Synthesis, structure, DNA binding and oxidative cleavage activity of ternary (l-leucine/isoleucine) copper(II) complexes of heterocyclic bases

Six ternary α-amino acid copper(II) complexes of the general formula Cu(AA)(B)(H 2O)(X) (1-6), where AA is l-leu = l-leucine (1-3) or l-ile = l-isoleucine (4-6), B is a N,N-donor heterocyclic base, viz. 2,2â²-bipyridine (bpy, 1, 4), 1,10-phenanthroline (phen, 2, 5) and dipyrido3,2:2â²,3â²-fquinoxaline (dpq, 3, 6) and X = ClO 4 - / NO 3 - have been synthesized, characterized, and their DNA binding and cleavage activity studied. The bpy and dpq complexes of l-ile (4, 6) have been structurally characterized by X-ray crystallography. The complexes show a distorted square-pyramidal (4 + 1) CuN 3O 2 coordination geometry. The one-electron paramagnetic complexes display a d-d band near 600 nm in water and show a cyclic voltammetric response due to a Cu(II)/Cu(I) couple near -0.1 V (vs. SCE) in DMF-0.1 M TBAP. All complexes are 1:1 electrolytes. Binding interactions of the complexes with calf thymus DNA (CT-DNA) have been investigated by absorption, emission, viscosity and DNA melting studies. The phen and dpq complexes are avid binders to the calf thymus DNA, giving an order: (3, 6) (dpq) > (2, 5) (phen) â« (1, 4) (bpy). The bpy complexes do not show any apparent binding to the DNA and hence show poor DNA cleavage activity. The phen and dpq complexes (2, 3, 5, 6) show efficient oxidative cleavage of pUC19 supercoiled DNA (SC-DNA) in the presence of the reducing agent 3-mercaptopropionic acid (MPA) involving hydroxyl radical ( {radical dot}OH) species, as evidenced from the control data showing inhibition of DNA cleavage in the presence of {radical dot}OH radical quenchers, viz. DMSO, mannitol, KI and catalase. © 2008 Elsevier Ltd. All rights reserved

TGA studies of metoclopramide complexes of cobalt(II) in the solid state

A new series of cobalt(II) complexes with metoclopramide (MCP) ligand have been prepared. The prepared Co(II)-MCP complexes were characterized for various analytical techniques. Conductivity and elemental analysis of complexes have been measured. The thermal stability and degradation kinetics have been measured using thermogravimetric analyser. Kinetic parameter was obtained for each stage of thermal degradation for Co(II)-MCP complexes using Horowitz-Metzger, Coats-Redfern and Broido's methods. The activation energy (Ea) of the complexes for the thermal degradation process lie in the range 31-168, 23-161 and 33-170 kJ mol-1 for Horowitz-Metzger, Coats-Redfern and Broido's methods, respectively. © 2003 Elsevier B.V. All rights reserved

DNA binding and oxidative cleavage activity of ternary (l-proline)copper(II) complexes of heterocyclic bases

Ternary copper(II) complexes Cu(l-pro)(B)(H 2O)(NO 3) (1, 2) where l-pro = l-proline, B is a N,N-donor heterocyclic base, viz. 2,2â²-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), are synthesized, characterized, and their DNA binding and cleavage activity studied. The bpy complex (1) is structurally characterized by single-crystal X-ray crystallography. The complexes show the presence of a distorted square-pyramidal (4 + 1) CuN 3O 2 coordination geometry. Complex Cu(l-pro)(bpy)(H 2O)(NO 3) (1) crystallizes in the triclinic space group P1 with unit cell parameters: a = 7.082(3) à , b = 10.483(5) à , c = 11.581(5) à , α = 89.700(7)°, β = 83.488(8)°, γ = 84.109(8)° and V = 849.7(7) à 3. The one-electron paramagnetic complexes display a d-d band near 600 nm in water and show a cyclic voltammetric response due to Cu(II)/Cu(I) couple near 0.1 V (versus SCE) in Tris-HCl buffer-0.1 M KCl. Binding interactions of the complexes with calf thymus (CT) DNA have been investigated by emission, absorption, viscosity and DNA thermal denaturation studies. The phen complex displays significant binding propensity to the CT DNA giving an order: 2 (phen) â 1 (bpy). The bpy complex does not show any apparent binding to the DNA and hence poor cleavage efficiency. Complex 2 shows efficient oxidative cleavage of SC-DNA in the presence of 3-mercaptopropionic acid (MPA) involving hydroxyl radical species as evidenced from the control data showing inhibition of DNA cleavage in the presence of DMSO and catalase. © 2007 Elsevier Ltd. All rights reserved

Synthesis, spectral and thermal degradation kinetics of divalent cadmium complexes of dothiepine and diphenhydramine

Cadmium(II) complexes with 3-(6H-dibenzob,e thiepin-11-ylidene) propyl dimethyl amine chloride (dot) and 2-diphenyl methoxy-N,N-dimethylamine hydrochloride (dp) were synthesised and characterised by reflectance, IR, 1H NMR, magnetic moments and conductivity measurements. The new complexes studied for kinetics of thermal degradation by thermogravimetric analyses (TGA) and derivative thermogravimetrie studies (DTG) in a static nitrogen atmosphere at a heating rate of 10°C min-1. The kinetic and thermodynamic parameters such as energy of activation (Ea), frequency factor (InA), enthalpy (ÎH), free energy (ÎH), and entropy (ÎS) evaluated. The energy of activation values for the degradation of (dot) and (dp) complexes were found to be in the range 22.3-125.4 kJ mol-1

“In Vitro Antimicrobial Activity and DNA Cleavage Studies: Synthesis and Characterization of Novel M(II) Complexes with O, N, O donor Schiff Base Ligand Derived from Phenylpropanehydrazide”

Three new ternary complexes of general formulation [M(L)n] (1–3), where L=N`-(5-chloro-2-hydroxybenzylidine)-3- phenylpropanehydrazide; n=2;M= Cu, Ni, Zn, complexes are synthesized, characterized by various physicochemical and UV-Vis, FTIR, 1H NMR and ESI-MS spectroscopic methods. The Cyclic voltammetry show a quasi-reversible cyclic voltammetric response due to one electron Cu(II)/Cu(I) reduction near 100 mV (versus SCE) in DMF–0.1 M KCl. All the compounds were screened for their in-vitro antibacterial activity against Gram positive and Gram negative bacterial strains. Among them, Cu complex showed good activity against all microbes. The copper complex shows moderate chemical nuclease activity in the presence of MPA as a reducing agen

New ternary copper(II) complexes of l-alanine and heterocyclic bases: DNA binding and oxidative DNA cleavage activity

Four new ternary copper(II) complexes of α-amino acid having polypyridyl bases of general formulation [Cu(l-ala)(B)(H2O)](X) (1–4), where l-ala is l-alanine, B is an N,N-donor heterocyclic base, viz. 2,2′-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2) and 5,6-phenanthroline dione (dione, 3), dipyrido[3,2:2′,3′-f]quinoxaline (dpq, 4), and X = View the MathML source/View the MathML source are synthesized, characterized by various spectroscopic and X-ray crystallographic methods. The complexes show a distorted square-pyramidal (4 + 1) CuN3O2 coordination geometry. The one-electron paramagnetic complexes (1–4) display a low energy d–d band near 600 nm in aqueous medium and show a quasi-reversible cyclic voltammetric response due to one-electron Cu(II)/Cu(I) reduction near −100 mV (versus SCE) in DMF–0.1 M TBAP. Binding interactions of the complexes with calf thymus DNA (CT-DNA) were investigated by UV–Vis absorption titration, ethidium bromide displacement assay, viscometric titration experiment and DNA melting studies. All the complexes barring the complexes 1 and 3 are avid binder to the CT-DNA in the DNA minor groove giving an order: 4 > 2 ⋙ 1, 3. The complexes 2 and 4 show appreciable chemical nuclease activity in the presence of 3-mercaptopropionic acid (MPA) as a reducing agent. Hydroxyl radical was investigated to be the DNA cleavage active species. Control experiments in the presence of distamycin-A show primarily minor groove-binding propensity for the complexes 2 and 4 to the DNA

In vitro antimicrobial activity and DNA cleavage studies: synthesis and characterization of novel M(II) complexes with tridentate [ONO] donor Schiff base ligand derived from phenylpropane hydrazide

Three new ternary complexes of general formulation [M(L)​n] (1-​3)​, where L = N'-​(5-​chloro-​2-​hydroxybenzylidine)​-​3-​phenylpropane hydrazide; n = 2; M = Cu, Ni, Zn, complexes are synthesized, characterized by various physicochem. and UV-​Vis, FT-​IR, 1H NMR and ESI-​MS spectroscopic methods. The Cyclic voltammetry show a quasi-​reversible cyclic voltammetric response due to one electron Cu(II)​/Cu(I) redn. near 100 mV (vs. SCE) in DMF-​0.1 M KCl. All the compds. were screened for their in-​vitro antibacterial activity against Gram pos. and Gram neg. bacterial strains. Among them, Cu complex showed good activity against all microbes. The copper complex shows moderate chem. nuclease activity in the presence of MPA as a reducing agent

Synthesis, Crystal Structure, Antioxidant, Antimicrobial, and Mutagenic Activities and DNA Interaction Studies of Ni(II) Schiff Base 4-Methoxy-3-Benzyloxybenzaldehyde Thiosemicarbazide Complexes

Three new Ni(II) square planar complexes of 4-methoxy-3-benzyloxybenzaldehyde thiosemicarbazide(4m3BTSC) having polypyridyl bases of general formulation [ML2] (1) and [MLB] (2, 3), where L = 4m3BTSC and B is N,N-donor heterocyclic bases, namely, 1,10-phenanthroline (phen, 2), 2,2′-bipyridine (bpy, 3), are synthesized and characterized. The free radical scavenging assay results showed that complex 1 possesses significant activity when compared to complexes 2 and 3. The biological studies showed that the ligand and its complexes exhibited significant and different biological activities and also the prepared compounds are nonmutagenic. They may be potential commercial antioxidants because of their nonmutagenic and nontoxic nature. The DNA interaction of the new complexes is evaluated by absorption, emission, and melting temperature methods, and the results suggested that the binding affinity of the complexes increases with the presence of planar ligand in the molecule. The nickel (II) complexes with planar phenanthroline bases show moderate DNA binding and cleavage ability

Synthesis and Chemical Nuclease Activities of Copper (II) and Ni (II) Complexes of 4-Chloro-2-(pyridine-3-Yliminomethyl) Phenol Schiff Bases

This communication describes a procedure to synthesize a novel Schiff base ligand4-chloro-2-(pyridine-3-yliminomethyl) phenol and its transition metal complexes of Cu(II) and Ni(II)and its characterization by physiochemical techniques such as elemental, FTIR,UVVisible, 1 H-NMR, Mass spectra and cyclic voltammetry. Further, the ligand was structurally characterized by X-ray crystallography and is found to be planar suitable for DNA studies. The complexes were screened for their in-vitro antimicrobial activity using various strains of gram positive and gram negative bacteria- Bacillus mycoides, Bacillus subtilis, Escherichia coli, Micrococcus luteus, Proteus mirabilis, Pseudomonas aeruginosa and Yersinia enterocolitica. The Schiff base ligand showed higher antibacterial activity than the ligand coordinated to either of the metal ion copper or nickel. The DNA cleavage studies of the complexes have been investigated and both the complexes showed extensive cleavage of DNA. However, Cu(II) complexes showed better cleavage activity compared to Ni(II) complex

Oxamido binuclear copper (II) complexes: Synthesis, crystal structure, DNA interaction and antibacterial studies

Four binuclear copper (II) complexes Cu(oxpn)Cu(B)2+ (2-5) bridged by N, Nâ²-bis3-(methylamino) propyl oxamide (oxpn), where, B is N, N-donor heterocyclic bases (viz. 2,2â²-bipyridine (bpy, 2), 1,10-phenathroline (phen, 3), dipyrido3,2-d:2â²,3â²-fquinoxaline (dpq, 4) and dipyrido3,2-a:2â²,3â²-cphenazine (dppz, 5) are synthesized, characterized by different spectroscopic and single crystal X-ray data technique. The phen (3) and dpq (4) complexes were structurally characterized by X-ray data analysis. Their DNA binding, oxidative cleavage and antibactirial activities were studied. The dpq (4) and dppz (5) complexes are avid binders to the Calf thymus DNA (CT-DNA). The phen (3), dpq (4) and dppz (5) complexes show efficient oxidative cleavage of supercoiled DNA (SC DNA) through hydroxyl radical (OH) pathway in the presence of Mercaptopropionic acid (MPA). © 2013 Elsevier Ltd. All rights reserved