The Interaction of Cobalt (Ⅲ) Mixed-Ligand Coordination Compound Containing Dipyrido[3,2-a:2′,3′-c] phenazine With Calf Thymus DNA -

The binding of Co (phen)2dppz3+ to calf thymus DNA,as investigated using absorption spectroscopy. viscosity and electrophoresis measurements,here dppz is dipyrido[3, 2-a: 2'3'-c]phenazine. The compound shows absorption hypochromicity and the specific viscosity increased upon binding to calf thymus DNA The complex is also shown to be more efficient photosensitisers for single strand breaks in plasmid DNA

Ruthenium Coordination Compounds with Polypyridines(Ⅵ)--Interaction of Ruthenium Polypyridine Complexes with Calf Thymus DNA-An Example of Non-intercalative Binding

Two new ruthenium polypyridine complexes, L 2RuL 2+ (L represents 2,2 bipyridine(bpy) or 1,10 phenanthroline(phen); L represents Schiff base derived from 4,5 diazafluoren 9 one(AFO) and n propylamine) have been prepared and characterized by means of elementary analyses, electronic absorption and IR spectra. The binding of the complexes to calf thymus DNA has been investigated via absorption, emission spectrometry, emission quenching, equilibrium dialysis and circular dichroism spectrometry. The experimental results show that these two complexes bind to calf thymus DNA by electrostatic mode and by non intercalative binding mode respectively.

Flow-injection Chemiluminescence Determination of Trace Calf Thymus DNA

A flow injection procedure for the determination of calf thymus DMA （CT DNA） over the range 2.1x10-6;.1x10-1 B.g mL-1 is described, based on measurement of the enhanced chemiluminescence emission of rhodamine B-Ce（IV） system, activated by imidazole-HCl buffer solution. This method is highly sensitive, with the linearity range broadened to five orders of magnitude. It has been applied to determine CT DNA in synthetic sample with satisfactory results.

Luminescence Studies on Interaction of an Isoquinoline Alkaloid with Calf Thymus DNA in Aqueous Medium and on Solid Substrate

The interaction of calf thymus DNA（ctDNA） with berberine（Ber） was systematically investigated via UV-Vis,fluorescence and phosphorescence spectroscopies in aqueous solution and on solid substrate.The very weak fluorescence intensity of Ber at 525 nm in aqueous solution can be greatly enhanced by ctDNA.The UV-Vis spectrum shows that Ber could bind with DNA by intercalation.In addition,strong fluorescence of Ber alone could be observed on filter paper substrate and can be quenched by ctDNA effectively,and the increase of fluorescence polarization of Ber on the filter paper implies the intercalation binding.Ber emits phosphorescence at 619 nm in the presence of thallium（I） acetate.The lifetime of Ber increased from 38.4 ms to 43.4 ms with the increase of ctDNA.The increase of lifetime is possibly attributed to the increase of rigidity of Ber after its intercalating into the ctDNA base pairs.This explanation is also augmented by the anionic quenching results.Ber behaves as a typical intercalating agent into ctDNA.The intrinsic binding constant between Ber and ctDNA is（1.84±0.12）×10^4 L/mol and n=0.16.

Synthesis, Characterization, Spectroscopic Properties of 2-(4-Dimethylaminophenyl)-5-fluoro-6-(morpholin-4-yl)-1H-benzimidazole and its Interaction with Calf Thymus DNA

Dimethylaminophenyl)-5-fluoro-6-(morpholin-4-yl)-1H-benzimidazole(1) has been synthesized and characterized by H-NMR, MS and elemental analysis. UV-Vis spectra of the 1 aqueous solutions at different pH values reveal that compound 1 can combine three protons. Its three protonation constants are determined by spectrophotometry and calculated by non-linear least squares. The results of steady-state fluorescence measurements indicate that a special interaction occurs between compound 1 and calf thymus DNA, of which the binding constant, Kb, is (2.30 ± 0.10)×l04 L/mol. Compound 1 in the concentration range of 10-8 to 1.2×10-6 mol/L could be used for quantitative determination of DNA.

Design,synthesis,and biological evaluation of novel benzimidazole derivatives and their interaction with calf thymus DNA and synergistic effects with clinical drugs

A series of new benzimidazole derivatives was synthesized and characterized by IR,1H NMR,13C NMR,MS,and HRMS spectra.All the new compounds were screened for their antimicrobial activities in vitro by a twofold serial dilution technique.The bioactive evaluation showed that 3,5-bis(trifluoromethyl)phenyl benzimidazoles were comparably or even more strongly antibacterial and antifungal than the reference drugs Chloromycin,Norfloxacin,and Fluconazole.The combination of2,4-difluorobenzyl benzimidazole derivative 5l and its hydrochloride 7 respectively with the antibacterials Chloromycin,Norfloxacin,and the antifungal Fluconazole was more sensitive to methicillin-resistant MRSA and Fluconazole-insensitive A.flavus.In addition,the interaction of compound 5l with calf thymus DNA demonstrated that this compound could effectively intercalate into DNA to form a compound 5l-DNA complex that might block DNA replication and thereby exert good antimicrobial activity.

Novel benzimidazole derived naphthalimide triazoles: synthesis, antimicrobial activity and interactions with calf thymus DNA

A novel series of benzimidazole derived naphthalimide triazoles and some corresponding triazoliums have been successfully synthesized and characterized by 1H NMR, 13 C NMR, 1H-1H COSY, IR and HRMS spectra. All the new compounds were screened for their antimicrobial activities in vitro by two-fold serial dilution. 2-Chlorobenzyl triazolium 8g and compound 9b with octyl group exhibited the best antibacterial activities among all the tested compounds, especially against S. aureus with inhibitory concentration of 2 μg/mL which was equipotent potency to Norfloxacin(MIC=2 μg/mL) and more active than Chloromycin(MIC=7 μg/mL). Triazoliums 8g and 8f bearing 3-fluorobenzyl moiety displayed the best antifungal activities(MIC=2-19 μg/mL) against all the tested fungal strains without being toxic to PC12 cell line within concentration of 128 μg/m L. Further investigations by fluorescence and UV-Vis spectroscopic methods revealed that the compound 8g could effectively intercalate into calf thymus DNA to form the 8g-DNA complex which could block DNA replication, exerting powerful antimicrobial activities.

Absorption, Fluorescence and Resonance Rayleigh Scattering Spectra of Interaction of Papain with Calf Thymus DNA

In weak acidic medium, interaction between papain and calf thymus DNA （ctDNA） resulted in absorption spectral change, fluorescence quenching of papain and remarkable enhancement of resonance Rayleigh scattering （RRS） The interaction types and binding modes were discussed by characteristics of RRS, absorption, fluorescence and circular dichroism spectra combining thermodynamic data. Four interaction types include electrostatic attraction, hydrophobic force, hydrogen bonding and aromatic stacking interaction. Papain interacted with the major groove of ctDNA. Aromatic stacking interaction is the main reason of change of absorption spectrum and fluorescence quenching of papain. Surface enhanced scattering effect, resonance energy transfer effect, increase of molecular volume and conformational change make contribution to RRS enhancement. The enhanced RRS intensity （△I） is directly proportional to the concentration of ctDNA or papain, The detection limit （3σ） is 5.2 ng·omL^-1 for ctDNA and 5.6 ng·mL-1 for papain. This creates conditions for determination of papain and ctDNA.

Interaction between Mitomycin C and DNA at Paraffined Graphite Electrode

Aim To investigate the electrochemical behaviors of Mitomycin C （MC） and its interaction with calf thymus DNA （ctDNA）. Methods The cyclic vohammetry （CV） was carried out at a paraffined graphite electrode. Results MC showed a well-defined oxidation-reduction peak. As a result of reaction with ctDNA, the peak current of MC decreased apparently. According to corresponding electrochemical equations, the diffusion coefficient of both free and MC-DNA complex have been determined, and the heterogeneous rate constants were also obtained simultaneously. Conclusion The solid paraffined graphite electrode could be used to estimate parameters of the interaction between DNA and MC, and provide the convenient and sensitive analysis.

Syntheses, Crystal Structures and DNA-binding Properties of Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) Compounds Containing Thiazole Derivatives

Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) compounds(1～3) based on 2-(2-pyridyl)benzothiazole(bpt) and terephthalic acid(PTA) were synthesized. The crystal structures of [Zn(bpt)(PTA)2](1), [Ni(bpt)(PTA)2](2), and [Co(bpt)(PTA)2](3) have been determined by single-crystal X-ray diffraction analysis, which shows that all the three complexes belong to monoclinic system with space group P21/c. Time-dependent density functional theory(TD-DFT) calculation is performed on a reference structure of compound 3. The excited electrons mainly localized at the π* of ligand 2-(2-pyridyl)benzothiazole, which will be convenient for them to bind with the DNA reacting sites. Fluorescence spectroscopy, ultraviolet(UV) spectroscopy and viscosity were used to characterize the interaction of the compounds with Calf thymus DNA(CT-DNA). The results indicate that compounds 1～3 bind to CT-DNA and have a strong interaction with DNA. The compounds can probably bind to CT-DNA via a non-intercalative mode as concluded by studying the viscosity of a DNA solution in the presence of the compounds. This combination can effectively break DNA, which speculates that these three compounds may interact with the cancer cell DNA in this binding mode, thereby damaging the cancer cells.

DNA Nano-netting Intertexture on Carbon Electrodes

Native calf thymus double stranded DNA (ct-dsDNA) is successfully immobilized from solution onto carbon substrates by covalent linkages under an optimized deposition potential of 1 .8±0.3 V vs. 50 mmol/L NaCl-Ag/AgCl. The long chain DNA fabricates a layer of well conductive nano-netting intertexture, which is stable in pH 14 alkaline solution and in boiling water. The ct-dsDNA modified carbon fiber disk electrode shows two to three orders of magnitude enlarged electrode effective surface area and similarly enlarged voltammetric responses to Co(phen)33+ and dopamine. Thermal dissociated single stranded ct-DNA can also lead to similar result. This modified electrode will find wide applications in the fields of DNA-based electrochemical biosensors.

Studies on a Novel Minor-groove Targeting Artificial Nuclease:Synthesis and DNA Binding Behavior

Nucleases play an important role in molecular biology, for example, in DNA sequencing. Synthetic polyamide conjugates can be considered as a novel tool for the selective inhibition of gene expressions and also as potential drugs in anticancer or antiviral chemotherapy. In this article, the synthesis of a novel minor-groove targeting artificial nuclease, an oligopyrrol-containing compound, has been reported. It was found that this novel compound can bind DNA in AT-rich minor groove with high affinity and site specificity. DNA binding behavior was determined by using UV-Vis and CD. It is indicated that compound 6 can enhance the Tm, of DNA from 80.4 ℃ to 84. 4 ℃ and that it possesses a high binding constant value（Kb =3.05 × 10^4 L/mol）.

Preliminary Study on Cordycepin-DNA Interaction by Raman Spectroscopy

The interaction of cordycepin with calf thymus DNA was investigated at physiological pH with drug/DNA molar ratio of 8. The Raman spectroscopy results indicated that the intercalation of high concentration cordycepin and the interaction of cordycepin with PO2 group led to a major reduction of B-form DNA structure in favor of A-form DNA.

Electrochemical,spectroscopic,and molecular docking studies of the interaction between the anti-retroviral drug indinavir and dsDNA

In this study,an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid(ctdsDNA)for the first time.The decrease in the oxidation signals of deoxyguanosine(dGuo)and deoxyadenosine(dAdo),measured by differential pulse voltammetry,upon incubation with different concentrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA.The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0 e10.0 mg/mL.The limit of detection and limit of quantification for indinavir were 0.29 and 0.98 mg/mL,respectively,based on the dGuo signal,and 0.23 and 0.78 mg/mL,respectively,based on the dAdo signal.To gain further insights into the interaction mechanism between indinavir and ct-dsDNA,spectroscopic measurements and molecular docking simulations were performed.The binding constant(Kb)between indinavir and ct-dsDNA was calculated to be 1.64108 M1,based on spectrofluorometric measurements.The obtained results can offer insights into the inhibitory activity of indinavir,which could help to broaden its applications.That is,indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.

Studies on the Interaction of Cobalt Mixed-Ligand Coordination Compound Containing Tetrapyrido [3,2-a:2′,3′-c:3″, 2″-h:2■,3■-j] phenazine with DNA

A new monometallic complex [Co(phen)_2tpphz]^(3+) (where tpphz is tetrapyrido [3,2-a:2′,3′-c:3″,2″-h:2′″,3′″-j] phenazine) was synthesized by the reaction of 5, 6-diamino-1,10-phenanthroline with [Co(phen)_2(phendione)]^(3+). It was characterized by elemental analysis, molar conductivity, IR, ~1H NMR, ultraviolet and fluorescence spectroscopy. The interaction of the complex with DNA was also investigated. The complex shows the absorption hypochromicity, fluorescence enhancement, the specific viscosity increased when bound to calf thymus DNA. The cyclic voltammetry (CV) measurement showed a change in peak current with the addition of DNA. All the results provide the support for the intercalative binding mode of the mononuclear complex.

Synthesis,Crystal Structure and Interaction with DNA of a Novel Chromium(Ⅲ) Complex Containing Salicylaldehyde Semicarbazone

The novel chromium（Ⅲ） complex with salicylaldehyde semicarbazone was synthesized and characterized by IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space group Pbca with a = 8.9849（13）, b = 12.0475（16）, c = 34.522（5）A, V = 3736.9（9）A3, Z = 8, C16H18C1CrN6O5, Mr= 461.81, De= 1.642 g/cm^3, F（000） = 1896,A（MoKα） = 0.799 mm^-1, the final R = 0.0370 and wR = 0.0827 for 2908 observed reflections with I 〉 2σ（I）. The interaction between the chromium（Ⅲ） complex with calf thymus DNA （Ct-DNA） has been investigated by absorption spectroscopy, fluorescence spectroscopy and viscosity measurements. The results indicated that the complex was bonded to Ct-DNA through a non-classical intercalative mode.

Coumarin-derived azolyl ethanols:synthesis,antimicrobial evaluation and preliminary action mechanism

A series of coumarin-derived azolyl ethanols including imidazolyl,triazolyl,tetrazolyl,benzotriazolyl,thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR,~1H NMR,^(13)C NMR and high-resolution mass spectra(HRMS) spectra.Some of the prepared compounds showed appropriate logP_(ow) values and effective antibacterial and antifungal activities.Noticeably,compound 14 with bis-triazolyl ethanol group exhibited low minimal inhibitory concentration(MIC)value of 8 μg/mL against MRSA,which was comparable or even superior to reference drugs Norfloxacin(MIC=8μg/mL)and Chloramphenicol(MIC=16μg/mL).It could also effectively inhibit the growth of the tested fungal strains compared to Fluconazole.Further binding studies of coumarin 14 with calf thymus DNA were investigated by UV-Vis absorption and fluorescence spectroscopy.It was found that compound 14 could interact with calf thymus DNA by groove binding to form14-DNA complex via both hydrogen bonds and van der Waals force,which might be the factor to exert the powerful antimicrobial activity.

Binding studies of DNA with Co(Ⅲ) coordination compound

The binding of Co(bpy)2dppz3+ to calf thymus DNA was investigated by using absorption and emission spectroscopy,DNA melting techniques,cyclic voltammetry,viscosity and electro-phoresis measurements,where bpy is 2,2'-bipyridyl,dppz is dipyrido[3,2-o:2',3'-c] phenazine.The binding compound shows absorption hypochromicity,fluorescence enhancement,and increasing of DNA melting temperature and the specific viscosity.CV measurement shows the shifts in oxidation-reduction potential and change in peak current with addition of DNA.The compound is also shown to be more efficient photosensitisers for strand breaks in plasmid DNA.

Fabrication of poly(2,6-pyridinedicarboxylic acid)/MWNTs modified electrode for simultaneous determination of guanine and adenine in DNA

The fabrication of poly（2,6-pyridinedicarboxylic acid）/MWNTs modified glass electrode（PPDA/MWNTs/GCE） was proposed and used for individual or simultaneous determination of guanine and adenine.The performances of the PPDA/MWNTs/GCE were characterized with cyclic voltammetry（CV）.The modified electrode exhibited enhanced electrocatalytic behavior and good stability for the detection of guanine and adenine.Differential pulse voltammetry（DPV） was used to determine the concentration of guanine,adenine.The detection limit（S/N = 3） for guanine and adenine was 0.045μmol/L and 0.05μmol/L,respectively.The electrochemical method for the measurement of guanine and adenine in calf thymus DNA was also developed with this modified electrode and the result was satisfactory.

Chalcone-Benzotriazole Conjugates as New Potential Antimicrobial Agents： Design, Synthesis, Biological Evaluation and Synergism with Clinical Drugs

A series of chalcone-benzotriazole conjugates as new potential antimicrobial agents were synthesized and char- acterized by ^1H NMR, ^13C NMR, IR and HRMS spectra. Antimicrobial assay manifested that some target com- pounds gave moderate to good antibacterial and antifungal activities. The N- 1 derived benzotriazole 5e and N-2 de- rived benzotriazole 6a exhibited valuable inhibitory efficacy against some tested strains. Especially, derivative 6a gave superior antifungal efficacies against C. utilis, S. cerevisiae and A. flavus （MIC^0.01, 0.02, 0.02 gmol/mL, respectively） to Fluconazole. The drug combination of compound 5e or 6a with antibacterial Chloromycin, Nor- floxacin and antifungal Fluconazole respectively showed stronger antimicrobial efficiency with less dosage and broader antimicrobial spectrum than their separated use alone. The preliminary interaction with calf thymus DNA revealed that compound 6a could intercalate into DNA to form 6a-DNA supramolecular complex which might be a factor to exert its powerful bioactivity. Molecular docking study indicated strong binding of compound 6a with DNA gyrase. The structural parameters such as molecular orbital energy and molecular electrostatic potential of compound 6a were also investigated, which provided better understanding for its good antimicrobial activity.