Iron(III) complex of 2-acetylpyrazine thiosemicarbazone: synthesis, spectral characterization, structural studies and antitumoral activity

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.

Thiosemicarbazone derivatives: Design, synthesis and in vitro antimalarial activity studies

Different types of thiosemicarbazone derivatives were designed and tested for their Drug-Like Molecular (DLM) nature by using Lipinski and Veber rules. Subsequently, compounds with DLM properties were synthesized and characterized by spectral methods. In vitro antimalarial activity studies of the synthesized thiosemicarbazone derivatives have been carried out against Plasmodium falciparum, 3D7 strain using fluorescence assay method and found that the compounds, (E)-2-(1-(4-fluorophenyl)ethylidene)hydrazine-1-carbothioamide (6), (E)-2-(1-(3-bromophenyl) ethylidene) hydrazine-1-carbothioamide (15) and (E)-2-(3,4,5-trimethoxybenzylidene) hydrazine-1-carbothioamide (29) showed notable antimalarial activity with EC₅₀ values of 13.54 μM, 15.83 μM and 14.52 μM respectively.

α-N-heterocyclic thiosemicarbazone Fe(III) complex: Characterization of its antitumor activity and identification of anticancer mechanism

We synthesized an α-N-heterocyclic thiosemicarbazone ligand (L) and its Fe complex (C1) and assessed their chemical and biological properties in order to understand their marked activity. Electrochemical studies and ascorbate oxidation studies demonstrated that C1 shows considerable redox activity, and Fe(III/II) redox potentials was within the range accessible to cellular oxidants and reductants. Absorption spectral, emission spectral and viscosity analysis reveal that L and C1 interacted with DNA through intercalation and C1 exhibited a higher DNA binding ability. Agarose gel electrophoresis experiments indicated that C1 exhibited the highest pBR322 DNA cleaving ability. In vitro, C1 showed significantly more anticancer activity than the ligand alone. Moreover, C1 induces production of reactive oxygen species (ROS) and DNA damage, resulting in activation of the p53 pathway, cell cycle arrest at the S phase, and mitochondria-mediated apoptosis by regulating the expression of Bcl-2 family proteins.

Main group bismuth(III), gallium(III) and diorganotin(IV) complexes derived from bis(2-acetylpyrazine)thiocarbonohydrazone: synthesis, crystal structures and biological evaluation

Up to now, the metal complexes with thiocarbonohydrazones have been comparatively rare. Herein, three main group monometallic complexes formulated as [Bi(HL)(NO3)2(H2O)] (1), [Ga(HL)2]OAc·EtOH (2) and [(Ph)2Sn(HL)(OAc)]·DMF (3), where H2L = bis(2-acetylpyrazine)thiocarbonohydrazone, have been synthesized and characterized. The crystal structures of complexes 2 and 3 have been determined by single-crystal X-ray diffraction. Growth inhibition assays have indicated that both the free ligand and the title complexes are capable of inhibiting cell proliferation growth and could slightly distinguish the human hepatocellular carcinoma HepG2 cells from normal hepatocyte QSG7701 cells. Of particular note is the fact that the bismuth(III) complex 1 is the most active compound of this study and is 14-fold more cytotoxic than H2L with an IC50 value of 2.96 ± 0.25 μM. Its possible apoptotic mechanism has been evaluated in HepG2 cells. Complex 1 promotes a dose-dependent apoptosis in HepG2 cells and the apoptosis is associated with an increase in intracellular reactive oxygen species (ROS) production and reduction of mitochondrial membrane potential (MMP).

Supramolecular and structural modification on conformational by mixed ligand

A novel series of platinum(II) and palladium(II) complexes have been synthesized by template condensation of 4-methoxybenzaldehyde, benzaldehyde, 4-chlorobenzaldehyde and 4-nitrobenzaldehyde, with appropriate 4-aminoantipyrine (4-AAP) in the presence of K(2)PtCl(4)/PdCl(2) to form complexes of the type [M(L(n))Cl(2)](where M=Pt(II) or Pd(II)). The corresponding Schiff base complexes mixed ligand were prepared by condensation of [M(L(n))Cl(2)] with ethanolamine (LH). The complexes have been characterized with the help of elemental analysis, IR, (1)H and (13)C NMR, electronic spectra, conductance measurements, magnetic susceptibilities and thermal analysis. On the basis of these studies, it is clear that ligands coordinated to metal atom in a mononuclear (NO) in (1-6), Schiff base complexes (NN(*)) in (7-9) and monobasic tridentate Schiff base complexes (NN(*)O) in (10-12). Thus, suitable square planar geometry for tetradentated state has been suggested for the metal complexes. Various ligand and nephelouxetic parameter have been calculated for the complexes. The thermal decomposition for complexes was studied.

Synthesis, Characterization, and Antimicrobial and Antispermatogenic Activity of Bismuth(III) and Arsenic(III) Derivatives of Biologically Potent Nitrogen and Sulfur Donor Ligands

A series of Bi(III) and As(III) complexes with two N∩S donor ligands, 1-(4-chloro-2-oxo-2H-chromen-3-yl)-methylene)-thiosemicarbazide (L1H) and N′-[1-(2-oxo-2H-chrome-3yl-ethylidene]-hydrazinecarbodithionic acid benzyl ester (L2H) have been synthesized by the reaction of BiCl3 and Ph3As with ligands in 1 : 1 and 1 : 2 molar ratios. All the synthesized compounds were characterized by elemental analyses, melting point determinations, and a combination of electronic, IR, 1H NMR, 13C NMR spectroscopic techniques, and X-ray diffraction for structure elucidation. In order to evaluate the effect of metal ions upon chelation, both the ligands and their complexes have been screened for their antimicrobial activity against the various pathogenic bacterial and fungal strains. The metal complexes have shown to be more antimicrobial against the microbial species as compared to free ligands. Both the ligands and their corresponding metal complexes have been tested for their antifertility activity in male albino rats. The marked reduction in sperm motility and density resulted in infertility. Significant alterations were found in biochemical parameters of reproductive organs in treated animals as compared to control group. It is concluded that all these effects may finally impair the fertility of male rats.

Comparative studies of mononuclear Ni(II) and UO2(II) complexes having bifunctional coordinated groups: synthesis, thermal analysis, X-ray diffraction, surface morphology studies and biological evaluation

Two Schiff base ligands derived from condensation of phthalaldehyde and o-phenylenediamine in 1:2 (L(1)) and 2:1 (L(2)) having bifunctional coordinated groups (NH(2) and CHO groups, respectively) and their metal complexes with Ni(II) and UO(2)(II) have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibilities and spectral data (IR, (1)H NMR, mass and solid reflectance) as well as thermal, XRPD and SEM analysis. The formula [Ni(L(1))Cl(2)]·2.5H(2)O, [UO(2)(L(1))(NO(3))(2)]·2H(2)O, [Ni(L(2))Cl(2)]·1.5H(2)O and [UO(2)(L(2))(NO(3))(2)] have been suggested for the complexes. The vibrational spectral data show that the ligands behave as neutral ligands and coordinated to the metal ions in a tetradentate manner. The Ni(II) complexes are six coordinate with octahedral geometry and the ligand field parameters: D(q), B, β and LFSE were calculated while, UO(2)(II) complexes are eight coordinate with dodecahedral geometry and the force constant, F(U-O) and bond length, R(U-O) were calculated. The thermal decomposition of complexes ended with metal chloride/nitrate as a final product and the highest thermal stability is displayed by [UO(2)(L(2))(NO(3))(2)] complex. The X-ray powder diffraction data revealed the formation of nano sized crystalline complexes. The SEM analysis provides the morphology of the synthesized compounds and SEM image of [UO(2)(L(2))(NO(3))(2)] complex exhibits nano rod structure. The growth-inhibiting potential of the ligands and their complexes has been assessed against a variety of bacterial and fungal strains.

Palladium(II) and platinum(II) derivatives of benzothiazoline ligands: Synthesis, characterization, antimicrobial and antispermatogenic activity

A series of Pd(II) and Pt(II) complexes with two N(∩)S donor ligands, 5-chloro-3-(indolin-2-one)benzothiazoline and 6-nitro-3-(indolin-2-one)benzothiazoline, have been synthesized by the reaction of metal chlorides (PdCl2 and PtCl2) with ligands in 1:2 molar ratios. All the synthesized compounds were characterized by elemental analyses, melting point determinations and a combination of electronic, IR, 1H NMR and 13C NMR spectroscopic techniques for structure elucidation. In order to evaluate the effect of metal ions upon chelation, both the ligands and their complexes have been screened for their antimicrobial activity against the various pathogenic bacterial and fungal strains. The metal complexes have shown to be more antimicrobial against the microbial species as compared to free ligands. One of the ligands, 5-chloro-3-(indolin-2-one)benzothiazoline and its corresponding palladium and platinum complexes have been tested for their antifertility activity in male albino rats. The marked reduction in sperm motility and density resulted in infertility by 62-90%. Significant alterations were found in biochemical parameters of reproductive organs in treated animals as compared to control group. It is concluded that all these effects may finally impair the fertility of male rats.