Cu(II)-dipeptide complexes of 2-(4'-thiazolyl)benzimidazole: synthesis, DNA oxidative damage, antioxidant and in vitro antitumor activity

Comprehensive Insights into Medicinal Research on Imidazole-Based Supramolecular Complexes

The electron-rich five-membered aromatic aza-heterocyclic imidazole, which contains two nitrogen atoms, is an important functional fragment widely present in a large number of biomolecules and medicinal drugs; its unique structure is beneficial to easily bind with various inorganic or organic ions and molecules through noncovalent interactions to form a variety of supramolecular complexes with broad medicinal potential, which is being paid an increasing amount of attention regarding more and more contributions to imidazole-based supramolecular complexes for possible medicinal application. This work gives systematical and comprehensive insights into medicinal research on imidazole-based supramolecular complexes, including anticancer, antibacterial, antifungal, antiparasitic, antidiabetic, antihypertensive, and anti-inflammatory aspects as well as ion receptors, imaging agents, and pathologic probes. The new trend of the foreseeable research in the near future toward imidazole-based supramolecular medicinal chemistry is also prospected. It is hoped that this work provides beneficial help for the rational design of imidazole-based drug molecules and supramolecular medicinal agents and more effective diagnostic agents and pathological probes.

Temporally Controlled Multienzyme Catalysis Using a Dissipative Supramolecular Nanozyme

The development of superior functional enzyme mimics (nanozymes) is essential for practical applications, including point-of-care diagnostics, biotechnological applications, biofuels, and environmental remediation. Nanozymes with the ability to control their catalytic activity in response to external fuels offer functionally valuable platforms mimicking nonequilibrium systems in nature. Herein, we fabricated a supramolecular coordination bonding-based dynamic vesicle that exhibits multienzymatic activity. The supramolecular nanozyme shows effective laccase-like catalytic activity with a K_M value better than the native enzyme and higher stability in harsh conditions. Besides, the nanostructure demonstrates an efficient peroxidase-like activity with NADH peroxidase-like properties. Generation of luminescence from luminol and oxidation of dopamine are efficiently catalyzed by the nanozyme with high sensitivity, which is useful for point-of-care detections. Notably, the active nanozyme exhibits dynamic laccase-mimetic activity in response to pH variation, which has never been explored before. While a neutral/high pH leads to the self-assembly, a low pH disintegrates the assembled nanostructures and consequently turns off the nanozyme activity. Altogether, the self-assembled Cu²⁺-based vesicular nanostructure presents a pH-fueled dissipative system demonstrating effective temporally controlled multienzymatic activity.

Nuclease-like metalloscissors: Biomimetic candidates for cancer and bacterial and viral infections therapy

Despite the extensive and rapid discovery of modern drugs for treatment of cancer, microbial infections, and viral illnesses; these diseases are still among major global health concerns. To take inspiration from natural nucleases and also the therapeutic potential of metallopeptide antibiotics such as the bleomycin family, artificial metallonucleases with the ability of promoting DNA/RNA cleavage and eventually affecting cellular biological processes can be introduced as a new class of therapeutic candidates. Metal complexes can be considered as one of the main categories of artificial metalloscissors, which can prompt nucleic acid strand scission. Accordingly, biologists, inorganic chemists, and medicinal inorganic chemists worldwide have been designing, synthesizing and evaluating the biological properties of metal complexes as artificial metalloscissors. In this review, we try to highlight the recent studies conducted on the nuclease-like metalloscissors and their potential therapeutic applications. Under the light of the concurrent Covid-19 pandemic, the human need for new therapeutics was highlighted much more than ever before. The nuclease-like metalloscissors with the potential of RNA cleavage of invading viral pathogens hence deserve prime attention.

The Bright and Dark Sides of Reactive Oxygen Species Generated by Copper–Peptide Complexes

Copper ions bind to biomolecules (e.g., peptides and proteins) playing an essential role in many biological and physiological pathways in the human body. The resulting complexes may contribute to the initiation of neurodegenerative diseases, cancer, and bacterial and viral diseases, or act as therapeutics. Some compounds can chemically damage biological macromolecules and initiate the development of pathogenic states. Conversely, a number of these compounds may have antibacterial, antiviral, and even anticancer properties. One of the most significant current discussions in Cu biochemistry relates to the mechanisms of the positive and negative actions of Cu ions based on the generation of reactive oxygen species, including radicals that can interact with DNA molecules. This review aims to analyze various peptide–copper complexes and the mechanism of their action.

Biochemical pathways of copper complexes: progress over the past 5 years

Copper is an essential trace element with vital roles in many metalloenzymes; it is also prominent among nonplatinum anticancer metallodrugs. Copper-based complexes are endogenously biocompatible, tenfold more potent than cisplatin, exhibit fewer adverse effects, and have a wide therapeutic window. In cancer biology, copper acts as an antitumor agent by inhibiting cancer via multiple pathways. Herein, we present an overview of advances in copper complexes as 'lead' antitumor drug candidates, and in understanding their biochemical and pharmacological pathways over the past 5 years. This review will help to develop more efficacious therapeutics to improve clinical outcomes for cancer treatments.

Recent Progress of Benzimidazole Hybrids for Anticancer Potential

This review presents the detailed account of factors leading to cancer and design strategy for the synthesis of benzimidazole derivatives as anticancer agents. The recent survey for cancer treatment in Cancer facts and figures 2017 American Chemical Society has shown progressive development in fighting cancer. Researchers all over the world in both developed and developing countries are in a continuous effort to tackle this serious concern. Benzimidazole and its derivatives showed a broad range of biological activities due to their resemblance with naturally occurring nitrogenous base i.e. purine. The review discussed benzimidazole derivatives showing anticancer properties through a different mechanism viz. intercalation, alkylating agents, topoisomerases, DHFR enzymes, and tubulin inhibitors. Benzimidazole derivatives act through a different mechanism and the substituents reported from the earlier and recent research articles are prerequisites for the synthesis of targeted based benzimidazole derivatives as anticancer agents. The review focuses on an easy comparison of the substituent essential for potency and selectivity through SAR presented in figures. This will further provide a better outlook or fulfills the challenges faced in the development of novel benzimidazole derivatives as anticancer.

Structural and spectral analysis of anticancer active cyclo(Ala-His) dipeptide

The theoretically possible most stable conformation of the cyclic dipeptide, which has a significant anticancer activity, was examined by conformational analysis method and then by DFT calculations. With DFT calculations, cyclo(Ala-His) dipeptide was found to be more stable in boat form than in planar conformation. Moreover, conformations of the dimeric forms of the title molecule were investigated. The dimeric forms of the cyclo(Ala-His) dipeptide were created by combining two identical cyclo(Ala-His) monomers, in lowest energy configuration and as a result three energetically possible dimeric structures were obtained. The solid phase FTIR and Raman spectra of cyclo(Ala-His) have been recorded. The spectra were interpreted with the aid of quantum chemical calculations based on density functional theory, using B3LYP and wb97xd methods with 6-311++G(d,p) basis set, in order to elucidate structural and spectral properties of the investigated molecule. Experimental vibrational spectra are found to be in accord with the simulated vibrational spectra. The assignment of the vibrational modes was performed depending on the calculated potential energy distribution (PED). In slico molecular docking of cyclo(Ala-His) was also carried out with DNA. The drug likeness and ADMET properties were analyzed for the prediction of pharmacokinetic profiles. The results revealed that the compound has the potential to be the leading molecule in the drug discovery process.

High-throughput screening and Bayesian machine learning for copper-dependent inhibitors of Staphylococcus aureus

One potential source of new antibacterials is through probing existing chemical libraries for copper-dependent inhibitors (CDIs), i.e., molecules with antibiotic activity only in the presence of copper. Recently, our group demonstrated that previously unknown staphylococcal CDIs were frequently present in a small pilot screen. Here, we report the outcome of a larger industrial anti-staphylococcal screen consisting of 40 771 compounds assayed in parallel, both in standard and in copper-supplemented media. Ultimately, 483 had confirmed copper-dependent IC50 values under 50 μM. Sphere-exclusion clustering revealed that these hits were largely dominated by sulfur-containing motifs, including benzimidazole-2-thiones, thiadiazines, thiazoline formamides, triazino-benzimidazoles, and pyridinyl thieno-pyrimidines. Structure-activity relationship analysis of the pyridinyl thieno-pyrimidines generated multiple improved CDIs, with activity likely dependent on ligand/ion coordination. Molecular fingerprint-based Bayesian classification models were built using Discovery Studio and Assay Central, a new platform for sharing and distributing cheminformatic models in a portable format, based on open-source tools. Finally, we used the latter model to evaluate a library of FDA-approved drugs for copper-dependent activity in silico. Two anti-helminths, albendazole and thiabendazole, scored highly and are known to coordinate copper ions, further validating the model's applicability.

Structural basis and effect of copper(II) complexes with 4-oxo-thiazolidine ligands on DNA binding and nuclease activity

Seven novel Copper(II) complexes, namely [Cu(Am4DHotaz)(H₂O)₂](ClO₄) (1), [Cu(Am4DHotaz)(NO₃)(MeOH)]·H₂O (2), [Cu(Am4Motaz)₂(H₂O)](ClO₄)₂·0.83H₂O (3), [Cu(Am4Motaz)₂(NO₃)]NO₃·MeOH (4), [Cu(Am4Eotaz)₂(NO₃)]₃(NO₃)₃·2H₂O (5), [Cu(Am4Eotaz)₂(ClO₄)](ClO₄) (6) and [Cu(Am4Eotaz)(ClO₄)(H₂O)](ClO₄) (6a) (HAm4DHotaz = N'-(4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide, Am4Motaz = N'-(3-methyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide and Am4Eotaz = N'-(3-ethyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide), have been successfully synthesized and characterized by several physicochemical techniques and, for 1-6 complexes, single crystal X-ray diffraction. Having the structural data as a base, complexes 1, 2 and 3 exhibited square pyramidal to square pyramidal slightly distorted geometry, whereas 4, 5 and 6 an intermediate between square pyramidal and trigonal bipyramidal. The ability of complexes 1-6 to cleave DNA was assayed with the aid of gel electrophoresis on supercoiled pUC18-DNA. Except for [Cu(Am4Motaz)₂(H₂O)](ClO₄)₂·0.83H₂O (3), the compounds were not able to perform DNA cleavage (data not shown). Since 3 has been shown to behave as a nuclease, its interaction with DNA was studied by means of thermal denaturation and viscosimetry measurements.

Synthesis and anticancer evaluation of benzo-N-heterocycles transition metal complexes against esophageal cancer cell lines

Three novel transition metal complexes, Cu(p-2-bmq)Cl₂ (1), Zn(p-2-bmq)Cl₂ (2) and [Co(p-2-bmq)Cl₂]₂ (3) (where p-2-bmq = 2-((1-(pyridin-2-yl)-1H-benzoimidazol-2-yl)methyl) quinolone, have been synthesized. The complexes were detected for their cytotoxicity in vitro against four human esophageal cancer cell lines (SMMC7721, BGC823, HCT116 and HT29) by MTT assay. The results showed that they all have anti-tumor cell proliferation activity. E specially, complex 1 exhibited significant cytotoxicity with IC₅₀ value of 15.89 μM against SMMC7721 cells for 72 h. The morphological changes of nuclei by fluorescence staining methods proved that complex 1 could induce intracellular DNA damage. The flow cytometry analysis revealed that the treatment of SMMC7721 cells with complex 1 induced intracellular ROS increased, mitochondrial potential collapse, G2/M-phase arrest, and even apoptosis. These studies should highly valuable for the development of transition metal-based compounds to the potential anticancer medicinal applications.

Theoretical study on the DNA interaction properties of copper(II) complexes

Theoretical studies on DNA-cleavage and DNA-binding properties of a series of Cu(II) complexes [Cu(bimda)(diimine)] 1-5 have been carried out by density functional theory (DFT). The optimized structures of Cu(II) complexes were docked into parallel, antiparallel and mixed G-quadruplexes, with which the binding energies of complexes 1-5 were obtained. The cytotoxicities of these complexes can be predicted preliminarily by the binding energies. To explore the energy changes of Cu(II) complexes in duplex DNA, the optimized structures of these complexes were docked into the duplex DNA, and the obtained docking models were further optimized using QM/MM method. The DNA-cleavage abilities of complexes 1-5 can be predicted accurately and explained reasonably by the computed intra-molecular reorganization energies of these complexes. This work reported here has implications for the understanding of the interaction Cu(II) complexes with the DNA, which might be helpful for the future directing the design of novel anticancer Cu(II) complexes.

CuI and CuII complexes with phosphine derivatives of fluoroquinolone antibiotics - A comparative study on the cytotoxic mode of action

In this paper, we present a comparative study on the cytotoxic mode of action of copper(I) and copper(II) complexes with phosphine derivatives of fluoroquinolone antibiotics (ciprofloxacin HCp and norfloxacin HNr). The in vitro cytotoxic activity of four new compounds was tested against two selected cancer cell lines. All complexes exhibited much better cytotoxicity against both cell lines than unmodified fluoroquinolone antibiotics, their phosphines (PCp, PNr), chalcogenide derivatives (oxides: OPCp, OPNr; sulfides: SPCp, SPNr and selenides: SePCp, SePNr) and previously described by us complexes with phosphines derived from different fluoroquinolones: lomefloxacin (HLm) and sparfloxacin (HSf) as well as cisplatin. Apoptosis, observed at a great predominance, was induced by all studied complexes. Importantly, it was concluded that coordination compounds with Cu(I) ion ([Cu^I-PNr] and [Cu^I-PCp]) were much more active than those with Cu(II) ion ([OPNr-Cu^II], [OPCp-Cu^II]), even though the highest efficacy to produce reactive oxygen species, participating in overall cytotoxicity, was proved for copper(II) complexes among all studied compounds. Herein, we discuss not only results obtained for copper(I)/(II) complexes with phosphines derived from HNr and HCp but we also compare them to previously described data for complexes with HLm and HSf derivatives. This is the first insight into a structure-activity relationship of copper complexes with phosphine derivatives of fluoroquinolone antibiotics.

Bioactive M(II) complexes of amino acid-based N3O donor mixed ligand: in vitro and in silico DNA binding studies

Three novel mixed ligand M(II) complexes, namely [CoL¹L²Cl₂] (1), [CuL¹L²Cl₂] (2), and [ZnL¹L²Cl₂] (3), were synthesized using 1,4-naphthoquinone, L-histidine, and 1,10-phenanthroline as ligands. The ligand framework and the corresponding structural changes on complexation were ascertained based on the results of elemental analysis, conductivity measurements, magnetic behavior, FT-IR, UV-visible, ¹H NMR, ¹³C NMR, ESR spectral studies, and ESI mass spectrometry. The biological action of the ligand (L) and complexes 1-3 such as DNA binding and cleaving ability were studied. Results suggest that the ligand and the complexes could interact with calf thymus-DNA (CT-DNA) via intercalation mode. Additionally, complex 2 displayed potential antioxidant activity in in vitro studies. Docking simulation was performed to position the ligand and the complexes into the active site of BDNA (IBNA) to determine the probable binding mode.

Mitochondrial and nuclear DNA dual damage induced by 2-(2′-quinolyl)benzimidazole copper complexes with potential anticancer activity

Complex 2 can induce nuclear and mitochondrial dual damage in HCT116 cells and can also induce apoptosis.

Structure-activity relationship (SAR) study and design strategies of nitrogen-containing heterocyclic moieties for their anticancer activities

The present review article offers a detailed account of the design strategies employed for the synthesis of nitrogen-containing anticancer agents. The results of different studies describe the N-heterocyclic ring system is a core structure in many synthetic compounds exhibiting a broad range of biological activities. Benzimidazole, benzothiazole, indole, acridine, oxadiazole, imidazole, isoxazole, pyrazole, triazoles, quinolines and quinazolines including others drugs containing pyridazine, pyridine and pyrimidines are covered. The following studies of these compounds suggested that these compounds showed their antitumor activities through multiple mechanisms including inhibiting protein kinase (CDK, MK-2, PLK1, kinesin-like protein Eg5 and IKK), topoisomerase I and II, microtubule inhibition, and many others. Our concise representation exploits the design and anticancer potency of these compounds. The direct comparison of anticancer activities with the standard enables a systematic analysis of the structure-activity relationship among the series.

Effects of N,N-heterocyclic ligands on the in vitro cytotoxicity and DNA interactions of copper(ii) chloride complexes from amidino-O-methylurea ligands

Four novel copper(ii) complexes based on guanidine derivatives have been synthesized by addition of N,N-heterocyclic ligands, and their interesting biological activities have been evaluated.

Synthesis, characterisation and antibacterial activity of [(p-cym)RuX(L)]+/2+ (X = Cl, H2O; L = bpmo, bpms) complexes

Simple replacement of Cl⁻ by H₂O in {(p-cym)Ru^II(L)X]ⁿ⁺ (X = Cl or H₂O) complexes enhances antibacterial activity significantly.