Synthesis, characterization of ruthenium(II), nickel(II), palladium(II), and platinum(II) triphenylphosphine-based complexes bearing an ONS-donor chelating agent: Interaction with biomolecules, antioxidant, in vitro cytotoxic, apoptotic activity and cell cycle analysis

Dissimilar effect of organometallic ruthenium complexes on the viability of MDR and non-MDR experimental models

Ruthenium complexes containing triphenylphosphine diamide ligands were prepared, characterized, and tested for their biological activity against various cancer cell lines and the malaria parasite, Plasmodium falciparum. The effect of M (mono-substituted) and B (bis-substituted) complexes on the human cervical carcinoma (HeLa) cell line was investigated using the MTT assay. Five (B2, B3, B5, B6, and B13) of the 24 synthesized ruthenium complexes showed significant effects with IC50 values ranging between 0.3 and 2.3 μM. Evaluation of the potential biomolecular targets of B2 and B13 by fluorescence spectroscopy revealed relevant interactions with BSA and only a weak affinity for ctDNA. Complexes M2, B2, M13 and B13 were selected for further biological characterization. Their effect on the viability of two ovarian cancer cell lines was compared to normal cell lines, denoting their selectivity. Upon treatment of four different drug-resistant gynaecological cancer cell lines, differing in their multidrug-resistant phenotypes, the efficacy of the bis-substituted complexes was shown to be greater than their mono-substituted counterparts. The non-MDR cells are sensitive to all the tested complexes, compared to MDR cells which are less sensitive. Upon investigation of complexes M2, M13, B2, and B13 against sensitive and multidrug-resistant parasite strains of P. falciparum, the bis-substituted complexes were again shown to be the most potent, with submicromolar activity against both strains. Furthermore, the resistance indexes for the complexes were approximately equal to 1, which is at least 5-fold lower than chloroquine diphosphate, suggesting the ability of these complexes to retain their activity in resistant forms of the parasite.

Palladium(ii), platinum(ii), and silver(i) complexes with 3-acetylcoumarin benzoylhydrazone Schiff base: Synthesis, characterization, biomolecular interactions, cytotoxic activity, and computational studies

New Pd(ii) (C1), Pt(ii) (C2), and Ag(i) (C3) complexes derived from 3-acetylcoumarin benzoylhydrazone (HL) Schiff base were synthesized and characterized by FTIR, 1H NMR, UV-visible spectroscopies along with elemental analysis (C, H, N), magnetic, molar conductivity measurements, and DFT calculations. The obtained results suggested that the ligand had different behaviors in the complexes: mono-negative tridentate (C1) and neutral tridentate (C2) as an ONO-donor and neutral bidentate (C3) as an ON-donor. Quantum chemistry calculations were performed to validate the stability of the suggested geometries and indicated that all the complexes possess tetra-coordinated metal ions. The binding affinity of all the compounds toward calf thymus (ctDNA), yeast (tRNA), and bovine serum albumin (BSA) was evaluated by absorption/emission spectral titration studies, which revealed the intercalative binding to ctDNA and tRNA and static binding upon complex formation with BSA. Molecular insights into the binding affinity of the characterized complexes were provided through conducting molecular docking analysis. Moreover, the cytotoxic activity (in vitro) of the compounds was screened against human cancerous cell lines and a non-cancerous lung fibroblast (WI38) one using cis-platin as a reference drug. The IC50 and selective index (SI) values indicated the higher cytotoxic activity of all the metal complexes compared to their parent ligand. Among all the compounds, the complex C2 showed the highest activity. These results confirmed the improvement of the anticancer activity of the ligand by incorporating the metal ions. In addition, flow cytometry results showed that complexes C1 and C2 induced cell cycle arrest at S and G1/S, respectively.

Pd(II) complexes bearing NNS pincer ligands: unveiling potent cytotoxicity against breast and pancreatic cancer

The continuously increasing rate of breast cancer is one of the major threats to female health worldwide. Recently, palladium complexes have emerged as impressive candidates with effective biocompatibility and anticancer activities. Hence, in the present study, we report a new series of palladium complexes bearing NNS pincer ligands for cytotoxicity studies. The reaction of thiophenol/4-chlorothiophenol/4-methylthiophenol/4-methoxythiophenol with 2-bromo-N-quinolin-8-yl-acetamide in the presence of sodium hydroxide in ethanol at 80 °C gave [C9H6N-NH-C(O)-CH2-S-Ar] [Ar = C6H5 (L1), C6H4Cl-4 (L2), C6H4Me-4 (L3), and C6H4-OMe-4 (L4)]. The corresponding reaction of L1-L4 with Na2PdCl4 in methanol at room temperature for 3 h resulted in complexes [(L1-H)PdCl] (C1), [(L2-H)PdCl] (C2), [(L3-H)PdCl] (C3), and [(L4-H)PdCl] (C4). All new compounds have been characterized by spectroscopic analyses. The structures of complexes C1, C3, and C4 have also been determined from single-crystal X-ray diffraction data. The cytotoxicities of L1-L4 and C1-C4 have been investigated for breast cancer 4T1 and pancreatic cancer MIA-PaCa-2 cells. The IC50 values for complexes C2 and C3 were observed to be comparable to or higher than those of cisplatin. The stressed morphology and cell death of cancerous cells were successfully observed through cellular morphology analysis and the assessment of cytoskeleton damage.

Structural Design, Anticancer Evaluation, and Molecular Docking of Newly Synthesized Ni(II) Complexes with ONS-Donor Dithiocarbazate Ligands

The current article reports the investigation of three new Ni(II) complexes with ONS-donor dithiocarbazate ligands: [Ni(L1)PPh3] (1), [Ni(L2)PPh3] (2), and [Ni(L2)Py] (3). Single-crystal X-ray analyses revealed mononuclear complexes with a distorted square planar geometry and the metal centers coordinated with a doubly deprotonated dithiocarbazate ligand and coligand pyridine or triphenylphosphine. The non-covalent interactions were investigated by the Hirshfeld surface and the results revealed that the strongest interactions were π⋅⋅⋅π stacking interactions and non-classical hydrogen bonds C-H···H and C-H···N. Physicochemical and spectroscopic methods indicate the same structures in the solid state and solution. The toxicity effects of the free ligands and Ni(II) complexes were tested on the human breast cancer cell line MCF-7 and non-malignant breast epithelial cell line MCF-10A. The half-maximal inhibitory concentration (IC50) values, indicating that the compounds were potent in inhibiting cell growth, were obtained for both cell lines at three distinct time points. While inhibitory effects were evident in both malignant and non-malignant cells, all three complexes demonstrated lower IC50 values for malignant breast cell lines than their non-malignant counterparts, suggesting a stronger impact on cancerous cell lines. Furthermore, molecular docking studies were performed showing the complex (2) as a promising candidate for further therapeutic exploration.

Recently Reported Biological Activities and Action Targets of Pt(II)- and Cu(II)-Based Complexes

Most diseases that affect human beings across the world are now treated with drugs of organic origin. However, some of these are associated with side effects, toxicity, and resistance phenomena. For the treatment of many illnesses, the development of new molecules with pharmacological potential is now an urgent matter. The biological activities of metal complexes have been reported to have antitumor, antimicrobial, anti-inflammatory, anti-infective and antiparasitic effects, amongst others. Metal complexes are effective because they possess unique properties. For example, the complex entity possesses the effective biological activity, then the formation of coordination bonds between the metal ions and ligands is controlled, metal ions provide it with extraordinary mechanisms of action because of characteristics such as d-orbitals, oxidation states, and specific orientations; metal complexes also exhibit good stability and good physicochemical properties such as water solubility. Platinum is a transition metal widely used in the design of drugs with antineoplastic activities; however, platinum is associated with side effects which have made it necessary to search for, and design, novel complexes based on other metals. Copper is a biometal which is found in living systems; it is now used in the design of metal complexes with biological activities that have demonstrated antitumoral, antimicrobial and anti-inflammatory effects, amongst others. In this review, we consider the open horizons of Cu(II)- and Pt(II)-based complexes, new trends in their design, their synthesis, their biological activities and their targets of action.

Bimetallic bis-Aroyldihydrazone-Isatin Complexes of High O=V(IV) and Low Cu(II) Valent Ions as Effective Biological Reagents for Antimicrobial and Anticancer Assays

Due to the versatile bioreactivity of aroyldihydrazone complexes as cost-effective alternatives with different transition metals, two novel bimetallic homo-complexes (VOLph and CuLph) were prepared via the coordination of a terephthalic dihydrazone diisatin ligand (H2Lph) with VO2+ and Cu2+ ions, respectively. The structure elucidation was confirmed by alternative spectral methods. Biologically, the H2Lph ligand and its MLph complexes (M2+ = VO2+ or Cu2+) were investigated as antimicrobial and anticancer agents. Their biochemical activities towards ctDNA (calf thymus DNA) were estimated using measurable titration viscometrically and spectrophotometrically, as well as the gel electrophoresis technique. The growth inhibition of both VOLph and CuLph complexes against microbial and cancer cells was measured, and the inhibition action, MIC, and IC50 were compared to the inhibition action of the free H2Lph ligand. Both VOLph and CuLph showed remarkable interactive binding with ctDNA compared to the free ligand H2Lph, based on Kb = 16.31, 16.04 and 12.41 × 107 mol-1 dm3 and ΔGb≠ = 47.11, -46.89, and -44.05 kJ mol-1 for VOLph, CuLph, and H2Lph, respectively, due to the central metal ion (VIVO and CuII ions). VOLph (with a higher oxidation state of the V4+ ion and oxo-ligand) exhibited enhanced interaction with the ctDNA molecule compared to CuLph, demonstrating the role and type of the central metal ion within the performed electronegative and electrophilic characters.

Synthesis, structural characterization, antioxidant, cytotoxic activities and docking studies of schiff base Cu(II) complexes

By combining hydrazide with 2-Acetylpyridine, a hydrazone ligand (HL) was successfully created. Several copper (II) salts have been used to create three copper (II) hydrazone complexes (acetate, sulphate, and chloride). The hydrazide ligand and its copper (II) complexes (1-3) were studied via variety of analytical techniques, including elemental analysis, electronic, infrared, UV-vis Spectrum, XRD study, thermal analysis, also molar conductivity amounts. The spectrum results indicate that in all complexes, the ligand exhibits monobasic tridentate behavior. Octahedral geometries were present in all metal complexes. The Coats-Redfern equations were used to compute and describe the dynamics properties of several steps of TGA (Ea, A, ΔH*, ΔS*, and ΔG*). Calculations using the density functional theory (DFT) were done at the molecular studio software toward examine ligands agent's and its complexes' best structures. The MCF-7 in addition to HepG-2 cell lines was resistant to tumor-inducing effects of the copper (II) chelates. The in vitro antioxidant capacities of all complexes have been estimated via DPPH free radical scavenger assays. Furthermore, zones of inhibition length accustomed to test antimicrobial effect of particular complexes in vitro towards Staphylococcus aureus (Gram positive bacteria) E. coli (Gram negative bacteria). Both absorption spectra and viscosity measurements in calf thymus DNA binding have been used to study the complexes. In order to explore docking research of copper (II) chelates, the crystallographic construction of the SARS-active CoV-2's site protein (PDB ID:6XBH) was used (COVID-19) and breast cancer distorted (PDB ID: 3hb5).

Rh(III) and Ru(II) complexes with phosphanyl-alkylamines: inhibition of DNA synthesis induced by anticancer Rh complex

Aim: This investigation was designed to synthesize half-sandwich Rh(III) and Ru(II) complexes and study their antiproliferative activity in human cancer cell lines. Materials & methods: Nine compounds were prepared and tested by various assays for their anticancer activity and mechanism of action. Results: Hit Rh(III) complex 6 showed low-micromolar potency in cisplatin-sensitive (A2780) and -resistant (A2780cis) ovarian carcinoma cell lines, promising selectivity toward these cancer cells over normal lung fibroblasts and an unprecedented mechanism of action in the treated cells. DNA synthesis was decreased and CDKN1A expression was upregulated, but p21 expression was not induced. Conclusion: Rh complex 6 showed high antiproliferative activity, which is induced through a p21-independent mechanism of action.

Experimental and computational studies of silver(I) dibenzoylmethane-based complexes, interaction with DNA/RNA/BSA biomolecules, and in vitro cytotoxic activity

Two silver(I) complexes of composition [Ag₂(L)₂] (1) and [Ag(L)(PPh₃)₂](2) (HL = dibenzoyl- methane, PPh₃ = triphenylphosphine) were synthesized and characterized by elemental analysis, FTIR, NMR, XRPD, and UV-visible spectra. The molecular structures of the studied ligands and Ag(I) complexes have been characterized using Density Function Theory (DFT) calculations. This analysis has enabled us to determine the reactivity and the coordination site(s) for each ligand. Ag(I) ion is found to be coordinated with the ligand's oxygens in almost a linear fashion in complex (1), while in complex (2) it adopts a tetrahedral geometry. The interaction compounds with biomolecules; calf thymus (ct DNA), yeast-tRNA, and bovine serum albumin (BSA) were investigated using both absorption and fluorescence spectroscopy. The in vitro cytotoxic studies of the complexes against normal human lung fibroblast (WI38), cancerous breast (MDA-MB-231), mammary gland breast (MCF7), hepatocellular (HePG2), and prostate (PC3) cell lines indicated that the complexes are highly toxic to the cancer cells but less toxic towards the normal one when compared with the ligand. Flow cytometric results showed that complex (1) induced cell cycle arrest at the G2/M phase, and complex (2) at G2/M and S phases. Moreover, the results of apoptotic genes (caspase3 and p53) and anti-apoptotic (Bcl2) led us to suggest an apoptotic killing mechanism of cells rather than a necrotic one.

Luminescence and Palladium: The Odd Couple

The synthesis, photophysical properties, and applications of highly fluorescent and phosphorescent palladium complexes are reviewed, covering the period 2018–2022. Despite the fact that the Pd atom appears closely related with an efficient quenching of the fluorescence of different molecules, different synthetic strategies have been recently optimized to achieve the preservation and even the amplification of the luminescent properties of several fluorophores after Pd incorporation. Beyond classical methodologies such as orthopalladation or the use of highly emissive ligands as porphyrins and related systems (for instance, biladiene), new concepts such as AIE (Aggregation Induced Emission) in metallacages or in coordination-driven supramolecular compounds (CDS) by restriction of intramolecular motions (RIM), or complexes showing TADF (Thermally Activated Delayed Fluorescence), are here described and analysed. Without pretending to be comprehensive, selected examples of applications in areas such as the fabrication of lighting devices, biological markers, photodynamic therapy, or oxygen sensing are also here reported.

Dithiocarbazate ligands and their Ni(II) complexes with potential biological activity: Structural, antitumor and molecular docking study

In the search for new metal complexes with antitumor potential, two dithiocarbazate ligands derived from 1,1,1-trifluoro-2,4-pentanedione (H2L1) and (H2L2) and four Ni(II) complexes, [Ni(L1)PPh3] (1), [Ni(L1)Py] (2), [Ni(L2)PPh3] (3), and [Ni(L2)Py] (4), were successfully synthesized and investigated by physical-chemistry and spectroscopic methods. The crystal structure of the H2L1 and the Ni(II) complexes has been elucidated by single-crystal X-ray diffraction. The obtained structure from H2L1 confirms the cyclization reaction and formation of the pyrazoline derivative. The results showed square planar geometry to the metal centers, in which dithiocarbazates coordinated by the ONS donor system and a triphenylphosphine or pyridine molecule complete the coordination sphere. Hirshfeld surface analysis by dnorm function was investigated and showed π–π stacking interactions upon the molecular packing of H2L1 and non-classical hydrogen bonds for all compounds. Fingerprint plots showed the main interactions attributed to H⋅H C⋅H, O⋅H, Br⋅H, and F⋅H, with contacts contributing between 1.9% and 38.2%. The mass spectrometry data indicated the presence of molecular ions [M + H]+ and characteristic fragmentations of the compounds, which indicated the same behavior of the compounds in solution and solid state. Molecular docking simulations were studied to evaluate the properties and interactions of the free dithiocarbazates and their Ni(II) complexes with selected proteins and DNA. These results were supported by in vitro cytotoxicity assays against four cancer cell lines, showing that the synthesized metal complexes display promising biological activity.

Synthesis, Spectral Characterization, Crystal Structure, and Antioxidant Properties of novel Palladium(II) Complex from ONS Donor 1,5-bis(2-hydroxybenzylidene)thiocarbohydrazone

A new Pd(II) complex, [Pd(PPh3)(L)] (L = 1,5-bis(2-hydroxybenzylidene)thiocarbohydrazone, PPh3 = triphenylphosphine), was synthesized and characterized by FTIR, 1H NMR and UV-Vis spectroscopies and elemental analysis. The molecular structure of [Pd(PPh3)(L)] was confirmed by the single-crystal X-ray diffraction technique. Palladium ion has distorted square planar geometry according to X-ray diffraction studies. The free thiocarbohydrazone (L), potentially a pentadentate ONSNO donor, acted as a tridentate ONS donor. The antioxidant capacity of the free thiocarbohydrazone and Pd(II) complex was determined using the CUPRAC (cupric reducing antioxidant capacity) method. Also, the DPPH method was used to test the free radical scavenging activity of the free thiocarbohydrazone and Pd(II) complex. Antioxidant activity studies showed that free thiocarbohydrazone exhibited better activity than Pd(II) complex.

A biophysical study of the interactions of palladium(II), platinum(II) and gold(III) complexes of aminopyridyl-2,2'-bipyridine ligands with RNAs and other nucleic acid structures

Metal compounds form an attractive class of ligands for a variety of nucleic acids. Five metal complexes bearing aminopyridyl-2,2'-bipyridine tetradentate ligands and possessing a quasi-planar geometry were challenged toward different types of nucleic acid molecules including RNA polynucleotides in the duplex or triplex form, an RNA Holliday four-way junction, natural double helix DNA and a DNA G-quadruplex. The binding process was monitored comparatively using different spectroscopic and melting methods. The binding preferences that emerge from our analysis are discussed in relation to the structural features of the metal complexes.

Ruthenium(II)-Dithiocarbazates as Anticancer Agents: Synthesis, Solution Behavior, and Mitochondria-Targeted Apoptotic Cell Death

The reaction of the Ru(PPh₃ )₃ Cl₂ with HL^1-3 -OH (-OH stands for the oxime hydroxyl group; HL¹ -OH=diacetylmonoxime-S-benzyldithiocarbazonate; HL² -OH=diacetylmonoxime-S-(4-methyl)benzyldithiocarbazonate; and HL³ -OH=diacetylmonoxime-S-(4-chloro)benzyl-dithiocarbazonate) gives three new ruthenium complexes [Ru^II (L^1-3 -H)(PPh₃ )₂ Cl] (1-3) (-H stands for imine hydrogen) coordinated with dithiocarbazate imine as the final products. All ruthenium(II) complexes (1-3) have been characterized by elemental (CHNS) analyses, IR, UV-vis, NMR (¹ H, ¹³ C, and ³¹ P) spectroscopy, HR-ESI-MS spectrometry and also, the structure of 1-2 was further confirmed by single crystal X-ray crystallography. The solution/aqueous stability, hydrophobicity, DNA interactions, and cell viability studies of 1-3 against HeLa, HT-29, and NIH-3T3 cell lines were performed. Cell viability results suggested 3 being the most cytotoxic of the series with IC₅₀ 6.9±0.2 μM against HeLa cells. Further, an apoptotic mechanism of cell death was confirmed by cell cycle analysis and Annexin V-FITC/PI double staining techniques. In this regard, the live cell confocal microscopy results revealed that compounds primarily target the mitochondria against HeLa, and HT-29 cell lines. Moreover, these ruthenium complexes elevate the ROS level by inducing mitochondria targeting apoptotic cell death.

Study of Synthesis, Characterization, DFT, and In Vitro Biological Activity of Cu(II), Co(II), and Fe(II) Metal Complexes Based on Heterocyclic Azo Pyrazole Dye Ligand

A new azo dye ligand was synthesized by coupling 5-amino-3-methyl-1-phenylpyrazole with a diazonium ion of 2-amino-1-naphthalene sulfonic acid. Its Co(II), Fe(II), and Cu(II) complexes were also synthesized. This ligand and its complexes were characterized based on elemental analysis, IR, 1H NMR, UV-vis spectra, and thermogravimetric analysis. The data showed that the proposed complexes have an octahedral geometry around the central metal ion. The nonelectrolytic nature of the complexes was confirmed by molar conductance measurement. X-ray powder diffraction indicates that Co(II) and Fe(II) complexes are amorphous in nature, whereas the Cu(II) complex has crystalline and amorphous phases. The bond strength and molecular stability between the interaction of metal ions and the ligand were investigated by density functional theory (DFT). The in vitro antibacterial activity of the ligand and complexes was tested against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and a fungus (Candida albicans). The Cu(II) complex exhibited a high antimicrobial effect against all tested microorganisms. The DNA fragmentation percentage and cytotoxic activity against human liver cancer cells (HepG2) were evaluated. All tested compounds showed potential anticancer activity, and the Co(II) complex showed better activity results than the other tested compounds, with IC50 = 19.55 μg/mL.

Metal Coordination and Biological Screening of a Schiff Base Derived from 8-Hydroxyquinoline and Benzothiazole

Designing new metallodrugs for anticancer therapy is a driving force in the scientific community. Aiming to contribute to this field, we hereby report the development of a Schiff base (H2L) derived from the condensation of 2-carbaldehyde-8-hydroxyquinoline with 2-hydrazinobenzothiazole and its complexation with transition metal ions. All compounds were characterised by analytical and spectroscopic techniques, which disclosed their structure: [Cu(HL)Cl], [Cu(HL)2], [Ni(HL)(acetate)], [Ni(HL)2], [Ru(HL)Cl(DMSO)], [VO(HL)2] and [Fe(HL)2Cl(H2O)]. Different binding modes were proposed, showing the ligand’s coordination versatility. The ligand proton dissociation constants were determined, and the tested compounds showed high lipophilicity and light sensitivity. The stability of all complexes in aqueous media and their ability to bind to albumin were screened. Based on an antiproliferative in vitro screening, [Ni(HL)(acetate)] and [Ru(HL)Cl(DMSO)] were selected for further studies aiming to investigate their mechanisms of action and therapeutic potential towards colon cancer. The complexes displayed IC50 < 21 μM towards murine (CT-26) and human (HCT-116) colon cancer cell lines. Importantly, both complexes exhibited superior antiproliferative properties compared to the clinically approved 5-fluorouracil. [Ni(HL)(acetate)] induced cell cycle arrest in S phase in CT-26 cells. For [Ru(HL)Cl(DMSO)] this effect was observed in both colon cancer cell lines. Additionally, both compounds significantly inhibited cell migration particularly in the human colon cancer cell line, HCT-116. Overall, the therapeutic potential of both metal complexes was demonstrated.

Three water-soluble acylhydrazone tetranuclear transition metal complexes: Crystal structures, DNA/BSA interactions and cytotoxicity studies

2-acetylpyridine-4-chloropyridine-2‑carbonyl hydrazone (C₁₃H₁₁ClN₄O, HL) and its three water-soluble tetranuclear complexes [Cu₄(NO₃)₂(L)₄]·(NO₃)₂ (1), [Co₄(NO₃)₂(H₂O)(C₂H₅OH)(L)₄]·(NO₃)₂ (2) and [Zn₄(NO₃)₂(H₂O)(C₂H₅OH)(L)₄]·(NO₃)₂ (3) were synthesized and characterized showing that 1-3 were all tetranuclear complexes. The interactions of HL, 1-3 with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were explored using ultraviolet-visible (UV-Vis) titration, fluorescence spectroscopy, microcalorimetry and molecular docking techniques. The UV-Vis spectroscopy measurements showed that complexes 1-3 could strongly bind to CT-DNA by the intercalation mode, while HL interacted with CT-DNA through groove binding. From the fluorescence spectroscopy results, the interaction between HL, 1-3 and BSA was a static quenching procedure, in which complexes 1-3 had two binding sites near Trp residues of BSA while HL only had one. The microcalorimetric studies revealed that the interactions of HL and 1-3 to CT-DNA/BSA were all endothermic and the duration of each interaction was all less than 30 min. The in silico molecular docking illustrated intermolecular interactions of 1-3 binding with DNA/BSA included hydrogen bond, halogen bond, hydrophobic and electrostatic interactions. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated that complex 1 possessed better cytotoxicity against HeLa, A549, MCF7 and HCT-116 than cisplatin and could be used as an alternative anticancer drug.

Biomolecular Interactions of Cytotoxic Ruthenium Compounds with Thiosemicarbazone or Benzothiazole Schiff Base Chelates

Herein we illustrate the formation and characterization of new paramagnetic ruthenium compounds, trans-P-[RuCl(PPh₃ )₂ (pmt)]Cl (1) (Hpmt=1-((pyridin-2-yl)methylene)thiosemicarbazide), trans-P-[RuCl(PPh₃ )₂ (tmc)]Cl (2) (Htmc=1-((thiophen-2-yl)methylene)thiosemicarbazide) and a diamagnetic ruthenium complex, cis-Cl, trans-P-[RuCl₂ (PPh₃ )₂ (btm)] (3) (btm=2-((5-hydroxypentylimino)methyl)benzothiazole). Agarose gel electrophoresis experiments of the metal compounds illustrated dose-dependent binding to gDNA by 1-3, while methylene blue competition assays suggested that 1 and 2 are also DNA intercalators. Assessment of the effects of the compounds on topoisomerase function indicated that 1-3 are capable of inhibiting topoisomerase I activity in terms of the ability to nick supercoiled plasmid DNA. The cytotoxic activities of the metal complexes were determined against a range of cancer cell lines versus a non-tumorigenic control cell line, and the complexes were, in general, more cytotoxic towards the cancer cells, displaying IC₅₀ values in the low micromolar range. Time-dependent stability studies showed that in the presence of strong nucleophilic species (such as DMSO), the chloride co-ligands of 1-3 are rapidly substituted by the former as proven by the suppression of the substitution reactions in the presence of an excess amount of chloride ions. The metal complexes are significantly stable in both DCM and an aqueous phosphate buffer containing 2 % DMSO.

Novel Zinc(II) and Copper(II) Complexes of 2-((2-Hydroxyethyl)amino)quinoline-3-carbaldehyde for Antibacterial and Antioxidant Activities: A Combined Experimental, DFT, and Docking Studies

In the present work, two novel complexes of zinc(II) and copper(II) were synthesized from the ligand 2-((2-hydroxyethyl)amino)quinoline-3-carbaldehyde (H ₂ L) in a 1:2 metal-to-ligand ratio in methanol. The complexes were characterized by UV-visible spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA) experimental techniques and density functional theory (DFT) calculations. The spectral data revealed that the mono-deprotonated (HL) ligand acted as a bidentate ligand, which bound to both Zn(II) and Cu(II) ions via the nitrogen atom of the amine (N-H) and the hydroxyl (O-H) groups through the deprotonated oxygen atom. Formation constants and thermal analysis indicated that both metal complexes are stable up to 100 °C with thermodynamically favored chemical reactions. The Cu(II) complex showed antibacterial activities with the zones of inhibition of 20.90 ± 2.00 mm against Pseudomonas aeruginosa, 19.69 ± 0.71 mm against Staphylococcus aureus, and 18.58 ± 1.04 mm against Streptococcus pyogenes. These results are relatively higher compared with the Zn(II) complex at the same concentration. The minimum inhibitory concentration (MIC) results for the complexes also showed similar trends against the three bacteria. On the other hand, radical scavenging activities of both Cu(II) and Zn(II) complexes showed half-maximal inhibitory concentrations (IC₅₀) of 4.72 and 8.2 μg/mL, respectively, while ascorbic acid (a positive control) has a value of 4.28 μg/mL. The Cu(II) complex exhibited better communication with the positive control, indicating its potential use for biological activities. The calculated and in silico molecular docking results also strongly support the experimental results.

Antioxidant Activity of Ruthenium Cyclopentadienyl Complexes Bearing Succinimidato and Phthalimidato Ligands

In these studies, we investigated the antioxidant activity of three ruthenium cyclopentadienyl complexes bearing different imidato ligands: (η⁵-cyclopentadienyl)Ru(CO)₂-N-methoxysuccinimidato (1), (η⁵-cyclopentadienyl)Ru(CO)₂-N-ethoxysuccinimidato (2), and (η⁵-cyclopentadienyl)Ru(CO)₂-N-phthalimidato (3). We studied the effects of ruthenium complexes 1–3 at a low concentration of 50 µM on the viability and the cell cycle of peripheral blood mononuclear cells (PBMCs) and HL-60 leukemic cells exposed to oxidative stress induced by hydrogen peroxide (H₂O₂). Moreover, we examined the influence of these complexes on DNA oxidative damage, the level of reactive oxygen species (ROS), and superoxide dismutase (SOD) activity. We have observed that ruthenium complexes 1–3 increase the viability of both normal and cancer cells decreased by H₂O₂ and also alter the HL-60 cell cycle arrested by H₂O₂ in the sub-G1 phase. In addition, we have shown that ruthenium complexes reduce the levels of ROS and oxidative DNA damage in both cell types. They also restore SOD activity reduced by H₂O₂. Our results indicate that ruthenium complexes 1–3 bearing succinimidato and phthalimidato ligands have antioxidant activity without cytotoxic effect at low concentrations. For this reason, the ruthenium complexes studied by us should be considered interesting molecules with clinical potential that require further detailed research.

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.

New Pd(II) complexes of the bisthiocarbohydrazones derived from isatin and disubstituted salicylaldehydes: Synthesis, characterization, crystal structures and inhibitory properties against some metabolic enzymes

Pd(II) complexes (Pd1, Pd2, and Pd3) were synthesized for the first time using asymmetric isatin bisthiocarbohydrazone ligands and PdCl₂(PPh₃)₂. All complexes were characterized by a range of spectroscopic and analytical techniques. The molecular structures of Pd1 and Pd3 have been determined by single-crystal X-ray diffraction analysis. The complexes are diamagnetic and exhibit square planar geometry. The asymmetric isatin bisthiocarbohydrazone ligands coordinate to Pd(II) ion in a tridentate manner, through the phenolic oxygen, imine nitrogen and thiol sulfur, forming five- and six-membered chelate rings within their structures. The fourth coordination site in these complexes is occupied by PPh₃ (triphenylphosphine). The free ligands and their Pd(II) complexes were evaluated for their carbonic anhydrase I, II (hCAs) and acetylcholinesterase (AChE) inhibitor activities. They showed a highly potent inhibition effect on AChE and hCAs. K_i values are in the range of 9 ± 0.6 - 30 ± 5.4 nM for AChE, 7 ± 0.5 - 16 ± 2.2 nM for hCA I and 3 ± 0.3-24 ± 1.9 nM for hCA II isoenzyme. The results clearly demonstrated that the ligands and their Pd(II) complexes effectively inhibited the used enzymes.

In vitro cytotoxicity and antibacterial activity of [Pd(AMTTO)(PPh3)2]: a novel promising palladium(ii) complex

The synthesis and characterization of a novel palladium complex based on a bioactive 3-mercapto-1,2,4-triazine derivative have been investigated. The Pd(ii) complex showed excellent anticancer and antibacterial activity.

Effect of chalcogen bonding interactions on molecular structures; theoretical and crystallographic studies on two palladium(ii) acetate complexes

New palladium complexes, [Pd(L)(OAc))], have been synthesized. The complexes and their ligand have been characterized by X-ray crystal structure analysis. Interestingly, the molecular structures of the two complexes are stabilized by S⋯O chalcogen bonds.

A new class of nickel(II) oxyquinoline-bipyridine complexes as potent anticancer agents induces apoptosis and autophagy in A549/DDP tumor cells through mitophagy pathways

A new class of nickel(II) oxyquinoline-bipyridine complexes, namely, [Ni(La1)2(Lb6)] (Ni1), [Ni(La1)2(Lb2)] CH3OH (Ni2), [Ni(La7)2(Lb11)]2H2O (Ni3), [Ni(La1)2(Lb9)] (Ni4), [Ni(La1)2(Lb8)] (Ni5), [Ni(La2)2(Lb1)] (Ni6), [Ni(La2)2(Lb6)]CH3OH (Ni7), [Ni(La2)2(Lb11)]CH3OH (Ni8), [Ni(La2)2(Lb3)] (Ni9), [Ni(La2)2(Lb2)]CH3OH (Ni10), [Ni(La2)2(Lb5)]CH3OH...

OUP accepted manuscript

Fourteen new organotin(IV) complexes were successfully synthesized and characterized by elemental analyses, Fourier transform infrared spectroscopy (FT-IR), multinuclear (1H, 13C, and 119Sn) NMR spectroscopy, high-resolution mass spectrometry (HRMS), and X-ray single-crystal techniques. Crystallographic data showed that the complexes 1b, 2b, 3b, and 5b were macrocyclic compounds, 4b exhibited a one-dimensional spiral chain structure with distorted trigonal bipyramidal geometry, other complexes were centrosymmetric dimers, and there was an Sn2O2 four-membered ring in the middle of the molecule. In-vitro anticancer activity against the three human tumor cell lines NCI-H460, MCF-7, and HepG2 was studied, and the dibutyltin complex 5a is a more potent antitumor agent than other complexes and cisplatin. Cell apoptosis study of 5a with the highest activity on HepG2 cancer cell lines was done by flow cytometry; it was shown that the antitumor activity of 5a was related to apoptosis, and it inhibited proliferation by blocking cells in the G2/M phase. The single-cell gel electrophoresis assay results show that 5a induces DNA damage. 5a interacts with ct-DNA by intercalating the mode of interaction. UV-visible absorption spectrometry, fluorescence competitive, viscosity measurements, and gel electrophoresis results also support the intercalative mode of interaction for 5a with DNA.