Evaluation of DNA binding, DNA cleavage, protein binding and in vitro cytotoxic activities of bivalent transition metal hydrazone complexes

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.

Synthesis, characterization, and BSA binding studies of newfangled 2-phenylacetohydrazide derivatives

Five 2-phenylacetohydrazide derivatives (BPAH = N'-benzylidene-2-phenylacetohydrazide, HBPAH = N'-(2-hydroxybenzylidene)-2-phenylacetohydrazide), PPAH = 2-phenyl-N'-3-phenylallylideneacetohydrazide, FMPAH = N'-(furan-2-ylmethylene)-2-phenylaceto hydrazide and EPAH = N'-ethylidene-2-phenylacetohydrazide were synthesized by the condensation of 2-phenylacetohydrazide with the corresponding aldehyde. The synthesized compounds were characterized by FTIR, 1D, and 2D NMR spectroscopy. The structure of the BPAH and PPAH were analyzed by single crystal X-ray diffraction analysis and in both crystallized compounds, the molecules adopted trans geometry around the -C[bond, double bond]N- (imine) functional group. To explore the pharmacological significance of these compounds, the binding ability of these compounds with Bovine Serum Albumin (BSA) was investigated using fluorescence spectroscopy. BPAH and PPAH showed the highest binding ability while EPAH, HBPAH, and FMPAH had lower binding ability to BSA molecules. Thermodynamic parameters ΔG, ΔH°, and ΔS° demonstrated that interactions of BSA with compounds BPAH, EPAH, FMAH, and HBPAH were exothermic while for PPAH it was endothermic. The negative enthalpy and entropy of the compounds BPAH, EPAH, FMAH, and HBPAH indicated that van der Waals' forces and hydrogen bonding played a major role in stabilizing the BSA binding with the molecules. Hydrophobic interactions were predominant in the binding of PPAH with BSA tends to interact with two sets of BSA binding sites with an increase in temperature.

Probing the interaction of uranyl(VI) complex with bovine serum albumin via in-depth experimental and computational perspectives

Interaction aspects of uranyl(VI) complexes as well as the coordinated ONNO-donor ligand with bovine serum albumin (BSA) were investigated by the fluorescence spectroscopy and computational insights. Under optimal physiological condition, it was observed that there was significant decrease in fluorescence intensity of BSA upon interaction with uranyl(VI) complexes as well as the ligand. The mechanism of interaction between the uranyl(VI) complex and BSA protein was examined by fluorescence measurement. The Stern-Volmer constant, binding affinity, binding constant, standard free energy, and fluorescence lifetime decay profile of BSA in the absence as well as in the presence of uranyl(VI) complex were determined. Furthermore, the conformational binding of uranyl(VI) complexes with BSA protein was explored via molecular docking studies, and confirmed that there is a strong affinity between the Trp-213 residue in the binding pocket of sub-domain IIA and uranyl(VI) complex.

A novel Cu(II)-based DNA-intercalating agent: Structural and biological insights using biophysical and in silico techniques

A new mixed-ligand Cu(II) complex formulated as [Cu(dipic)(amp)(H₂O)].H₂O (dipic: pyridine-2,6-dicarboxylic acid, amp: 2-amino-4-methylpyridine), was synthesized and structurally characterized by FTIR spectroscopy, CHN analysis, and the single-crystal X-ray crystallographic method. The complex crystallizes in an orthorhombic space group Pna2_1, and the coordination environment around the metal center was found to be a pentacoordinate CuN₂O₂O_W distorted square-pyramidal geometry. In order to systematically explore a detailed in vitro and in silico study of the DNA binding of the title complex, various biophysical (UV-Vis absorption spectroscopy, fluorescence, competitive binding with ethidium bromide) and theoretical (DFT, molecular docking simulation, and QM/MM) methods were applied which revealed that the complex could intercalate with the insertion of the amp ligand between the DNA base pairs. The experimental thermodynamic parameters of the interaction revealed the spontaneity of the process and the domination of the hydrophobic interactions in the association and stabilization of the DNA-Cu(II) complex adduct, which was in line with the docking and QM/MM data. In vitro cytotoxic potential of the complex against the human breast adenocarcinoma (MCF-7) cells was examined using MTT assay, which indicated that cancerous cells showed inhibition in presence of the complex.

Nano zinc Oxide-Ruthenium (III) complex of novel coumarin derivative: Synthesis, Characterization, DNA Cleavage, anticancer and bioimaging activities

The uniqueness of nanofunctionalized metal complexes would play a prominent role in medicinal chemistry, especially in cancer chemotherapy. Among the metal based chemotherapeutic drugs, ruthenium complexes exhibit different oxidation states, lower toxicity and remarkable antitumor activities than other anticancer drugs. In this investigation bioactive ruthenium(III) complex has been synthesized from novel coumarin derivative and it is functionalized with nanostructured zinc oxide (ZnO) under well defined condition. An octahedral geometry is proposed for the ruthenium complex based on analytical and spectrochemical characterization techniques (UV, FT-IR and NMR). The g|| and g⊥ values obtained from the ESR spectrum indicated high symmetry and octahedral field around ruthenium ion. The XRD patterns of all synthesized compounds explicit average particle sizes are nanometer range. The morphology and particle size of Nano ZnO-Ru(III) complex is also confirmed by using SEM and TEM analysis. The nanofunctionalized material exhibited enhanced fluorescence emissions at 674 nm and 681 nm. The evaluation of DNA cleavage study indicated compounds were effectively cleaved supercoiled pUC18 DNA by gel electrophoresis method. The examinations of in-vitro anticancer activities of compounds were studied against human breast (MCF-7) and leukemia (K-562) cancer cell lines. The ruthenium complex showed greater effect against MCF-7 with < 10 IC50 value. Nowadays, the cell imaging property of nanofunctionalized materials receive more attention. The fluorescence microscopic images of Nano ZnO-Ru(III) complex displayed higher luminescence at 100 μg/ mL against L6 rat skeletal muscle cell line.

The biological functions of europium-containing biomaterials: A systematic review

The biological functions of rare-earth elements (REEs) have become a focus of intense research. Recent studies have demonstrated that ion doping or alloying of some REEs can optimize the properties of traditional biomaterials. Europium (Eu), which is an REE with low toxicity and good biocompatibility, has promising applications in biomedicine. This article systematically reviews the osteogenic, angiogenic, neuritogenic, antibacterial, and anti-tumor properties of Eu-containing biomaterials, thereby paving the way for biomedical applications of Eu. Data collection for this review was completed in October 2022, and 30 relevant articles were finally included. Most articles indicated that doping of Eu ions or Eu-compound nanoparticles in biomaterials can improve their osteogenic, angiogenic, neuritogenic, antibacterial, and anti-tumor properties. The angiogenic, antibacterial, and potential neuritogenic effects of Eu(OH)₃ nanoparticles have also been demonstrated.

Interaction with bioligands and in vitro cytotoxicity of a new dinuclear dioxido vanadium(V) complex

One centrosymmetric bis(μ-oxido)-bridged vanadium(V) dimer with molecular formula [(V^VO₂)₂(pedf)₂] (1) has been synthesized from the reaction of VOSO₄·5H₂O with a Schiff base ligand (abbreviated with pedf^-) obtained from 2-acetylpyridine and 2-furoic hydrazide in methanol. Complex 1 was characterized by elemental analysis, UV-visible (UV-Vis), Fourier-transform infrared spectra (FT-IR), cyclic voltammetry (CV), electron paramagnetic resonance spectroscopy (EPR) and electrospray ionization-mass spectrometry (ESI-MS) techniques along with single crystal X-ray diffraction (SCXRD). The FT-IR spectral data of 1 indicated the involvement of oxygen and azomethine nitrogen in coordination to the central metal ion. The crystallographic studies revealed a dinuclear oxovanadium(V) complex with the Schiff base coordinated via the ONN donor set with formation of two five-membered chelate rings resulting in a distorted octahedral geometry. The interaction of 1 with calf thymus DNA (CT-DNA) was investigated by spectroscopic measurements and results suggested that the complex binds to CT-DNA via moderate intercalative mode with a binding constant (K_b) around 10³ M^-1. In addition, the in vitro protein binding behavior was studied by fluorescence spectrophotometric method using both bovine serum albumin (BSA) and human serum albumin (HSA) and a static quenching mechanism was observed for the interaction of the complex with both albumins that occurs with a K_b in the range (5-6) × 10³ M^-1. In vitro cytotoxicity of complex 1 on lung cancer cells (A549) and human skin carcinoma cell line (A431) demonstrated that the complex had a broad-spectrum of anti-proliferative activity with IC₅₀ value of 64.2 μM and 56.2 μM.

Synthesis and characterization of violurate - based Mn(II) and Cu(II) complexes nano-crystallites as DNA-binders and therapeutics agents against SARS-CoV-2 virus

Synthesis and structural characterization of nano crystallites of bis-violurate-based manganese(II) and copper(II) chelates is the subject of the present study. Analytical data and mass spectra as well as thermal analysis determined the molecular formulas of the present metal chelates. Spectroscopic and magnetic measurements assigned the structural formula of the present violurate metal complexes. The spectroscopic and magnetic investigations along with structural analysis results indicated the square planar geometry of both the Mn(II) and Cu(II) complexes. The structural analysis of the synthesized metal complexes was achieved by processing the PXRD data using specialized software Expo 2014. Spectrophotometeric and viscosity measurements showed that violuric acid and its Mn(II) and Cu(II) complexes successfully bind to DNA with intrinsic binding constants K_b from 38.2 × 10⁵ to 26.4 × 10⁶ M⁻¹. The antiviral activity study displayed that the inhibitory concentrations (IC₅₀) of SARS-CoV-2 by violuric acid and its Mn(II) and Cu(II) complexes are 84.01, 39.58 and 44.86 μM respectively. Molecular docking calculations were performed on the SARS-CoV-2 virus protein and the computed binding energy values are −0.8, −3.860 −5.187 and −4.790, kcal/mol for the native ligand, violuric acid and its Mn(II) and Cu(II) complexes respectively. Insights into the relationship between structures of the current compounds and their degree of reactivity are discussed.

Design, synthesis, and biological evaluation of dinuclear bismuth(III) complexes with Isoniazid-derived Schiff bases

Four dinuclear bismuth(III) Schiff-base complexes bearing Schiff-base ligands have been synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis, and spectral techniques (FT-IR, NMR and MS). The analytical data reveal the bismuth(III) complexes possess 1:1 metal-ligand ratios. In vitro biological studies have revealed that bismuth(III) complexes displayed much higher antibacterial and antitumor activities than their parent ligands, which involves two gram-negative (S. aureus, B. subtili) and two gram-positive (E. coli, P. aeruginosa) bacteria, and human gastric cancer SNU-16 cells. The power-time curves of S. pombe exposed to tested compounds were detected by bio-microcalorimetry. Some thermokinetic parameters (k, P_max,t_G and Q_total) were derived based on the metabolic power-time curves, and their quantitative relationships with the concentrations (c) were further discussed.

Mo(VI) Potential Metallodrugs: Explaining the Transport and Cytotoxicity by Chemical Transformations

The transport and cytotoxicity of molybdenum-based drugs have been explained with the concept of chemical transformation, a very important idea in inorganic medicinal chemistry that is often overlooked in the interpretation of the biological activity of metal-containing systems. Two monomeric, [MoO₂(L¹)(MeOH)] (1) and [MoO₂(L²)(EtOH)] (2), and two mixed-ligand dimeric Mo^VIO₂ species, [{MoO₂(L^1-2)}₂(μ-4,4'-bipy)] (3-4), were synthesized and characterized. The structures of the solid complexes were solved through SC-XRD, while their transformation in water was clarified by UV-vis, ESI-MS, and DFT. In aqueous solution, 1-4 lead to the penta-coordinated [MoO₂(L^1-2)] active species after the release of the solvent molecule (1 and 2) or removal of the 4,4'-bipy bridge (3 and 4). [MoO₂(L^1-2)] are stable in solution and react with neither serum bioligand nor cellular reductants. The binding affinity of 1-4 toward HSA and DNA were evaluated through analytical and computational methods and in both cases a non-covalent interaction is expected. Furthermore, the in vitro cytotoxicity of the complexes was also determined and flow cytometry analysis showed the apoptotic death of the cancer cells. Interestingly, μ-4,4'-bipy bridged complexes 3 and 4 were found to be more active than monomeric 1 and 2, due to the mixture of species generated, that is [MoO₂(L^1-2)] and the cytotoxic 4,4'-bipy released after their dissociation. Since in the cytosol neither the reduction of Mo^VI to Mo^V/IV takes place nor the production of reactive oxygen species (ROS) through Fenton-like reactions of 1-4 with H₂O₂ occurs, the mechanism of cytotoxicity should be attributable to the direct interaction with DNA that happens with a minor-groove binding which results in cell death through an apoptotic mechanism.

Stimulation of Sulfonamides Antibacterial Drugs Activity as a Result of Complexation with Ru(III): Physicochemical and Biological Study

Antibiotic resistance is a global problem, and one promising solution to overcome this issue is using metallodrugs, which are drugs containing metal ions and ligands. These complexes are superior to free ligands in various characteristics including anticancer properties and mechanism of action. The pharmacological potential of metallodrugs can be modulated by the appropriate selection of ligands and metal ions. A good example of proper coordination is the combination of sulfonamides (sulfamerazine, sulfathiazole) with a ruthenium(III) ion. This work aimed to confirm that the activity of sulfonamides antibacterial drugs is initiated and/or stimulated by their coordination to an Ru(III) ion. The study determined the structure, electrochemical profile, CT-DNA affinity, and antimicrobial as well as anticancer properties of the synthesized complexes. The results proved that Ru(III) complexes exhibited better biological properties than the free ligands.

Exploring the Noncovalent Interactions of the Dinuclear Cu(II) Schiff Base Complex with Bovine Serum Albumin and Cell Viability against the SiHa Cancer Cell Line

In the present study, a dinuclear bis(μ-acetate) dicopper(II) complex [Cu₂L₂(μ_1.1-CH₃COO^-)₂] has been synthesized from a tridentate NNO Schiff Base ligand L (L = 2,4-dibromo-6-((3-(methylamino)propylimino)methyl)phenol) and characterized by elemental, ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR), ¹H NMR, and electrospray ionization-mass spectrometry (ESI-MS) spectroscopic studies. The single-crystal X-ray structure, different noncovalent interactions, Hirshfeld surface analysis, and density functional theory (DFT) studies of the dinuclear complex were determined by crystallographic computational studies. The structural study exposed that the complex consists of the penta-coordinated double μ_1.1-acetato-bridged dinuclear units of Cu(II), and it is a centrosymmetric dimer in which the center of inversion lies at the midpoint of two Cu(II) ions. Hirshfeld surface and DFT studies pointed out the probable potentiality of the crystal in prospective binding with the protein. This was experimentally verified by carrying out the binding interaction studies against bovine serum albumin (BSA) protein using various spectroscopic methods. It was observed that the copper(II) complex could strongly bind to BSA and could quench the intrinsic fluorescence of BSA. Further, the studied complex was appraised for cell viability studies against SiHa cancer cells. It is observed that cell viability increases with time, demonstrating the biocompatible nature of the complex.

Investigation of bovine serum albumin aggregation upon exposure to silver(i) and copper(ii) metal ions using Zetasizer

Depending upon the metal coordination capacity and the binding sites of proteins, interaction between metal and proteins leads to a number of changes in the protein molecule which may include the change in conformation, unfolding, overall charge, and aggregation in some cases. In this study, Cu(ii) and Ag(i) metal ions were selected to investigate aggregation of bovine serum albumin (BSA) molecule upon interaction by measuring the size and charge of the aggregates using nano-Zetasizer instrument. Two concentrations of metal ions were made to interact with a specific concentration of BSA and the size and zeta potential of BSA aggregates were measured from 0 min upto 18 h. The Cu(ii) and Ag(i) metal ions showed almost similar behavior in inducing the BSA aggregation and the intensity of peak corresponding to the normal-sized protein decreased with time, whereas the peak corresponding to the protein aggregate increased. However, the effect on zeta potential of the aggregates was observed to be different with both metal ions. The aggregation of protein due to interaction of different metal ions is important to study as it gives insight to the pathogenesis of many neurological disorders and would result in developing effective ways to limit their exposure.

Spectroscopic and Small-angle X-ray scattering analysis of binding between Copper(II) -1-allylimidazole complex, a potential anti-tumor agent, and bovine serum albumin

Interactions between transport proteins and compounds with therapeutic potential are pharmacologically important. In this study, using fluorescence, circular dichroism (CD), and small-angle X-ray Scattering (SAXS), we investigated the interaction between bovine serum albumin (BSA) and a copper(II)-1-allylimidazole complex with potential anti-cancer properties. The results revealed dynamic fluorescence quenching of the model carrier protein BSA by the copper(II) complex. The enthalpy change (ΔH), free energy (ΔG), and entropy change (ΔS) were calculated to be 108 kJ/mol, -16.47 kJ/mol, and 419 J/mol K, respectively, according to the Van't Hoff equation. The reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in binding. The results indicate a much lower affinity (K_b ∼ 10²-10³) for the metal complex compared with similar compounds (K_b ∼ 10³-10⁵). CD showed that the studied copper(II) complex does not change the secondary structure of the protein, while SAXS showed that the this compound may attach to the protein surface and stimulate interactions between proteins. The results suggest that the copper(II) complex with 1-allylimidazole binds weakly to BSA, leading to aggregation of albumin in solution, thereby altering its pharmacokinetic properties. The findings are pertinent to drug design.

Protein binding and cytotoxic activities of monomeric and dimeric oxido-vanadium(V) salan complexes: Exploring the solution behavior of monoalkoxido-bound oxido-vanadium(V) complex

Three ONNO donor tetradentate diamino bis(phenolato) "salan" ligands, N, N'-dimethyl-N, N'-bis-(5-chloro-2-hydroxy-3-methyl-benzyl)-1,2-diaminoethane (H₂L¹), N, N'-dimethyl-N, N'-bis-(5-chloro-2-hydroxy-3-isopropyl-6-methyl-benzyl)-1,2-diamino-ethane (H₂L²) and N, N'-bis-(5-chloro-2-hydroxy-3-isopropyl-6-methyl-benzyl)-1,2-diaminocyclohexane (H₂L³) have been synthesized by following Mannich condensation reaction. Reaction of these ligands with their corresponding vanadium metal precursors gave one oxidomethoxidovanadium(V) [V^VOL¹(OCH₃)] (1) and two monooxido-bridged divanadium (V, V) complexes [V^VOL^2-3]₂(μ-O) (2-3). The complexes were characterized by IR, UV-vis, NMR and ESI mass spectrometry. Also, the structure of all the complexes (1-3) was confirmed by the Single-Crystal X-ray diffraction analysis, which revealed a distorted octahedral geometry around the metal centres. The solution behavior of the [V^VOL¹(OCH₃)] (1) reveals the formation of two different types of V(V) species in solution, the structurally characterized compound 1 and its corresponding monooxido-bridged divanadium (V, V) complex [V^VOL¹]₂(μ-O), which was further studied by IR, and NMR spectroscopy. The electrochemical behavior of all the complexes was evaluated through cyclic voltammetry. Interaction of the salan-V(V) complexes with human serum albumin (HSA) and bovine serum albumin (BSA) were analysed through fluorescence quenching, UV-vis absorption titration, synchronous fluorescence, circular dichroism studies, and förster resonance energy transfer (FRET). Finally, the in vitro cytotoxicity of the complexes was investigated against MCF-7 and HT-29 and NIH-3T3 cell lines. Cytotoxicity value of complexes in both MCF-7 and HT-29 follows the same trend that is 3 > 1 > 2 which is in line with protein binding affinity of the complexes.

Study of DNA Interaction and Cytotoxicity Activity of Oxidovanadium(V) Complexes with ONO Donor Schiff Base Ligands

Two new oxidovanadium(V) complexes, (HNEt3)[VVO2L] (1) and [(VVOL)2μ-O] (2), have been synthesized using a tridentate Schiff base ligand H2L [where H2L = 4-((E)-(2-hydroxy-5-nitrophenylimino)methyl)benzene-1,3-diol] and VO(acac)2 as starting metal precursor. The ligand and corresponding metal complexes are characterized by physicochemical (elemental analysis), spectroscopic (FT-IR, UV–Vis, and NMR), and spectrometric (ESI–MS) methods. X-ray crystallographic analysis indicates the anion in salt 1 features a distorted square-pyramidal geometry for the vanadium(V) center defined by imine-N, two phenoxide-O, and two oxido-O atoms. The interaction of the compounds with CT–DNA was studied through UV–Vis absorption titration and circular dichroism methods. The results indicated that complexes showed enhanced binding affinity towards DNA compared to the ligand molecule. Finally, the in vitro cytotoxicity studies of H2L, 1, and 2 were evaluated against colon cancer (HT-29) and mouse embryonic fibroblast (NIH-3T3) cell lines by MTT assay. The results demonstrated that the compounds manifested a cytotoxic potential comparable with clinically referred drugs and caused cell death by apoptosis.

Synthesis, characterization and utility of a series of novel copper(II) complexes as excellent surface disinfectants against nosocomial infections

Nosocomial infections are among the major public health concerns, especially during the ongoing Covid19 pandemic. There is a great demand for novel chemical agents that are capable of killing specific pathogens or augmenting the efficiency of existing disinfectants. Herein, we report the synthesis and comprehensive characterization (through FT-IR, HR-MS, SEM, TGA-DSC, CV, UV and SCXRD analyses) of six novel copper(ii) complexes, [CuL(4X-An)] (5a-5d), [CuL(An)] (5e), and [CuL(benzhydrylamine)] (5f), and their evaluation as anti-microbial agents against WHO priority pathogens, confirming their possible use in hospital settings. The compounds were synthesized with a Schiff base (H2L) obtained by the condensation reaction of 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (DHA) and benzohydrazide and further addition of different p-substituted aniline (An) molecules. Single crystal structure analyses revealed that the aniline derivatives are isostructural to the copper atom in a square planar coordination, while the benzhydrylamine complex forms a dimer (5f), with a square pyramidal coordination geometry for the metal. Time-kill kinetics and reduced microbial recovery studies revealed excellent bactericidal action against Staphylococcus aureus and Enterococcus faecalis. Particularly, the novel compound 5f significantly reduced microbial recovery compared to ethanol-based sanitisers. In fact, addition of 5f to 70% ethanol remarkably synergized the killing with >6-log reduction in microbial burden. Overall, our novel compounds would increase the disinfection efficacy in hospitals and industries, thereby improving the efficiency and minimizing the risk of infections.

Selective anticancer activities of ruthenium(II)-tetrazole complexes and their mechanistic insights

Ruthenium-based metallotherapeutics is an interesting alternative for platinum complexes acting as anticancer agents after the entry of KP1019, NAMI-A, and TLD1339 in clinical trials. Herein, we have synthesized three new arene ruthenium(II)-tetrazole complexes viz. [Ru₂(η⁶-p-cymene)₂(2-pytz)₂Cl₂] (1), [Ru₂(η⁶-p-cymene)₂(3-pytz)Cl₃] (2), [Ru₂(η⁶-p-cymene)₂(4-pytz)Cl₃] (3) [2-pytzH = 2-pyridyl tetrazole; 3-pytzH = 3-pyridyl tetrazole; 4-pytzH = 4-pyridyl tetrazole] which have been characterized by different analytical techniques. To aid the understanding of the complex formation, reactions of the arene ruthenium(II) dimer with tetrazoles were investigated using the first principles-based Density Functional Theory (DFT) B3LYP method. Electronic structures, equilibrium geometries of the reactants and products with the first-order saddle points, reactions mechanism, the changes of enthalpy (∆H) and free energy (∆G), chemical stability, and reaction barriers of the complexes were computed using the B3LYP DFT approach. The in vitro cytotoxicity of these complexes was investigated by MTT assay on different cancer cell lines which reveal complex 2 as the most significant cytotoxic agent toward the HeLa cell line. The complexes have also shown a strong binding affinity towards CT-DNA and albumin proteins (HSA and BSA) as analyzed through spectroscopic techniques. Investigation of the mechanism of cell death by complex 2 was further performed by various staining techniques, flow cytometry, and gene expression analysis by RT-PCR. Inhibition of cell migration study has been also revealed the possibility of complex 2 to act as a prospective anti-metastatic agent.

Synthesis, characterization and anticancer activity of Fe(II) and Fe(III) complexes containing N-(8-quinolyl)salicylaldimine Schiff base ligands

A series of Fe(II) complexes (1-4) and Fe(III) complexes (5-8) from Fe(II)/(III) chloride and N-(8-quinolyl)-X-salicylaldimine Schiff base ligands (Hqsal-X₂/X: X = Br, Cl) were successfully synthesized and characterized by spectroscopic (FT-IR, ¹H-NMR), mass spectrometry, thermogravimetric analysis (TGA), and single crystal X-ray crystallographic techniques. The interaction of complexes 1-8 with calf thymus DNA (CT-DNA) was determined by UV-Vis and fluorescence spectroscopy. The complexes exhibited good DNA-binding activity via intercalation. The molecular docking between a selected complex and DNA was also investigated. The in vitro anticancer activity of the Schiff base ligands and their complexes were screened against the A549 human lung adenocarcinoma cell line. The complexes showed anticancer activity toward A549 cancer cells while the free ligands and iron chloride salts showed no inhibitory effects at 100 µM. In this series, complex [Fe(qsal-Cl₂)₂]Cl 6 showed the highest anticancer activity aginst A549 cells (IC₅₀ = 10 µM). This is better than two well-known anticancer agents (Etoposide and Cisplatin). Furthermore, the possible mechanism for complexes 1-8 penetrating A549 cells through intracellular ROS generation was investigated. The complexes containing dihalogen substituents 1, 2, 5, and 6 can increase ROS in A549 cells, leading to DNA or macromolecular damage and cell-death induction.

Interaction of Conazole Pesticides Epoxiconazole and Prothioconazole with Human and Bovine Serum Albumin Studied Using Spectroscopic Methods and Molecular Modeling

The interactions of epoxiconazole and prothioconazole with human serum albumin and bovine serum albumin were investigated using spectroscopic methods complemented with molecular modeling. Spectroscopic techniques showed the formation of pesticide/serum albumin complexes with the static type as the dominant mechanism. The association constants ranged from 3.80 × 104-6.45 × 105 L/mol depending on the pesticide molecule (epoxiconazole, prothioconazole) and albumin type (human or bovine serum albumin). The calculated thermodynamic parameters revealed that the binding of pesticides into serum albumin macromolecules mainly depended on hydrogen bonds and van der Waals interactions. Synchronous fluorescence spectroscopy and the competitive experiments method showed that pesticides bind to subdomain IIA, near tryptophan; in the case of bovine serum albumin also on the macromolecule surface. Concerning prothioconazole, we observed the existence of an additional binding site at the junction of domains I and III of serum albumin macromolecules. These observations were corroborated well by molecular modeling predictions. The conformation changes in secondary structure were characterized by circular dichroism, three-dimensional fluorescence, and UV/VIS absorption methods.

Experimental and theoretical investigation of water-soluble silicon(IV) phthalocyanine and its interaction with bovine serum albumin

Photodynamic therapy (PDT) has drawn a great scientific attention to cancer treatment over the last decades. However, the bottleneck for the PDT is to find good photosensitizers (PSs) with greater water solubility, no aggregation, and fast discharge from the body. Therefore, there are still a big scientific desire for the synthesizing new rational PSs for treatment of cancer by PDT technique. In favor of improving the competence of PDT, an axially bis[4-(diphenylamino-1,1'-biphenyl-4-ol)] substituted silicon(IV) phthalocyanine (3) was converted to its water-soluble quaternized derivative (3Q). Their structures were fully characterized by single-crystal X-ray diffraction, elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF, and ¹H-NMR. The photophysical properties such as fluorescence quantum yields and lifetimes, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated. Ground and excited-state calculations were performed to explain the observed electronic absorption spectra. The addition of the 4-diphenylamino-1,1'-biphenyl-4-ol groups on the axially positions of the silicon(IV) phthalocyanine increased the singlet oxygen quantum yield from 0.15 to around 0.20. Especially quaternized compound 3Q showed high singlet oxygen quantum yield of 0.26 in water solution. In addition, a spectroscopic investigation of the binding behavior of the quaternized silicon (IV) phthalocyanine complex to bovine serum albumin (BSA) is also studied in this work, confirming the possible interaction. Further theoretical calculations were carried out to find out the plausible-binding regions of the BSA protein. Axially bis[4-(diphenylamino-1,1'-biphenyl-4-ol)] substituted silicon(IV) phthalocyanine (3) was converted to its quaternized water soluble derivative (3Q). The photophysical properties such as fluorescence quantum yields and lifetimes, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated. In addition, a spectroscopic investigation of the binding behavior of the quaternized silicon (IV) phthalocyanine complex to bovine serum albumin (BSA) is also studied in this work, confirming the possible interaction. Further theoretical calculations were carried out to find out the plausible binding regions of the BSA protein.

Synthesis of Pt(II) complexes of the type [Pt(1,10-phenanthroline)(SArFn)2] (SArFn = SC6H3-3,4-F2; SC6F4-4-H; SC6F5). Preliminary evaluation of their in vitro anticancer activity

A series of Pt(II) complexes of the type [Pt(1,10-phenanthroline)(SArF_n)₂] (SArF_n = SC₆H₃-3,4-F₂(1); SC₆F₄-4-H (2); SC₆F₅(3)) were synthesized from [Pt(1,10-phenanthroline)(Cl)₂] and [Pb(SArF_n)₂] via metathesis reactions. The complexes were fully characterized including the unambiguous determination of their molecular structures by single-crystal X-ray diffraction techniques, showing the metal centers to be into a slightly distorted square-planar environments. The in vitro cytotoxic activity of the complexes was evaluated on six cancerous cell lines, i.e: glial cells of nervous central system (U-251), prostate (PC-3), leukemia (K-562), colon (HCT-15), breast (MCF-7) and lung (SKLU-1); we also included a healthy cell line of COS-7 (African green monkey kidney) for comparative purposes. We found that complex 2 was selective for PC-3. In addition, the IC₅₀ values for the series of complexes were determined using the U-251, HCT-15 and SKLU-1 cancerous cell lines, as well as in the healthy cell line (COS-7), where complex 1 exhibited the best activity, with IC₅₀ values going from 4.56 to 4.78 μM. These studies where further complemented with DNA docking theoretical calculations and DNA affinity experiments.