Walaa H. Mahmoud

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO2(VI) ions: Synthesis, structural characterization and biological activity studies

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV-vis, (1)H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25±1°C and at 0.1 M KNO(3) ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO(2)(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H(2)O)(4)]·Cl(2) and [Zn(LFX)(H(2)O)(4)]·Cl(2) were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 μg/ml.

Coordination modes of bidentate lornoxicam drug with some transition metal ions. Synthesis, characterization and in vitro antimicrobial and antibreastic cancer activity studies.

The NSAID lornoxicam (LOR) drug was used for complex formation reactions with different metal salts like Cr(III), Mn(II), Fe(III) and Ni(II) chlorides and Fe(II), Co(II), Cu(II) and Zn(II) borates. Mononuclear complexes of these metals are obtained that coordinated to NO sites of LOR ligand molecule. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV-Vis, (1)H NMR, mass, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG-DTG) and further confirmed by X-ray powder diffraction. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The data show that the complexes have composition of ML2 type except for Fe(II) where the type is [ML3]. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion for all the complexes. The antimicrobial data reveals that LOR ligand in solution show inhibition capacity less or sometimes more than the corresponding complexes against all the species under study. In order to establish their future potential in biomedical applications, anticancer evaluation studies against standard breast cancer cell lines (MCF7) was performed using different concentrations. The obtained results indicate high inhibition activity for Cr(III), Fe(II) and Cu(II) complexes against breast cancer cell line (MCF7) and recommends them for testing as antitumor agents.

Ternary metal complexes of guaifenesin drug: Synthesis, spectroscopic characterization and in vitro anticancer activity of the metal complexes.

The coordination behavior of a series of transition metal ions named Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with a mono negative tridentate guaifenesin ligand (GFS) (OOO donation sites) and 1,10-phenanthroline (Phen) is reported. The metal complexes are characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, UV-vis spectral studies, mass spectroscopy, ESR, XRD and thermal analysis (TG and DTG). The ternary metal complexes were found to have the formulae of [M(GFS)(Phen)Cl]Cl·nH2O (M=Cr(III) (n=1) and Fe(III) (n=0)), [M(GFS)(Phen)Cl]·nH2O (M=Mn(II) (n=0), Zn(II) (n=0) and Cu(II) (n=3)) and [M(GFS)(Phen)(H2O)]Cl·nH2O (M=Co(II) (n=0), Ni(II) (n=0) and Cd(II) (n=4)). All the chelates are found to have octahedral geometrical structures. The ligand and its ternary chelates are subjected to thermal analyses (TG and DTG). The GFS ligand, in comparison to its ternary metal complexes also was screened for their antibacterial activity on gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), gram negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and for in vitro antifungal activity against (Candida albicans). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent GFS ligand. The complexes were also screened for its in vitro anticancer activity against the Breast cell line (MFC7) and the results obtained show that they exhibit a considerable anticancer activity.

Synthesis, spectral characterization, thermal, anticancer and antimicrobial studies of bidentate azo dye metal complexes

As a part of systematic investigation of biologically active compound, m-phenylene diamine, new azo dye ligand was synthesized by diazotization of m-phenylene diamine and coupled with coupling compound, p-methoxy benzaldehyde. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes derived from this azo dye ligand (L) were synthesized. The structures of the ligand and metal complexes were confirmed by elemental analysis, spectroscopic studies (IR, UV–Vis, 1H NMR, mass spectrometry, electronic spectra, magnetic susceptibility and ESR), conductivity measurements, thermogravimetric analyses (TG-DTG) and X-ray powder diffraction. The molar conductance measurements of the complexes in DMF determine electrolytic nature of the complexes. On the basis of elemental and thermal analyses, magnetic moment, electronic and ESR spectral studies, an octahedral geometry was assigned for metal complexes. XRD data reflect that azo dye ligand and its Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes are amorphous while Cd(II) complex is crystalline. Also, the newly synthesized azo dye ligand, in comparison with metal complexes, is screened for its antimicrobial and anticancer activity against breast cancer cell line (MCF7). The results showed that Mn(II), Ni(II) and Zn(II) metal complexes have higher anti-breast cancer activity than free ligand.

Preparation, geometric structure, molecular docking thermal and spectroscopic characterization of novel Schiff base ligand and its metal chelates

The condensation of o-benzoyl benzoic acid and 4-aminoantipyrine resulted in the formation of novel Schiff base ligand (HL) with the IUPAC name 2-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)(phenyl)methyl)benzoic acid. The synthesized Schiff base ligand and its complexes with M(II)/(III) transition elements (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)) were characterized by elemental, magnetic susceptibility, molar conductivity, spectroscopic (1H NMR, mass, UV–visible, FTIR, ESR), thermal and X-ray powder diffraction. The data showed that the complexes had composition of the MHL type. The diffused reflectance spectra, magnetic susceptibility and ESR spectral data of the complexes confirm an octahedral geometry around metal ions. The thermal analysis data revealed the decomposition of the complexes in three to five successive decomposition steps within the temperature range of 30–1000°C, and the activation thermodynamic parameters were reported. The molecular structures of the Schiff base ligand and its Mn(II) and Zn(II) metal complexes are optimized theoretically, and the quantum chemical parameters are calculated. In order to predict the binding between o-benzoyl benzoic acid, 4-aminoantipyrine and HL ligand with the Escherichia coli bacterial RNA (4p20) receptor, molecular docking was carried out. The in vitro antimicrobial screening of the newly synthesized compounds was tested against different bacterial and fungal organisms. The results showed that the metal complexes have biologically activity more than the new Schiff base ligand against the tested organisms. The Schiff base ligand and its complexes were also screened for their anticancer activity against breast cancer cell line (MCF7). The Mn(II), Cr(III) and Cd(II) complexes were found to have low IC50 values which support the possibility of using them as cytotoxic agents and hence might become good anticancer agent in clinical trials.

Spectroscopic and thermal characterization of biologically and anticancer active novel Schiff base metal complexes

The novel Schiff base ligand 2,2′-((1Z,1′Z)-(1,3-phenylenebis(azanylylidene))-bis(phenylmethanylylidene))dibenzoic acid (H2L) was obtained by the condensation of m-phenylenediamine with o-benzoylbenzoic acid. The molecular and electronic structure of Schiff base ligand (H2L) was optimized theoretically, and the quantum chemical parameters are calculated. Molecular docking was used to predict the binding between Schiff base ligand (H2L) and the receptors of breast cancer mutant 3hb5-oxidoreductase, crystal structure E. coli (3t88) and crystal structure of S. aureus (3q8u). The newly synthesized Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) complexes were characterized by elemental microanalysis, molar conductance, spectroscopic techniques (IR, 1H NMR, ESI-mass, ESR, UV–Vis), magnetic susceptibility, thermal (TG/DTG) and powder X-ray diffraction data to explicate their structures. The data showed that the complexes had composition of MH2L type. The IR results confirmed the bidentate binding of the ligand involving two azomethine nitrogens. 1H NMR spectral data of the ligand (H2L) and its Zn(II) and Cd(II) complexes agreed well with the proposed structures. On the basis of electronic spectra and the magnetic measurements, octahedral geometry of the complexes was proposed. Thermogravimetric data (TG and DTG) were also studied. The kinetic and thermodynamic parameters for thermal decomposition of the complexes were calculated using the Coats–Redfern and Horowitz–Metzger methods. In order to appraise the effect of antimicrobial activity of metal ions upon chelation, the newly synthesized ligand and its metal complexes were screened against a number of bacteria organisms as Bacillus subtilis, Staphylococcus aureus,Escherichia coli, and Neisseria gonorrhoeae and against one fungus, Candida albicans, to assess their inhibiting potential by using the disc diffusion method. The results showed that in some cases the antimicrobial activity of complexes was more biologically active than the Schiff base ligand. Anticancer activity of the ligand and its metal complexes were evaluated in human cancer (MCF-7 cells viability). It was found that [Cd(H2L)(H2O)2Cl2]2H2O complex showed lowest IC50 than the others, and hence was the more active. The activity index was calculated.

Spectroscopic characterization and molecular docking studies of acetyl ferrocene-derived Schiff base ligand with phenanthroline and some transition metal ions

As a part of systematic investigation of the reactivity of a novel ferrocene-based Schiff base ligand, HL ligand was synthesized by condensation of 2-acetylferrocene with 2-aminophenol and mixed with 1,10-phenanthroline to give new mixed chelates. Series of transition metal ions Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were synthesized. The structures of the ligand and mixed ligand complexes were confirmed by elemental analysis, spectroscopic studies [IR, 1H NMR, UV–Vis, mass spectrometry, SEM] and thermal analysis (TG/DTG). The molar conductance measurements of the complexes in DMF determine electrolytic and non-electronic nature of the complexes. Significant applications have been done to ensure the biological importance of the new mixed metal complexes like antimicrobial activities (four bacterial organisms and four fungal organisms), anticancer activities (MCF7 breast cancer cell line) and Molecular Operating Environment studies with the crystal structure of acetylcholinesterase (PDB: 1B41), the synthetic DNA dodecamer (PDB: 1BNA) and virus protein U (Vpu) of human immune deficiency virus (HIV-1) (PDB: 2N28).