Silver(I) N-Heterocyclic Carbene Complexes Derived from Clotrimazole: Antiproliferative Activity and Interaction with an Artificial Membrane-Based Biosensor

Fluorinated N-Heterocyclic Carbene Silver(I) Complexes with High Cancer Cell Selectivity

This work presents the synthesis of five new functionalized (benz)imidazolium N-heterocyclic (NHC) ligands (L) and four new (benz)imidazole silver(I) NHC (Ag(I)-NHC) complexes of mononuclear [Ag(L)2](PF6) or binuclear [Ag2(L)2](PF6)2 type. The complexes have been fully characterized, including single crystal X-ray diffraction of three new structures. The complexes and their corresponding free NHC ligands have been screened against breast cancer and noncancerous cell lines, showing the mononuclear benzimidazole complex has the highest activity, while the binuclear benzimidazole complex has the highest cancer cell selectivity. The silver uptake was measured by ICP-MS and highlights a strong link between cytotoxicity and cellular uptake. DNA interaction studies, molecular docking, and evaluation of reactive oxygen species (ROS) have been conducted for the most promising complexes to identify modes of action. Overall, the binuclear benzimidazole complex is the most selective and promising candidate against the MDA-MD-231 (breast cancer) cell line and has potential to be developed for treatment of late-stage breast cancers.

Acetylated galactopyranosyl N-heterocyclic monocarbene complexes of Silver(I) as novel anti-proliferative agents in a rhabdomyosarcoma cell line

Herein, four silver(I) complexes bearing acetylated d-galactopyranoside-based N-heterocyclic carbene ligands were synthesized and fully characterized by elemental analysis, NMR, and X-ray photoelectron spectroscopy. All complexes were obtained with an anomeric β-configuration and as monocarbene species. In this study, we investigated the biological effects of the silver(I) complexes 2a-d on the human rhabdomyosarcoma cell line, RD. Our results show concentration-dependent effects on cell density, growth inhibition, and activation of key signaling pathways such as Akt 1/2, ERK 1/2, and p38-MAPK, indicating their potential as anticancer agents. Notably, at 35.5 µM, the complexes induced mitochondrial network disruption, as observed with 2b and 2c, whereas with 2a, this disruption was accompanied by nuclear content release. These results provide insight into the utility of carbohydrate incorporated NHC complexes of silver(I) as new agents in cancer therapy.

Resurgence and Repurposing of Antifungal Azoles by Transition Metal Coordination for Drug Discovery

Coordination compounds featuring one or more antifungal azole (AA) ligands constitute an interesting family of candidate molecules, given their medicinal polyvalence and the viability of drug complexation as a strategy to improve and repurpose available medications. This review reports the work performed in the field of coordination derivatives of AAs synthesized for medical purposes by discussing the corresponding publications and emphasizing the most promising compounds discovered so far. The resulting overview highlights the efficiency of AAs and their metallic species, as well as the potential still lying in this research area.

Silver(I) complexes containing N-heterocyclic carbene azole drugs: Synthesis, characterization, cytotoxic activity, and their BSA interactions

Cancer is one of the main public health problems globally, there is a public demand for better drugs. Rational strategies or approaches are used to improve the success of drug discovery. Our strategy was to the repurposing of well-known antifungal agents as potential anticancer drugs, such as Clotrimazole (CTZ) and Ketoconazole (KTZ). We prepared the respective iodide imidazolium salt L1: (CTZ-Me)I and L2: (KTZ-Me)I to be the intermediates toward the synthesis of its respective NHC ligand and achieve the respective silver(I)-monoNHC and silver(I)-bisNHC derivatives: [Ag(L1)I] (1), [AgI(L2)] (2) [Ag(L1)2]I. (3), [Ag(L2)2]I. (4), as well as their corresponding coordination compounds [Ag(CTZ)2]NO3 (5) and [Ag(KTZ)2]NO3 (6) where these ligands (CTZ and KTZ) coordinate to silver through the N-imidazole atom. These compounds (L1, L2 and complexes 1-6) exhibited significant activity against the tested cancer cell lines (B16-F1, murine melanoma strains and CT26WT, murine colon carcinoma). The silver(I) complexes were more active than the free ligands, complexes 2 and 4 being the most selective in B16-F1 cancer cell line. Two possibles biological targets such as DNA and albumin were examined for the observed anticancer activity. Results show that DNA is not the main target, however, the interactions with albumin suggest it can transport/delivery the metal complexes.

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.

Heterogeneous Rate Constant for Amorphous Silica Nanoparticle Adsorption on Phospholipid Monolayers

The interaction of amorphous silica nanoparticles with phospholipid monolayers and bilayers has received a great deal of interest in recent years and is of importance for assessing potential cellular toxicity of such species, whether natural or synthesized for the purpose of nanomedical drug delivery and other applications. This present communication studies the rate of silica nanoparticle adsorption on to phospholipid monolayers in order to extract a heterogeneous rate constant from the data. This rate constant relates to the initial rate of growth of an adsorbed layer of nanoparticles as SiO2 on a unit area of the monolayer surface from unit concentration in dispersion. Experiments were carried out using the system of dioleoyl phosphatidylcholine (DOPC) monolayers deposited on Pt/Hg electrodes in a flow cell. Additional studies were carried out on the interaction of soluble silica with these layers. Results show that the rate constant is effectively constant with respect to silica nanoparticle size. This is interpreted as indicating that the interaction of hydrated SiO2 molecular species with phospholipid polar groups is the molecular initiating event (MIE) defined as the initial interaction of the silica particle surface with the phospholipid layer surface promoting the adsorption of silica nanoparticles on DOPC. The conclusion is consistent with the observed significant interaction of soluble SiO2 with the DOPC layer and the established properties of the silica-water interface.

Distinct mechanism of action for antitumoral neutral cyclometalated Pt(II)-complexes bearing antifungal imidazolyl-based drugs

Three neutral Pt(II) complexes containing 1-Methylimidazole and the antifungal imidazolyl drugs Clotrimazole and Bifonazole have been prepared. The general formula of the new derivatives is [Pt(κ²-(C^N)Cl(L)], where C^N stands for ppy = 2-phenylpyridinate, and L = 1-Methylimidazole (MeIm) for [Pt-MeIm]; L = Clotrimazole (CTZ) for [Pt-CTZ] and L = Bifonazole (BFZ) for [Pt-BFZ]). The complexes have been completely characterized in solution and the crystal structures of [Pt-BFZ] and [Pt-CTZ] have been resolved. Complexes [Pt-MeIm] and [Pt-BFZ] present higher cytotoxicity than cisplatin in SW480 (colon adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian cancer) cell lines. [Pt-MeIm] shows the highest accumulation in A549 cells, in agreement with its inability to interact with serum albumin. By contrast, [Pt-CTZ] and [Pt-BFZ] interact with serum proteins, a fact that reduces their bioavailability. The strongest interaction with bovine serum albumin (BSA) is found for [Pt-BFZ], which is the least internalized inside the cells. All the complexes are able to covalently interact with DNA. The most cytotoxic complexes, [Pt-MeIm] and [Pt-BFZ] induce cellular accumulation in G0/G1 and apoptosis by a similar pathway, probably involving a reactive oxygen species (ROS) generation mechanism. [Pt-BFZ] turns out to be the most efficient complex regarding ROS generation and causes mitochondrial membrane depolarization, whereas [Pt-MeIm] induces the opposite effect, hyperpolarization of the mitochondrial membrane. On the contrary, the least cytotoxic complex, [Pt-CTZ] cannot block the cell cycle or generate ROS and the mechanism by which it induces apoptosis could be a different one.

Synthesis, structure, fluorescence, electrochemical, and antioxidant studies of a new silver(I) complex with 2,6-bis(N-methylbenzimidazol-2-yl)pyridine

A new silver(I) complex of the type [Ag2(mbbp)2](pic)2·DMF·CH3OH [mbbp = 2,6-bis( N-methylbenzimidazol-2-yl)pyridine] is synthesized and analyzed using a range of spectroscopic and crystallographic techniques. This compound contains cationic Ag2(mbbp)2 dimers, in which the crossed eight-shaped structure is formed by two mbbp ligands bridging two silver(I) centers and Ag–Ag bonds. Two-dimensional supramolecular networks of the silver(I) complex are connected by π···π interactions and hydrogen bonds. Hirshfeld analyses are performed to support the aforementioned intermolecular interactions. The effect of π···π stacking interactions on the fluorescence properties of the complex is investigated. Cyclic voltammetry indicates two irreversible redox processes. In addition, an antioxidant assay in vitro demonstrates that the silver(I) complex displays excellent scavenging activity toward hydroxyl radicals.