title: DNA studies of newly synthesized heteroleptic platinum(II) complexes [Pt(bpy)(iip)](2+) and [Pt(bpy)(miip)](2.).
abstract: Two new mono-nuclear heteroleptic platinum(II) complexes, [Pt(bpy)(iip)](PF6)2 (1) and [Pt(bpy)(miip)](PF6)2·2H2O (2) (bpy is 2,2'-bipyridine; iip is 2-(imidazo-4-yl)-1H-imidazo[4,5-f] [1,10] phenanthroline; miip is 2-(1-methylimidazo-2-yl)-1H-imidazo[4,5-f] [1, 10] phenanthroline), have been synthesized and fully characterized by CHN analysis, electrospray ionization and MALDI-TOF mass spectrometry, (1)H NMR, FT-IR (ATR), and UV-Vis spectrophotometer. Cytotoxicity, ability to inhibit DNA transcription and DNAse activity of the complexes were studied. The DNA-binding behaviors of both complexes have also been studied by spectroscopic methods, cyclic voltammetry and viscosity measurements. Both complexes showed cytotoxic properties and 2 was more cytotoxic than 1. DNA transcription was inhibited upon increasing concentrations of both complexes. The complex 2 was found to be a better inhibitor than 1. The same pattern can be seen in the DNAse profile of the complexes. In addition, 2 was found to promote cleavage of pBR322 DNA at a lower concentration than 1. The spectroscopic, electrochemical and viscometric results indicate that both complexes show some degree of binding to DNA in an intercalative mode, resulting in intrinsic binding constants K b = 3.55 ± 0.6 × 10(4) M(-1) and 7.01 ± 0.9 × 10(4) M(-1) for 1 and 2, respectively. The difference in the DNA-binding affinities of 1 and 2 may presumably be explained by the methylated imidazole nitrogen atom that makes the compound more hydrophobic and gives better intercalative binding ability to DNA's hydrophobic environment.
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Bulent Ecevit University, 67100, Zonguldak, Turkey. burakcoban@yahoo.com.
authors.forename: Burak
authors.initials: B
authors.lastname: Coban
authors.affiliation: Department of Immunology, Faculty of Medicine, Bulent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Ishak Ozel
authors.initials: IO
authors.lastname: Tekin
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Bulent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Abdurrahman
authors.initials: A
authors.lastname: Sengul
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Bulent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Yildiz
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Bulent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Izzet
authors.initials: I
authors.lastname: Kocak
authors.affiliation: Department of Immunology, Faculty of Medicine, Bulent Ecevit University, 67100, Zonguldak, Turkey.
authors.forename: Nergis
authors.initials: N
authors.lastname: Sevinc
mesh_terms: D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D017671:Platinum Compounds / Q000737:chemistry*; D066244:Proton Magnetic Resonance Spectroscopy; D021241:Spectrometry, Mass, Electrospray Ionization; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008024:Ligands; D017671:Platinum Compounds; D004247:DNA
keywords: Cytotoxicity; DNA binding; Platinum; Polypyridyl ligand; Transcription inhibition