Pd(Lphen)2][OTf]2 (5), were synthesized by treatment of bis(benzonitrile)dichloropalladium(ii) with [H2Len][OTf]2 (2) or [H2Lphen][OTf]2 (3), respectively, in the presence of a weak base. The pro-ligands 2 and 3 were synthesized by melt reactions between N-methyl-4-chloropyridinium triflate (1) and the amines ethylenediamine or phenylenediamine, respectively. The water-soluble compounds 2-5 were fully characterized, including by single-crystal X-ray crystal structure determinations for 2-4. UV-Vis and fluorescence spectroscopy were used to study the binding interactions of 2-5 with CT-DNA. The spectroscopic data suggested the presence of intercalative and groove binding modes and this was supported by molecular docking studies. The in vitro cytotoxicity studies (IC50 values) showed that the human breast cancer cell lines MCF-7 and T47D were more sensitive towards 3, 4 and 5 than cisplatin. The cytotoxicity of the new compounds decreased in the order 5 > 4 > 3 > 2. Furthermore, the annexin V-FITC staining method strongly suggested the presence of phosphatidylserine (PS) on the outer membrane of the treated cells, which is a hallmark of apoptosis.

Synthesis, DFT Calculation, and Antimicrobial Studies of Novel Zn(II), Co(II), Cu(II), and Mn(II) Heteroleptic Complexes Containing Benzoylacetone and Dithiocarbamate

Heteroleptic complexes of zinc(II), copper(II), manganese(II), and cobalt(II) of the types [MLL'(H2O)2]·nH2O and [MLL']·nH2O have been synthesized using sodium N-methyl-N-phenyldithiocarbamate (L) and benzoylacetone (L'). The metal complexes were characterized by elemental analysis, electrical conductance, magnetic susceptibility, infrared (IR), and UV-visible spectroscopic studies. The electrical conductance measurements revealed the nonelectrolytic nature of the synthesized complexes. The results of the elemental analyses, magnetic susceptibility measurements, and electronic spectra inferred that the Zn(II) complex adopted a four-coordinate geometry while the Co(II), Cu(II), and Mn(II) complexes assumed octahedral geometries. The IR spectra showed that the metal ions coordinated with the ligands via the S- and O-donor atoms. The geometry, electronic, and thermodynamic parameters of the complexes were obtained from density functional theory (DFT) calculations. The spin density distributions, relative strength of H-bonds, and thermodynamic parameters revealed that the order of stability of the metal complexes is Mn < Co < Cu > Zn. The agar diffusion methods were used to study the antimicrobial activity of the complexes against two Gram positive bacteria (S. aureus and S. pneumoniae), one Gram negative bacterium (E. coli), and two fungi organisms (A. niger and A. candida) and the complexes showed a broad spectrum of activities against the microbes.

Conformational insights and vibrational study of a promising anticancer agent: the role of the ligand in Pd(ii)–amine complexes

This study reports the first complete vibrational analysis of a dinuclear polyamine-based compound displaying antitumour properties.

Synthetic aspects, spectral, thermal studies and antimicrobial screening on bis(N,N-dimethyldithiocarbamato-S,S')antimony(III) complexes with oxo or thio donor ligands

The bis(N,N-dimethyldithiocarbamato-S,S')antimony(III) complexes have been obtained by the reaction of chloro bis(N,N-dimethyldithiocarbamato-S,S')antimony(III) with corresponding oxo or thio donor ligands such as sodium benzoate 1, sodium thioglycolate 2, phenol 3, sodium 1-propanethiolate 4, potassium thioacetate 5, sodium salicylate 6, ethane-1,2-dithiolate 7 and disodium oxalate 8. These complexes have been characterized by the physicochemical [melting point, molecular weight determination and elemental analysis (C, H, N, S and Sb)], spectral [UV-Visible, FT-IR, far IR, NMR (1H and 13C)], thermogravimetric (TG & DTA) analysis, ESI-Mass and powder X-ray diffraction studies. Thermogravimetric analysis of the complexes confirmed the final decomposition product as highly pure antimony sulfide (Sb2S3) and powder X-ray diffraction studies show that the complexes are in lower symmetry with monoclinic crystal lattice and nano-ranged particle size (11.51-20.82 nm). The complexes have also been screened against some bacterial and fungal strains for their antibacterial and antifungal activities and compared with standard drugs. These show that the complexes have greater activities against some human pathogenic bacteria and fungi than the activities of standard drugs.

Spectral, thermal and in vitro antimicrobial studies of cyclohexylamine-N-dithiocarbamate transition metal complexes

Transition metal complexes of the type [M(L)(2)] and those containing monodentate phosphines of the type [M(L)(2)(PPh(3))] {M=Ni, Co, Cu and Zn; L=cyclohexylamine-N-dithiocarbamate; PPh(3)=triphenylphosphine} have been synthesized. The complexes were characterized using IR, UV-vis, NMR spectroscopy, and thermal analysis (TGA). The (1)H NMR, (13)C NMR and (31)P NMR showed the expected signals for the dithiocarbamate and triphenylphosphine moieties. The spectral studies in all compounds revealed that the coordination of metals occurs via the sulphur atom of the dithiocarbamate ligand in a bidentate fashion. Thermal behavior of the complexes showed that the complexes were more stable than their parent ligands. The ligand moiety is lost in the first step and the rest of the organic moiety decomposes in the subsequent steps. Furthermore, the ligand and their metal complexes were screened in vitro for their antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, Enterococcus faecalis, Pseudomonas aeruginosa and Bacillus cereus and antifungal activities against Aspergillus flavus, Aspergillus carbonarius, Aspergillus niger and Aspergillus fumigatus. The metal complexes exhibited higher antimicrobial activity than the parent ligands. Generally, the zinc complexes were effective against the growth of bacteria with Zn(L)(2) displaying broad spectrum bacteriocidal activity at concentrations of 50microg/mL; and Ni(L)(2) was more effective against the growth of fungi at concentrations of 100-400microg/mL under laboratory conditions.

Synthesis and anti-tumor activities of some new pyridines and pyrazolo[1,5-a]pyrimidines

Cyclocondensation of cyanoacetamide, cyanothioacetamide and 3-aminopyrazols with sodium salt of 3-hydroxy-1-(2-naphthyl)prop-2-en-1-one gives pyridin-2-one, pyridin-2(1H)-thione, and pyrazolo[1,5-a]pyrimidine derivatives. These derivatives showed potent anti-tumor cytotoxic activity in vitro using different human cancer cell lines.