Synthesis, DNA binding and cleavage activities of copper (II) thiocyanate complex with 4-(N,N-dimethylamino)pyridine and N,N-dimethylformamide.

Two novel copper(II) thiocyanate complexes with 4-(N,N-dimethylamino) pyridine and N,N-dimethylformamide (1) and with 4-(N,N-dimethylamino) pyridine (2) have been synthesized and characterized. The crystal and molecular structures of complexes 1 and 2 were determined by single-crystal X-ray diffraction. Antioxidative activity tests in vitro showed that complex 1 has significant antioxidative activity against hydroxyl free radicals from the Fenton reaction and also oxygen free radicals, which is better than standard antioxidants like vitamin C and mannitol. The interaction of complex 1 with calf thymus DNA was investigated by spectroscopic, cyclic voltammetry, and viscosity measurements. Results suggest that complex 1 can bind to DNA via partial intercalation mode. Moreover, complex 1 has been found to cleavage of plasmid DNA pBR322.

Spectroscopic studies on the interaction between Pr(III) complex of an ofloxacin derivative and bovine serum albumin or DNA.

The binding properties on [PrL2(NO3)](NO3)2 (L=9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperaziny)-7-oxo-7Hpyrido[1,2,3-de]-1,4-benzoxazine-6-carbaldehyde benzoyl hydrazone) to bovine serum albumin (BSA) have been studied for the first time using fluorescence spectroscopy in combination with UV-Vis absorbance spectroscopy. The results showed that [PrL2(NO3)](NO3)2 strongly quenched the intrinsic fluorescence of BSA through a static quenching procedure, and non-radiation energy transfer happened within molecules. The number of binding site was about 1, and the efficiency of Förster energy transfer provided a distance of 4.26 nm between tryptophan and [PrL2(NO3)](NO3)2 binding site. At 288, 298, 310 K, the quenching constants of BSA-[PrL2(NO3)](NO3)2 system were 5.11×10(4), 4.33×10(4) and 3.71×10(4) l M(-1). ΔH, ΔS and ΔG were obtained based on the quenching constants and thermodynamic theory (ΔH<0, ΔS>0 and ΔG<0). These results indicated that hydrophobic and electrostatic interactions are the mainly binding forces in the [PrL2(NO3)](NO3)2-BSA system. In addition, the CD spectra have proved that BSA secondary structure changed in the presence of [PrL2(NO3)](NO3)2 in aqueous solution. Moreover, the interaction between [PrL2(NO3)](NO3)2 and calf thymus DNA (CT DNA) was studied by spectroscopy and viscosity measurements, which showed that the binding mode of the [PrL2(NO3)](NO3)2 with DNA is intercalation. The DNA cleavage results show that in the absence of any reducing agent, the [PrL2(NO3)](NO3)2 can cleave plasmid pBR322 DNA and its hydrolytic mechanism was demonstrated with hydroxyl radical scavengers and singlet oxygen quenchers.

Analysis of binding interaction between bovine serum albumin and the cobalt(II) complex with salicylaldehyde-2-phenylquinoline-4-carboylhydrazone.

The interaction between bovine serum albumin (BSA) and the cobalt(II) complex with salicylaldehyde-2-phenylquinoline-4-carboylhydrazone (Co-SPC) was investigated using fluorescence spectroscopy, UV absorption, and circular dichroism (CD) under simulated physiologic conditions for the first time. Fluorescence data and UV absorption spectra revealed that the intrinsic fluorescence of BSA was strongly quenched by Co-SPC in terms of a static quenching process at a lower concentration of the complex and a combined quenching process at a higher concentration of the complex. Binding constants and binding sites were evaluated. The average binding distance between Co-SPC and BSA was obtained (2.28 nm) on the basis of Förster's theory. The thermodynamic parameters indicated that hydrophobic force played a major role in the binding. The binding of Co-SPC to BSA leads to changes in the conformation of BSA according to synchronous fluorescence spectra and CD data.

Dual-rhodamine urea derivative, a novel chemidosimeter for Hg(II) and its application in imaging Hg(II) in living cells.

The synthesis and spectral properties of a chemidosimeter 1,4-di[2-(6-ethylamino-3-ethylimino-2,7-dimethyl-3H-xanthen-9-yl) benzoic acid (aminomethyl)-3-phenylthiourea] benzene (1) for Hg(II) ions are reported, and it has been demonstrated that 1 can be used as a fluorescent probe for monitoring Hg(II) ions in living cells.

Study on synthesis, structure, and DNA-binding of Ni, Zn complexes with 2-phenylquinoline-4-carboylhydrazide.

2-Phenylquinoline-4-carboylhydrazide (HL), and its novel nickel(II), zinc(II) complexes [M(HL)(2)(L)].2H(2)O.NO(3) (M=Ni (1), M=Zn (2)), have been synthesized and characterized by elemental analysis, molar conductivity, and IR spectra. The crystal structure of [Ni(HL)(2)(L)].2H(2)O.NO(3) obtained from ethanol solution was determined by X-ray diffraction analysis, crystallized in the rhombohedral system, space group R3 , Z=18, a=31.913(3)A, b=31.913(3)A, c=27.709(2)A, alpha=90 degrees , beta=90 degrees , gamma=120 degrees , R(1)=0.0647. The interactions of the complexes and the ligand with calf thymus DNA had been investigated using UV-Vis spectra, fluorescent spectra, CD (circular dichroism) spectra, CV (cyclic voltammetry) and viscosity measurements. These compounds were tested against MFC (mouse forestomach carcinoma) cell lines. The complex 1 showed significant cytotoxic activity against MFC cell lines. The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. Results suggest that the two complexes bound to DNA via a groove binding mode and the complexes can cleave pBR322 DNA.

Synthesis, characterization, antioxidant activity and DNA-binding studies of three rare earth (III) complexes with 1-(4-aminoantipyrine)-3-tosylurea ligand.

1-(4-aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M=Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties of the three complexes have been investigated by UV-vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol.

Spectroscopic studies on binding of 1-phenyl-3-(coumarin-6-yl)sulfonylurea to bovine serum albumin.

The interaction of 1-phenyl-3-(coumarin-6-yl)sulfonylurea (SU22) with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectroscopy combined with UV-absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy techniques under simulative physiological conditions for the first time. Fluorescence data and UV-absorption spectra revealed that the quenching mechanism of fluorescence of BSA by SU22 was a static quenching process and the number of binding sites was about 0.8858; the thermodynamic parameters (DeltaG=-29.23 kJ mol(-1), DeltaH=-47.48 kJ mol(-1), and DeltaS=-61.24 J mol(-1)K(-1)) explained that hydrogen bond and Van der Waals interaction were the main binding force stabilizing the complex. The binding average distance between SU22 and BSA was obtained (3.20 nm) on the basis of the Förster's theory. In addition, The CD spectra and FT-IR spectra have proved that BSA secondary structure changed in the presence of SU22 in aqueous solution.

Synthesis, characterization, antioxidant activity, and DNA-binding studies of 1-cyclohexyl-3-tosylurea and its Nd(III), Eu(III) complexes.

A new ligand, 1-cyclohexyl-3-tosylurea (H(2)L), was prepared by condensation ethyl N-(3-tossulfonyl) carbamate and cyclohexanamine. Its two lanthanide(III) complexes, Ln(H(2)L)(3) . 3NO(3) [Ln=Nd (1), and Eu (2)], have been synthesized and characterized on the base of element analyses, ESI-MS, molar conductivities, IR spectra and thermogravimetry/differential thermal analysis (TG-DTA). In addition, the DNA-binding properties of the ligand and its complexes have been investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic (CD) spectroscopy and viscosity measurements. The experiment results suggest that the ligand and its two complexes bind to DNA via a groove binding mode, and the binding affinity of the complex 2 is higher than that of the complex 1 and the ligand. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the ligand and its metal complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol. In particular, complex 2 displayed excellent activity on the superoxide and hydroxyl radical.

Synthesis, characterization and DNA-binding studies of 1-cyclohexyl-3-tosylurea and its Ni(II), and Cd(II) complexes.

1-Cyclohexyl-3-tosylurea (HL) and its two complexes, ML2.2H2O [M=Ni(1), and Cd(2)], have been synthesized and characterized on the basis of elemental analyses, molar conductivities, IR spectra and thermal analyses. In addition, the DNA-binding properties of the ligand and the two complexes have been investigated by electronic absorption, fluorescence, CD spectroscopy and viscosity measurements. The experiment results suggest that the ligand and its two complexes bind to DNA via a groove binding mode, and the binding affinity of the complex 2 is higher than that of the complex 1 and the ligand.