Crystal structures, spectroscopic properties of new cobalt(II), nickel(II), zinc(II) and palladium(II) complexes derived from 2-acetyl-5-chloro thiophene thiosemicarbazone: Anticancer evaluation

Anticancer potential of benzo[b]thiophene functionalized thiosemicarbazone ligands and their organoruthenium complexes

As novel promising anticancer candidates, the piano-stool type complexes of ruthenium, [RuCl(η6-p-cymene)(N,S-Ln)]PF6, K1-4, were synthesized from the reaction of the substituted benzo[b]thiophene based thiosemicarbazone ligands (L1-4) with [{RuCl(η6-p-cymene)}2(μ-Cl)2]. All complexes were fully characterized using elemental analysis, and spectroscopic methods such as FT-IR and 1H NMR. The molecular masses of the complexes were proved by MALDI-TOF analysis. Single crystal X-ray diffraction study was employed in the structural elucidation of complex K1 which shows a distorted octahedral geometry around the Ru(II) ion. Furthermore, spectroscopic methods revealed that in all complexes the ligands are coordinated to the metal center in neutral thione form via N, S donors. In this study, the effect of all ligands, complexes and commercial drugs with a different concentration on the viability of OVCAR-3, A2780 and OSE cells were compared. In this comparison, the cytotoxicity of ruthenium (II) complexes on two ovarian cancer cell lines (human A2780 and human OVCAR-3) was evaluated. For this purpose, the resazurin assay was performed. Based on our studies, complex K2 showed the highest toxicity against OVCAR-3 and A2780 cells. The cytotoxic effect of K2 was found to be higher than that of the commercial anticancer agents Oxalpin and Carbodex, 1.8-34.7-fold for OVCAR-3 cells and 1.9-11.8-fold for A2780 cells, respectively. These results provide insight into the potential of ruthenium (II) complexes as a cytotoxic agent for the treatment of ovarian cancer, particularly for primary tumors.

Sustainable synthesis of benzimidazole-based Schiff base using reusable CaAl2O4 nanophosphors catalyst: Insights into metal(II) complexes and DNA interactions

This article presents a new and facile method for the synthesis of Schiff base compounds with a benzimidazole group using a low-cost and reusable calcium aluminate nanophosphorus catalyst (CaAl2O4). This approach avoids harmful solvents and reactants, supporting a more environmentally friendly synthesis process. The catalyst maintained its activity and heterogeneity over four cycles with minimal loss of efficiency. The synthesis process was straightforward and eliminated the need for column chromatography. The Schiff base ligand (HL=(E)-N-((6-(thiophen-2-yl)pyridin-2-yl)methylene)-1H-benzo[d]imidazol-2-amine)) was synthesized by the reaction of 6-(thiophen-2-yl)pyridine-2-carbaldehyde with 1H-benzimidazole-2-amine. Subsequently, metal(II) complexes of Co(II), Ni(II), and Cu(II) were prepared using this ligand. Structural analysis of both the ligand and its metal complexes was carried out using various physicochemical and spectroscopic methods. Ni(II) and Co(II) complexes were found to adopt an octahedral geometry, while the Cu(II) complex exhibited a square-planar structure. Binding studies with calf thymus DNA (CT-DNA) at pH 7.2 were performed using UV-visible spectroscopy, viscosity measurements, and thermal denaturation studies and showed that the metal complexes intercalate into the DNA and produced a distinct binding pattern. Molecular docking simulations with AutoDock Vina provided insights into the interaction of these complexes with the B-DNA dodecamer. Furthermore, the ligand and its metal complexes showed UV-visible photonuclease activity against pUC19 DNA. Agarose gel electrophoresis showed that the metal complexes exhibit photoinduced nuclease activity, confirming their ability to cleave DNA upon exposure to light.

The strong in vitro and vivo cytotoxicity of three new cobalt(II) complexes with 8-methoxyquinoline

Three new cobalt(II) complexes, [Co(MQL)₂Cl₂] (CoCl), [Co(MQL)₂Br₂] (CoBr), and [Co(MQL)₂I₂] (CoI), bearing 8-methoxyquinoline (MQL) have been designed for the first time. MTT assays showed that CoCl, CoBr, and CoI exhibit much better antiproliferative activities than cisplatin toward cisplatin-resistant SK-OV-3/DDP and SK-OV-3 ovarian cancer cells, with IC₅₀ values of as low as 0.32-5.49 μM. Further, CoCl and CoI can regulate autophagy-related proteins in SK-OV-3/DDP cells and, therefore, they can induce primarily autophagy-mediated cell apoptosis in the following order: CoCl > CoI. The different antiproliferative activities of the MQL complexes CoCl, CoBr, and CoI could be correlated with the lengths of their Co-X bonds, which adopted the following order: CoI > CoBr > CoCl. The 8-HOMQ complexes CoCl (ca. 60.1%) and CoI (ca. 48.8%) also showed potent in vivo anticancer effects after 15 days of treatment. In summary, the MQL ligand highly enhances the antiproliferative activities of cobalt(II) complexes in comparison to other previously reported 8-hydroxyquinoline metal complexes.

The Significant Influence of a Second Metal on the Antiproliferative Properties of the Complex [Ru(η6 -C10 H14 )(Cl2 )(dmoPTA)]

Complexes [Ru(η6 -C10 H14 )(Cl2 )(HdmoPTA)](OSO2 CF3 ) (1), [Ru(η6 -C10 H14 )(Cl2 )(dmoPTA)] (2) and [Ru(η6 -C10 H14 )(Cl2 )-μ-dmoPTA-1κP:2κ2 N,N'-MCl2 ] (M=Zn (3), Co (4), Ni (5), dmoPTA=3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) have been synthesized and characterized by elemental analysis and spectroscopic techniques. The crystal structures of 1, 3 and 5 were obtained by single-crystal X-ray diffraction. The antiproliferative activity of the complexes was evaluated against colon cancer cell line Caco-2/TC7 by using the MTT protocol. The monometallic ruthenium complexes 1 and 2 were found to be inactive, but the bimetallic complexes 3, 4 and 5 display an increased activity (IC50 3: 9.07±0.27, 4: 5.40±0.19, 5: 7.15±0.30 μM) compared to cisplatin (IC50 =45.6±8.08 μM). Importantly, no reduction in normal cell viability was observed in the presence of the complexes. Experiments targeted to obtain information on the possible action mechanism of the complexes, such as cell cycle, ROS and gene expression studies, were performed. The results showed that the complexes display different properties and action mechanism depending on the nature of metal, M, bonded to the CH3 NdmoPTA atoms.

New thiosemicarbazone-based Zinc(II) complexes. In vitro cytotoxicity competing with cisplatin on malignant melanoma A375 cells and its relation to neuraminidase inhibition

New thiosemicarbazone-based zinc(II) complexes were synthesized to study their cytotoxicity on A375 malignant melanoma cells. The complexes containing salicylidene (Zn1a), 3-methoxy-salicylidene (Zn1b) or 4-methoxy-salicylidene (Zn1c) moiety were characterized by analytical and spectroscopic methods. Anticancer potential of the complexes was determined by MTT test and HUVEC endothelial cells line was used to comprehend the effect on normal cells. Zn1b with an IC₅₀ of 13 μM was found to be highly cytotoxic against A375 cancer cells, more effective than cisplatin (IC₅₀: 37 μM). Zn1a and Zn1c did not have a negative effect on cell viability in the normal cells and gave the impression that they are more advantageous than cisplatin in this respect. Further, the ability of Zn1a-c to inhibit neuraminidase enzyme and its role in cytotoxicity was discussed. The test revealed that the Zn1b with 3-methoxy substituent exhibited higher inhibition activity against the neuraminidase than the Zn1a and Zn1c as analogical to the cytotoxicity results. In neuraminidase inhibition, IC₅₀ values of Zn1b and Zn1c were 14 and 66 μM, respectively. These concentrations were very close to the cytotoxicity concentrations for Zn1b and Zn1c. The findings may indicate the role of neuraminidase enzyme inhibition in cell death for Zn1b and Zn1c.

Nanomedicines in the treatment of colon cancer: a focus on metallodrugs

Worldwide, colon cancer (CC) represents the fourth most common type of cancer and the fifth major cause of cancer-associated deaths. Surgical resection is considered the standard therapeutic choice for CC in early stages. However, in latter stages of the disease, adjuvant chemotherapy is essential for an appropriate management of this pathology. Metal-based complexes displaying cytotoxic properties towards tumor cells emerge as potential chemotherapeutic options. One metallodrug, oxaliplatin, was already approved for clinical use, playing an important role in the treatment of CC patients. Unfortunately, most of the newly designed metal-based complexes exhibit lack of selectivity against cancer cells, low solubility and permeability, high dose-limiting toxicity, and emergence of resistances. Nanodelivery systems enable the incorporation of metallodrugs at adequate payloads, solving the above-referred drawbacks. Moreover, drug delivery systems, depending on their physicochemical properties, are able to release the incorporated material preferentially at affected tissues/organs, enhancing the therapeutic activity in vivo, with concomitant fewer side effects. In this review, the general features and therapeutic management of CC will be addressed, with a special focus on preclinical or clinical studies using metal-based compounds. Furthermore, the use of different nanodelivery systems will also be described as tools to potentiate the therapeutic index of metallodrugs for the management of CC.

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.

Co(ii), Ni(ii), Cu(ii) and Cd(ii)-thiocarbonohydrazone complexes: spectroscopic, DFT, thermal, and electrical conductivity studies

New and stable coordinated compounds have been isolated in a good yield. The chelates have been prepared by mixing Co(ii), Ni(ii), Cu(ii), and Cd(ii) metal ions with (1E)-1-((6-methyl-4-oxo-4H-chromen-3-yl)methylene)thiocarbonohydrazide (MCMT) in 2 : 1 stoichiometry (MCMT : M²⁺). Various techniques, including elemental microanalyses, molar conductance, thermal studies, FT-IR, ¹H-NMR, UV-Vis, and XRD spectral analyses, magnetic moment measurements, and electrical conductivity, were applied for the structural and spectroscopic elucidation of the coordinating compounds. Further, computational studies using the DFT-B3LYP method were reported for MCMT and its metal complexes. MCMT behaves as a neutral NS bidentate moiety that forms octahedral complexes with general formula [M(MCMT)₂Cl(OH₂)]Cl·XH₂O (M = Cu²⁺; (X = ½), Ni²⁺, Co²⁺; (X = 1)); [Cd(MCMT)₂Cl₂]·½H₂O. There is good confirmation between experimental infrared spectral data and theoretical DFT-B3LYP computational outcomes where MCMT acts as a five-membered chelate bonded to the metal ion through azomethine nitrogen and thiocarbonyl sulphur donors. The thermal analysis is studied to confirm the elucidated structure of the complexes. Also, the kinetic and thermodynamic parameters of the thermal decomposition steps were evaluated. The measured optical band gap values of the prepared compounds exhibited semiconducting nature. AC conductivity and dielectric properties of the ligand and its complexes were examined, which showed that Cu(ii) complex has the highest dielectric constant referring to its high polarization and storage ability.

Synthesis, Characterization, DNA/HSA Interactions, and Anticancer Activity of Two Novel Copper(II) Complexes with 4-Chloro-3-Nitrobenzoic Acid Ligand

The purpose of this study was to identify new metal-based anticancer drugs; to this end, we synthesized two new copper(II) complexes, namely [Cu(ncba)₄(phen)] (1) and [Cu(ncba)₄(bpy)] (2), comprised 4-chloro-3-nitrobenzoic acid as the main ligand. The single-crystal XRD approach was employed to determine the copper(II) complex structures. Binding between these complexes and calf thymus DNA (CT-DNA) and human serum albumin (HSA) was explored by electronic absorption, fluorescence spectroscopy, and viscometry. Both complexes intercalatively bound CT-DNA and statically and spontaneously quenched DNA/HSA fluorescence. A CCK-8 assay revealed that complex 1 and complex 2 had substantial antiproliferative influences against human cancer cell lines. Moreover, complex 1 had greater antitumor efficacy than the positive control cisplatin. Flow cytometry assessment of the cell cycle demonstrated that these complexes arrested the HepG2 cell cycle and caused the accumulation of G0/G1-phase cells. The mechanism of cell death was elucidated by flow cytometry-based apoptosis assays. Western blotting revealed that both copper(II) complexes induced apoptosis by regulating the expression of the Bcl-2(Bcl-2, B cell lymphoma 2) protein family.

Cobalt mediated N-alkylation of amines by alcohols: role of hydrogen bonding pocket

Cobalt complexes of amide-based pincers provide a H-bonding pocket that binds a reagent in the vicinity of the metal center. These complexes function as catalysts for the N-alkylation of amines using alcohols via a borrowing hydrogen strategy.

Synthesis, Spectroscopic Characterization, Structural Studies, and In Vitro Antitumor Activities of Pyridine-3-carbaldehyde Thiosemicarbazone Derivatives

Eight new thiosemicarbazone derivatives, 6-(1-trifluoroethoxy)pyridine-3-carbaldehyde thiosemicarbazone (1), 6-(4′-fluorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (2), 5-chloro-pyridine-3-carbaldehyde thiosemicarbazone (3), 2-chloro-5-bromo-pyridine-3-carbaldehyde thiosemicarbazone (4), 6-(3′,4′-dimethoxyphenyl)pyridine-3-carbaldehyde thiosemicarbazone (5), 2-chloro-5-fluor-pyridine-3-carbaldehyde thiosemicarbazone, (6), 5-iodo-pyridine-3-carbaldehyde thiosemicarbazone (7), and 6-(3′,5′-dichlorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (8) were synthesized, from the reaction of the corresponding pyridine-3-carbaldehyde with thiosemicarbazide. The synthesized compounds were characterized by ESI-Mass, UV-Vis, IR, and NMR (1H, 13C, 19F) spectroscopic techniques. Molar mass values and spectroscopic data are consistent with the proposed structural formulas. The molecular structure of 7 has been also confirmed by single crystal X-ray diffraction. In the solid state 7 exists in the E conformation about the N2-N3 bond; 7 also presents the E conformation in solution, as evidenced by 1H NMR spectroscopy. The in vitro antitumor activity of the synthesized compounds was studied on six human tumor cell lines: H460 (lung large cell carcinoma), HuTu80 (duodenum adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), M-14 (amelanotic melanoma), and HT-29 (colon adenocarcinoma). Furthermore, toxicity studies in 3T3 normal cells were carried out for the prepared compounds. The results were expressed as IC50 and the selectivity index (SI) was calculated. Biological studies revealed that 1 (IC50 = 3.36 to 21.35 μM) displayed the highest antiproliferative activity, as compared to the other tested thiosemicarbazones (IC50 = 40.00 to >582.26 μM) against different types of human tumor cell lines. 1 was found to be about twice as cytotoxic (SI = 1.82) than 5-fluorouracile (5-FU) against the M14 cell line, indicating its efficiency in inhibiting the cell growth even at low concentrations. A slightly less efficient activity was shown by 1 towards the HuTu80 and MCF7 tumor cell lines, as compared to that of 5-FU. Therefore, 1 can be considered as a promising candidate to be used as a pharmacological agent, since it presents significant activity and was found to be more innocuous than the 5-FU anticancer drug against the 3T3 mouse embryo fibroblast cells.