Oxidative DNA cleavage mediated by a new copper (II) terpyridine complex: Crystal structure and DNA binding studies

Heavy-Metal Ions Removal and Iodine Capture by Terpyridine Covalent Organic Frameworks

Porous materials are excellent candidates for water remediation in environmental issues. However, it is still a key challenge to design efficient adsorbents for rapid water purification from various heavy metal ions-contaminated wastewater in one step. Here, two robust nitrogen-rich covalent organic frameworks (COFs) bearing terpyridine units on the pore walls by a "bottom-up" strategy are reported. Benefitting from the strong chelation interaction between the terpyridine units and various heavy metal ions, these two terpyridine COFs show excellent removal efficiency and capability for Pb2+, Hg2+, Cu2+, Ag+, Cd2+, Ni2+, and Cr3+ from water. These COFs are shown to remove such heavy metal ions with >90% of contents at one time after the aqueous metal ions mixture is passed through the COF filter. The nitrogen-rich features of the COFs also endow them with the capability of capturing iodine vapors, offering the terpyridine COFs the potential for environmental remediation applications.

Synthesis, characterization, DNA interaction, molecular docking, and α-amylase and α-glucosidase inhibition studies of a water soluble Zn(II) phthalocyanine

In this study, 2(3),9(10),16(17),23(24)-tetrakis-[(N-methyl-(1-benzylpiperidin-4-yl)oxy)phthalocyaninato]zinc(II) iodide (ZnPc-2) was synthesized and characterized using spectral methods (FT-IR, 1H-NMR, UV-Vis and mass spectroscopy). The interaction of ZnPc-2 with DNA was investigated by using the UV/Vis titrimetric method, thermal denaturation profile, agarose gel electrophoresis and molecular docking studies. Additionally, the antidiabetic activity of ZnPc-2 was revealed spectroscopically by studying α-amylase and α-glucosidase inhibition activities. The spectroscopic results indicated that ZnPc-2 effectively binds to calf thymus-DNA (CT-DNA) with a Kb value of 7.5 × 104 M-1 and interacts with CT-DNA via noncovalent binding mode. Gel electrophoresis results also show that ZnPc-2 binds strongly to DNA molecules and exhibits effective nuclease activity even at low concentrations. Furthermore, docking studies suggest that ZnPc-2 exhibits a stronger binding tendency with DNA than the control compounds ethidium bromide and cisplatin. Consequently, due to its strong DNA binding and nuclease activity, ZnPc-2 may be suitable for antimicrobial and anticancer applications after further toxicological tests. Additionally, antidiabetic studies showed that ZnPc-2 had both α-amylase and α-glucosidase inhibition activity. Moreover, the α-glucosidase inhibitory effect of ZnPc-2 was approximately 3500 times higher than that of the standard inhibitor, acarbose. Considering these results, it can be said that ZnPc-2 is a moderate α-amylase and a highly effective α-glucosidase inhibitor. This suggests that ZnPc-2 may have the potential to be used as a therapeutic agent for the treatment of type 2 diabetes.

Novel Bidentate Amine Ligand and the Interplay between Pd(II) and Pt(II) Coordination and Biological Activity

Pt(II) and Pd(II) coordinating N-donor ligands have been extensively studied as anticancer agents after the success of cisplatin. In this work, a novel bidentate N-donor ligand, the N-[[4-(phenylmethoxy)phenyl]methyl]-2-pyridinemethanamine, was designed to explore the antiparasitic, antiviral and antitumor activity of its Pt(II) and Pd(II) complexes. Chemical and spectroscopic characterization confirm the formation of [MLCl2 ] complexes, where M=Pt(II) and Pd(II). Single crystal X-ray diffraction confirmed a square-planar geometry for the Pd(II) complex. Spectroscopic characterization of the Pt(II) complex suggests a similar structure. 1 H NMR, 195 Pt NMR and HR-ESI-MS(+) analysis of DMSO solution of complexes indicated that both compounds exchange the chloride trans to the pyridine for a solvent molecule with different reaction rates. The ligand and the two complexes were tested for in vitro antitumoral, antileishmanial, and antiviral activity. The Pt(II) complex resulted in a GI50 of 10.5 μM against the NCI/ADR-RES (multidrug-resistant ovarian carcinoma) cell line. The ligand and the Pd(II) complex showed good anti-SARS-CoV-2 activity with around 65 % reduction in viral replication at a concentration of 50 μM.

Precisely modulating the chromatin tracker via substituent engineering: reporting pathological oxidative stress during mitosis

An in-depth understanding of cancer-cell mitosis presents unprecedented advantages for solving metastasis and proliferation of tumors, which has aroused great interest in visualizing the behavior via a luminescence tool. We developed a fluorescent molecule CBTZ-yne based on substituent engineering to acquire befitting lipophilicity and electrophilicity for anchoring lipid droplets and the nucleus, in which the low polarity environment and nucleic acids triggered a "weak-strong" fluorescence and "short-long" fluorescence-lifetime response. Meaningfully, CBTZ-yne visualized chromatin condensation, alignment, pull-push, and separation as well as lipid droplet dynamics, for the first time, precisely unveiling the asynchronous cellular mitosis processes affected by photo-generation reactive oxygen species according to the subtle change of fluorescence-lifetime. Our work suggested a new guideline for tracking the issue of the proliferation of malignant tumors in photodynamic therapy.

Anti-Inflammatory and Antioxidant Pyrrolo[3,4-d]pyridazinone Derivatives Interact with DNA and Bind to Plasma Proteins-Spectroscopic and In Silico Studies

From the point of view of the search for new pharmaceuticals, pyridazinone derivatives are a very promising group of compounds. In our previous works, we have proved that newly synthesized ligands from this group have desirable biological and pharmacokinetic properties. Therefore, we decided to continue the research evaluating the activity of pyrrolo[3,4-dpyridazinone derivatives. In this work, we focused on the interactions of five pyridazinone derivatives with the following biomolecules: DNA and two plasma proteins: orosomucoid and gamma globulin. Using several of spectroscopic methods, such as UV-Vis, CD, and fluorescence spectroscopy, we proved that the tested compounds form stable complexes with all biomacromolecules selected for analysis. These findings were also confirmed by the results obtained by molecular modeling. All tested pyridazinone derivatives bind to the ctDNA molecule via groove binding mechanisms. All these molecules can also be bound and transported by the tested plasma proteins; however, the stability of the complexes formed is lower than those formed with serum albumin.

Regulation of c-Kit gene transcription selectively by bisacridine derivative through promoter dual i-motif structures

BACKGROUND

c-Kit protein is a signal transduction protein involved in multiple signal pathways, which play an important role in a variety of cellular events such as cell proliferation, apoptosis and differentiation. Special DNA secondary structures on the promoter of c-Kit gene, including G-quadruplex and i-motif structures, could act as "molecular switch" for gene transcriptional regulation, which are potentially important target for development of new anti-cancer drugs.

METHODS

We screened and evaluated the effect of compounds on c-Kit through several experiments, including SPR, FRET, CD, MST, NMR, dual-luciferase reporter assay, Western blot, qPCR, immunofluorescence, MTT assay, colony formation, cell scrape, cell apoptosis, cell cycle analysis, and transwell assay.

RESULTS

After extensive screening, we found that bisacridine derivative B05 had selective binding and stabilization to dual i-motif structures on c-Kit gene promoter, which could down-regulate c-Kit gene transcription and translation, resulting in inhibition of cell proliferation and metastasis. B05 exhibited potent anti-tumor activity on HGC-27 cells, and strongly suppressed tumor growth in HGC-27 xenograft mice model.

CONCLUSIONS

B05 could interact with c-Kit promoter dual i-motif structures with excellent selectivity, which make it possible for selective regulation of gene transcription and translation. B05 could be further developed for selective anti-cancer agent targeting c-Kit promoter i-motifs.

GENERAL SIGNIFICANCE

i-Motifs on different proto-oncogene promoters are diversified, and especially binding of dual i-motifs on the same promoter simultaneously could significantly down-regulate gene transcription with decreased dosage, and therefore increasing the selectivity. This new strategy shed bight light on development of selective DNA-targeting ligands.

Complexation of Oligo- and Polynucleotides with Methoxyphenyl-Functionalized Imidazolium Surfactants

Interaction between cationic surfactants and nucleic acids attracts much attention due to the possibility of using such systems for gene delivery. Herein, the lipoplexes based on cationic surfactants with imidazolium head group bearing methoxyphenyl fragment (MPI-n, n = 10, 12, 14, 16) and nucleic acids (oligonucleotide and plasmid DNA) were explored. The complex formation was confirmed by dynamic/electrophoretic light scattering, transmission electron microscopy, fluorescence spectroscopy, circular dichroism, and gel electrophoresis. The nanosized lipoplex formation (of about 100-200 nm), contributed by electrostatic, hydrophobic interactions, and intercalation mechanism, has been shown. Significant effects of the hydrocarbon tail length of surfactant and the type of nucleic acid on their interaction was revealed. The cytotoxic effect and transfection ability of lipoplexes studied were determined using M-HeLa, A549 cancer cell lines, and normal Chang liver cells. A selective reduced cytotoxic effect of the complexes on M-HeLa cancer cells was established, as well as a high ability of the systems to be transfected into cancer cells. MPI-n/DNA complexes showed a pronounced transfection activity equal to the commercial preparation Lipofectamine 3000. Thus, it has been shown that MPI-n surfactants are effective agents for nucleic acid condensation and can be considered as potential non-viral vectors for gene delivery.

Oxoperoxovanadium Complexes of Hetero Ligands: X-Ray Crystal Structure, Density Functional Theory, and Investigations on DNA/BSA Interactions, Cytotoxic, and Molecular Docking Studies

Oxoperoxovanadium (V) complexes [VO (O)2 (nf) (bp)] (1) and [VO (O)2 (ox) (bp)] (2) based on 5-nitro-2-furoic acid (nf), oxine (ox) and 2, 2' bipyridine (bp) bidentate ligands have been synthesized and characterized by FT-IR, UV-visible, mass, and NMR spectroscopic techniques. The structure of complex 2 shows distorted pentagonal-bipyramidal geometry, as confirmed by a single-crystal XRD diffraction study. The interactions of complexes with bovine serum albumin (BSA) and calf thymus DNA (CT-DNA) are investigated using UV-visible and fluorescence spectroscopic techniques. It has been observed that CT-DNA interacts with complexes through groove binding mode and the binding constants for complexes 1 and 2 are 8.7 × 103 M-1 and 8.6 × 103 M-1, respectively, and BSA quenching constants for complexes 1 and 2 are 0.0628 × 106 M-1 and 0.0163 × 106 M-1, respectively. The ability of complexes to cleave DNA is investigated using the gel electrophoresis method with pBR322 plasmid DNA. Furthermore, the cytotoxic effect of the complexes is evaluated against the HeLa cell line using an MTT assay. The complexes are subjected to density functional theory calculations to gain insight into their molecular geometries and are in accordance with the results of docking studies. Furthermore, based on molecular docking studies, the intermolecular interactions responsible for the stronger binding affinities between metal complexes and DNA are discussed.

Mixed Ligand Mononuclear Copper(II) Complex as a Promising Anticancer Agent: Interaction Studies with DNA/HSA, Molecular Docking, and In Vitro Cytotoxicity Studies

The isolated copper(II) complex [CuL(o-phen)]·H2O (1) [H2L = o-HO-C6H4C(H)=N-C6H4-SH-o, o-phen = 1,10-phenanthroline] was structurally characterized using single-crystal X-ray crystallography. 1 in CH3CN at liquid nitrogen temperature displayed a characteristic monomeric X-band electron paramagnetic resonance spectrum having a tetragonal character with g ∥ = 2.1479 and g ⊥ = 2.0691 and A ∥ ≈ 18.0 mT and A ⊥ ≤ 3.9 mT, respectively. 1 showed a strong binding affinity toward calf thymus DNA as reflected from its intrinsic binding constant (K b = 7.88 × 105 M-1), and its competitive displacement of ethidium bromide suggested an intercalative DNA-binding mode (K app = 1.32 × 106 M-1). This was confirmed from the viscosity study that showed an increase in the viscosity of DNA with an increasing concentration of 1. Complex 1 is highly efficient in promoting oxidative and hydrolytic DNA cleavage (k obs = 1.987 h-1). 1 showed a strong binding affinity with the carrier protein human serum albumin (HSA) (K a = 5.22 × 105 M-1). A high bimolecular quenching constant k q = 2.29 × 1013 M-1s-1 indicated a static quenching mechanism involved in the fluorescence quenching of HSA by 1. Fluorescence resonance energy transfer theory suggested that the distance (r = 3.52 nm) between 1 and HSA is very close. Molecular docking studies suggested that 1 primarily binds to HSA in subdomain IIA. A protein-ligand interaction profiler was used to visualize hydrophobic, hydrogen bonds, and π-cation interactions between HSA and 1. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using HeLa and MDA-MB-231 cells showed a significant in vitro anticancer activity of 1 (IC50 2.63 and 2.68 μM, respectively). Nuclear staining assays suggested apoptotic cell death in HeLa cells treated with 1. The effect of 1 on the cytoskeletal actin filaments visualized using phalloidin staining showed extensive destruction of actin filaments. Flow cytometric analysis indicated that 1 inhibits the growth of HeLa cells through cell cycle arrest in the S phase. Western blot analysis showed upregulation in the expression of apoptotic marker proteins caspase 3, p53, and Bax. These results collectively indicate that 1 induces apoptosis by promoting DNA damage and has a high potential to act as an anticancer agent.

A Nuclear-Targeted AIE Photosensitizer for Enzyme Inhibition and Photosensitization in Cancer Cell Ablation

The nucleus is considered the ideal target for anti-tumor therapy because DNA and some enzymes in the nucleus are the main causes of cell canceration and malignant proliferation. However, nuclear target drugs with good biosafety and high efficiency in cancer treatment are rare. Herein, a nuclear-targeted material MeTPAE with aggregation-induced emission (AIE) characteristics was developed based on a triphenylamine structure skeleton. MeTPAE can not only interact with histone deacetylases (HDACs) to inhibit cell proliferation but also damage telomere and nucleic acids precisely through photodynamic treatment (PDT). The cocktail strategy of MeTPAE caused obvious cell cycle arrest and showed excellent PDT anti-tumor activity, which offered new opportunities for the effective treatment of malignant tumors.

Enhanced antitumor effect of L-buthionine sulfoximine or ionizing radiation by copper complexes with 2,2´-biquinoline and sulfonamides on A549 2D and 3D lung cancer cell models

Two ternary copper(II) complexes with 2,2'-biquinoline (BQ) and with sulfonamides: sulfamethazine (SMT) or sulfaquinoxaline (SDQ) whose formulae are Cu(SMT)(BQ)Cl and Cu(SDQ)(BQ)Cl·CH₃OH, in what follows SMTCu and SDQCu, respectively, induced oxidative stress by increasing ROS level from 1.0 μM and the reduction potential of the couple GSSG/GSH². The co-treatment with L-buthionine sulfoximine (BSO), which inhibits the production of GSH, enhanced the effect of copper complexes on tumor cell viability and on oxidative damage. Both complexes generated DNA strand breaks given by-at least partially-the oxidation of pyrimidine bases, which caused the arrest of the cell cycle in the G2/M phase. These phenomena triggered processes of apoptosis proven by activation of caspase 3 and externalization of phosphatidylserine and loss of cell integrity from 1.0 μM. The combination with BSO induced a marked increase in the apoptotic population. On the other hand, an improved cell proliferation effect was observed when combining SDQCu with a radiation dose of 2 Gy from 1.0 μM or with 6 Gy from 1.5 μM. Finally, studies in multicellular spheroids demonstrated that even though copper(II) complexes did not inhibit cell invasion in collagen gels up to 48 h of treatment at the higher concentrations, multicellular resistance outperformed several drugs currently used in cancer treatment. Overall, our results reveal an antitumor effect of both complexes in monolayer and multicellular spheroids and an improvement with the addition of BSO. However, only SDQCu was the best adjuvant of ionizing radiation treatment.

Macrocyclic "tet a"-Derived Cobalt(III) Complex with a N,N'-Disubstituted Hexadentate Ligand: Crystal Structure, Photonuclease Activity, and as a Photosensitizer

A cobalt(III) complex, [Co(L)]Cl (complex 1, where L = 1,8-[N,N-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}]-1,4,8,11-tetraaza-5,5,7,12,12,14-hexamethylcyclotetradecane) with distorted octahedral geometry has been synthesized and characterized using various spectroscopic techniques. The structure of the ligand has remarkably rich hydrogen intermolecular interactions such as H···H, H···C/C···H, and H···O/O···H that vary with the presence of the metal ion, and the structure of complex 1 has Cl···H interactions; this result has been proved by Hirshfeld surface and two-dimensional (2D) fingerprint maps analyses. The complex exhibits a quasi-reversible Co(III)/Co(II) redox couple with E _1/2 = -0.76 V. Calf thymus DNA (CT DNA) binding abilities of the ligand and complex 1 were confirmed by spectroscopic and electrochemical analyses. According to absorption studies, the ligand and complex 1 bind to CT DNA via intercalative binding mode, with intrinsic binding strengths of 1.41 × 10³ and 8.64 × 10³ M^-1, respectively. A gel electrophoresis assay shows that complex 1 promotes the pUC19 DNA cleavage under dark and light irradiation conditions. Complex 1 has superior antimicrobial activity than the ligand. The cytotoxicity of complex 1 was tested against MDA-MB-231 breast cancer cells with values of IC₅₀ of 1.369 μg mL^-1 in the dark and 0.9034 μg mL^-1 after light irradiation. Besides, cell morphological studies confirmed the morphological changes with AO/EB dual staining, reactive oxygen species (ROS) staining, mitochondria staining, and Hoechst staining on MDA-MB-231 cancer cells by fluorescence microscopy. Complex 1 was found to be a potent antiproliferative agent against MDA-MB-231 cells, and it can induce mitochondrial-mediated and caspase-dependent apoptosis with activation of downregulated caspases. The biotoxicity assay of complex 1 on the development of Artemia nauplii was evaluated at an IC₅₀ value of 200 μg mL^-1 and with excellent biocompatibility.

Deciphering the sensing of α-amyrin acetate with hs-DNA: a multipronged biological probe

In this study, we focus on the biomimetic development of small molecules and their biological sensing with DNA. The binding of herring sperm deoxyribonucleic acid (hs-DNA) with naturally occurring bioactive small molecule α-amyrin acetate (α-AA), a biomimetic - isolated from the leaves of Ficus (F.) arnottiana is investigated. Collective information from various imaging, spectroscopic and biophysical experiments provides evidence that α-AA is a minor groove sensor of hs-DNA and preferentially binds to the A-T-rich regions. Interactions of different concentrations of small molecule α-AA with hsDNA were evaluated via various analytical techniques such as UV-Vis, circular dichroism (CD) and fluorescence emission spectroscopy. Fluorescence emission spectroscopy results suggest that α-AA decreases the emission level of hsDNA. DNA minor groove sensor Hoechst 33258 and intercalative sensor EB, melting transition analysis (T M) and viscosity analysis clarified that α-AA binds to hs-DNA via a groove site. Biophysical chemistry and molecular docking studies show that hydrophobic interactions play a major role in this binding. The present research deals with a natural product biosynthesis-linked chemical-biology interface sensor as a biological probe for α-AA: hs-DNA.

DNA binding, antitubercular, antibacterial and anticancer studies of newly designed piano-stool ruthenium(ii) complexes

The chemotherapeutic potential of ruthenium(ii) complexes as DNA binding, antitubercular, antibacterial, and anticancer agents.

Antibacterial Activity of Co(III) Complexes with Diamine Chelate Ligands against a Broad Spectrum of Bacteria with a DNA Interaction Mechanism

Cobalt coordination complexes are very attractive compounds for their therapeutic uses as antiviral, antibacterial, antifungal, antiparasitic, or antitumor agents. Two Co(III) complexes with diamine chelate ligands ([CoCl₂(dap)₂]Cl (1) and [CoCl₂(en)₂]Cl (2)) (where dap = 1,3-diaminopropane, en = ethylenediamine) were synthesized and characterized by elemental analysis, an ATR technique, and a scan method and sequentially tested against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration results revealed that anaerobic and microaerophilic bacteria were found to be the most sensitive; the serial passages assay presented insignificant increases in bacterial resistance to both compounds after 20 passages. The synergy assay showed a significant reduction in the MIC values of nalidixic acid when combined with Compounds (1) or (2). The assessment of cell damage by the complexes was performed using scanning electron microscopy, transmission electron microscopy, and confocal microscopy, which indicated cell membrane permeability, deformation, and altered cell morphology. DNA interaction studies of the Co(III) complexes with plasmid pBR322 using spectrophotometric titration methods revealed that the interaction between Complex (1) or (2) and DNA suggested an electrostatic and intercalative mode of binding, respectively. Furthermore, the DNA cleavage ability of compounds by agarose gel electrophoresis showed nuclease activity for both complexes. The results suggest that the effect of the tested compounds against bacteria can be complex.

DNA Binding and DNA Cleavage Activities of Newly Synthesized CoII and CuII Complexes of a β-Cyclodextrin Based Azo-Functionalized Schiff Base

Two water soluble complexes with CoII and CuII ions were synthesized using a novel β-cyclodextrin based azo-functionalized Schiff base as a ligand. The Schiff base and its metal complexes were characterized by different physico-chemical and spectroscopic methods. From the analyses of the experimental data, distorted octahedral geometry has been assigned for both the metal complexes. The binding interactions between the metal complexes and DNA were investigated by means of a thermal denaturation study and viscosity measurements as well as by electronic absorption and fluorescence spectroscopy. The DNA cleavage efficacy of the metal complexes was also studied by agarose gel electrophoresis using pBR DNA. These studies revealed that both the metal complexes followed an intercalative mode of binding to calf thymus (CT)-DNA and also effectively cleaved the supercoiled pBR DNA. The CoII complex, however, more efficiently cleaved CT-DNA than the CuII complex as much as the experimental results are concerned.

Synthesis and crystal structures of two new lead(II) complexes with the pincer-type ligand 4′-(4-chlorophenyl)-2,2′:6′,2″-terpyridine (Cl-Ph-tpy): subtle interplay of weak intermolecular interactions

A dinuclear and a tetranuclear complex of lead(II) with the pincer-type ligand 4′-(4-chlorophenyl)-2,2′:6′,2″-terpyridine (Cl-Ph-tpy), [Pb2(Cl-Ph-tpy)2(μ-I)2I2] (1) and [Pb4(Cl-Ph-tpy)4(μ-Br)4(μ-OH2)Br4]·2CH3OH (2), have been synthesized and characterized by elemental analysis, FT-IR and 1H NMR spectroscopy, and by single-crystal X-ray diffraction. In the binuclear structure of 1, the Pb atom has a hemidirected PbN3I3 environment with a Pb(μ-I)2Pb central unit. In the tetranuclear structure of 2, two crystallographically independent Pb(II) centres having hemidirected PbN3Br3 and PbN3OBr2 environments are connected to Pb(μ-Br)Pb(μ-Br)2(μ-OH2)Pb(μ-Br)Pb chains. The supramolecular features in 1 and 2 are supported through weak but directional C–H···Cl, C–H···I and C–H···Br, C–H···O, O–H···Br, and O···Br interactions and aromatic π-π stacking.

Copper (II)-based halogen-substituted chromone antitumor drug entities: Studying biomolecular interactions with ct-DNA mediated by sigma hole formation and cytotoxicity activity

Copper-based antitumor drug entities 1-3 derived from substituted (F^-, Br^-, -CH₃) 3-formylchromone pharmacophore were synthesized and thoroughly characterized by spectroscopic and single X-ray crystallographic studies. These complexes show structural novelty due to presence of the X-bonds in chromone scaffold which could facilitate higher propensity for nucleic acids via sigma σ-hole interactions. Therefore, structure-activity relationship of 1-3 was studied by performing ct-DNA binding, pBR322 cleavage and cytotoxicity activity to validate their potential to act as chemotherapeutic drug entities. The binding studies of 1-3 with ct- DNA were carried out employing many biophysical techniques and the corroborative results of these experiments showed intercalation mode of binding and the order of binding was found to be 2 > 1 > 3. The structure of drug entities could facilitated strong halogen bonding interaction (in case of 1 &2) and stability of X bond was rationalized by sigma hole region of positive electrostatic potential on the surface of C-X covalent bond, as determined by gas phase B3LYP computational DFT studies. Interestingly, 2 exhibited most avid binding affinity due to presence of Br^- electron withdrawing and polarizable group. Further, cleavage studies of 1-3 with pBR322 plasmid DNA were performed which demonstrated significant cleavage activity, the supercoiled form (Form I) of plasmid DNA was converted to nicked form (Form II) with the appearance of linearized form (Form III) in between two, implicating lethal double strand breaks of DNA. 2 showed predominantly higher cleavage activity following the similar trend as observed for binding studies. The cytotoxicity of the complexes 1-3 was evaluated by MTT assay against the human liver carcinoma (Huh-7) and prostate cancer (DU-145) cell lines; complex 2 exhibited specific and selective cytotoxicity for the DU-145 cancer cell line with LC₅₀ value of 1.6 μM.

Targeting an Artificial Metal Nuclease to DNA by a Simple Chemical Modification and Its Drastic Effect on Catalysis

A novel metal complex was synthesized containing a purine derived ligand in order to increase its binding to DNA. We observed a huge increase in nuclease activity and, quite interestingly, an improvement on DNA sequence selectivity. A potential site of specific cleavage in the presence of a reductant in the reaction medium is suggested. We were able to synthesize a novel metal nuclease with improved activity on DNA, and with sequence specificity when exposed to a coreactant, this opens up new possibilities to create site specific and redox status modulated artificial nucleases.

Synthesis, crystal structures, DFT studies, antibacterial assays and interaction assessments with biomolecules of new platinum(ii) complexes with adamantane derivatives

Synthesis, crystal structures and antibacterial activities of new Pt(ii) complexes with adamantane derivatives are presented in this article.

Structure elucidation {spectroscopic, single crystal X-ray diffraction and computational DFT studies} of new tailored benzenesulfonamide derived Schiff base copper(II) intercalating complexes: Comprehensive biological profile {DNA binding, pBR322 DNA cleavage, Topo I inhibition and cytotoxic activity}

New tailored copper(II)-based intercalating complexes [Cu(L1)2] (1) and [Cu(L2)2] (2) were synthesized from Schiff base scaffold HL1 and HL2(E)-4-(2-((2-hydroxy-3-methoxybenzylidene)amino)ethyl)benzenesulfonamide and (E)-4-(2-((2-hydroxybenzylidene)amino)ethyl)benzenesulfonamide, respectively. The structure elucidation of complexes 1 and 2 was carried out by employing various spectroscopic techniques viz., FT-IR, UV-vis, ESI-MS, EPR and single X-ray crystal diffraction studies. The complexes 1 and 2 were crystallized in monoclinic P21/n and triclinic P-1 space group, respectively possessing square planar geometry around Cu(II) coordinated with N,O-donor Schiff base ligands. An analysis of Hirshfeld surfaces of complexes 1 and 2 were performed to ascertain different intra and intermolecular non-covalent interactions (H-bonding, CH⋯ πetc.) responsible for the stabilization of crystal lattices. Calculations based on Density functional theory (B3LYP/DFT), have been carried out to obtain energies of Frontier molecular orbitals. Comparative in vitro binding profile of complexes 1 and 2 with ct-DNA was evaluated employing various biophysical techniques viz., UV-vis, fluorescence, circular dichroism and cyclic voltammetry which suggested non-covalent intercalative binding mode with more avid binding propensity of complex 1 compared to complex 2. The cleavage experiments of complex 1 was performed by gel electrophoretic assay which revealed efficient cleavage mediated via oxidative pathway. Furthermore, topoisomerase I enzymatic activity of complex 1 was carried out employing gel electrophoretic assay which demonstrated significant inhibitory effects at a low concentration of 25 µM. The cytotoxic potential of complex 1 was analyzed by SRB assay on a panel of selected human cancer cell lines which revealed selective activity for MCF-7 (breast cancer) cell line with GI50 = 16.21 µg/ml.

Homo- and heteroleptic trimethoxy terpyridine–Cu(ii) complexes: synthesis, characterization, DNA/BSA binding, DNA cleavage and cytotoxicity studies

In the current study, four novel mononuclear Cu(ii) complexes with terpyridine (L) and different co-ligands (phen, bipy, and imd) were synthesized and characterized in detail, whereLis 4′-(3,4,5-trimethoxyphenyl)-2,2′:6′,2′′-terpyridine.

In silico and in vitro studies of transition metal complexes derived from curcumin-isoniazid Schiff base

A series of transition metal complexes have been synthesized from biologically active curcumin and isoniazid Schiff base. They are characterized by various spectral techniques like UV-Vis, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) and mass spectroscopies. Moreover, elemental analysis, magnetic susceptibility and molar conductivity measurements are also carried out. All these data evidence that the metal complexes acquire square planar except zinc(II) which adopts a tetrahedral geometry, and they are non-electrolytic in nature. Groove mode of binding between the calf thymus DNA (CT DNA) and metal complexes is confirmed by electronic absorption titration, viscosity and cyclic voltammetry studies. In addition to that, all the metal complexes are able to cleave pUC 19 DNA. Optimized geometry and ground-state electronic structure calculations of all the synthesized compounds are established out by density functional theory (DFT) using B3LYP method which theoretically reveals that copper(II) complex explores higher stability and higher biological accessibility. This is experimentally corroborated by antimicrobial studies. In silico Absorption, Distribution, Metabolism, Excretion (ADME) studies reveal the biological potential of all synthesized complexes, and also biological activity of the ligand is predicted by PASS online biological activity prediction software. Molecular docking studies are also carried out to confirm the groove mode of binding and receptor-complex interactions.

K, Bodke YD, Malojirao VH, T. R. RN, Kandagalla S, B. T. P. Synthesis, characterization and tumor inhibitory activity of a novel Pd(ii) complex derived from methanethiol-bridged (2-((1H-benzo[d]imidazol-2-yl)methylthio)-1H-benzo[d]imidazol-6-yl)(phenyl)methanone

This manuscript demonstrates the synthesis and tumor inhibitory activity of (2-((1H-benzo[d]imidazol-2-yl)methylthio)-1H-benzo[d]imidazol-6-yl)(phenyl)methanone and its Pd(ii) complex.

Synthesis, characterization, photoluminescence, anti-tumor activity, DFT calculations and molecular docking with proteins of zinc(ii) halogen substituted terpyridine compounds

Study on the synthesis, characterization, photoluminescence and anti-tumor activity of a series of zinc(ii) halogen substituted terpyridine complexes.