title: Antibacterial combination therapy using Co3+, Cu2+, Zn2+and Pd2+complexes: Their calf thymus DNA binding studies.
abstract: Four Co(III)-, Cu(II)-, Zn(II)-, and Pd(II)-based potent antibacterial complexes of formula K3[Co(ox)3].3H2O (I), [Cu(bpy)2Cl]Cl.5H2O (II), [Zn(bpy)3]Cl2(III), and [Pd(bpy)2](NO3)2(IV) (where ox is oxalate and bpy is 2,2'-bipyridine) were synthesized. They were characterized by elemental analyses, molar conductance measurements, UV-Vis, FTIR,1H NMR, and13C NMR spectra. These metal complexes were ordered in three combination series of I + II, I + II + III, and I + II + III + IV. Antibacterial activity was tested for each of these four metal complexes and their combinations against Gram-positive and Gram-negative bacteria. All compounds were more potent antibacterial agents against the Gram-negative than those of the Gram-positive bacteria. The four metal complexes showed antibacterial activity in the order I > II > III > IV and the activity of their combinations followed the order of I + II + III + IV > I + II + III > I + II. CT-DNA binding studies of complex I and its three combinations were carried out using UV-vis spectral titration, displacement of ethidium bromide (EB), and electrophoretic mobility assay. The results obtained from UV-vis studies indicated that all series interact effectively with CT-DNA. Fluorescence titration revealed that the complexes quench DNA-EB strongly through the static quenching procedures. The binding constant (Kb), the Stern-Volmer constant (Ksv), and the number of binding sites (n) were determined at different temperatures of 293, 300, and 310 K, respectively. The calculated thermodynamic parameters supported that hydrogen binding and Van der Waals forces play a major role in association of each series of metal complexes with CT-DNA and follow the above-binding affinity order for the series.
authors.affiliation: a Faculty of Science, Department of Chemistry , University of Sistan and Baluchestan , Zahedan , Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Khosravi
authors.affiliation: a Faculty of Science, Department of Chemistry , University of Sistan and Baluchestan , Zahedan , Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Mansouri-Torshizi
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects* / Q000472:pathogenicity; D001665:Binding Sites / Q000187:drug effects; D003035:Cobalt / Q000737:chemistry / Q000494:pharmacology; D056831:Coordination Complexes / Q000737:chemistry* / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000187:drug effects*; D004996:Ethidium / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D010165:Palladium / Q000737:chemistry / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D056831:Coordination Complexes; D003035:Cobalt; D010165:Palladium; D004247:DNA; C427203:calf thymus DNA; D004996:Ethidium; D015032:Zinc
keywords: DNA-binding; antibacterial activity; combination therapy; metal complexes