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.

Chemical and photo-induced nuclease activity of a novel minor groove DNA binder Cu(II) complex

“…An oxidative mechanism is the major way for DNA cleavage by copper complexes. [35][36][37] In an oxidative DNA cleavage mechanism, the formation of a reactive hydroxyl radical ( • OH), a superoxide anion radical ( • O 2 -), and/or a singlet oxygen species ( 1 O 2 ), or a peroxide radical ( • O 2 -2 ) may lead to damage to the base or/and sugar of DNA. To specify which reactive oxygen species (ROS) was responsible for the DNA cleavage, the DNA cleavage reactions of the complex were performed in the presence of ROS scavengers, such as DMSO, NaN 3 , KI, and t-BuOH (D 2 O, Fig.…”

DNA binding and in vitro anticancer activity of 2‐((1H‐benzimidazol‐2‐yl)methylamino)acetic acid and its copper(II) mixed‐polypyridyl complexes: Synthesis and crystal structure

“…K b for complexes 1 – 6 were 0.24 × 10 3 , 2.94 × 10 3 , 5.55 × 10 3 , 9.99 × 10 3 , 4.34 × 10 3 and 0.33 × 10 3 M −1 , respectively. These behaviours may arise from the electron‐donating characteristics of the methyl group on the bipyridine, which can improve stacking between the substituted compound and CT‐DNA bases in the binding sites . Enhancement of base stacking interactions between the ligand and the π‐system of the CT‐DNA bases may result from the substituent‐induced changes in electron density distribution in the bipyridyl ring.…”

Novel 3‐Hydroxy‐2‐naphthoic hydrazone and Ni(II), Co(II) and Cu(II) Complexes: Synthesis, Spectroscopic Characterization, Antimicrobial, DNA Cleavage and Computational Studies

“…Solutions of calf thymus DNA (CT‐DNA, purchased from Sigma) in 50 mM ammonium acetate (pH 7.5) had a UV–Vis absorbance ratio of 1.8–1.9: 1 at 260 and 280 nm (A 260 /A 280 = 1.9), indicating that the DNA was sufficiently free of protein. The concentration of the DNA was determined spectrophotometrically, using a molar absorptivity of 6600 M −1 cm −1 (260 nm) . Double‐distilled water was used to prepare buffers.…”

“…The absorption titrations was done according to literature procedure . The ligand and complexes (about 1 mmol) were dissolved in a minimum amount of DMSO (0.5 ml), and were then diluted in buffer (5 mM ammonium acetate, pH 7.5), to a final concentration of 20 μM.…”

“…Gel electrophoresis experiments were performed according to reported procedure, using pBR322 negatively supercoiled plasmid DNA on 1% agarose gels, by using a tris–borate–EDTA‐running buffer solution. Reaction mixtures (10 μL) containing 0.1 μg of pBR322, together with different amounts of the complexes (1, 10, 100 μM) were prepared in 50‐mM ammonium acetate buffer, pH 7.5 at 0 °C, and then allowed to incubate at 36 °C for 1 hr, in the dark, then in the presence of peroxide solution.…”