Preliminary Investigation of Copper(II) Ion Binding or Complex Coordination in Lysozeme Molecules

Hydrophobic Val derivative Schiff base copper(II) complexes and dipeptide (AlaAla, GlyGly) derivative Schiff base copper(II) complexes were introduced into egg white lysozyme. X-ray crystal structure analysis revealed amino acid derivative Schiff base copper(II) complexes were obtained. Herein we discuss primarily on the binding mode of copper(II) of the complexes obtained with egg white lysozyme. The electron density of copper(II) ions was confirmed by X-ray crystal structure analysis. The Val derivative Schiff base copper(II) complex was weakly bound at Arg114 of egg white lysozyme. In other copper(II) complexes, binding of copper(II) ions with dissociated ligands to various residues was observed. The binding sites of copper(II) ions were compared with computational scientific predictions.

Syntheses of Coordination Compounds of 2-Amino-3-Methylbutanoic Acid Their Mixed Ligand Complexes and Antibacterial Activities

Coordination compounds of 2-amino-3-methylbutanoic acid were synthesized with chromium(III) and oxovanadium(IV) ions. M:L;1:2. Adducts of these complexes using 1,10-phenantroline and ethylenediamine were further synthesized, M:L, (1:2). These compounds were characterized using electronic, infra-red spectrophotometry, magnetic susceptibility measurement and percentage metal analyses. The zones of inhibition and minimum inhibitory concentrations of the compounds against eight microbes were studied. The results obtained indicated an octahedral geometry for the Cr(III) complexes, indicative of additional coordination of two water molecules. On the other hand a square pyramid geometry was obtained for the binary oxovanadium complex and its 1,10-phenantroline adduct. However, for the oxovanadium ethylenediamine adduct a distorted octahedral geometry was proposed. The result for the antibacterial studies indicated that both mixed ligand complexes of 1,10-phenantroline exhibited good antibacterial activity, and in some cases better activity than the standard, streptomycin.

Synthesis, Characterization, Antimicrobial and DNA Binding Studies of a Tetradentate N2O2 Amino Acid Schiff Base and Its Coordination Compounds

Aminoethanoic acid undergoes condensation with 1,4-benzenedicarboxaldehyde to form an O, N, N, O donor Schiff base, N,N'-di(carboxymethylene) terephthalaldehyde, Ligand L. Coordination compounds of this Schiff base using Ni (II), Cu (II), VO (IV) and Co (II) were then obtained in-situ. The Schiff base and the complexes were evaluated for their antimicrobial and DNA binding abilities. Molecular docking studies of the ligand and synthesized compounds were also carried out. Evidence for the formation of the Schiff base coordination compounds and the coordinating atoms was obtained from 1H NMR, infrared and ultraviolet spectral data, EDX, EDTA complexometric titration and magnetic susceptibility measurement. The results obtained are consistent with octahedral geometry for Ni (II) complex, the metal ion coordinating to one molecule of Ligand L and with additional coordination with two oxygen atoms of two molecules of the solvent. A square-planar geometry was suggested for both Co (II), and Cu (II) complexes and a five-coordinate, square pyramidal geometry for the VO (IV) complex. The results further indicated that the carboxylic acid of Ligand L was not deprotonated both in the free base and also the complexes. In addition, the results showed that Compound 2 elicited the best antimicrobial activity potential. Generally, the compounds exhibited considerable good affinity to CT-DNA.

Syntheses, Characterization and Biological Activity of Novel Thiazoylazo Dye and Its Coordination Compounds

The present work describes the synthesis of a novel heterocyclic azo dye by general diazonization of 2-amino-4,5-dimethylthiazole followed by the diazo- coupling of the resulting diazonium ion with 5-methyl-2-(propan-2-yl)phenol to obtain ligand L. This was characterized using Fourier-transformed infrared and electronic spectrophotometry. Ligand L was further coordinated with five metal ions, M:L, 1:2 [M = Cu(II), Mn(II), Zn(II), Ni(II) and Co(II)]. The coordination compounds obtained were characterized by electronic, IR spectrophotometry, magnetic susceptibility and percentage metal analyses. The results obtained suggested that a thiazoylazo dye was obtained as ligand L. It was proposed that two molecules of the solvent coordinated to the metal ion in addition with the ligands to give an octahedral geometry for copper(II), manganese(II) and nickel(II) complexes. On the other hand, square planar geometry was suggested for zinc(II) and cobalt(II) complexes. The anti-infla- mmatory activity of the ligand and coordination compounds was evaluated using four in vitro-based assays viz: xanthine oxidase and lipoxygenase inhibition assay, membrane stability and protein denaturation assay. The synthesized compounds generally exhibited good anti-inflammatory activity in all the assays carried out. However, the reference standards, in this instance, were more effective in the case of xanthine oxidase, lipoxygenase and protein denaturation inhibitory assays. For the membrane stability study, the coordination compounds and ligand L elicited more potent anti-inflammatory activity than the standard drug.

Syntheses of Coordination Compounds of (±)-2-Amino-3-(4-Hydroxyphenyl)Propionic Acid, Mixed Ligand Complexes and Their Biological Activities

Coordination compounds of (±)-2-amino-3-(4-hydroxyphenyl) propionic acid and their mixed ligand complexes with 1,10-phenantroline were synthesized, characterized using electronic and infrared spectral analyses and magnetic susceptibility. The compounds were evaluated for antimicrobial and antioxidant activities. Four different assays were applied for evaluating antioxidant capacity of the compounds. The results obtained indicated a diametric square planar geometry for both cobalt (±)-2-amino-3-(4-hydroxyphenyl) propionic acid complex and its mixed ligand complex. It was suggested that for the binary cobalt(II) complex, the phenolic substituent coordinated with neighbouring central metal ions. However, for the ternary cobalt(II) complex it was suggested it was deprotonated. Octahedral geometry was proposed for both copper complexes. Square planar geometry was indicated for the nickel?(±)-2-amino-3-(4-hydroxyphenyl) propionic acid complex and a mixture of square planar and octahedral geometry for the nickel mixed ligand complex. The cobalt mixed ligand complex elicited the highest activity for all the antioxidant assays. In most cases the binary complexes exhibited better antimicrobial activities relative to their ternary counterparts.

Syntheses, Characterization and Biological Activity of Coordination Compounds of 3-Hydroxy-2-methyl-4<i>H</i>-pyran-4-one and Its Mixed Ligand Complexes with 1,2-Diaminocyclohexane

Coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one with iron(III), cobat(III) and chromium(III) were synthesized with M:L (1:2). Mixed ligand coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one and 1,2-diaminocyclohexane using the same metal ions were also synthesized M:L1:L2 (1:1:1) where L1 is 3-hydroxy-2-methyl-4H-pyran-4-one and L2 is 1,2-diaminocyclohexane. The coordination compounds obtained were characterized using electronic and infrared spectral analyses, magnetic susceptibility and percentage metal analysis. They were also evaluated for their cytotoxic and antioxidant activities. The result obtained suggested that octahedral geometry was obtained for all the compounds, as a result of additional two molecules of the solvent coordinated to the metal ions. Both the primary and secondary ligands coordinated in a bidentate fashion. The synthesized compounds exhibited moderate cytotoxicity, although none was as active as the standard. The cobalt(III) mixed ligand complex elicited the highest activity. The synthesized compounds all exhibited good to moderate antioxidant activity.