Intercalative Mode Research Articles

Synthesis of a cross-linked polycarboxylate ether superplasticizer and its effects on the properties of cement paste containing montmorillonite

The polycarboxylate ether superplasticizer with cross-linked structure (TPCE) was synthesized and characterized in this paper. The adsorption isotherms and kinetics of TPCE on cement and montmorillonite (MMT) were measured and the adsorption layer thicknesses on cement particles were calculated. Its dispersion capability and effects on the hydration of cement were also examined. Results show that TPCE has stronger adsorption, dispersion and dispersion-retention capability on cement containing MMT system than conventional PCE (CPCE). Regardless of PCE types, the maximum d-value of MMT after intercalation is the same, but TPCE shows different intercalation modes from CPCE. The side chains of CPCE initially insert into the galleries of more MMT in monolayer, and further intercalate to form MMT with the maximum d-value. Comparably, MMT exhibits the maximum d-value, even at a low TPCE concentration, but the multi-branches of TPCE decrease the numbers of intercalated molecules.

The interactions of monomeric acridines and unsymmetrical bisacridines (UAs) with DNA duplexes: an insight provided by NMR and MD studies

Members of a novel class of anticancer compounds, exhibiting high antitumor activity, i.e. the unsymmetrical bisacridines (UAs), consist of two heteroaromatic ring systems. One of the ring systems is an imidazoacridinone moiety, with the skeleton identical to the structural base of Symadex. The second one is a 1-nitroacridine moiety, hence it may be regarded as Nitracrine’s structural basis. These monoacridine units are connected by an aminoalkyl linker, which vary in structure. In theory, these unsymmetrical dimers should act as double-stranded DNA (dsDNA) bis-intercalators, since the monomeric units constituting the UAs were previously reported to exhibit an intercalating mode of binding into dsDNA. On the contrary, our earlier, preliminary studies have suggested that specific and/or structurally well-defined binding of UAs into DNA duplexes might not be the case. In this contribution, we have revisited and carefully examined the dsDNA-binding properties of monoacridines C-1305, C-1311 (Symadex), C-283 (Ledakrin/Nitracrine) and C-1748, as well as bisacridines C-2028, C-2041, C-2045 and C-2053 using advanced NMR techniques, aided by molecular modelling calculations and the analysis of UV–VIS spectra, decomposed by chemometric techniques. These studies allowed us to explain, why the properties of UAs are not a simple sum of the features exhibited by the acridine monomers.

Crystal structure, fluorescence, magnetic properties and DNA interaction of four novel binuclear LnⅢ2 compounds with Schiff ligand

Four new Ln2 compounds, [Ln2(H2L−)2(acac)2(CH3O)2] (Ln = Sm(1), Tb(2), Ho(3) and Er(4), H3L = 2‑hydroxy-N’-[(1E)-(8-hydroxyquinolin-2-yl)methylidene]benzohydrazide), were synthesized by using a multidentate Schiff ligand and lanthanide β-diketone salts via solvent evaporation methods. The X-ray structural analysis reveal that the four Ln2 compounds are dinuclear compounds and each Ln(Ⅲ) ion is eight-coordinated. The two central Ln(Ⅲ) ions are bridged by two μ2O atoms from 8-hydroxyquinoline Schiff base ligands, leading to a parallelogram Ln2O2 core. The magnetism investigation shows that compound 2 display slow magnetic relaxation behavior under zero dc field (ΔE/kB = 19.77 K and τ0 = 1.35 × 10−6 s). Subsequent studies strongly suggested that the four Ln2 compounds binded to Calf thymus DNA (CT-DNA) through intercalative mode and have pBR322 plasmid DNA cleavage ability. This work will provide more insights for the design and investigation of lanthanide-based SMMs, and has certain reference value to study the interaction between compound and DNA.

Centro‐symmetric copper complex as a novel antitumor drug for therapeutic applications: Fabrication, structure, theoretical calculations, cytotoxicity, DNA binding/cleavage, and molecular docking

This study presents the fabrication and structural analysis of the newly synthesized Cu(AHC)2 complex to explore its biological functionalities such as cytotoxicity, DNA binding, and DNA cleavage. For the Cu(AHC)2 complex synthesis, the bioactive 3‐acetyl‐4‐hydroxy coumarin (AHC) has been used as a ligand. The complex has been investigated using analytical and spectroscopic techniques. The resultant data have demonstrated that the AHC is coordinated to the metal ion in a monoanionic form with bidentate through O, O donor atoms forming a square planner coordinated compound. X‐ray diffraction and transmittance electron microscope analysis have shown that Cu(AHC)2 complex has hybrid morphology of irregular nano‐sphere (5 nm) and irregular sheets arranged in the format of a cluster with crystallinity form. The Cu(AHC)2 complex has been screened for in vitro cytotoxicity against HepG‐2 cell line. If it compared with different standard drugs, copper complex, it can be said, has excellent cytotoxicity (IC50 = 6.8 μg ml−1). Furthermore, the binding properties of Cu(AHC)2 complex with herring sperm DNA has been detected via UV–Vis spectroscopy and viscosity measurements. The electronic absorption spectroscopic data have revealed that the prepared Cu(AHC)2 complex strongly binds to herring sperm DNA through intercalative mode with Kb of 0.19 × 106 M−1. Confirming previously obtained spectroscopy data, the interaction of Cu(AHC)2 complex with DNA has also been explored via molecular docking analysis. DNA cleavage study has been, moreover, carried out by agarose gel electrophoresis. The data have shown that the complex has a good ability to destroy DNA. In supporting experimental data, theoretical calculations and optimized Cu(AHC)2 complex structure have been obtained from density functional theory calculations. The calculated results are consistent with the experimental findings. In conclusion, the data discussed above may offer helpful information that helps in the design of a novel copper complex that can function as a potent pharmaceutical agent.

Noncrystalline Carbon Anodes for Advanced Sodium-Ion Storage.

Developing an anode with excellent rate performance, long-cycle stability, high coulombic efficiency, and high specific capacity is one of the key research directions of sodium-ion batteries. Among all the anode materials, noncrystalline carbon (NCC) has great possibilities according to its supreme performance and low cost, but with the complexity and variability of the structure. With the in-depth study of the sodium storage behaviors of NCC in recent years, three modes of interlayer intercalation, clustering into micropores, and adsorption are reported and summarized. Although the storage mechanism has gradually become more evident, the complex behavior of the ions at different voltage regions, especially in the low-voltage (plateau) region, still remains controversial. It is essential to understand further the relationship between ions and NCC structure during energy storage processes. Based on the summary of previous works, this article has reviewed the storage mechanism of sodium ions in NCC and evaluated the structure-behavior relationship between sodium-ion storage and the carbon structure.

Cancer cells inhibition by cationic carbon dots targeting the cellular nucleus

Nucleus targeting is tremendously important in cancer therapy. Cationic carbon dots (CCDs) are potential nanoparticles which might enter cells and penetrate nuclear membranes. Although some CCDs have been investigated in nucleus targeting and applied in nuclear imaging, the CCDs derived from drugs, that are able to target the nucleus, bind with DNA and inhibit the growth of cancer cells have not been reported. In this project, 1, 2, 4, 5-benzenetetramine (Y15, a focal adhesion kinase inhibitor) derived cationic carbon dots (Y15-CDs) were prepared via a hydrothermal approach utilizing Y15, folic acid and 1,2-ethylenediamine as precursors. Based on the structural, optical, and morphologic characterizations, Y15-CDs possess rich amine groups and nitrogen in structure, an excitation-dependent photoluminescence emission, and a small particle size of 2 to 4 nm. The DNA binding experiments conducted through agarose gel electrophoresis, UV–vis absorption, fluorescence emission, and circular dichroism spectroscopies, prove that Y15-CDs might bind with DNA via electrostatic interactions and partially intercalative binding modes. In addition, the cell imaging and cytotoxicity studies in human foreskin fibroblasts (HFF), prostate cancer (PC3) and osteosarcoma cells (U2OS) indicate the nucleus targeting and anticancer abilities of Y15-CDs. Most interestingly, Y15-CDs exhibit a higher cytotoxicity to cancer cells (PC3 and U2OS) than to normal cells (HFF), inferring that Y15-CDs might be potentially applied in cancer therapy.

Synthesis, crystal structures and DNA-binding properties of Zn(II), Cd(II), Mn(II), Cu(II) complexes based on a thiazole derivative and carboxylic acids

By single-crystal X-ray diffraction (XRD) analysis, five complexes, catena-[(µ-2,2-bis(4-carboxyphenyl)hexafluoropropane)-(2-(pyidin-2-yl)-1,3-benzothiazole)-aqua-zinc(II)] (1), catena-[(µ-2,2-bis(4-carboxyphenyl)hexafluoropropane)-(2-(pyidin-2-yl)1,3-benzothiazole)-aqua-cadmium(II)] (2), catena-[hepta(µ-2,2-bis(4carboxyphenyl)hexafluoropropane)-diaqua-bis(2-(pyidin-2-yl)-1,3-benzothiazole)-tri-manganes(II)] (3), catena-[(µ-benzene-1,2,4,5-tetracarboxylato)-(2-(pyidin-2-yl)-1,3benzothiazole)copper(II)] (4) and catena-[(µ-3-nitrobenzene-1,2-dicarboxylato)-(2-(pyidin-2-yl)1,3-benzothiazole)-aqua-zinc(II)] (5), were characterized in this research. In these five complexes, H2hfipbb = 2,2-bis(4-carboxyphenyl)hexafluoropropane, H4btec = 1,2,4,5-benzenetetracarboxylic acid, H2NPTA = 3-nitrophthalic acid and bpt = 2-(pyridin-2-yl)benzo[d]thiazole). Complexes 1 and 2 occur in the monoclinic system with space group C2/c, 4 and 5 occur in the monoclinic system with space group P21/c, and 3 occurs in the triclinic system with space group P-1. The interaction between CT-DNA (calf thymus DNA) and those complexes was examined using UV spectroscopic analysis, fluorescent spectroscopic analysis, circular dichroism spectroscopy (CD) and viscosity analysis. This research reveals that those complexes have strong ability to interact with DNA, and they all bind to DNA in an intercalation mode, thus affecting the structure of DNA. This binding mode can arise from the interaction between the benzothiazole metal complexes and DNA. Hence, we hope to provide some scientific research bases for studying benzothiazole complexes and designing new thiazole anticancer drugs.

Synthesis, spectroscopic elucidation, in vitro antimicrobial, cytotoxic and CT-DNA binding evaluation of heterobimetallic complexes of Ni(II) with main group/transition metal dichlorides

Heterobimetallic complexes of Nickel (II) have been synthesized and characterized of the type [Ni(L)2(M)2R4Cl2], where L = 2,6-diaminopyridine (C5H7N3), M = Sn, Si, Ti and Zr and R = Ph, Me, C5H5 etc. The monometallic complexes of nickel have been synthesized by using 2,6-diaminopyridine in the presence of NiCl2·6H2O dissolved in methanol to form complexes of the type [Ni(L)2]Cl2. To synthesize heterobimetallic complexes, these synthesized complexes were further processed with main group metal or transition metal dichlorides in a 1:2 molar ratio in MeOH. Elemental analyses, molecular weight calculations, electronic, infrared, magnetic susceptibility, conductivity measurements, mass spectra, 1HNMR , 13CNMR , and powder X-ray diffraction studies have been used to evaluate these synthesized compounds. Using a monometallic complex, the heterobimetallic complexes were synthesized, and an octahedral geometry was perceived for these heterobimetallic complexes. The antimicrobial potency of the synthesized complexes has been evaluated against four different bacterial and three fungal strain at different concentrations. The cytotoxicity activity of these resulting complexes against MCF-7, HeLa and HaCaT cell lines using MTT assay has been scrutinized. Also, the interaction of the reported complexes with calf thymus DNA (CT-DNA) by different techniques revealed that the complexes could bind to CT-DNA by intercalative mode. The binding of the reported complexes to CT-DNA has been investigated using UV–vis and fluorescence spectra. The results indicated a much lower binding affinity of monometallic complex than that of the heterobimetallic complexes.

Thioether-based novel transition metal complexes: Synthesis, DNA interaction, in vitro biological assay, DFT calculations, and molecular docking studies

A novel Schiff base ligand 2-(((2-(benzylthio)phenyl)imino)methyl)-4-chlorophenol and its cobalt, nickel, copper, and zinc metal complexes were prepared. Using B3LYP/6–31++G(d,p) method with LanL2DZ as basis set, the molecular structure of metal complexes has been optimized, and their parameters have been explored. The distorted octahedral geometries have been observed in cobalt, nickel, and copper complexes. In contrast, zinc complex exhibited distorted tetrahedral geometry indicating the coordination of metal ions with ligands through ONS binding sites, which are confirmed by various spectroscopic techniques, magnetic measurements, molar conductivity, elemental analysis, and DFT studies. The intercalative binding mode between CT-DNA and synthesized metal complexes has been determined by absorption and fluorescence spectroscopy. The binding constant values of metal complexes found to be varied from 5.28 × 103 M−1 to 9.18 × 104 M−1. Furthermore, several methods have been used to scrutinize the bioactivities, such as in vitro anti-diabetic, anti-inflammatory, and antioxidant. From the obtained results, it can be concluded that zinc metal complex exhibited excellent anti-inflammatory and anti-diabetic activity compared to others. However, the copper complex has good antioxidant property. Besides deducing the prospective binding energies of inhibitors, molecular docking simulations have also been conducted utilizing the enzyme structures of B-DNA, 6-COX, α-amylase, and α-glucosidase.

A novel tetranuclear Cu(ii) complex for DNA-binding and in vitro anticancer activity.

A novel tetranuclear Cu(ii) complex (TNC) was successfully synthesized and characterized by X-ray single crystal diffraction. The interaction of the complex with calf thymus DNA (CT-DNA) has been studied by UV-vis absorption titration, fluorescence technology and molecular docking. The results indicated that TNC could bind to the DNA through an intercalative mode. The agarose gel electrophoresis experiment showed that TNC could cleave supercoiled plasmid DNA into linear DNA. The anticancer activity of TNC was tested on four cancer cell lines: MCF7, A549, 4T1 and HepG2. The results indicated that TNC shown significant activity against all of above cell lines.

Mononuclear discrete Ag(I) complexes of aryl substituted (E)-N-phenyl-1-(pyridin-3-yl)methanimine: In vitro biological activities and interactions with biomolecules

The synthesis of three pyridinyl imines (L1-L3) with electron-donating and electron-withdrawing functional groups, as well as their silver(I) complexes (1a-3a, 1b-3b and 1c-3c), resulted from our ongoing search for novel metallodrugs with potential pharmacological activity. Various analytical and spectroscopic analyses were used to characterize the Ag(I) complexes. The single crystal X-ray diffraction analysis of complexes 3a and 3b in the solid state confirmed their linear geometry around the Ag(I) center. In vitro antibacterial properties of the complexes evaluated using the minimum inhibitory concentration (MIC) method revealed that complexes containing either a Me- or an F-substituent exhibited greater activity. The ferric-reducing antioxidant power (FRAP) experiment revealed that complexes with hydroxyl substituents have high antioxidant potential. These complexes with IC50 values ranging from 0.86 to 2.47 mg mL-1 outperformed ascorbic acid, with an IC50 of 2.68 mg mL-1. The reported complexes bound to CT-DNA via intercalation mode with significant binding constants for complexes whose ligands bore the OH- substituent. Bovine serum albumin (BSA) binding affinity to the complexes ranges from moderate to high. The studied complexes with methyl substituents are promising anti-cervical cancer candidates.

Copper(ii) complexes of the CuN4S core: selective cytotoxicity to cancerous cells, ROS generation and induction of apoptosis

New copper(ii) complexes display distorted square pyramidal geometry with CuN4S core and bind to CT DNA partial intercalative mode. Cytotoxicity is selective to cancerous cells and causes cell death mostly through the apoptotic mechanism, which produces the most ROS.

Novel copper (II) binary complexes with N,O-donor isoxazole Schiff base ligands: Synthesis, characterization, DPPH scavenging, antimicrobial, and DNA binding and cleavage studies

Cu(II) binary complexes of the type [Cu(Ln)2], where n = 1–3, HL1 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-tert-butylphenol (C1), HL2 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4-bromo-6-methoxyphenol (C2), HL3 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-5-methylphenol (C3) have been synthesized and characterized by analytical, structural, and spectral methods. The antioxidant studies of novel Cu(II) complexes revealed, significant activity against DPPH radical. The synthesized compounds were monitored for antimicrobial activities and the results of these studies indicated that the complexes exhibit a good antimicrobial efficiency compared to ligands. The interaction of CT–DNA with the Cu(II) complexes has been explored using absorption and emission spectral techniques. Spectral evidence showed the intercalative mode of DNA binding with the complexes. Agarose gel electrophoresis results revealed that all Cu(II) complexes induced double strand breaks of pBR 322 plasmid DNA in the presence of H2O2 and UV light.

Synthesis, Structural Elucidation, and Therapeutic Screening of Organotin(IV) derivatives of oxo-ethyl carbonodithioate

Exploring the therapeutic potential of organotin-based oxo-ethyl carbonodithioates, a series of organotin(IV) thiocarboamates (1-5) were synthesized with diverse alkyl and phenyl substituents. The chemical- composition, morphology, theoretical properties, and drug-DNA binding capabilities of the synthesized derivatives were performed by applying different characterization techniques like FT-IR, NMR (1H, 13C), AFM, DFT analysis, and UV-Vis spectroscopy respectively. The NMR data indicated six and four coordinated geometries, while the AFM results revealed smart surfaces concerning the grain size and root mean square (RMS) roughness, signifying catalytic and biocidal uses. The drug-DNA binding via intercalative mode of interaction with blue and red shifts was determined by using using UV spectroscopy. The in vitro biocidal capacity of selected complexes was evaluated against typical bacterial, fungal, cytotoxic, and leishmanial strains respectively. As a result of the surface and biocidal characterization, the synthesized complexes may be applied with greater potential in biomedical, pharmaceutical, infectious, catalysis, and cosmetics industries

Synthesis, characterization, X-ray crystal structure, antioxidant, antimicrobial, and DNA binding interaction studies of novel copper (II)-isoxazole binary complexes

Cu (II) binary complexes of the type [Cu(HLx)2], where x = 1–3, HL1 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-methylphenol (C1), HL2 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-ethoxyphenol (C2) and HL3 = 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4,6-di-tert-butylphenol (C3) have been synthesized and characterized by various analytical, structural, and spectral methods. Single crystal X–ray diffraction analysis of ligand HL1, complexes C2 &C3 revealed that the compounds are crystallized in monoclinic crystal system with the space groups of P1 21/c1 for HL1 &C2, and P1 21/n1 for C3. The antioxidant studies of the synthesized Cu(II) complexes were carried out and it was shown as significant activity against DPPH radical. The synthesized Schiff bases and Cu(II) complexes were explored for antimicrobial activities and the complexes exhibited better potency against diverse microorganisms compared to Schiff bases as ligands. The interaction of Cu(II) complexes with CT–DNA has been explored with absorption and emission spectral techniques and the obtained results were evidence to the intercalative mode of DNA binding. The study of Agarose gel electrophoresis was resulted in three Cu(II) complexes stimulate the double strand breakage of pBR 322 plasmid DNA in the presence and absence of H2O2.

Oxadiazole Schiff Base as Fe3+ Ion Chemosensor: "Turn-off" Fluorescent, Biological and Computational Studies.

Compound, (E)-5-(4-((thiophen-2-ylmethylene)amino)phenyl)-1,3,4-oxadiazole-2-thiol (3) was synthesized via condensation reaction of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol with thiophene-2-carbaldehyde in ethanol. For the synthesis and structural confirmation the FT-IR, 1H, 13C-NMR, UV-visible spectroscopy, and mass spectrometry were carried out. The long-term stability of the probe (3) was validated by the experimental as well as theoretical studies. The sensing behaviour of the compound 3 was monitored with various metal ions (Ca2+, Cr3+, Fe3+, Co2+, Mg2+, Na+, Ni2+, K+) using UV- Vis. and fluorescence spectroscopy techniques by various methods (effect of pH and density functional theory) which showing the most potent sensing behaviour with iron. Job's plot analysis confirmed the binding stoichiometry ratio 1:1 of Fe3+ ion and compound 3. The limit of detection (LOD), the limit of quantification (LOQ), and association constant (Ka) were calculated as 0.113µM, 0.375µM, and 5.226 × 105 respectively. The sensing behavior was further confirmed through spectroscopic techniques (FT-IR and 1H-NMR) and DFT calculations. The intercalative mode of binding of oxadiazole derivative 3 with Ct-DNA was supported through UV-Vis spectroscopy, fluorescence spectroscopy, viscosity, cyclic voltammetry, and circular dichroism measurements. The binding constant, Gibb's free energy, and stern-volmer constant were find out as 1.24 × 105, -29.057kJ/mol, and 1.82 × 105 respectively. The cleavage activity of pBR322 plasmid DNA was also observed at 3 × 10-5M concentration of compound 3. The computational binding score through molecular docking study was obtained as -7.4kcal/mol. Additionally, the antifungal activity for compound 3 was also screened using broth dilution and disc diffusion method against C. albicans strain. The synthesized compound 3 showed good potential scavenging antioxidant activity against DPPH and H2O2 free radicals.

Purine-based Schiff base Co(II), Cu(II), and Zn(II) complexes: Synthesis, characterization, DFT calculations, DNA binding study, and molecular docking

A series of metal complexes of Co(II), Zn(II), and Cu(II) of purine base Schiff base ligand L1 6,6′-((1E,1′E)-((7H-purine-2,6-diyl)bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol) and L2 3,3′-((1E,1′E)-((7H-purine-2,6-diyl)bis(azanylylidene))bis (methanylylidene))bis(4H-chromen-4-one) were synthesized. The characterization of synthesized compounds was investigated through elemental analysis, UV–vis, FT-IR, NMR, and mass spectrometry. The spectroscopic and DFT studies validate the coordination of ligand to the metal centers along with their structural details. In complexes of L1 and L2, the N and O atoms coordinate to metal centers of zinc, cobalt, and copper. However, in the case of L1 complexes the binding mode of oxygen is through phenolic –OH of vanillin moiety. In contrast, complexes of L2 the binding mode of oxygen source is carbonyl oxygen of chromone carboxaldehyde moiety. The stability order follow- ZnL1 < CoL1 < CuL1 < CuL2 < CoL2 < ZnL2. The CT-DNA binding activity of all synthesized complexes with the help of UV–vis absorption titration, fluorescence titration, and viscosity measurement was studied. In both cases, cobalt complexes of L1 and L2 showed high DNA binding activity. The binding constant values are in the order of 105 via intercalation mode of binding. The molecular docking study was performed to speculate on the active binding site between metal complexes and CT-DNA.

Synthesis, cytotoxicity and DNA binding of novel Ni(II), Co(II) and Zn(II) complexes bearing pyrimidinyl hydrazone ligand

To develop efficient new antitumor agents, Ni(II), Co(II) and Zn(II) complexes 1–3 derived from 2-((2-pyrimidin-2-yl)hydrazono)methyl)quinoline (HL) were prepared and structurally characterized using IR, elemental analysis, UV-Vis, fluorescence spectrometry and single crystal X-ray diffraction analysis. The in vitro cytotoxicity of complexes 1–3 against MCF-7, BGC-823, A549, BEL-7402 tumor cell lines and human normal cell line HL-7702 was evaluated using MTT assay. Complexes 1-3 display higher cytotoxic activity than cisplatin as well as HL against BGC-823 tumor cell line, with IC50 values ranging from 5.57 µM to 11.20 µM, and less toxicity toward the normal cell line HL-7702. In particular, complex 3 exhibits the most prominent antiproliferative activity. Complex 3 was found to induce apoptosis of BGC-823 cells greatly in a dose-dependent manner, which was suggested by Annexin V-FITC/PI and AO/EB dual-staining assays. The DNA binding studies, which were performed using UV-Vis, fluorescence and CD spectral analyzes, revealed that complex 3 interacts with CT-DNA mainly via a partial intercalative binding mode. The molecular docking of the interaction of complex 3 with DNA is in accordance with the experimental data.

Mechanism of interactions of dsDNA binding with quercetin and its two novel sulfonate derivatives using multispectroscopic, voltammetric, and molecular docking studies

Flavonoids have an important place in chemistry and pharmacology. Several flavonoids, especially Quercetin, have the potential to form molecular complexes with nucleic acid structure and have recently attracted attention due to their prospective clinical and pharmacological uses. DNA is the main target for a wide variety of therapeutic agents. Therefore, there is great interest in studies of binding small molecules with DNA. The interaction of small molecules with DNA provides a structural guide in rational drug design and the synthesis of new and improved drugs with enhanced selective activity and higher clinical efficacy. Even if newly synthesized candidate drug molecules with small molecular weight are capable of indirectly interacting with DNA, the mechanisms that accomplish this need to be clearly known. In this study, the mechanism of fish sperm double strain deoxyribonucleic acid (dsDNA) binding with Quercetin (QCR) and its two novel sulfonate derivatives (quercetin mesylate (QMS) and quercetin tosylate-A (QTS-A)) were researched. For investigating the interaction between the molecules and dsDNA was studied by analytical (spectrophotometric, viscosimetric, and electrochemical) methods. The interaction of dsDNA and two quercetin sulfonate derivatives were compared with the interaction of the QCR standard after all experimental studies. Moreover, the DNA binding constants Kb were determined using each method. The Kb constants calculated for QCR, QMS, and QTS-A are in harmony for all techniques. The results showed that QCR binds to dsDNA via intercalation mode, while QMS and QTS-A bind through minor groove binding mode. In addition to experimental studies, theoretical studies were conducted at room temperature under physiological conditions (pH 7.4). Molecular docking calculations and molecular dynamics (MD) simulations have been found to be compatible with experimental studies.

Ferrocenyl chalcone armed macrocyclic tet a‐based cobalt(II) and copper(II) complexes: DNA photocleavage activity and photocytotoxicity

Ferrocenyl chalcone armed ‘tet a’ macrocyclic cobalt(II) and copper(II) complexes (1) and (2) were synthesised and characterised by various physico‐chemical methodologies. The complexes exhibit Co(II)/Co(I) and Cu(II)/Cu(I) redox couple (quasi‐reversible) with E1/2 value of −0.82 and −0.82 V, respectively. Complex 1 is oxidised as quasi‐reversible two‐electron transfer processes with oxidation potential of E1pa = 0.64 and E1pc = 0.68 V, and complex 2 with oxidation potential of E1pa = 0.62 and E1pc = 0.66 V over 0.37 V of ferrocene was observed. The above scenario is indicating the positive charge destabilisation of mono‐ and dications originating a challenging condition for ferrocene oxidation. The DNA binding abilities of both the complexes (1 and 2) with calf thymus DNA (CT‐DNA) were investigated by spectroscopic studies (absorption/fluorescence) and electrochemical methods. Absorption spectral studies revealed that complexes 1 and 2 bind with CT‐DNA by partial intercalative mode of binding with Kb values of 1.04 × 106 and 7.29 × 105 M−1, respectively. Chemical nuclease activity is exhibited moderately in these complexes generating singlet oxygen (1O2) species and acting as effective photocleavers of pUC19 DNA in the red light region. As irradiated by red light, their cytotoxicity toward MDA‐MB‐231 displays a typical increase in cytotoxicity values. In comparing the dark and red light irradiated cell, MDA‐MB‐231 cells that were exposed to red light exhibited significant morphological alternations. Cell morphological studies were confirmed the morphological changes with dual staining by using AO/EB, Hoechst 33342 and PI against MDA‐MB‐231 cells. Furthermore, complexes 1 and 2 have less toxicity on Artemia nauplii even at higher concentrations, indicating that the synthesised complexes 1 and 2 are biocompatible.