Interaction of mixed ligand copper(II) complexes with CT DNA and BSA: Effect of primary ligand hydrophobicity on DNA and protein binding and cleavage and anticancer activities

In-silico and in-detail experimental interaction studies of new antitumor Zn(II) complex with CT-DNA and serum albumin

In this study, a novel Zn(II) complex with the formula [Zn(pyrr-ac)2] (pyrr-ac: pyrrolidineacetate) was synthesized and characterized through molar conductivity, elemental analysis, 1H Nuclear Magnetic Resonance (1H NMR), UV-Visible spectroscopy, and Fourier transform infrared (FT-IR) methods. B3LYP level of DFT method along with aug-cc-pVTZ-PP/6-311G(d,p) basis set was utilized to perform the geometry optimization and HOMO-LUMO analysis. In addition, MEP, NLO and NBO computations were also performed at the same level of theory. In vitro antitumor activity of the mentioned complex on leukemia cell line, K562, was investigated using the MTT assay which surprisingly revealed the effective antitumor activity of the studied zinc complex. Interaction of this compound with biological macromolecules viz., CT-DNA and BSA was studied via different spectroscopic methods. The results of fluorescence experiment displayed that the metal complex binds to both macromolecules through hydrogen bond (H-bond) and van der Waals (vdW) forces. UV-Vis tests indicated a decline in the absorption spectra of CT-DNA/BSA in the presence of the compound. The interaction was further corroborated for CT-DNA via gel electrophoresis, CD spectroscopy and viscosity experiments and for BSA using CD spectroscopy. Furthermore, molecular docking simulation was done to evaluate the nature of interaction between the aforementioned zinc complex and CT-DNA/BSA. These results were in agreement with experimental findings and demonstrated that the main interaction is hydrogen bonding. The above type of investigations may provide a pathway through which zinc complexes join the anticancer category.[Figure: see text]The in-silico and in-vitro results confirm that the newly made [Zn(pyrr-ac)2] complex interacts with CT-DNA than BSA.Communicated by Ramaswamy H. Sarma.

Study of novel bidentate heterocyclic amine-based metal complexes and their biological activities: cytotoxicity and antimicrobial activity evaluation

Metallic antitumor drugs with heterocyclic ligands, such as novel AMI (amino methyl imidazole) complexes [Pd(AMI)Cl₂](1), [Cu(AMI)L¹](2), and [Cu(AMI)L²·2H₂O](3) where L¹ = oxalate and L² = malonate, were synthesized and characterized. Assessments included elemental analyses, mass spectrometry, Fourier transform-infrared spectroscopy, ultraviolet-visible spectroscopy, and thermal analysis. The cytotoxicity of AMI complexes compared to cisplatin was assessed using MTT (3-[4,5-dimethylthiazol-2-yl] 2,5diphenyl tetrazolium bromide) assay with breast (MCF-7) and cervical (HeLa) cancer cell lines. After treating these cells with the AMI complexes' IC₅₀ values for 48 h, malondialdehyde levels and catalase activity were used to assess oxidative stress, antioxidant activity was evaluated with DPPH radical scavenging method, comet assays assessed DNA damage, and DNA fragmentation was evaluated using the gel electrophoresis. In vitro, antimicrobial activity was assessed using a disc diffusion method. The anticancer activity results showed that IC₅₀ (half-maximal inhibitory concentration) values of complex one, two, and three against MCF-7 and HeLa cancer cells are 0.156 ± 0.0006, 0.125 ± 0.001, 0.277 ± 0.002 μM respectively for MCF-7 cells and 0.222 ± 0.0005, 0.126 ± 0.0009, 0.152 ± 0.001 μM respectively for HeLa cells. Complex two demonstrated strong anticancer activity against MCF-7 and Hela cells. The study of oxidative stress parameters revealed that Malondialdehyde levels increased in cancer cell lines treated with complexes compared to untreated cells. Catalase activity decreased in cells treated with palladium chelate. The DPPH radical scavenging assay results identified that complex one was a more potent antioxidant in MCF-7 and Hela cells than other complexes with SC₅₀ values of 227.5 ± 0.28 and 361 ± 1.2 μL/mL, respectively. The comet assay results showed that complex two caused significant DNA damage in MCF-7 and HeLa cancer cells treated. Antimicrobial assays identified complex three as the most effective. Copper complexes give better antifungal activity against A. flavus than the palladium complex. We conclude that complex two is the most active in both cell types and might be assessed as a clinically useful drug for breast cancer treatment. The significance of the current study is the synthesis of antitumor drugs containing heterocyclic ligands, such as novel AMI complexes, and the study of their biological activities.

Synthesis and characterization of novel copper(ii) complexes as potential drug candidates against SARS-CoV-2 main protease

Two novel copper(ii) Schiff base complexes, [Cu(L1)2] (1) and [Cu(L2)(CH3OH)(Cl)] (2) of [(Z)-(5-chloro-2-((3,5-dichloro-2-hydroxybenzylidene)amino)phenyl)(phenyl)methanone (L1H) and (Z)-(2((5-bromo-2-hydroxybenzylidene)amino-5-chlorophenyl)(phenyl)methanone)(L2H)], have been designed, synthesized and characterized.

Coordination compounds of biogenic metals as cytotoxic agents in cancer therapy

The review summarizes the data on the structures and methods for the synthesis of compounds with anticancer activity based on biogenic metals, which can replace platinum drugs prevailing in cytotoxic therapy. The main focus is given to the comparison of the mechanisms of the cytotoxic action of these complexes, their efficacy and prospects of their use in clinical practice. This is the first systematic review of cytotoxic zinc, iron, cobalt and copper compounds. The structure – activity relationships and the mechanisms of antitumour action are formulated for each type of metal complexes.

The bibliography includes 181 references.

Ruthenium (II)/allopurinol complex inhibits breast cancer progression via multiple targets

Metal complexes based on ruthenium have established excellent activity with less toxicity and great selectivity for tumor cells. This study aims to assess the anticancer potential of ruthenium(II)/allopurinol complexes called [RuCl₂(allo)₂(PPh₃)₂] (1) and [RuCl₂(allo)₂(dppb)] (2), where allo means allopurinol, PPh₃ is triphenylphosphine and dppb, 1,4-bis(diphenylphosphino)butane. The complexes were synthesized and characterized by elemental analysis, IR, UV-Vis and NMR spectroscopies, cyclic voltammetry, molar conductance measurements, as well as the X-ray crystallographic analysis of complex 2. The antitumor effects of compounds were determined by cytotoxic activity and cellular and molecular responses to cell death mechanisms. Complex 2 showed good antitumor profile prospects because in addition to its cytotoxicity, it causes cell cycle arrest, induction of DNA damage, morphological and biochemical alterations in the cells. Moreover, complex 2 induces cell death by p53-mediated apoptosis, caspase activation, increased Beclin-1 levels and decreased ROS levels. Therefore, complex 2 can be considered a suitable compound in antitumor treatment due to its cytotoxic mechanism.

Interaction of a Vanadyl Schiff Base Complex with DNA and BSA: A Combination of Experimental and Computational Studies

BACKGROUND AND PURPOSE

Cancer is the primary cause of death in the world. Vanadium (IV) is a metal ion complex which has been proposed as a suitable candidate for cancer treatment. In this study, the interaction of the oxido-vanadium (IV) complex [VOL(bipy)] with salmon sperm DNA and Bovine Serum Albumin (BSA) was investigated through experimental and computational approaches. With the results of this experimental study, the mechanism and parameters related to the interaction of [VOL(bipy)] with DNA and BSA were determined.

MATERIALS AND METHODS

The kinetic interaction of DNA and BSA with [VOL(bipy)] was determined using absorption titration and fluorescence quenching, respectively. Moreover, the possible interactions were calculated by molecular docking prediction using the available software.

RESULTS

The binding constant (Kb) of the complex-DNA interaction was calculated to be 2.34×104 M-1, indicating a relatively strong interaction between the complex and DNA. It was found that the V(IV) complex interacted with DNA through the groove binding mode followed by partial intercalation into the DNA helix. The Kb values obtained for [VOL(bipy)]-BSA interaction were in the range of 1.07×103-5.82×104 M-1. The V(IV) complex was found to prefer the domain I binding pocket of BSA with the ΔGb value of -7.52 kcal/mol.

CONCLUSION

Both experimental and computational analyses confirmed the interaction of the vanadium complex with DNA and BSA. The moderate affinity of [VOL(bipy)] for BSA indicates that this protein is a good candidate for transferring the complex.

Copper(ii) complexes of 2-methyl-8-hydroxyquinoline and tri/diimine co-ligand: DFT calculations, DNA and BSA binding, DNA cleavage, cytotoxicity and induction of apoptosis

Four-coordinate copper(ii) complex cleaves supercoiled ϕX174 RF DNA without reductant while five-coordinate complex cleaves with reductant. The cytotoxicity against cancer cells are higher than cisplatin, less-toxic to normal cells and induce apoptosis.

Antiproliferative Activities of Diimine-Based Mixed Ligand Copper(II) Complexes

A series of Cu(diimine)(X-sal)(NO₃) complexes, where the diimine is either 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and X-sal is a monoanionic halogenated salicylaldehyde (X = Cl, Br, I, or H), have been synthesized and characterized by elemental analysis and X-ray crystallography. Penta-coordinate geometries copper(II) were observed for all cases. The influence of the diimine coligands and different halogen atoms on the antiproliferative activities toward human cancer cell lines have been investigated. All Cu(II) complexes were able to induce a loss of A2780 ovarian carcinoma cell viability, with phen derivatives more active than bpy derivatives. In contrast, no in vitro antiproliferative effects were observed against the HCT116 colorectal cancer cell line. These cytotoxicity differences were not due to a different intracellular concentration of the complexes determined by inductively coupled plasma atomic emission spectroscopy. A small effect of different halogen substituents on the phenolic ring was observed, with X = Cl being the most highly active toward A2780 cells among the phen derivatives, while X = Br presented the lowest IC₅₀ in A2780 cells for bpy analogs. Importantly, no reduction in normal primary fibroblasts cell viability was observed in the presence of bpy derivatives (IC₅₀ > 40 μM). Mechanistically, complex 1 seems to induce a stronger apoptotic response with a higher increase in mitochondrial membrane depolarization and an increased level of intracellular reactive oxygen species (ROS) compared to complex 3. Together, these data and the low IC₅₀ compared to cisplatin in A2780 ovarian carcinoma cell line demonstrate the potential of these bpy derivatives for further in vivo studies.

Structural-Dependent N,O-Donor Imine-Appended Cu(II)/Zn(II) Complexes: Synthesis, Spectral, and in Vitro Pharmacological Assessment

Four mononuclear bioefficient imine-based coordination complexes, [(L ¹ ) ₂ Cu], [(L ¹ ) ₂ Zn], [(L ² )Cu(H ₂ O)], and [(L ² )Zn(H ₂ O)], were synthesized using ligands [L ¹ = 2-(((3-hydroxynaphthalen-2-yl)methylene)amino)-2-methylpropane-1,3-diol and L ² = 4-(1-((1,3-dihydroxy-2-methylpropan-2-yl)imino)ethyl)benzene-1,3-diol]. The formation of the complexes was ascertained by elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, electrospray ionization-mass spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The comparative binding propensity profiles of the above-synthesized complexes with the DNA/human serum albumin (HSA) were investigated via UV absorption, fluorescence, and Förster resonance energy-transfer studies. On the basis of extended conjugation and planarity, L ¹ complexes exhibited superior bioactivity with greater calculated DNA binding constant values, (K _b) 2.9444 × 10³ [(L ¹ ) ₂ Cu] and 2.2693 × 10³ [(L ¹ ) ₂ Zn], as compared to L ² complexes, 1.793 × 10³ [(L ² )Cu(H ₂ O)] and 9.801 × 10² [(L ² )Zn(H ₂ O)]. The competitive displacement assay of complexes was performed by means of fluorogenic dyes (EtBr and Hoechst), which corroborates the occurrence of minor groove binding because of the enhanced displacement activity with Hoechst 33258. The minor groove binding of the [(L ¹ ) ₂ Cu] complex is further confirmed by the molecular docking study. Moreover, the HSA study demonstrated effective static quenching of complexes with substantial K _sv values. The [(L ¹ ) ₂ Cu] complex was found to have pronounced cleavage efficiency as evaluated from sodium dodecyl sulfate polyacrylamide gel electrophoresis electrophoresis. Furthermore, in vitro antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals further proclaimed the remarkable bioefficiency of compounds, which make them promising as active chemotherapeutic agents.

Octahedral copper(ii)-diimine complexes of triethylenetetramine: effect of stereochemical fluxionality and ligand hydrophobicity on CuII/CuIredox, DNA binding and cleavage, cytotoxicity and apoptosis-inducing ability

Stereochemical fluxionality of octahedral [Cu(trien)(diimine)]²⁺complexes determines the Cu^II/Cu^Iredox potential, DNA binding affinity, ROS generation, cytotoxicity and apoptosis-inducing ability.

Copper(ii) complexes with NNO ligands: synthesis, crystal structures, DNA cleavage, and anticancer activities

Three novel copper(ii) complexes, Cu(L1)₂ (1), Cu(L2)₂·2DMF (2), and Cu(L3)₂·2DMF (3), were synthesized using three aroylhydrazone ligands, (E)-2-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL1), (E)-3-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL2) and (E)-4-hydroxy-N'-(1-(pyrazin-2-yl)ethylidene)benzohydrazide (HL3). The complexes were characterized by elemental analysis, infrared (IR), and Ultraviolet-visible light (UV-vis) spectroscopy. The X-ray crystal structures of the complexes all possess a distorted octahedral coordination geometry. Both an absorption spectral titration and a competitive binding assay (ethidium bromide, 4',6-diamidino-2-phenylindole (DAPI), and methyl green) revealed that complexes 2 and 3 bind readily to calf thymus DNA (ctDNA) through intercalative and minor groove binding modes. Complexes 2 and 3 also exhibited oxidative cleavage of supercoiled plasmid DNA (pUC19) in the presence of ascorbic acid as an activator. Cytotoxicity studies showed that complexes 2 and 3 possessed high cytotoxicities toward the HeLa human cervical cancer cell line, but weak toxicities toward the L929 normal mouse fibroblast cell line. We therefore have reason to believe that complexes 2 and 3 both show potential as promising anticancer candidate drugs.

Synthesis of New Cu Complex Based on Natural 5Z,9Z-Eicosadienoic Acid: Effective Topoisomerase I Inhibitor and Cytotoxin against the Cisplatin-Resistant Cell Line

The complex (bipy)2Cu(5,9-eicd) was prepared by the reaction of Cu(OAc)2 with 5Z,9Z-eicosadienoic acid and 2,2'-bipyridine in methanol. The new copper complex showed high antitumor activity in vitro toward A2780cis, A2780, Hek293, K562, HL60, Jurkat, and U937 cell lines and efficiently inhibited human topoisomerase I. Using flow cytofluorometry, (bipy)2Cu(5,9-eicd) was studied for the effect on the cell cycle and apoptosis-inducing activity in tumor cells.

Targeting ROS overgeneration by N-benzyl-2-nitro-1-imidazole-acetamide as a potential therapeutic reposition approach for cancer therapy

BackgroundWe investigated the role of reactive oxygen species (ROS) in the anticancer mechanism of N-benzyl-2-nitro-1-imidazole-acetamide (BZN), a drug used in Chagas' disease treatment. MethodsBALB/c mice, inoculated with Ehrlich ascites carcinoma (EAC), were treated with BZN or BZN + Nacylcysteine (NAC) or NAC for 9 days. Subsequently, the inhibition of tumor growth and angiogenesis as well as animal survival were evaluated. Apoptosis and the cell cycle were evaluated using fluorescence microscopy and flow cytometry, while oxidative stress was evaluated by measuring TBARS content, DNA damage, calcium influx and ROS generation and antioxidant defenses (CAT, SOD, GPx, GST and GR). Immunoblotting was used to evaluate key death and cell cycle proteins. Results BZN treatment inhibited tumor progression (79%), angiogenesis (2.8-fold) and increased animal survival (29%). Moreover, BZN increased ROS levels (42%), calcium influx (55%), TBARS contents (1.9-fold), SOD (4.4-fold), GPx (17.5-fold) and GST (3-fold) activities and GSH depletion (2.5-fold) also caused DNA fragmentation (7.6-fold), increased cleaved PARP and promoted the trapping of cells in the G1 phase, as corroborated by the reduction in cyclin A and increased CDK2 protein levels. In silico DNA and molecular dynamic simulations showed H-bonds and hydrophobic interactions that were confirmed by circular dichroism. Increased apoptosis (232%), induced by treatment with BZN, was demonstrated by apoptotic cell staining and p53 level. Conclusion The current findings indicate that BZN acts as a tumor growth inhibitor and anti-angiogenic agent by ROS overgeneration, which interact with DNA causing damage and triggering apoptosis.

Structure, DNA/proteins binding, docking and cytotoxicity studies of copper(II) complexes with the first quinolone drug nalidixic acid and 2,2'‑dipyridylamine

This work presents the synthesis, structural characterization and biological affinity of the newly synthesized copper(II) complexes with the first antibacterial quinolone drug nalidixic acid (nal) or N-donor ligand 2,2'‑dipyridylamine (bipyam). [Cu(II)(nal)(bipyam)Cl], (2) reveals a distorted square pyramidal based geometry in Cu(II) atom confirmed by X-ray crystallography technique. The theoretical stabilities and optimized structures of the complex were obtained from DFT calculations. The ability of the complexes to bind with calf thymus DNA (CT DNA) were investigated by electronic absorption, fluorescence, circular dichroism, and viscosity measurements techniques. The experimental results reveal that the complexes strongly interact with CT DNA via intercalative mode but complex 2 exhibits the highest affinity giving K_b=3.91±0.13×10⁶, M^-1. The fluorescence spectroscopy measurements show that both complexes have the superior ability to the replacement of EtBr from DNA-bound EtBr solution and bind to DNA through intercalative mode. Both complex also shows the superior affinity towards proteins with comparatively high binding constant values which have been further revealed by fluorescence spectroscopy measurements. Molecular docking analysis indicates that the interaction of the complexes and proteins are stabilized by hydrogen bonding and hydrophobic interaction. Furthermore, the results of in vitro cytotoxicity reveal that the complex 2 has excellent cytotoxicity than 1 against human breast cancer cell lines (MCF-7).

Example of two novel thiocyanato bridged copper (II) complexes derived from substituted thiosemicarbazone ligand: structural elucidation, DNA/albumin binding, biological profile analysis, and molecular docking study

Two novel copper (II) substituted thiosemicarbazone Schiff base complexes [Cu(L₁)(µ-SCN)]_n(NO₃)₂ (1) and [Cu₂(µ-SCN)(SCN)(L₂)₂](NO₃) (2) have been synthesized by condensing substituted thiosemicarbazides like 4-methyl-3-thiosemicarbazide or 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine. Both the metal complexes 1 and 2 are characterized using different spectroscopic techniques like IR, UV-Vis, ESR spectroscopy followed by elemental analysis, cyclic voltammetric measurement and single crystal X-ray structure analysis. X-ray crystal structure analysis reveal that complex 1 is polymeric while complex 2 is dimeric in nature. The coordination geometry around Cu(II) are square pyramidal in which thiosemicarbazone Schiff base ligand coordinate to the central Cu(II) atom in tridentate fashion. The prominent interaction patterns of 1 and 2 with CT-DNA were examined by employing electronic absorption and emission spectral titrations, cyclic voltammetry and viscosity measurements. All the results show that CT-DNA binds with both copper (II) complexes 1 and 2. Furthermore, protein binding ability in vitro of complexes 1 and 2 with both BSA and HSA were carried out using multispectroscopic techniques and a static quenching pattern was observed in both cases. Molecular docking study was employed to ascertain the exact mechanism of action of 1 and 2 with DNA and protein molecules (BSA and HSA). In vitro cytotoxicity activity of complexes 1 and 2 toward AGS and A549 was evaluated using MTT assay which demonstrates that both complexes 1 and 2 have superior prospectus to act as anticancer agents. Communicated by Ramaswamy H. Sarma.

Evaluation of the binding of four anti-tumor Casiopeínas® to human serum albumin

The metal complexes designated by Casiopeínas® are mixed-ligand Cu^II-compounds some of them having promising antineoplastic properties. We report studies of binding of Cu(glycinato)(4,7-dimethyl-1,10-phenanthroline) (Cas-II-Gly (1)), Cu(acetylacetonato)(4,7-dimethyl-1,10-phenanthroline) (Cas-III-Ea (2)), Cu(glycinato)(4,4'-dimethyl-2,2'-bipyridine) (Cas-IV-Gly (3)) and Cu(acetylacetonato)(4,4'-dimethyl-2,2'-bipyridine) (Cas-III-ia (4)) to human serum albumin (HSA) by circular dichroism (CD), Electron paramagnetic resonance (EPR) and fluorescence spectroscopy. The results indicate that HSA may bind up to three molecules of the tested Casiopeínas. This is confirmed by inductively coupled plasma - atomic absorption spectroscopy measurements of samples of HSA-Casiopeínas after passing by adequate size-exclusion columns. The binding of Cas-II-Gly to HSA was also confirmed by MALDI-TOF mass spectrometric experiments. In the physiological range of concentrations the Casiopeínas form 1:1 adducts with HSA, with conditional binding constants of ca. 1×10⁹ (1), 4×10⁷ (2), 1×10⁶ (3) and 2×10⁵ (4), values determined from the CD spectra measured, and the fluorescence emission spectra indicates that the binding takes place close to the Trp214 residue. Overall, the data confirm that these Casiopeínas may bind to HSA and may be transported in blood serum by this protein; this might allow some selective tumor targeting, particularly in the case of Cas-II-Gly. In this work we also discuss aspects associated to the reliability of the frequently used methodologies to determine binding constants based on the measurement of fluorescence emission spectra of solutions containing low concentrations of proteins such as HSA and BSA, by titrations with solutions of metal complexes.

Cobalt (II) complex with novel unsymmetrical tetradentate Schiff base (ON) ligand: in vitro cytotoxicity studies of complex, interaction with DNA/protein, molecular docking studies, and antibacterial activity

[C₂₀H₁₇N₃O₂] and cobalt (II) complex [Co(L²)(MeOH)₂].ClO₄, (L² = 4-((E)-1-((2-(((E)-pyridin-2-ylmethylene) amino) phenyl) imino) ethyl) benzene-1, 3-diol) novel Schiff base has been synthesiszed and chracterized by Fourier transform infrared, UV-vis, ¹H-NMR spectroscopy, and elemental analysis techniques. The interaction of Co(II) complex with DNA and BSA was investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism, and thermal denaturation studies. Our experiments indicate that this complex could strongly bind to CT-DNA via minor groove mechanism. In addition, fluorescence spectrometry of BSA with the complex showed that the fluorescence quenching mechanism of BSA was of static type. The complex exhibited significant in vitro cytotoxicity against three human cancer cell lines (JURKAT, SKOV3, and U87). The molecular docking experiment effectively proved the binding of complex to DNA and BSA. Finally, antibacterial assay over gram-positive and gram-negative pathogenic bacterial strains was studied.