Mononuclear dioxomolybdenum(VI) complexes with the quinolones enrofloxacin and sparfloxacin: Synthesis,structure, antibacterial activity and interaction with DNA

The neutral mononuclear dioxomolybdenum(VI) complexes of the quinolone antibacterial agents enrofloxacin and sparfloxacin have been prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, enrofloxacin and sparfloxacin act as bidentate deprotonated ligands bound to the metal through the pyridone oxygen and one carboxylate oxygen. The central molybdenum atoms are six-coordinate with slightly distorted octahedral geometry. The lowest energy model structure of each complex has been proposed with molecular modeling calculations. The antimicrobial activity of the complexes has been tested on three different microorganisms. The investigation of the interaction of the complexes with calf-thymus DNA has been performed with diverse spectroscopic techniques.     

Synthesis,characterization and interaction with DNA of mononuclear metal complexes with oxolinic acid

Seven new neutral mononuclear metal complexes of VO²⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺ and Cd²⁺ with the quinolone antibacterial agent oxolinic acid (=Hoxo) have been prepared and characterized with physicochemical and spectroscopic techniques. In all the complexes, oxolinic acid acts as a bidentate deprotonated ligand bound to the metal through the pyridone oxygen and one carboxylate oxygen. The metals in all the complexes are six-coordinate with slightly distorted octahedral geometry. The lowest energy model structures of the complexes Fe(oxo)₃, VO(oxo)₂(H₂O) and Mn(oxo)₂(H₂O)₂ have been determined with molecular modeling calculations. The ability of all the complexes to bind to calf-thymus DNA has been investigated with diverse spectroscopic techniques.     

Synthesis and antibacterial activity of cephradine metal complexes

Cephradine (Hcephra) interacts with transition metal ions to give [Fe(cephra)Cl₂] and [M(cephra)Cl] complexes (M?=?Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) which were characterized by physicochemical and spectroscopic methods; a tetrahedral geometry is suggested for their structures where cephradine behaves as monoanionic tridentate ligand. The complexes have been screened for antibacterial activity against several bacteria, and the results showed that all metal complexes tested had lower antibiotic activity than the free ligand.     

Synthesis and antibacterial activity of cephalexin metal complexes

The interactions of cephalexin (Hcepha) with transition and d¹⁰ metal ions have been investigated. The complexes [M(cepha)Cl]nH₂O [M?=?Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II)] were characterized by physicochemical and spectroscopic methods. The IR and ¹H NMR spectra of the complexes suggest that cephalexin behaves as a monoanionic tridentate ligand. In vitro antibacterial activities of Hcepha and the complexes were tested.     

Synthesis,antibacterial, anticancer and molecular docking studies of macrocyclic metal complexes of dihydrazide and diketone

The complexes of Co(II), Ni(II), Cu(II) and Zn(II) metal ions has been synthesized through template method by the condensation of succinic acid dihydrazide with 5-chloroisatin in alcoholic medium. Complexes were characterized by C H N analysis, molar conductance, thermal analysis, magnetic susceptibility, mass spectrometry, FTIR, EPR, ¹H NMR, UV–Visible spectroscopy. These studies suggest an octahedral geometry for all the complexes. The compounds were found active against B. subtilis and S. aureus and P. aeruginosa and E. coli bacteria. The Zn(II) complex showed significant anticancer activity against Squamous Cell Carcinoma cells tested by the MTT assay method. Molecular docking studies with EGFR tyrosine kinase were also carried out. All these results show that some of the synthesized compounds have remarkable antibacterial and anticancer property.     

Metalloantibiotics: synthesis and antibacterial activity of ceftazidime metal complexes

Ceftazidime (Hceftaz) interacts with transition metal(II) ions to give octahedral [M(ceftaz)(H₂O)Cl] complexes [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Cd(II)] which were characterized by physicochemical and spectroscopic methods. The spectra indicated that the ligand is a multidentate chelating agent. The complexes are insoluble in water and common organic solvents and probably have polymeric structures. The antibacterial activity of the metal complexes was found to be lower than that of free ceftazidime.     

Structure and DNA-binding properties of bis(quinolonato)bis(pyridine)zinc(II) complexes

The novel neutral mononuclear zinc complexes with the quinolone antibacterial drugs enrofloxacin and oxolinic acid in the presence of the nitrogen donor heterocyclic ligand pyridine have been synthesized and characterized. The experimental data suggest that the quinolone ligands are on the deprotonated mode acting as bidentate ligands coordinated to the zinc(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of the complex bis(enrofloxacinato)bis(pyridine)zinc(II), 1, has been determined with X-ray crystallography. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT-DNA) with UV and fluorescence spectroscopies. UV spectroscopic titration studies of the interaction of the complexes with DNA have shown that they can bind to CT-DNA and the DNA binding constants have been calculated. Competitive studies with ethidium bromide (EB) have shown that the complexes exhibit the ability to displace the DNA-bound EB indicating that they can bind to DNA in strong competition with EB for the intercalative binding site.     

Preparation,characterization of some transition metal complexes of hydrazone derivatives and their antibacterial and antioxidant activities

A new series of metal complexes of Pd(II), Cd(II) and Cu(II, I) of polydentate Schiff base ligand (H₂L), namely ((Z)-2-(phenylamino)-N'-(thiophen-2-ylmethylene) acetohydrazide) have been prepared. The ligand and its metal complexes have been characterized based on various physicochemical studies as elemental analyses, molar conductance, spectral (UV–Vis, MS, IR, ¹H NMR, ¹³C NMR and XRD), magnetic moment measurements and thermal studies (TG, DTG). In the view of previous studies, the ligand (H₂L) acts as polydentate one and coordinates with metal ions to form all metal complexes. The kinetic and thermodynamic parameters of decomposition process (ΔG, ΔH, ΔS) were calculated. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program. The calculations are performed to obtain the optimized molecular geometry. The antibacterial study of the selected compounds was assayed against two pathogenic bacteria. Moreover, the complexes (Cu II, I), Cd(II), Pd(II)) and the ligand revealed excellent antioxidant properties and could be useful in fighting the free radicals which occur in close connection with cancerous cells. It was remarkable that the two complexes (Cu II, I) demonstrated stronger antioxidant effects than their parent compounds. It is clear that the new complexes are good active compounds for use in a variety of applications.     

Synthesis,characterization, potentiometry,and antimicrobial studies of transition metal complexes of a tridentate ligand

Complexes of Cu(II), Ni(II), Co(II), Mn(II), and Fe(III) with the tridentate Schiff base, 4-hydroxy-3(1-{2-(benzylideneamino)-phenylimino}-ethyl)-6-methyl-2H-pyran-2-one (HL) derived from 3-acetyl-6-methyl-(2H)-pyran-2,4(3H)-dione (dehydroacetic acid or DHA), o-phenylenediamine, and benzaldehyde were characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, ¹H-NMR, UV-Vis spectroscopy, and mass spectra. From analytical data, the stiochiometry of the complexes was found to be 1?:?2 (metal?:?ligand) with octahedral geometry. The molar conductance values suggest nonelectrolytes. X-ray diffraction data suggest monoclinic crystal systems. IR spectral data suggest that the ligand is dibasic tridentate with ONN donors. To investigate the relationship between formation constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff base and stability constants of its binary metal complexes have been determined potentiometrically in THF–water (60?:?40) at 30?±?1°C and at 0.1?mol?L^?1 NaClO₄ ionic strength. The potentiometric titrations suggest 1?:?1 and 1?:?2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli, Aspergillus niger, and Trichoderma with determination of minimum inhibitory concentrations of ligand and metal complexes. The structure–activity correlation based on stability constants of metal complexes is discussed. Activity enhances upon complexation and the order of activity is in accord with the stability order of metal ions.     

1,10-邻菲啰啉衍生物钌配合物的合成、 表征及与DNA和BSA的相互作用

通过2-(4-吡啶)-咪唑[4,5-f]-1,10-邻菲啰啉(L₁)与[Ru(η⁶-cymene)(μ-Cl)Cl]₂反应合成了3种新型芳基钌配合物, 并利用新配体2-(4-咪唑基苯基)咪唑[4,5-f]-1,10-邻菲啰啉(L₂)与RuCl₃反应合成了配合物4. 利用核磁共振波谱、 质谱等对配合物进行了表征. 通过紫外光谱和圆二色谱研究了配合物在缓冲溶液中的稳定性及与CT-DNA的相互作用, 利用荧光光谱研究了配合物与牛血清蛋白的作用, 用乌氏黏度计测试了配合物对DNA黏度的影响, 并通过荧光光谱、 凝胶电泳研究了配合物4在不同pH条件下的荧光响应及与pBR322 DNA的作用. 结果表明, 配合物通过嵌入的方式与DNA作用, 并对DNA的二级结构产生影响; 配合物1~4均可与牛血清蛋白的一个位点发生相互作用并使其发生静态荧光猝灭. 配合物4在光照条件下有活性氧生成, 可以使pBR322 DNA断裂并在酸性溶液中荧光增强.     

Synthesis,spectroscopic studies,and antibacterial activities of 14-membered tetraazamacrocyclic complexes of divalent transition metal ions

A new series of macrocyclic complexes, [M(C₄₈H₃₂N₄)X₂], where M?=?Co(II),?Ni(II),?Cu(II), and Zn(II); X?=?Cl^?,?NO₃ ^?,?CH₃COO^?, have been synthesized by condensation of 1,8-diaminonaphthalene and benzil, in the presence of divalent metal salts in methanolic medium. The complexes have been characterized by elemental analyses, conductance measurements, magnetic measurements, and electronic, NMR, IR, and MS spectral studies. The low value of molar conductance indicates the presence of non-electrolytes. A distorted octahedral geometry is proposed for the complexes. The metal complexes were also tested for their in vitro antibacterial activities against some bacterial strains and compared with the standard antibiotic Ciprofloxacin. Some tested complexes show good antibacterial activities against some bacterial strains.     

Synthesis,crystal structure,DNA interaction and anticancer evaluation of pyruvic acid derived hydrazone and its transition metal complexes

A novel tridentate chelating ligand, Ethyl 2‐(2‐(2‐chlorobenzoyl)hydrazono)propanoate and its late transition metal complexes were synthesized, characterized and evaluated for anticancer behavior. The structures were elucidated with the help of elemental analyses, spectral (vibrational, electronic, NMR and mass) and thermo‐gravimetric techniques. Single crystal X‐ray crystallographic studies of the ligand suggest an orthorhombic lattice structure with Pna21 space group. The interaction of ligand and complexes with DNA (CT‐DNA) has been extensively studied using absorption, emission, viscosity and thermal denaturation studies with E. coli DNA. The DNA cleavage ability of ligand and metal complexes was tested using plasmid pBR322 DNA by gel electrophoresis method. The ligand and its copper complex have been evaluated for their in vitro anticancer activity against human cancer cells of different origin such as KB (Oral), A431 (Skin), Mia‐Pa‐Ca (Pancreases), K‐549 (Lung), K‐562 (Leukemia), MCF‐7 (Breast) and VERO by MTT assay and the apoptosis assay was carried out with acridine orange/ethidium bromide (AO/EB) staining method. The studies suggest that ligand and copper complex exhibit significant cytotoxic activity on KB, MCF‐7, A‐431, Mia‐Pa‐Ca‐2 an d A‐549 cell lines compared to K‐562 and VERO cell lines.     

Synthesis,characterisation, crystal structure and biological activity of metal(II) complexes with theophylline

Three metal complexes with empirical formulae [Mn(theop)₂(H₂O)₄] (1), [Co(theop)₂(H₂O)₄] (2), [Ni(theop)₂(H₂O)₄] (3), (where: theop?=?theophylline) were synthesized and characterized by elemental analysis, FTIR- spectroscopy and thermal decomposition techniques. Their crystal structures were determined by single crystal Xray diffraction analysis. Complexes are isomorphous and crystallise in the monocyclic space group P21/c. Their thermal behavior was studied by TGA methods under non-isothermal condition in air. Upon heating all compounds decompose progressively to metal oxides, which are the final products of pyrolysis. Furthermore, antimicrobial and antioxidant activity of the complexes was examined.     

Metalloantibiotics: synthesis and antibacterial activity of cefepime metal complexes

Cefepime interacts with transition metal(II) ions to give [M(cefepime)Cl₂] complexes (M = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) which were characterized by physicochemical and spectroscopic methods. The complexes are insoluble in water and common organic solvents, and probably have polymeric structures. The spectra indicated that the ligand is a multidentate chelating agent. The complexes have been screened for antibacterial activity against several bacteria and showed activity less than that of free cefepime.     

Synthesis,characterization, and biological activity of metal complexes of azohydrazone ligand

A new azohydrazone, 2-hydroxy-N′-2-hydroxy-5-(phenyldiazenyl)benzohydrazide (H₃L) and its copper(II), nickel(II), cobalt(II), manganese(II), zinc(II), cadmium(II), mercury(II), vanadyl(II), uranyl(II), iron(III), and ruthenium(III) complexes have been prepared and characterized by elemental and thermal analyses as well as spectroscopic techniques (¹H-NMR, IR, UV-Vis, ESR), magnetic, and conductivity measurements. Spectral data showed a neutral bidentate, monobasic bidentate, monobasic tridentate, and dibasic tridentate bonding to metal ions via the carbonyl oxygen in ketonic or enolic form, azomethine nitrogen, and/or deprotonated phenolic hydroxyl oxygen. ESR spectra of solid vanadyl(II) complex (2), copper(II) complexes (3–5), and (7) and manganese(II) complex (10) at room temperature show isotropic spectra, while copper(II) complex (6) shows axial symmetry with covalent character. Biological results show that the ligand is biologically inactive but the complexes exhibit mild effect on Gram positive bacteria (Bacillus subtilis), some octahedral complexes exhibit moderate effect on Gram negative bacteria (Escherichia coli), and VO(II), Cd(II), UO(II), and Hg(II) complexes show higher effect on Fungus (Aspergillus niger). When compared to previous results, metal complexes of this hydrazone have a mild effect on microorganisms due to the presence of the azo group.     

X-ray crystal structure of a Cu(II) complex with the antiparasitic drug tinidazole,interaction with calf thymus DNA and evidence for antibacterial activity

Interaction of metal ions with biologically active molecules like 5-nitroimidazoles modulates their electronic environment and therefore influences their biological function. In the present work, an antiparasitic drug tinidazole (tnz) was selected and a Cu(II) complex of tnz [Cu₂(OAc)₄(tnz)₂] was prepared. A dinuclear paddle-wheel [Cu₂(OAc)₄(tnz)₂] was obtained by single-crystal XRD and further characterized by spectroscopic techniques and cyclic voltammetry. To understand the biological implications of complex formation, interaction of tnz and its complex was studied with calf thymus DNA, bacterial and fungal cell lines. Results of calf thymus DNA interaction using cyclic voltammetry indicate the overall binding constant (K^*) of Cu₂(OAc)₄(tnz)₂ [(59?±?6)?×?10⁴?M^?1] is ~17 times greater than that of tnz [(3.3?±?0.4)?×?10⁴?M^?1]. Minimum inhibitory concentration values suggest that [Cu₂(OAc)₄(tnz)₂] possesses better antibacterial activity than tnz on both bacterial strains, while the activity on a fungal strain was comparable.     

A comparative DFT study of some N-based aromatic ligand metal complexes as anticancer agents and analysis of their mode of interaction with DNA base pair

Metal complexed anticancer agents interact with DNA nucleobase pairs (AT and GC) through different types of binding mode such as intercalation, groove binding, covalent binding, etc. Minor and major groove binding mechanism of DNA base pair is the key factor for all kinds of anticancer agent; as metal complexes have a great affinity to bind with DNA nucleobase either through minor or major groove. Ligands in metal complexes also play a vital role during the interaction with DNA base pairs; these ligands directly interact with DNA through different interacting modes. Generally, anticancer agents with less sterically hindered N-based aromatic and planar ligands are the key component for DNA binding; as the structure of such ligands are quite compatible for following intercalation and groove binding mechanism. Since, the experimental investigation for drug-DNA nucleobase complexes are extremely complicated, therefore; quantum mechanical calculations might be very helpful for computing the actual interactions in drug-DNA complexes. Quantum mechanical approaches such as density functional theory (DFT) might be a very important and useful tool to investigate the actual mode of interaction of metal complexed antitumor agents with DNA nucleobase. Herein, we have taken some metal complexes with N-based aromatic ligands as antitumor agents to investigate the proper mode of interaction between drug-DNA complexes.     

Synthesis,spectroscopic investigations,and biological activity of metal complexes of N-benzoylthiosemicarbazide

N-Benzoylthiosemicarbazide, HL, was obtained by fusion of benzoylhydrazide and ammonium thiocyanate. Reactions of HL with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), cadmium(II), oxovanadium(IV), and dioxouranium(VI) in 1 : 1 molar ratio yield the corresponding complexes. The N-benzoylthiosemicarbazide may act as a neutral or monobasic bidentate ligand coordinated through NS or NO sites. The structures of the HL ligand and its complexes were identified by elemental analysis, infrared, electronic, mass, ¹H-NMR, and ESR spectra as well as magnetic susceptibility and molar conductivity measurements. Different geometries were obtained for the metal complexes. The ligand and its metal complexes were investigated for antibacterial and antifungal properties. Two Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes, two Gram-negative, bacteria, Pseudomonas fluorescens and Pseudomonas phaseolicola and two fungi, Fusarium oxysporum and Aspergillus fumigatus, were used in this study. The metal complexes were more effective than the free ligand.