Calf Thymus DNA Research Articles

Synthesis, characterisation, and in vitro antiparasitic activity of new flavanoidal tetrazinan-6′-ones and their binding study with calf thymus DNA using molecular modelling and spectroscopic techniques

With the developing resistance to traditional antiparasitic medications, the purpose of this study was to efficiently develop a series of six noble flavanoidal tetrazinane-6′-one derivatives by a one-pot reaction pathway. FT-IR, 1HNMR, 13CNMR, and Mass spectra were employed for the structural elucidation of the synthesized compounds (7–12). Clinostomum complanatum, a parasite infection model that has been well-established, demonstrated that all the synthesized compounds are potent antiparasitic agents. DNA is the main target for various medicinal compounds. As a result, thestudy of how small molecules attach to DNA has received a lot of attention. In the present study, we have performed various biophysical techniques to determine the mode of binding of synthesized compounds (7–12) with calf thymus DNA (ct-DNA). It was observed from the UV–visible absorbance and fluorescence spectra that all synthesized compounds (7–12) form complexes with the ct-DNA. The value of binding constant (Kb) was obtained to be in the range of 4.36–––24.50 × 103 M - 1 at 298 K. Competitive displacement assay with ethidium bromide (EB), CD spectral analysis, viscosity measurements, and in silico molecular docking confirmed that ligands (7–12) incorporate with ct-DNA through groove binding only. Molecular docking studies were performed for all synthesized compounds with the calf thymus DNA and it was found that all the newly synthesized compounds strongly bind with the chain B of DNA in the minor groove with the value of binding energy in the range of −8.54 to −9.04 kcal per mole and several hydrogen bonding interactions.

Multifunctional Ln2 compounds with butterfly-shaped structures: Remarkable Single-Molecule Magnet behaviors, and biological activities

The efficient design and reasonable construction of multifunctional Ln(III)-based compounds with fascinating structures have always attracted great concern, and it is also an immense challenge in recent times for chemists and materials scientists. Herein, two new binuclear Ln(III)-based compounds with molecular formula [Ln2L2(dbm)2(CH3OH)2]·xCH3OH·yCHCl3 (LnIII = Tb (1), x =2, y = 0; LnIII = Dy (2), x =0, y = 2; H2L = (E)-N'-(5-bromo-2-hydroxy-3-methoxybenzylidene)nicotinohydrazide; and Hdbm = 1,3-diphenyl-1,3-propanedione) have been constructed by a polydentate Schiff base ligand (H2L) via solvothermal method. The structures, magnet behaviors, and biological activities of compounds 1 and 2 have been studied systematically. Structure studies suggest that the two Ln2 compounds 1 and 2 are isostructural and possess butterfly-shaped molecular structures. Magnetic studies exhibit that Dy2 compound 2 shows remarkable single-molecule magnet behavior under zero-field conditions with Ueff/kB = 55.91 K and τ0 = 4.02×10−7 s. Moreover, solid-state fluorescent properties research shows that the two Ln2 compounds display the characteristic Tb3+ and Dy3+ ions luminescence at room temperature. Furthermore, biological activities research reveal that the two Ln2 compounds have better antibacterial activities against four common types of bacteria (Escherichia coli, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) than the polydentate Schiff base ligand (H2L) and β-diketo salts Ln(dbm)3⋅2H2O (Ln(III) = TbIII and DyIII). The interaction between Ln2 compounds (1 and 2) and calf thymus DNA have also been studied, and the result reveal that both Tb2 and Dy2 compounds were mainly intercalated with calf thymus DNA. To our knowledge, compounds 1 and 2 are rarely reported multifunctional Ln(III)-based compounds owning single-molecule magnet behavior, fluorescent properties, and biological activities simultaneously.

Competitive Binding of Methylene Blue to Calf Thymus DNA and Carrageenan: Implications for Sensor Development

Carrageenans are sulfated polysaccharides widely used in the food industry due to their excellent thickening, stabilising, and gelling properties. Objective: This study delves into two key aspects: 1) the binding interaction between the cationic dye methylene blue (MB) and carrageenan compared to other polyanions (alginate, starch, and Arabic gum), and 2) the competitive binding behavior of carrageenan and DNA for MB. Methods: Spectroscopy methods were employed to determine the total amount of carrageenan by utilising MB, which creates complexes with carrageenan. The investigation into the competitive binding between polysaccharides and double-stranded DNA modified with screen-printed electrodes (SPEs) (dsDNA/SPE) for methylene blue (MB) involved the addition of varying quantities of polysaccharide to a solution containing 100 µM MB after a 5-minute accumulation period. Subsequently, cyclic voltammograms were directly recorded to analyse the interactions. Results: Strong electrostatic binding between MB and carrageenan was confirmed using various techniques, including UV-vis, fluorescence, and cyclic voltammetry. Moreover, photoluminescence (PL) spectroscopy was more sensitive than Ultraviolet-visible (UV-vis) spectroscopy, detecting carrageenans in a linear range from 0.5-15 ppm, 2-15 ppm, with correlation coefficients 0.998, 0.997, respectively. Notably, the preference for binding increased with increasing sulfate content, following the order kappa > iota > lambda carrageenan, highlighting the crucial role of sulfate groups in complex formation. Additionally, carrageenan exhibited the strongest competitive binding towards MB at low concentrations compared to other tested polyanions, implying its effectiveness in hindering MB-DNA interactions. Conclusions: These findings pave the way for exciting developments in DNA biosensors. The sensitive colorimetric assay holds promise for the rapid and selective determination of carrageenan levels in food products. Moreover, the competitive binding between carrageenan and MB can be harnessed in DNA biosensors by monitoring changes in MB binding due to specific DNA sequences.

Development of a targeted method for DNA adductome and its application as sensitive biomarkers of ambient air pollution exposure

DNA adducts are widely recognized as biomarkers of exposure to environmental carcinogens and associated health effects in toxicological and epidemiological studies. This study presents a targeted and sensitive method for comprehensive DNA adductome analysis using ultra-high-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). The method was developed using calf thymus DNA, with careful optimization of mass spectrometric parameters, chromatographic separation conditions, and pretreatment methods. Ultimately, a targeted method was established for 41 DNA adducts, which showed good linearity (R2 ≥0.992), recovery (80.1–119.4 %), accuracy (81.3–117.8 %), and precision (relative standard deviation <14.2 %). The established method was employed to analyze DNA adducts in peripheral blood cells from pregnant women in Shanxi and Beijing. Up to 23 DNA adducts were successfully detected in samples of varying sizes. From 2 μg of maternal DNA samples, seven specific adducts were identified: 5-methyl-2'-deoxycytidine (5-MedC), 5-hydroxymethyl-2'-deoxycytidine (5-HmdC), N6-methyl-2'-deoxyadenosine (N6-MedA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), 5-hydroxy-2'-deoxycytidine (5-OHdC), 1,N6-etheno-2'-deoxyadenosine (1,N6-εdA), and N2-methyl-2'-deoxyguanosine (N2-MedG). This study reveals that exposure to higher concentrations of ambient air pollutants may elevate the levels of DNA methylation and oxidative damage at different base sites, highlighting the application potential of DNA adducts as sensitive biomarkers of air pollution exposure.

Elucidating the Interaction of Indole-3-Propionic Acid and Calf Thymus DNA: Multispectroscopic and Computational Modeling Approaches.

Indole-3-propionic acid (IPA) is a plant growth regulator with good specificity and long action. IPA may be harmful to human health because of its accumulation in vegetables and fruits. Therefore, in this study, the properties of the interaction between calf thymus DNA (ctDNA) and IPA were systematically explored using multispectroscopic and computational modeling approaches. Analysis of fluorescence spectra showed that IPA binding to ctDNA to spontaneously form a complex was mainly driven by hydrogen bonds and hydrophobic interaction. DNA melting analysis, viscosity analysis, DNA cleavage study, and circular dichroism measurement revealed the groove binding of IPA to ctDNA and showed that the binding did not significantly change ctDNA confirmation. Furthermore, molecular docking found that IPA attached in the A-T rich minor groove region of the DNA. Molecular dynamics simulation showed that DNA and IPA formed a stable complex and IPA caused slight fluctuations for the residues at the binding site. Gel electrophoresis experiments showed that IPA did not significantly disrupt the DNA structure. These findings may provide useful information on the potential toxicological effects and environmental risk assessments of IPA residue in food at the molecular level.

Synthesis, characterization and biological applications of substituted indolo[2,1-b]quinazolin-12(6H)-one based rhenium(I) organometallic compounds.

The Re(I) organometallic compounds [(Re(CO)3L1-6 )Cl], where Ligand(L) = Tryptanthrin derivatives were prepared and characterized by various spectroscopic techniques. To assess the binding capacities and binding manner, tests of Calf thymus DNA under the impact of organometallic complexes were conducted using absorption titration and viscosity measuring techniques. Data from the research mentioned above point to an intercalation type of binding, which was verified by the docking study. Swiss ADME tools carried out an ADME study. The work focuses on computing the molecular orbital energies for the synthesized compounds using the density functional theory (DFT). The compounds were tested against the MCF-7 cell line to determine their anticancer effects. It was observed that their IC50 values were equivalent to those of the standard medication, indicating that they had a similar antiproliferative impact.

Rosmarinic acid, a natural polyphenol, has a potential pro-oxidant risk via NADH-mediated oxidative DNA damage

BackgroundRosmarinic acid (RA) has a wide range of beneficial effects on human health. On the other hand, RA has been reported to induce metal-mediated reactive oxygen species (ROS) generation and DNA damage. However, its mechanism remains unknown. In this study, to clarify the underlying mechanism, we analyzed metal-mediated DNA damage in isolated DNA treated with RA and its analog isorinic acid.ResultsRA plus Cu(II), but not Fe(III), significantly increased 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG) formation, an indicator of oxidative DNA damage, in calf thymus DNA. Furthermore, a comparison of the 8-oxodG formation induced by RA and its analog isorinic acid suggested that the catechol groups in RA could be associated with their abilities to form 8-oxodG. Interestingly, the 8-oxodG formation induced by RA and isorinic acid plus Cu(II) was markedly enhanced by the addition of NADH, an endogenous reductant. To elucidate the mechanism of RA plus Cu(II)-induced oxidative DNA damage, we examined DNA damage in 32P-labeled DNA treated with RA in the presence of Cu(II). RA plus Cu(II) caused DNA cleavage, which was enhanced by piperidine treatment, suggesting that RA causes not only DNA strand breakage but also base modification. RA plus Cu(II)-induced DNA damage was inhibited by catalase (H2O2 scavenger), bathocuproine (Cu(I) chelator), and methional (scavenger of a variety of ROS other than •OH) but not by typical •OH scavengers and SOD, indicating the involvement of H2O2, Cu(I), and ROS other than •OH. DNA cleavage site analysis showing RA-induced site-specific DNA damage (frequently at thymine and some cytosine residues) supports the involvement of ROS other than •OH, because •OH causes DNA cleavage without site specificity. Based on these results, Cu(I) and H2O2 generation with concomitant RA autoxidation could lead to the production of Cu(I)-hydroperoxide, which induces oxidative DNA damage. o-Quinone and o-semiquinone radicals are likely to be again reduced to RA by NADH, which dramatically increases oxidative DNA damage, particularly at low concentrations of RA.ConclusionsIn this study, physiologically relevant concentrations of RA effectively induced oxidative DNA damage in isolated DNA through redox cycle reactions with copper and NADH.

The conceptual design of pH responsive ZnO-adamantane nanosystems for insulin amyloidosis

Adamantane derivatives are already being explored in amyloidogenic diseases, while ZnO nanoparticles (NPs) have the potential for affecting amyloidosis. Herein, the transformation of ZnO NPs and adamantane-1-carboxylic acid (ADA) to advanced pH responsive nanosystems is reported. Primary ZnO NPs were isolated under a simple solvothermal self-assembly synthetic procedure in the sole presence of octadecylamine (ODA). By adjusting the reaction time (8–24 h), wurtzites of crystallite sizes 19, 21 and 23 nm, respectively, were synthesized with co-crystallized ODA in monoloayer or bilayer conformation. The NPs with the bilayer of ODA have been functionalized with ADA through an amide bond, while those with the ODA monolayer were further PEGylated and ADA was loaded. Loaded ADA-ZnO nanosystems affected insulin amyloidosis in acidic pH (4.8), both in terms of final aggregation status (40 %) and by retarding the lag phase of amyloids formation. The sustained release profile of ADA was confirmed, while interaction with calf thymus DNA (CT-DNA) was evidenced by hyperchromicity. The pH of 4.8 was not enough to cleave the peptide bond, and thus the direct conjugation of ADA was effective only in prolonging the lag phase, without affecting the final amyloid formation, giving rise to the inherent properties of ZnO, foregrounding a prodrug character.

New Silver(I) Lawsone-based complexes: Synthesis, characterization, interaction with biological macromolecules, in vitro antineoplastic, antimetastatic, and antimicrobial activity

New silver(I) complexes of formula [Ag(Lw)]2 (1), [Ag(Lw)(B)], where (Lw= lawsonate, B = 2,2`bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3) and [Ag(Lw)(PPh3)2], (PPh3=triphenylphosphine (4)) have been isolated and characterized using elemental analysis (C, H, N), and FTIR, NMR(1H, 13C and 31P), UV–visible spectroscopy along with thermal analysis and molar conductivity measurements. The resulting data showed that the lawsone coordinates to the Ag(I) as a mono-negative O,O-donor ligand. The interaction of the ligand and complexes with (ctDNA, calf thymus DNA, tRNA, yeast RNA, and BSA, bovine serum albumin) has been studied utilizing absorption and fluorescence spectroscopy. The binding constant data (Kb) revealed that the complexes interact with the biomolecules more strongly than the ligand (HLw). Furthermore, in vitro, cytotoxic activity against normal lung cells (WI38), and various malignant cells, including breast (MCF7 and MDA-231), and colon (HCT116) was studied using cisplatin as a standard drug. The IC50 and selective index (SI) data showed that complex (3) is more selective towards the HCT116 cells. Flow cytometric study of complex (3) revealed that cells are arrested in the G0/G1 phase and induced cell death by an apoptotic mechanism rather than necrosis. The anti-metastatic activity (wound healing) of complex (3) indicated its ability to prevent the migration of cancer cells. The antimicrobial activity of the compounds has been also studied against gram +ve, gram -ve bacteria, and yeast (C. Albican), using penicillin and miconazole, respectively as a reference to show that the complexes (1) and (3) possess the highest activity against these microorganisms.

Supramolecular assemblies of Zn(II) complex based on dithiolate-amine binary ligands: Synthesis, crystal structure, Hirshfeld surface, DFT, molecular docking, and anticancer studies

In this article, synthesis of the novel zinc(II) complex [Zn(tren)(i-mnt)] from diethylenetriamine (tren) and 1,1-dicyano-2,2-ethylenedithiolate di-potassium salt (K2i-mnt) has been presented and characterized by spectroscopic methods. The trigonal bipyramidal geometry of [Zn(tren)(i-mnt)] in solid state has been confirmed by X-ray diffraction analysis where stacked assembly of parallel chains interlinked by N–H⋯S, N–H⋯N, and C–H⋯N type hydrogen bonds observed in 3D supramolecular packing. Hirshfeld Surface (HS) optimizations show prominent N⋯H/H⋯N (32%), S⋯H/H⋯S (21%), and C⋯H/H⋯C (18.5%) interactions that well corroborate with X-ray data. Moreover, Density Functional Theory (DFT) at B3LYP/6-31 g(d) and LMKLL/DZDP basis sets have been used to ascertain geometry and long-range interactions in the complex. In addition, DNA-binding analysis has been assessed by inspecting its binding capability to calf-thymus DNA (CT DNA) and cytotoxic effects of the complex, and K2i-mnt were investigated against Dalton’s Lymphoma (DL) malignant cancer cells to assess their anticancer activity. The molecular docking study shows that the complex has a better binding affinity for 3DK8 (Protein Data Bank ID), leading to a higher inhibition constant and interactions.

Dioxomolybdenum(VI) and oxovanadium(IV) organo-complexes of tartrato-dihydrazone ligand as reactive antitumor and antimicrobial agents. ctDNA interactive nature

Form the condensed > C = O of salicyldehyde with -NH2 of tartric dihydrazide, a new chelating bis-tridentate tartrato-dihydrazone ligand (HTL) was constructed. Due to the high applicability of metal aryl/aroyl-hydrazone complexes, its ligational behavior versus two high valent dioxo/oxo-metal ions of MoO22+ and VO2+ ions was explored to build up two new organo-dimetallic complexes (MoO2TL and VOTL, respectively). Chemical structure elucidation of HTL, MoO2TL, and VOTL was formulated through the analyses of different spectroscopic tools, along with the thermogravimetric and micro-elemental analyses, the conductance and magnetic measurements.The inhibition strength of the current compounds against the growth of various entitled microorganisms and tumor cell lines of humans was evaluated regarding the role action of the high valent metal ions (MoO22+ and VO2+ ions in their metallodrug candidates). Both MoO2TL and VOTL displayed a significant inhibition action more than that of HTL based on the inhibition zone areas in mm for the microbial series and the half inhibitory concentration in µM (IC50) for the tumor cell lines of their cells’ growth.Also, the interactive and binding nature of HTL, MoO2TL, and VOTL with calf thymus DNA (ctDNA) was evaluated viscometric and spectrophotometric titrations. The interactive modes of HTL, MoO2TL, and VOTL was estimated within the chromism type, the Gibb’s free energy, and binding constant values (ΔGb≠ and Kb, respectively), with reported magnitudes ΔGb≠ (Gibb’s free energy) = -42.06, −48.11 and −47.67 kJ mol−1, and Kb (binding constant) = 14.09, 17.11 and 16.89 × 107 mol−1 dm3, respectively. The bio-reactivity of both MoO2TL and VOTL complexes was modified compared to that of HTL towards ctDNA with covalent/non-covalent and replacement binding interaction.

New chelating quinoxalyl hydrazone derivative, as tridentate ligand for complexation with Co(II), Ni(II), and Cu(II) ions. Development of antitumor, antimicrobial, and DNA reactivity

With the facile condensed carbonyl gourp of 2-hydorxybenzaldehyde with the amino group of quinoxalyl-2-carbohydrazide, a new chelating quinoxalyl hydrazone derivative ligand (H2Lpx) was constructed. Its coordination behavior towards three divalent Co2+, Ni2+, and Cu2+ ions was discovered by building up three new metallo-organic complexes (CoLpx, NiLpx, and CuLpx, respectively). Confirmation of their chemical structure was formulated by applying different spectroscopic methods, as well as, the micro-elemental (C,H,N) and thermogravimetric analyses, the conductance, and magnetic evaluations. The inhibition behavior of the free ligand and its metallo-organic complexes against the cell growth of six entitled microorganisms (three fungal and three bacterial types) and three tumors of humans was estimated considering the effective role of the divalent metal ions (Co2+, Ni2+, and Cu2+ ions in their metallo-organic complexes). The interacting nature of H2Lpx, CoLpx, NiLpx, and CuLpx, with calf thymus DNA (ctDNA) was manifested within the viscometric, spectrophotometric titrations and gel electrophoresis.The three complexes (CoLpx, NiLpx, and CuLpx) exposed a respectable inhibition attitude more than that of H2Lpx depending on the inhibition zone areas of the microbial series growth in mm and the half-inhibition concentration in µM (IC50) for the tumor cell lines’ growth. Establishing of the interacted modes between H2Lpx and MLpx with ctDNA was built upon the shifts of the spectral scans for their solutions. In addition, chromism type, Gibb’s free energy, and binding constant values (ΔGb≠ and Kb, respectively) helped to distinguish their interacted modes, which supported DNA damage. The bio-action of MLpx complexes was highly modified compared to that of H2Lpx towards ctDNA.

Synthesis, structure and in vitro anticancer activity of copper(II) and platinum(II) complexes with pyrrol-appended dipicolylamine ligand

Copper complexes exhibit important potential applications as non-platinum based metallodrugs particularly in the field of anticancer research. In this paper, mononuclear copper(II) and platinum(II) complexes containing pyrrole-linked dipicolylamine, namely PPMdpa-Cu and PPMdpa-Pt, were synthesized and characterized. Among these complexes, PPMdpa-Cu exhibited a stronger ability to bind to CT-DNA (calf-thymus DNA) compared to PPMdpa-Pt. In addition, an MTT assay performed throughout our studies demonstrated that PPMdpa-Cu featured significant antitumor activity against the three cancer cell lines U87, AsPC-1 and HepG2, superior to that of PPMdpa-Pt as well as the ligand, PPMdpa. Particularly, the IC50 of PPMdpa-Cu against HepG2 was found to be as low as 27.3 μM. Finally, anticancer mechanism studies showed that PPMdpa-Cu could induce apoptosis in HepG2 cells associated with mitochondrial damage and oxidative stress caused by the generation of reactive oxygen species (ROS).

DOX-DNA Interactions on the Nanoscale: In Situ Studies Using Tip-Enhanced Raman Scattering.

Chemotherapeutic anthracyclines, like doxorubicin (DOX), are drugs endowed with cytostatic activity and are widely used in antitumor therapy. Their molecular mechanism of action involves the formation of a stable anthracycline-DNA complex, which prevents cell division and results in cell death. It is known that elevated DOX concentrations induce DNA chain loops and overlaps. Here, for the first time, tip-enhanced Raman scattering was used to identify and localize intercalated DOX in isolated double-stranded calf thymus DNA, and the correlated near-field spectroscopic and morphologic experiments locate the DOX molecules in the DNA and provide further information regarding specific DOX-nucleobase interactions. Thus, the study provides a tool specifically for identifying intercalation markers and generally analyzing drug-DNA interactions. The structure of such complexes down to the molecular level provides mechanistic information about cytotoxicity and the development of potential anticancer drugs.

Experimental biological studies of novel tetradentate hydrazone Cu(II) complexes for potential applications in medicinal chemistry

A series of mononuclear Cu(II) complexes were synthesized using a potential tetradentate hydrazone ligand obtained from the reaction between phenylhydrazine groups and 2,5-thiophenedicarboxaldehyde. The structures of ligands and complexes were elucidated through various spectroscopic techniques, confirming their composition. All complexes were found to adopt four-coordinated geometries, indicating the formation of stable structures. Spectroscopic analysis revealed that the hydrazone ligand coordinated with the Cu(II) metal ions as a dibasic tetradentate ligand by utilizing the phenolic oxygen and azomethine nitrogen atoms. The binding affinity of the complexes with calf thymus DNA (CT-DNA) was investigated using absorption and viscosity measurements, demonstrating their interaction through the intercalation mode. The binding studies showed that the Cu(II) complexes exhibited varying degrees of binding affinity, with Cu(L4) demonstrating the highest affinity, followed by Cu(L1), Cu(L2), and Cu(L3). Moreover, the DNA fragmentation properties of the Cu(II) complexes were evaluated, suggesting their potential utilization in pharmaceutical applications. The obtained results highlight the significance of these novel complexes in the field of medicinal chemistry.

HSA and DNA binding analysis of antiviral drug cidofovir: Spectroscopic and molecular docking techniques

This article discusses the interaction of antiviral drug cidofovir (CDV) with biomolecules (HSA and DNA) under simulated physiological conditions (pH 7.4). The binding propensity of CDV with DNA was assessed through UV–visible absorption spectroscopy, fluorescence spectroscopy, and molecular docking. The results of fluorescence spectroscopy indicated that the binding of CDV to DNA induced fluorescence quenching through a static quenching mechanism, with a binding constant of 1.03 × 103 M−1 at 293 K. The groove mode of CDV binding to calf thymus DNA (ct-DNA) was validated using dye displacement assays. The results from molecular docking confirmed the binding mode and supported the findings obtained through spectroscopic techniques. Furthermore, the binding propensity of CDV with HSA was assessed through fluorescence spectroscopy, UV–visible absorption spectroscopy, and docking simulation. The fluorescence data indicated that CDV quenches the intrinsic fluorescence of the protein through a static quenching process, with a binding constant of 5.60 × 103 M−1 at 293 K. Meanwhile, the results of docking simulation confirmed our spectroscopic findings.

Gallium(III) complexes with 1,3-pdta-type of ligands: The influence of an alkyl substituent in 1,3-propanediamine chain and the metal counter cation on the structural properties of the complex

The hexadentate 1,3-propanediamine-N,N,N’,N’-tetraacetate (1,3-pdta4−) and (±)-1,3-pentanediamine-N,N,N’,N’-tetraacetate (1,3-pndta4−) ligands were used for the synthesis of two new gallium(III) complexes, Na[Ga(1,3-pdta)]·3H2O (1) and Ba[Ga(1,3-pndta)]2·3H2O (2). Complexes 1 and 2 were characterized by IR and NMR (1H and 13C) spectroscopy and single crystal X-ray diffraction analysis. The obtained results have shown that both hexadentate 1,3-pdta4− and 1,3-pndta4− ligands are coordinated to gallium(III) ion through the two nitrogen and four carboxylate oxygen atoms. Both complexes show significant octahedral distortion since the mean angular deviation is nearly four degrees per angle. However, the octahedral distortion of complex 2 is lower than of 1, as indicated by the ΣΔ(Oh) values (48° and 49° versus 53°, respectively). The binding interactions of the complexes 1 and 2 with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) were studied by fluorescence emission spectroscopy. Both complexes can bind to the serum albumin reversibly, while their affinity to ct-DNA is rather low.

Antibacterial potentials and DNA study of cobalt(II) complexes containing aminophenol Schiff base moiety

The present study was carried out to investigate the effect of substituent groups on the antibacterial activities of 2-aminophenol Schiff bases and their cobalt (II) complexes. Development of new compounds with potential effects against pathogenic organisms has become necessary due to the increase in microbial resistance reported for existing antiseptics and disinfectants. In line with this, new cobalt (II) complexes with Schiff bases derived from 2-aminophenol and p-substituted benzaldehydes were synthesized. The compounds were characterized using elemental analysis, mass spectrometry, atomic absorption spectroscopy, electrospray ionization mass spectrometry, infrared spectroscopy, 1H NMR and electronic absorption spectroscopy. Results indicate that all metal complexes had a 1:2 metal ligand ratio with magnetic moments characteristic of tetrahedral geometry around the metal ion. The Schiff bases and their metal complexes were screened for in-vitro antibacterial activities against 6 human pathogenic bacteria usually found around the hospitals and homes; Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 19582), Bacillus cereus (10702), Enterococcus faecalis (ATCC 29212) and Kribsella pneumonia (ATCC 10031) with ampicillin used as the reference compound. DNA binding study using calf thymus DNA revealed intercalative mode of activity. The result showed that Schiff bases exhibited moderate inhibitory activity against the tested microorganisms while Schiff base metal complexes exhibited higher antibacterial activity when compared to ampicillin. Our results indicate that these complexes can be employed as active ingredients in development of broad-spectrum antibacterial agents.

Experimental and Computational Studies on the Interaction of DNA with Hesperetin Schiff Base CuII Complexes.

The interactions with calf thymus DNA (CT-DNA) of three Schiff bases formed by the condensation of hesperetin with benzohydrazide (HHSB or L1H3), isoniazid (HIN or L2H3), or thiosemicarbazide (HTSC or L3H3) and their CuII complexes (CuHHSB, CuHIN, and CuHTSC with the general formula [CuLnH2(AcO)]) were evaluated in aqueous solution both experimentally and theoretically. UV-Vis studies indicate that the ligands and complexes exhibit hypochromism, which suggests helical ordering in the DNA helix. The intrinsic binding constants (Kb) of the Cu compounds with CT-DNA, in the range (2.3-9.2) × 106, from CuHTSC to CuHHSB, were higher than other copper-based potential drugs, suggesting that π-π stacking interaction due to the presence of the aromatic rings favors the binding. Thiazole orange (TO) assays confirmed that ligands and Cu complexes displace TO from the DNA binding site, quenching the fluorescence emission. DFT calculations allow for an assessment of the equilibrium between [Cu(LnH2)(AcO)] and [Cu(LnH2)(H2O)]+, the tautomer that binds CuII, amido (am) and not imido (im), and the coordination mode of HTSC (O-, N, S), instead of (O-, N, NH2). The docking studies indicate that the intercalative is preferred over the minor groove binding to CT-DNA with the order [Cu(L1H2am)(AcO)] > [Cu(L2H2am)(AcO)] ≈ TO ≈ L1H3 > [Cu(L3H2am)(AcO)], in line with the experimental Kb constants, obtained from the UV-Vis spectroscopy. Moreover, dockings predict that the binding strength of [Cu(L1H2am)(AcO)] is larger than [Cu(L1H2am)(H2O)]+. Overall, the results suggest that when different enantiomers, tautomers, and donor sets are possible for a metal complex, a computational approach should be recommended to predict the type and strength of binding to DNA and, in general, to macromolecules.

Coordination Compounds of Nickel(II) with 3,5–Dibromo–Salicylaldehyde: Structure and Interaction with Biomolecules

Three neutral nickel(II) complexes of 3,5–dibromo–salicylaldehyde (3,5–diBr–saloH) were synthesized in the presence or absence of 1,10–phenanthroline (phen) or its derivative 2,9–dimethyl–1,10–phenanthroline (neoc) as co–ligands, namely [Ni(3,5–diBr–salo)2(neoc)] (complex 1), [Ni(3,5–diBr–salo)2(phen)] (complex 2) and [Ni(3,5–diBr–salo)2(H2O)2] (complex 3), and were characterized by various techniques. The crystal structure of [Ni(3,5–diBr–salo)2(neoc)] was determined by single-crystal X-ray crystallography. According to employed studying techniques, the complexes interact tightly with calf-thymus DNA by an intercalative fashion. Furthermore, compounds 1–3 bind tightly and reversibly to human and bovine serum albumin.