Synthesis, characterization, and biological activity of a triphenylphosphonium-containing imidazolium salt against select bladder cancer cell lines

The impact of wingtip N-substitution on the bioactivity of azolium salts

Studies have shown that the physicochemical properties of five-membered heterocyclic azolium compounds directly affect their biological activity as therapeutic drugs (spectrum of activity and potency) and the associated pharmacokinetic, pharmacologic, and toxicological profiles of the compounds. Hence, this review focused on the influence of N-functionalisation at the wingtip of such compounds, mainly the diazolium and the triazolium-based salts. The contribution of the N-donor groups to the overall biological efficacy of the azolium compounds and the ensuing structure-activity mechanisms in their pharmacological applications are comprehensively discussed.

Self-Assembling Imidazolium Nanoaggregates Trigger a Unique Dynamin-Dependent Cell Death via Cytoplasmic Vacuolization and Mitochondrial Dysfunction in Human Lung Adenocarcinoma

The identification of alternative cell death pathways is key to developing therapies for apoptosis-resistant cancers. We investigated cell death induced by delocalized lipophilic cation (DLC) nanoaggregates in A549 lung carcinoma cells. These DLCs trigger a dynamin-dependent, nonapoptotic pathway involving cytoplasmic vesicle accumulation and mitochondrial dysfunction. Leveraging the mitochondria-targeting ability of lipophilic cations, we designed and synthesized fluorescent mitochondrion-toxic molecules with potent cytotoxicity against A549, MDA-MB-231, and MCF-7 cells. Dynamic light scattering revealed the nanoaggregate formation of the lead compound, L3, in the RPMI media. L3 inhibited metastasis and clonal expansion, induced vacuole formation post endocytosis, and impaired the mitochondrial function, disrupting ATP levels. This led to mitochondrial permeability transition pore (MPTP) opening and oxidative imbalance via glutathione perturbation. L3 demonstrated strong antitumor activity in vitro and in vivo, showing high potential for treating apoptosis-resistant cancers.

Recent animal models of bladder cancer and their application in drug discovery: an update of the literature

INTRODUCTION

Bladder cancer presents a significant health problem worldwide, with environmental and genetic factors contributing to its incidence. Histologically, it can be classified as carcinoma in situ, non-muscle invasive and muscle-invasive carcinoma, each one with distinct genetic alterations impacting prognosis and response to therapy. While traditional transurethral resection is commonly performed in carcinoma in situ and non-muscle invasive carcinoma, it often fails to prevent recurrence or progression to more aggressive phenotypes, leading to the frequent need for additional treatment such as intravesical chemotherapy or immunotherapy. Despite the advances made in recent years, treatment options for bladder cancer are still lacking due to the complex nature of this disease. So, animal models may hold potential for addressing these limitations, because they not only allow the study of disease progression but also the evaluation of therapies and the investigation of drug repositioning.

AREAS COVERED

This review discusses the use of animal models over the past decade, highlighting key discoveries and discussing advantages and disadvantages for new drug discovery.

EXPERT OPINION

Over the past decade animal models have been employed to evaluate new mechanisms underlying the responses to standard therapies, aiming to optimize bladder cancer treatment. The authors propose that molecular engineering techniques and AI may hold promise for the future development of more precise and effective targeted therapies in bladder cancer.

Synthesis, Characterisation, and In Vitro Evaluation of Biocompatibility, Antibacterial and Antitumor Activity of Imidazolium Ionic Liquids

In recent decades, ionic liquids (ILs) have garnered research interest for their noteworthy properties, such as thermal stability, low or no flammability, and negligible vapour pressure. Moreover, their tunability offers limitless opportunities to design ILs with properties suitable for applications in many industrial fields. This study aims to synthetise two series of methylimidazolium ILs bearing long alkyl chain in their cations (C9, C10, C12, C14, C16, C18, C20) and with tetrafluoroborate (BF4) and the 1,3-dimethyl-5-sulfoisophthalate (DMSIP) as counter ions. The ILs were characterised using 1H-NMR and MALDI-TOF, and their thermal behaviour was investigated through DSC and TGA. Additionally, the antimicrobial, anticancer, and cytotoxic activities of the ILs were analysed. Moreover, the most promising ILs were incorporated at different concentrations (0.5, 1, 5 wt%) into polyvinyl chloride (PVC) by solvent casting to obtain antimicrobial blend films. The thermal properties and stability of the resulting PVC/IL films, along with their hydrophobicity/hydrophilicity, IL surface distribution, and release, were studied using DSC and TGA, contact angle (CA), SEM, and UV-vis spectrometry, respectively. Furthermore, the antimicrobial and cytotoxic properties of blends were analysed. The in vitro results demonstrated that the antimicrobial and antitumor activities of pure ILs against t Listeria monocytogenes, Escherichia coli, Pseudomonas fluorescens strains, and the breast cancer cell line (MCF7), respectively, were mainly dependent on their structure. These activities were higher in the series containing the BF4 anion and increased with the increase in the methylimidazolium cation alkyl chain length. However, the elongation of the alkyl chain beyond C16 induced a decrease in antimicrobial activity, indicating a cut-off effect. A similar trend was also observed in terms of in vitro biocompatibility. The loading of both the series of ILs into the PVC matrix did not affect the thermal stability of PVC blend films. However, their Tonset decreased with increased IL concentration and alkyl chain length. Similarly, both the series of PVC/IL films became more hydrophilic with increasing IL concentration and alkyl chain. The loading of ILs at 5% concentration led to considerable IL accumulation on the blend film surfaces (as observed in SEM images) and, subsequently, their higher release. The biocompatibility assessment with healthy human dermal fibroblast (HDF) cells and the investigation of antitumoral properties unveiled promising pharmacological characteristics. These findings provide strong support for the potential utilisation of ILs in biomedical applications, especially in the context of cancer therapy and as antibacterial agents to address the challenge of antibiotic resistance. Furthermore, the unique properties of the PVC/IL films make them versatile materials for advancing healthcare technologies, from drug delivery to tissue engineering and antimicrobial coatings to diagnostic devices.

Ionic liquids meet lipid bilayers: a state-of-the-art review

In the past 25 years, a vast family of complex organic salts known as room-temperature ionic liquids (ILs) has received increasing attention due to their potential applications. ILs are composed by an organic cation and either an organic or inorganic anion, and possess several intriguing properties such as low vapor pressure and being liquid around room temperature. Several biological studies flagged their moderate-to-high (cyto)-toxicity. Toxicity is, however, also a synonym of affinity, and this boosted a series of biophysical and chemical-physical investigations aimed at exploiting ILs in bio-nanomedicine, drug-delivery, pharmacology, and bio-nanotechnology. Several of these investigations focused on the interaction between ILs and lipid membranes, aimed at determining the microscopic mechanisms behind their interaction. This is the focus of this review work. These studies have been carried out on a variety of different lipid bilayer systems ranging from 1-lipid to 5-lipids systems, and also on cell-extracted membranes. They have been carried out at different chemical-physical conditions and by the use of a number of different approaches, including atomic force microscopy, neutron and X-ray scattering, dynamic light scattering, differential scanning calorimetry, surface quartz microbalance, nuclear magnetic resonance, confocal fluorescence microscopy, and molecular dynamics simulations. The aim of this "2023 Michèle Auger Award" review work is to provide the reader with an up-to-date overview of this fascinating research field where "ILs meet lipid bilayers (aka biomembranes)," with the aim to boost it further and expand its cross-disciplinary edges towards novel high-impact ideas/applications in pharmacology, drug delivery, biomedicine, and bio-nanotechnology.

Strategies for Solubility and Bioavailability Enhancement and Toxicity Reduction of Norcantharidin

Cantharidin (CTD) is the main active ingredient isolated from Mylabris, and norcantharidin (NCTD) is a demethylated derivative of CTD, which has similar antitumor activity to CTD and lower toxicity than CTD. However, the clinical use of NCTD is limited due to its poor solubility, low bioavailability, and toxic effects on normal cells. To overcome these shortcomings, researchers have explored a number of strategies, such as chemical structural modifications, microsphere dispersion systems, and nanodrug delivery systems. This review summarizes the structure-activity relationship of NCTD and novel strategies to improve the solubility and bioavailability of NCTD as well as reduce the toxicity. This review can provide evidence for further research of NCTD.

Establishment of In Vitro and In Vivo Anticolorectal Cancer Efficacy of Lithocholic Acid-Based Imidazolium Salts

Imidazolium salts (IMSs) are the subject of many studies showing their anticancer activities. In this research, a series of novel imidazolium salts substituted with lithocholic acid (LCA) and alkyl chains of various lengths (S1–S10) were evaluated against colon cancer cells. A significant reduction in the viability and metabolic activity was obtained in vitro for DLD-1 and HT-29 cell lines when treated with tested salts. The results showed that the activities of tested agents are directly related to the alkyl chain length, where S6–S8 compounds were the most cytotoxic against the DLD-1 line and S4–S10 against HT-29. The research performed on the xenograft model of mice demonstrated a lower tendency of tumor growth in the group receiving compound S6, compared with the group receiving 5-fluorouracil (5-FU). Obtained results indicate the activity of S6 in the induction of apoptosis and necrosis in induced colorectal cancer. LCA-based imidazolium salts may be candidates for chemotherapeutic agents against colorectal cancer.

Synthesis, Characterization, and Biological Activity of Anthraquinone-Substituted Imidazolium Salts for the Treatment of Bladder Cancer

BACKGROUND: Bladder cancer is one of the most common types of cancer diagnosed each year, and more than half of patients have non-muscle invasive bladder cancer (NMIBC). The standard of care for patients with high-grade NMIBC is Bacillus Calmette-Guerin (BCG). Unfortunately, multiple BCG shortages have limited access to this treatment. Available alternatives using intravesical administration of chemotherapy have some efficacy, but lack prospective validation and long-term outcomes. Development of novel intravesical therapies may provide more active alternatives to BCG for patients with high-grade NMIBC. OBJECTIVE: To develop an optimal imidazolium salt for the intravesical treatment of NMIBC and determine preliminary in vitro activity of anthraquinone-substituted imidazolium salts. METHODS: The development of the anthraquinone-substituted imidazolium salts was undertaken in an attempt to increase the potency of this class of compounds by incorporating the quinone functional group observed in the chemotherapeutics doxorubicin, valrubicin, and mitomycin. All compounds were characterized by 1H and 13C NMR spectroscopy and infrared spectroscopy. Furthermore, these imidazolium salts were tested for in vitro cytotoxicity by the Developmental Therapeutics Program (DTP) on the NCI-60 human tumor cell line screening. Additional in vitro testing was performed against diverse bladder cancer cell lines (RT112, TCCSUP, J82, and UMUC13) using CellTiter-Glo® assays and colony-forming assays. RESULTS: The NCI-60 cell line screening indicated that compound 7 had the highest activity and was concluded to be the optimal compound for further study. Using CellTiter-Glo® assays on bladder cancer cell lines, 50% growth inhibitory concentration (IC50) values were determined to range from 32–50μM after an exposure of 1 h, for compound 7. Further evaluation of the compound by colony-forming assays showed the complete inhibition of growth at 10 days post a 100μM dose of compound 7 for 1 h. CONCLUSIONS: The most active lipophilic anthraquinone imidazolium salt, compound 7, could be a viable treatment for non-muscle invasive bladder cancer as it exhibits a cell-killing effect at a 1 h time period and completely inhibits cancer regrowth in colony-forming assays.

Mitochondria as a Novel Target for Cancer Chemoprevention: Emergence of Mitochondrial-targeting Agents

Cancer chemoprevention is the most effective approach to control cancer in the population. Despite significant progress, chemoprevention has not been widely adopted because agents that are safe tend to be less effective and those that are highly effective tend to be toxic. Thus, there is an urgent need to develop novel and effective chemopreventive agents, such as mitochondria-targeted agents, that can prevent cancer and prolong survival. Mitochondria, the central site for cellular energy production, have important functions in cell survival and death. Several studies have revealed a significant role for mitochondrial metabolism in promoting cancer development and progression, making mitochondria a promising new target for cancer prevention. Conjugating delocalized lipophilic cations, such as triphenylphosphonium cation (TPP+), to compounds of interest is an effective approach for mitochondrial targeting. The hyperpolarized tumor cell membrane and mitochondrial membrane potential allow for selective accumulation of TPP⁺ conjugates in tumor cell mitochondria versus those in normal cells. This could enhance direct killing of precancerous, dysplastic, and tumor cells while minimizing potential toxicities to normal cells.

An Imidazolium-Based Lipid Analogue as a Gene Transfer Agent

A dicationic imidazolium salt is described and investigated towards its application for gene transfer. The polar head group and the long alkyl chains in the backbone contribute to a lipid-like behavior, while an alkyl ammonium group provides the ability for crucial electrostatic interaction for the transfection process. Detailed biophysical studies regarding its impact on biological membrane models and the propensity of vesicle fusion are presented. Fluorescence spectroscopy, atomic force microscopy and confocal fluorescence microscopy show that the imidazolium salt leads to negligible changes in lipid packing, while displaying distinct vesicle fusion properties. Cell culture experiments reveal that mixed liposomes containing the novel imidazolium salt can serve as plasmid DNA delivery vehicles. In contrast, a structurally similar imidazolium salt without a second positive charge showed no ability to support DNA transfection into cultured cells. Thus, we introduce a novel and variable structural motif for cationic lipids, expanding the field of lipofection agents.

Probing CO Generation through Metal-Assisted Alcohol Dehydrogenation in Metal-2-(arylazo)phenol Complexes Using Isotopic Labeling (Metal = Ru, Ir): Synthesis, Characterization, and Cytotoxicity Studies

The reaction of 2-{2-(benzo[1,3]dioxol-5-yl)- diazo}-4-methylphenol (HL) with [Ru(PPh₃)₃Cl₂] in ethanol resulted in the carbonylated ruthenium complex [RuL(PPh₃)₂(CO)] (1), wherein metal-assisted decarbonylation via in situ ethanol dehydrogenation is observed. When the reaction was performed in acetonitrile, however, the complex [RuL(PPh₃)₂(CH₃CN)] (2) was obtained as the main product, probably by trapping of a common intermediate through coordination of CH₃CN to the Ru(II) center. The analogous reaction of HL with [Ir(PPh₃)₃Cl] in ethanol did not result in ethanol decarbonylation and instead gave the organoiridium hydride complex [IrL(PPh₃)₂(H)] (3). Unambiguous evidence for the generation of CO via ruthenium-assisted ethanol oxidation is provided by the synthesis of the ¹³C-labeled complex, [Ru(PPh₃)₂L(¹³CO)] (1A) using isotopically labeled ethanol, CH₃¹³CH₂OH. To summarize all the evidence, a ruthenium-assisted mechanistic pathway for the decarbonylation and generation of alkane via alcohol dehydrogenation is proposed. In addition, the in vitro antiproliferative activity of complexes 1-3 was tested against human cervical (HeLa) and human colorectal adenocarcinoma (HT-29) cell lines. Complexes 1-3 showed impressive cytotoxicity against both HeLa (half-maximal inhibitory concentration (IC₅₀) value of 3.84-4.22 μM) and HT-29 cancer cells (IC₅₀ values between 3.3 and 4.5 μM). Moreover, the complexes were comparatively less toxic to noncancerous NIH-3T3 cells.

Mechanisms of action of ionic liquids on living cells: the state of the art

Ionic liquids (ILs) are a relatively new class of organic electrolytes composed of an organic cation and either an organic or inorganic anion, whose melting temperature falls around room-temperature. In the last 20 years, the toxicity of ILs towards cells and micro-organisms has been heavily investigated with the main aim to assess the risks associated with their potential use in (industrial) applications, and to develop strategies to design greener ILs. Toxicity, however, is synonym with affinity, and this has stimulated, in turn, a series of biophysical and chemical-physical investigations as well as few biochemical studies focused on the mechanisms of action (MoAs) of ILs, key step in the development of applications in bio-nanomedicine and bio-nanotechnology. This review has the intent to present an overview of the state of the art of the MoAs of ILs, which have been the focus of a limited number of studies but still sufficient enough to provide a first glimpse on the subject. The overall picture that emerges is quite intriguing and shows that ILs interact with cells in a variety of different mechanisms, including alteration of lipid distribution and cell membrane viscoelasticity, disruption of cell and nuclear membranes, mitochondrial permeabilization and dysfunction, generation of reactive oxygen species, chloroplast damage (in plants), alteration of transmembrane and cytoplasmatic proteins/enzyme functions, alteration of signaling pathways, and DNA fragmentation. Together with our earlier review work on the biophysics and chemical-physics of IL-cell membrane interactions (Biophys. Rev. 9:309, 2017), we hope that the present review, focused instead on the biochemical aspects, will stimulate a series of new investigations and discoveries in the still new and interdisciplinary field of "ILs, biomolecules, and cells."

Synthesis, Selected Transformations, and Biological Activity of Alkoxy Analogues of Lepidilines A and C

Condensation of diacetyl monooxime with formaldimines derived from alkoxyamines in glacial acetic acid at room temperature leads to corresponding 2-unsubstituted imidazole N-oxides bearing an alkoxy substituent at the N(1) atom of the imidazole ring. Subsequent O-benzylation afforded, depending on the type of alkylating agent, either symmetric or nonsymmetric alkoxyimidazolium salts considered as structural analogues of naturally occurring imidazole alkaloids, lepidilines A and C. Some of the obtained salts were tested as precursors of nucleophilic heterocyclic carbenes (NHCs), which in situ reacted with elemental sulfur to give the corresponding N-alkoxyimidazole-2-thiones. The cytotoxic activity of selected 4,5-dimethylimidazolium salts bearing either two benzyloxy or benzyloxy and 1-adamantyloxy groups at N(1) and N(3) atoms was evaluated against HL-60 and MCF-7 cell lines using the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Notably, in two cases of alkoxyimidazolium salts, no effect of the counterion exchange (Br^- → PF₆^-) on the biological activity was observed.