DNA interaction studies and evaluation of biological activity of homo- and hetero-trihalide mononuclear Cu(II) Schiff base complexes. Quantitative structure-activity relationships
Department of Chemistry, Laboratory of Inorganic Chemistry, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.Journal of inorganic biochemistry (Impact Factor: 3.44). 06/2008; 102(9):1749-64. DOI: 10.1016/j.jinorgbio.2008.05.005
A new series of mixed-ligand mono- or hetero-trihalide Cu(II) complexes of the type [Cu(dienXX)Y(YZ(2))], where dienXX=Schiff dibase of diethylenetriamine with 2-thiophene-carboxaldehyde (dienSS), 2-furaldehyde (dienOO) or 2-pyrrole-2-carboxaldehyde (dienNN), Y=Cl, Br and Z=Br, I was synthesized by the reaction of the precursors of the type [Cu(dienXX)Y]Y with iodine or bromine in 1:1 molar ratio. The distorted square pyramidal configuration of the new homo- and hetero-trihalide Cu(II) mononuclear complexes was identified by C, H, N, Cu analysis, spectroscopic methods (IR, UV-visible), molar conductivity and magnetic measurements. The basal plane consists of three nitrogen atoms of the Schiff base and one halogen (terminal) atom while another axially located trihalogen moiety occupies the fifth side of the square pyramid as a YZ(2) entity, adopting an almost linear configuration. The equilibrium geometry of these complexes was further corroborated by theoretical studies at the B3LYP/DGDZVP level. A series of quantum chemical descriptors (e.g. SOMO (singly occupied molecular orbital) LUMO (lowest occupied molecular orbital), SOMO and LUMO energies, SOMO-LUMO gap, dipole moment, polarizability, molar volume, etc.) have been utilized in order to deduce quantitative structure-activity relationships (QSARs). The effect of the new compounds on the single stranded (ss), double stranded (ds) and pDNA led either to the formation of a DNA-complex cationic adduct, or to its degradation, evidenced by DNA electrophoretic mobility and DNA interaction spectroscopic titration studies. Moreover, the antimicrobial activity of Cu(II) complexes against Gram(+) and Gram(-) bacteria can be attributed to the synergistic action of the dissociation species, namely the cationic [Cu(dienXX)Y](+) and anionic [YZ(2)](-) ones. Finally, de Novo linear regression analysis correlating the bioactivity of these complexes with their structural substituents has been carried out, leading to some interesting qualitative observations/conclusions.
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ABSTRACT: Interaction of chiral Ru(II) salen complexes (S)-1 and (R)-1 with Calf Thymus DNA (CT-DNA) was studied by absorption spectroscopy, competitive binding study, viscosity measurements, CD measurements, thermal denaturation study and cleavage studies by agarose gel electrophoresis. The DNA binding affinity of (S)-1 (6.25 x 10(3)M(-1)) was found to be greater than (R)-1 (3.0 x 10(3)M(-1)). The antimicrobial studies of these complexes on five different gram (+)/(-) bacteria and three different fungal organisms showed selective inhibition of the growth of gram (+) bacteria and were not affective against gram (-) and fungal organisms. Further, the (S)-1 enantiomer inhibited the growth of organisms to a greater extent as compared to (R)-1 enantiomer.Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2009; 74(1):113-9. DOI:10.1016/j.saa.2009.05.016 · 2.35 Impact Factor
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ABSTRACT: A series of mixed-ligand neutral nickel(II) complexes of the general formula [Ni(i-MNT)(2a-5mt)(2)] (1), [Ni(i-MNT)(2a-2tzn)(2)] (2) and [Ni(i-MNT)(Im)(2)] (3), [where i-MNT(2-)=the dianion of 1,1-dicyano-2,2-ethylenedithiolate, 2a-5mt=2-amino-5-methyl thiazole, 2a-2tzn=2-amino-2-thiazoline and Im=imidazole] were prepared and characterized with elemental analyses, spectroscopic (IR, UV-vis) methods, magnetic susceptibility, molar conductivity and cyclic voltammetry measurements. The magnetic data, the electronic spectra and the electrical conductivity measurements indicated mononuclear neutral complexes with square-planar geometry. The X-ray analysis of [Ni(i-MNT)(2a-5mt)(2)] shows the nickel atom being fourfold coordinated with the two sulfur atoms of the dithiolate (i-MNT) ligand and the endocyclic nitrogen atoms from the two 2a-5mt ring giving rise to a slightly distorted square-planar arrangement. The cyclic voltammograms of the complexes have been recorded and the corresponding redox potentials have been estimated. The DNA-binding studies of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. Both studies have shown that the complexes can bind to CT-DNA by the intercalative and the electrostatic binding mode. Competitive binding studies with ethidium bromide (EB) with fluorescence spectroscopy have also 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.Bioorganic & medicinal chemistry 07/2009; 17(16):6054-62. DOI:10.1016/j.bmc.2009.06.058 · 2.79 Impact Factor
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ABSTRACT: Two chiral dimeric CuII Schiff base complexes, Na2[Cu(S-lys)2·(H2O)2]·(ClO4)2 (1) and [Cu(S-ornH)2·(H2O)2]·(ClO4)2 (2) have been prepared by an easy one-pot method in which the L-lysine and L-ornithine-based Schiff base ligands are generated in situ. These complexes have been characterized by various spectroscopic techniques and single-crystal X-ray diffraction. The molecular structures show that both complexes are indeed dimeric with CuII centers that are phenolate-bridged. Variable-temperature magnetic analysis revealed that a strong antiferromagnetic coupling interaction was mediated through the phenolate bridge between the two CuII centers. Since these compounds were highly soluble in water, we explored carboxylate sensing capability through colorimetric indicator displacement assays (IDAs). By using pyrocatechol violet (PV) as a displaceable colorimetric indicator, citrate ion selectivity was demonstrated in 100 % water solution in the physiological pH range.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)Berichte der deutschen chemischen Gesellschaft 08/2009; 2009(22):3266 - 3274. DOI:10.1002/ejic.200900357 · 2.94 Impact Factor
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