Toward Multi-Targeted Platinum and Ruthenium Drugs-A New Paradigm in Cancer Drug Treatment Regimens?

Thiourea compounds as multifaceted bioactive agents in medicinal chemistry

Microbial resistance (MR) and cancer are global healthcare pitfalls that have caused millions of deaths and pose a significant pharmaceutical challenge, with clinical cases increasing. Thioureas are preferred structures in medicinal chemistry, chemosensors, and organic synthesis platforms. In fact, thiourea (TU) moieties serve as a common framework for several medications and bioactive substances, demonstrating a wide range of therapeutic and pharmacological accomplishments. The integration of the thiourea moiety into a diverse range of organic molecules has resulted in very flexible compounds with widespread uses in medicinal chemistry. Moreover, for over a century, TU and its metal complexes have been characterized for their biological activity. Finally, we provide an assessment and future outlook of different organo-thiourea derivatives, from the very beginning to the most recent discoveries in medicinal activity.

The Chemistry of Anticancer Mononuclear and N-Bridged Dinuclear 8-Aminoquinoline Half-sandwich Metal Complexes

Piano-stool complexes of ruthenium and other platinum group metals have shown promising preclinical results as anticancer agents, often with alternative modes of action to traditional platinum-based compounds. Quinoline is considered a privileged structure in medicinal chemistry and many complexes with potent anticancer activity have been reported. To assess the effect of incorporating bidentate 8-aminoquinoline-η2N-1,N-8 (AQH) ligands in half-sandwich piano-stool metal complexes of the general formula [M(L)(AQH)Cl]+, the respective Ru, Os (L=η6-p-cymene), Rh and Ir (L=η5-pentamethylcyclopentadienyl) complexes were prepared. Deprotonation of AQH during the reaction gave dinuclear [M(L)(AQ)]2 2+ complexes with the deprotonated μ-κ1N-8-aminoquinolinato-η2N-1,N-8 (AQ) ligands acting as bridges between the metal centers. Conversion of the mononuclear Ru, Rh and Ir compounds to the dimetallic analogues was facilitated under basic conditions and improved for the Ru derivative by the addition of AgNO3 to abstract the chlorido ligand. In in vitro anticancer activity studies, the dimetallic complexes were in general more potent than mononuclear analogues. The higher activity of the dimetallic compounds can be explained by higher uptake into cancer cells, as demonstrated for the respective Ru complexes, while zebrafish embryo studies demonstrated low toxicity, irrespective of the number of metal centers in the complexes.

Exploring the effect of Ru(II) arene complexes on cytotoxicity upon co-ligand variation and loading on amine-functionalized silica nanoparticles

To overcome the undesirable side effects and acquired resistance associated with platinum-based chemotherapeutics, scientists are searching for alternative strategies involving novel metal-based compounds with improved pharmacological properties. Ruthenium complexes have emerged as prospective candidates to combat side effects and improve the selectivity of anticancer agents. In this work, a benzimidazole-based chelating ligand, HL (4-(1H-naphth[2,3-d]imidazol-2-yl)-1,3-benzenediol) with O and N donor atoms, was synthesized and used for complexation with ruthenium to obtain three Ru(II) arene complexes represented by [Ru(η6-p-cym)(L)Cl], [Ru(η6-p-cym)(L)(PPh3)]+ and [Ru(η6-p-cym)(L)(PTA)]+ (where p-cym = p-cymene, PPh3 = triphenylphosphine and PTA = 1,3,5-triaza-7-phosphaadamantane). The synthesized complexes were characterized using spectroscopic techniques. UV-Vis absorption spectroscopy and LC-MS were used to study the stability of the complexes in biological medium. Their lipophilicity was studied by calculating the partition coefficient in n-octanol and water. The complexes showed significant binding with biomolecules like albumin proteins and nucleic acids. All the complexes were found to be cytotoxic, with complex [Ru(η6-p-cym)(L)PPh3]PF6 exhibiting the highest anticancer activity. The mechanism of anticancer activity was attributed to the ability of the complexes to induce apoptosis and generate reactive oxygen species (ROS). The complexes also exhibited antimetastatic properties. Furthermore, complex [Ru(η6-p-cym)(L)PPh3]PF6 was loaded onto amine-functionalized mesoporous silica nanoparticles which led to an increase in its cytotoxic activity.

Interaction of half-sandwich Rh(III) ion and some of its complexes with endogenous imidazole derivatives

An increasing number of {Rh(η5-Cp*)}2+ complexes are reported to possess promising medical, mostly anticancer activities. In parallel, growing interest has also focused on the interactions between {Rh(η5-Cp*)}2+-based metallodrugs and macromolecular components of biological fluids, since the biospeciation of these potential metallodrugs may strongly influence their overall pharmacological properties. Less attention was paid to the interaction of {Rh(η5-Cp*)}2+ complexes with low molecular mass (LMM) constituents of biological fluids, which may also have significant impact on their biospeciation. From this point of view, the biogenic imidazole derivatives are the most important, since the primary binding sites of proteins for {Rh(η5-Cp*)}2+ cation are the surface histidine groups. Several imidazole containing endogenous LMM components are known, which have relevant concentrations in certain biological fluids, such as plasma. Therefore, here we report systematic solution thermodynamic and solution structural (potentiometric, UV-Vis, ESI-MS and 1H NMR) study on the interaction of {Rh(η5-Cp*)}2+ cation with thyrotropin-releasing hormone (TRH, pGlu-His-Pro-NH2, L1), carnosine (β-alanyl-histidine, L2), carcinine (β-alanyl-histamine, L3), histidine (L4) and the human growth modulator tripeptide GHK (Gly-His-Lys, L5). The results indicate, that these biogenic ligands, especially histidine and GHK, possess very high binding ability towards {Rh(η5-Cp*)}2+ cation, higher than for the well-known histidine-peptide binder copper(II). In addition, we also studied the interaction of two simple [Rh(η5-Cp*)(A)Cl]+ complexes (where A = 2,2'-bipyridyl (bpy) or ethylenediamine (en)), as mimics of potentially anticancer compounds, with the above listed endogenous imidazole derivatives. Beside the formation of ternary [Rh(η5-Cp*)(A)(L)] complexes, histidine and GHK, having exceptionally high {Rh(η5-Cp*)}2+ binding ability, are also able to displace en or bpy from the coordination sphere of Rh(III). Moreover, histidine and GHK successfully compete even with human serum albumin under near physiological conditions, and thus may have fundamental effect on the blood transport and biodistribution of any {Rh(η5-Cp*)}2+-based bioactive compounds.

Study on the Mechanism of Action of the Pt(IV) Complex with Lonidamine Ligands by Ultrafast Chemical Proteomics

Platinum(II) complexes such as cisplatin, among a few others, are well-known anticancer metal-based drugs approved for clinical use. In spite of their wide acceptance, the respective chemotherapy is associated with severe side effects and the ability of tumors to quickly develop resistance. To overcome these drawbacks, the novel strategy is considered, which is based on the use of platinum complexes with bioactive ligands attached to act in synergy with platinum and to further improve its pharmacological properties. Among the recently introduced multiaction prodrugs is the Pt(IV) complex with two lonidamine ligands, the latter selectively inhibiting hexokinase and, thus, glycolysis in cancer cells. While platinum-based multiaction prodrugs exhibit increased levels of activity toward cancer cells and, thus, are considered potent to overcome the resistance to cisplatin, there is a crucial need to uncover their mechanism of action by revealing all possibly affected processes and targets across the whole cellular proteome. These are challenging tasks in proteomics requiring high-throughput analysis of hundreds of samples for just a single drug-to-proteome system. In this work, we performed these analyses for 8-azaguanine and the experimental Pt(IV)-lonidamine complex applied to ovarian cancer cell line A2780 employing both mechanism- and compound-centric ultrafast chemical proteomics approaches. These approaches were based on protein expression analysis and thermal proteome profiling, respectively. Data obtained for the Pt(IV)-lonidamine complex revealed regulation of proteins involved in the glucose metabolic process associated with lonidamine, further supporting the multiaction mechanism of this prodrug action.

Cyclometalated Iridium(III) Schiff Base Complexes for Chemiluminogenic Bioprobes

Chemiluminogenic bioimaging has emerged as a promising paradigm due to its independence from light excitation, thereby circumventing challenges related to light penetration depth and background autofluorescence. However, the availability of effective chemiluminophores remains limited, which substantially impedes their bio-applications. Herein, we discovered for the first time that cyclometalated iridium(III) Schiff base complexes can unexpectedly generate chemiluminescence. Notably, the chemiluminescence reaction was rapid, with a half-life of only 0.86 s, significantly faster than previously reported examples. Unlike conventional chemiluminescent scaffolds, the distinguishing feature of the chemiluminogenic iridium(III) complex is its unique intramolecular imine-to-amide conversion upon reaction with reactive oxygen species (ROS). Intriguingly, the chemiluminogenicity of these complexes is not influenced by the cyclometalating ligands but is closely associated with the Schiff base ligand, allowing for tuning of the emission colors via altering the cyclometalating ligands. Additionally, we formulated one of the Schiff base complexes (1) as water-soluble chemiluminogenic nanoparticles (CLNPs) and successfully employed them as activatable chemiluminescence bioprobes for precise and rapid imaging of hypochlorite-related biological events both in vitro and in vivo. We believe that this significant finding of the development of chemiluminogenic Schiff base complexes will greatly facilitate the designing of innovative chemiluminophores for theranostic applications.

Investigating the antimicrobial activity of 1-heteroaryl benzotriazole silver compounds

Five (1-5) Ag(i) compounds, derived from different N,N'-bidentate 1-heteroaryl benzotriazole ligands, were synthesised and characterised using SXRD, IR, UV-Vis, elemental analysis, ESI-MS, and NMR. Variations in ligands and counter-anions produced distinct structures and morphologies. Preliminary antimicrobial testing at the micromolar level, in DMSO, revealed that only compound 2, based on 1-(2-pyridyl)benzotriazole and triflate anion, exhibited interesting antimicrobial properties, thus marking the introduction of a new class of Ag(i) compounds in medicinal inorganic chemistry.

Albumin-targeted oxaliplatin(iv) prodrugs bearing STING agonists

The anticancer platinum complex oxaliplatin exerts its activity through DNA damage and immune-stimulatory mechanisms, but is associated with adverse treatment side effects. Platinum(iv) complexes represent a promising prodrug strategy to improve tolerability and to enhance antitumor efficacy via attachment of additional bioactive ligands or tumor-targeting moieties. In the present study, oxaliplatin(iv) complexes containing immune-stimulatory STING agonists SR-717 or MSA-2 were synthesized and their biological properties were studied. Whereas the Pt-SR-717 compound was fast reduced, Pt-MSA-2 complexes displayed significantly higher reductive stability reflected by low in vitro cytotoxicity. Although the platinum(iv) complexes activated interferon regulatory factor (IRF) and NF-κB signaling pathways less effectively compared to the free STING agonists, reducing conditions elevated cytotoxicity and STING downstream signaling, particularly for MSA-2-containing prodrugs. Rapid albumin binding of a maleimide-containing Pt-MSA-2 derivative resulted in elevated plasma levels, prolonged blood circulation, and enhanced tumor accumulation of platinum in CT-26 tumor-bearing mice. The Pt-MSA-2 complexes triggered immune activation and cytokine secretion without hematotoxicity usually associated with free oxaliplatin. The albumin-targeted Pt-MSA-2 drug significantly inhibited tumor growth after intravenous application, while the non-maleimide complex was effective only when applied peritumorally. However, the effects were not enhanced compared to mono-treatment with oxaliplatin or MSA-2, indicating a lack of synergism between the two simultaneously released agents. Our results demonstrate that oxaliplatin(iv) complexes represent a valuable strategy for enhanced tumor-targeting and adverse effect reduction, but question the simultaneous release of STING agonists and free oxaliplatin as a potent strategy towards synergistic antineoplastic activity.

Discovery of a Novel EF24 Analogue-Conjugated Pt(IV) Complex as Multi-Target Pt(IV) Prodrugs Aims to Enhance Anticancer Activity and Overcome Cisplatin Resistance

Acquired resistance in cancer remains a significant challenge in oncology, posing obstacles to the efficacy of diverse therapeutic approaches. The nuclear factor-kappa B (NF-κB) signaling pathway plays an important role in the development of drug resistance in tumor cells. Herein, we employed NF-κB inhibitors and cisplatin to synthesize multitarget Pt(IV) antitumor prodrugs. Among them, the antiproliferation activity of complex 8 demonstrated a remarkable 146.92-time increase compared to cisplatin against A549/CDDP cells. Moreover, complex 8 could effectively induce DNA damage, promote ROS generation, induce autophagy, trigger the mitochondrial apoptosis pathway, and suppress cell proliferation through the NF-κB signaling pathway. Furthermore, complex 8 effectively downregulated the levels of VEGF and HIF-1α and exerted antiproliferative activity through the PI3K/AKT and STAT-3 pathway in A549/CDDP cells. Interestingly, complex 8 showed a superior in vivo antitumor activity than cisplatin, 5a, or their combination, suggesting its potential as a promising candidate for further drug development in lung cancer treatment.

Multi-Pathway Study for Oxaliplatin Resistance Reduction

Chemotherapy for cancer frequently uses platinum-based medications, including oxaliplatin, carboplatin, and cisplatin; however, due to their high systemic toxicity, lack of selectivity, drug resistance, and other side effects, platinum-based medications have very limited clinical application. As a first-line medication in antitumor therapy, oxaliplatin must be administered to minimize side effects while achieving anticancer objectives. A new CDC7 inhibitor called XL413 has demonstrated promising antitumor therapeutic effects in a variety of malignant tumors and may have anticancer properties. This offers a fresh viewpoint on how to lessen oxaliplatin resistance and, specifically, increase the potency of already prescribed anticancer therapies. In this paper, the current developments in anticancer therapy are discussed, along with the many mechanisms of oxaliplatin's antitumor effects, clinical treatment challenges, and related approaches. We conducted more research on oxaliplatin resistance that arose during chemotherapy and searched for ways to lessen it in order to enhance its chemotherapeutic performance. Ultimately, we studied how distinct resistance routes relate to one another. Meanwhile, XL413, a novel CDC7 inhibitor, offers a perspective on the possibilities for developing treatment approaches for this innovation point. The search terms "Oxaliplatin, XL413, drug resistance, cancer treatment," etc., were applied in the X-MOL and PubMed databases for this review's literature search. Boolean logic was then employed to maximize the search approach. These databases can offer thorough research data and cover a broad range of biological publications. Excluded publications were works of low relevance, duplicates, or those with insufficient information. The mechanism of oxaliplatin's anticancer effect, oxaliplatin resistance and its amelioration, and the role of XL413 in oxaliplatin treatment were the main topics of the 140 publications that were ultimately included for analysis.

Recent advances in ruthenium (III) complex-loaded nanomaterial for enhanced cancer therapy efficacy

OBJECTIVE

Amid the escalating global cancer incidence, the development of effective and safe anticancer drugs is a critical priority in medical research. Addressing the clinical shortcomings of ruthenium-based anticancer drugs are currently a prominent focus of research.

SIGNIFICANCE AND METHODS

Since the pioneering work with platinum derivatives, significant progress has been made in the fundamental studies of metal complexes for the treatment of a wide range of cancers, and there has been a growing interest in their properties and biomedical applications. Although chemotherapy is crucial in clinical tumor management, platinum(II) anticancer drugs like cisplatin and carboplatin suffer from severe toxicity and drug resistance issues. Among various metal-based drugs, ruthenium(III) complexes are notable for their selectivity, cytotoxic activity in vitro, and effective anticancer properties in vivo. Despite some drug candidates reaching late-stage clinical trials, their clinical application remains constrained by problems such as low solubility, poor stability, and inadequate cellular uptake.

RESULTS

The development of efficient and stable nanocarrier-based drug delivery systems for ruthenium(III) complexes, enhancing pharmacokinetic properties, and enabling slow, controlled release and targeted drug delivery, offers potential solutions to these limitations.

CONCLUSIONS

This review delves into the recent strides in nanomaterial-based drug delivery for ruthenium complexes, encompassing research on platinum (II) and ruthenium (III) metal complexes, nano-delivery system designs, and addresses pivotal challenges and future trajectories in this domain.

Self-Assembled Metal Complexes in Biomedical Research

Cisplatin is widely used in clinical cancer treatment; however, its application is often hindered by severe side effects, particularly inherent or acquired resistance of target cells. To address these challenges, an effective strategy is to modify the metal core of the complex and introduce alternative coordination modes or valence states, leading to the development of a series of metal complexes, such as platinum (IV) prodrugs and cyclometalated complexes. Recent advances in nanotechnology have facilitated the development of multifunctional nanomaterials that can selectively deliver drugs to tumor cells, thereby overcoming the pharmacological limitations of metal-based drugs. This review first explores the self-assembly of metal complexes into spherical, linear, and irregular nanoparticles in the context of biomedical applications. The mechanisms underlying the self-assembly of metal complexes into nanoparticles are subsequently analyzed, followed by a discussion of their applications in biomedical fields, including detection, imaging, and antitumor research.

A new fluorescent oxaliplatin(iv) complex with EGFR-inhibiting properties for the treatment of drug-resistant cancer cells

Platinum chemotherapy is part of every second anticancer treatment regimen. However, its application is limited by severe side effects and drug resistance. The combination of platinum-based chemotherapeutics with EGFR inhibitors has shown remarkable synergism in clinical treatment. To enhance the tolerability of this combination, we designed a novel multi-action oxaliplatin-based platinum(iv) complex with an EGFR-inhibiting moiety (KP2749). KP2749 releases two independent cytotoxic agents upon reduction: oxaliplatin and the EGFR inhibitor KP2187, which was selected for its strong intrinsic fluorescence that became quenched upon complexation to metal ions. In particular, KP2749 demonstrated high stability and specific KP2187 release, with quenched fluorescent properties in its intact form, facilitating the investigation of its intracellular reduction. Notably, by exploiting its fluorescence, we demonstrated that intact KP2749 itself exhibited EGFR-inhibitory properties. Furthermore, subsequent experiments indicated that our complex was able to overcome resistance to oxaliplatin and EGFR inhibitors in vitro and in xenograft models in vivo. These effects were not only based on EGFR inhibition and DNA damage, but also improved cellular drug uptake. Finally, in silico docking analysis confirmed that the intact KP2749 complex had EGFR-binding properties, which were different from free KP2187. Consequently, these data suggested that the coordination of EGFR inhibitors to metal cores (like platinum) allow the fine-tuning of their EGFR-targeting properties. In conclusion, this study not only presents a new potential anticancer drug but also offers a novel fluorescent tool to study the intracellular drug release kinetics of platinum(iv) complexes.

Exploring the Structure-Activity Relationships of Albumin-Targeted Picoplatin-Based Platinum(IV) Prodrugs

Platinum(II) complexes prevail as first-line treatment for many cancers but are associated with serious side effects and resistance development. Picoplatin emerged as a promising alternative to circumvent GSH-induced tumor resistance by introducing a bulky 2-picoline ligand. Although clinical studies were encouraging, picoplatin did not receive approval. Interestingly, the anticancer potential of prodrugs based on picoplatin is widely underexplored, and even less so the respective tumor-targeting approaches. We synthesized two new "hybrid" picoplatin(II) derivatives with an oxalate or cyclobutane dicarboxylate leaving group and their corresponding platinum(IV) prodrugs with an albumin-targeting maleimide moiety or a succinimide as reference. Picoplatin(II) and its derivatives indeed reacted much slower with GSH compared to the respective analogs cisplatin, carboplatin, or oxaliplatin. While PicoCarbo(IV) and PicoOxali(IV) were reduced slowly in the presence of ascorbic acid, picoplatin(IV) was extremely unstable. All three prodrugs were widely inactive in the MTT assays. The platinum(IV)-maleimide complexes rapidly bound to albumin with stable conjugates for >25 h. Albumin-binding resulted in elevated platinum plasma levels, prolonged blood circulation, and enhanced tumor accumulation of the prodrugs in mice bearing CT26 tumors. However, only maleimide-functionalized PicoCarbo(IV) and picoplatin(II) significantly inhibited tumor growth. One possible explanation is that for albumin-binding platinum(IV) prodrugs, the bulky 2-picoline moiety prevents sufficient activation/reduction to unlock their full anticancer potential.

Synergistic strategies: histone deacetylase inhibitors and platinum-based drugs in cancer therapy

INTRODUCTION

The synergistic combination of histone deacetylase inhibitors and platinum-based medicines represents a promising therapeutic strategy to efficacy and overcome drug resistance in cancer therapy, necessitating a comprehensive understanding on their molecular interactions and clinical potential.

AREAS COVERED

The objective of presented review is to investigate the molecular pathways of platinum medicines and HDAC inhibitors. A comprehensive literature review from 2011 to 2024 was conducted across multiple databases like MEDLINE, PubMed, Google Scholar, Science Direct, Scopus and official websites of ClinicalTrial.gov to explore publications on HDAC inhibitors, platinum drugs, and combination cancer therapies, revealing preliminary evidence of innovative treatment strategies involving HDAC inhibitors and platinum chemotherapeutics. Several new platinum (IV) complexes, with HDAC inhibitory moieties and better cytotoxicity profiles than conventional platinum drugs, are also reviewed here.

EXPERT OPINION

The above combination has great potential in cancer treatment, however managing toxicity, dosage regimens, and patient selection biomarkers are problematic. More selective HDAC inhibitors and innovative delivery techniques are potential areas for future research. An adaptation toward changing cancer therapeutic landscapes, highlights combining HDAC inhibitors with platinum-based medicines serves as a new concept for personalized medicine, however, a deeper research is still needed at this time.

Positively-charged, chalcone-hydroxypyrone hybrid ruthenium(II)-arene complexes functionalized with ethacrynic acid: Synthesis, characterizaion, and antitumor effect

A new family of ethacrynic acid-functionalized, chalcone-hydroxypyrone hybrid ruthenium(II)-arene complexes (4a-4e) have been designed, synthesis and fully characterized by 1H and 13C NMR, ESI-MS, elemental analysis, and melting point tests. The molecular structure of 3a, one of the precursor complexes, has been determined by single-crystal X-ray diffraction. The cytotoxicity of the obtained complexes toward human cancer cell lines such as HeLa, MGC803, A549, MDA-MB-231, and MCF-7 cells have been investigated by MTT assay. Whereas complexes 4d and 4e showed significantly higher cytotoxicity than cisplatin (the positive control group) and complexes 3a-3e. Moreover, complexes 4d and 4e exhibited a certain selectivity (selectivity index: 7.33 and 7.57) toward MCF-7 cells over MCF-10a normal cells. Glutathione S-transferases (GSTs) activity assay indicate that complexes 4d and 4e exhibited higher GST inhibitory activity than ethacrynic acid (EA, the best characterized GST inhibitor), consistent with their higher cytotoxicity. Further mechanistic studies showed that 4e-induced cell apoptosis may be aroused by the production of ROS, the loss of mitochondrial membrane potential and G2/M phase cell arrest in MCF-7 cells. In addition, the in vivo antitumor effect study on the xenograft mouse models of MCF-7 cells reveal that complex 4e significantly inhibited tumor growth with a higher inhibition efficiency of 68.80 %, in comparison with the groups treated with cisplatin (59.25 %). These results highlight the strong possibility to develop positively-charged, chalcone-hydroxypyrone hybrid ruthenium(II)-arene complexes funcionalized with GST inhibitor as promising anticancer agents.

Platinum(ii) complexes of aryl guanidine-like derivatives as potential anticancer agents: between coordination and cyclometallation

The preparation of a wide variety of Pt(ii) complexes with aryl guanidines and their potential application as anticancer agents have been explored. A relatively facile synthesis of cyclometallated Pt(ii) complexes of arylguanidines, preparation of Pt(ii) guanidine coordination complexes and an in situ activation of platinum arylguanidine complexes with acetonitrile to create a bidentate aryl iminoguanidine Pt(ii) complex were achieved. Cyclometallation methodology was extended to create a water-stable conjugate incorporating two Pt(ii) ions and a diaryl bis-guanidine DNA minor groove binder. Several crystal structures were obtained confirming these complexation modes. The cyclometallated Pt(ii) complexes were particularly stable to aqueous environments and were tested for Reactive Oxygen Species generation and anticancer activity in a leukaemia cancer cell line.

Targeting Ribosome Biogenesis for Cancer Therapy with Oral Platinum Complexes

Cancer cells often upregulate ribosome biogenesis to meet increased protein synthesis demands for rapid proliferation; therefore, targeting ribosome biogenesis has emerged as a promising cancer therapeutic strategy. Herein, we introduce two Pt complexes, ataluren monosubstituted platinum(IV) (SPA, formula: c,c,t,-[Pt(NH3)2Cl2(OH)(C15H8FN2O3)], where C15H8FN2O3 = ataluren) and ataluren bisubstituted platinum(IV) complex (DPA, formula: c,c,t,-[Pt(NH3)2Cl2(C15H8FN2O3)2], where C15H8FN2O3 = ataluren), which effectively suppress ribosome biogenesis by inhibiting 47s pre-RNA expression. Furthermore, SPA and DPA induce nucleolar stress by dispersing nucleolar protein NPM1, ultimately inhibiting protein generation in tumor cells. More importantly, DPA exhibits superior cytotoxicity to various cancer cells and in vivo antitumor efficacy compared to cisplatin, with lower systemic toxicity. Notably, in clinically relevant models, including orthotopic hepatic tumor-bearing mice and patient-derived bladder cancer organoids, DPA outperforms cisplatin significantly, with the added benefit of oral administration, enhancing clinical feasibility. To our knowledge, DPA emerges as the pioneering Pt(IV) agent targeting the ribosome, providing new insights for designing next-generation metal-based therapeutics.

Recent advances in biotin-based therapeutic agents for cancer therapy

Biotin receptors, as biomarkers for cancer cells, are overexpressed in various tumor types. Compared to other vitamin receptors, such as folate receptors and vitamin B12 receptors, biotin receptor-based targeting strategies exhibit superior specificity and broader potential in treating aggressive cancers, including ovarian cancer, leukemia, colon cancer, breast cancer, kidney cancer, and lung cancer. These strategies promote biotin transport via receptor-mediated endocytosis, which is triggered upon ligand binding. Biotin, as the ligand of the biotin receptor, can be conjugated to anti-cancer drugs to form targeted therapies that bind to receptors overexpressed on tumor cells, thus increasing drug uptake. Despite these advantages, many candidate drugs have progressed slowly and remain in the preclinical stage, impeding clinical translation. This is mainly due to the effects of various conjugation methods and drug formulations on their functionality and efficacy. Therefore, developing novel biotin-based therapeutics is crucial. The innovation of this strategy lies in its multifunctionality-researchers can use different conjugation methods to design and synthesize these drugs, enabling precise targeting of various tumor types while minimizing toxicity to normal cells. These drugs include small-molecule-biotin conjugates (SMBCs) and nano-biotin conjugates (NBCs). This dual-platform approach represents a significant advancement in targeted therapy, offering unprecedented flexibility in drug design and delivery. Compared to chemotherapy drugs and traditional delivery systems, biotin-based drugs with tumor-specific targeting demonstrate enhanced targeting, improved efficacy, and reduced toxicity. This review examines strategies and applications for enhancing the delivery of chemotherapy drugs to cancer cells, highlighting the need for high-quality conjugates and strategies. It not only summarizes the latest progress but also provides key insights into how this emerging field could revolutionize personalized cancer treatment, especially in the context of precision medicine. Additionally, it offers perspectives on future research directions in this field.

Impact of a Palladium(II)-tris(2-carboxyethyl)phosphine Complex on Normal Cells: Toxicity and Membrane Interaction

Palladium(II) complexes with tris(2-carboxyethyl)phosphine (PdTCEP) show promise for biomedical applications due to their distinct chemical characteristics. This study explored the toxicity of PdTCEP towards normal human cells and examined its interactions with model cell membranes. Two cell types were used to evaluate cytotoxicity: human microvascular endothelial cells (HMEC-1) and red blood cells (RBCs). In HMEC-1 cells, PdTCEP reduced survival to about 80% at 15 µM, with the most significant drop-down to 40%-occurring at 40 µM. The production of reactive oxygen species (ROS) increased in a manner dependent on both dose and time, especially after 72 h of incubation. Despite these effects, PdTCEP caused only minor hemolysis in RBCs, with hemolysis levels staying below 10% even at higher concentrations. Fluorescence anisotropy measurements showed that PdTCEP minimally affects the hydrophobic core of the lipid bilayer, with slight changes observed at concentrations above 40 µM. Generalized polarization (GP) analysis indicated a slight decrease in lipid polar head packing with increasing PdTCEP concentration. Complementary FTIR analysis supported these findings by providing detailed insights into PdTCEP-membrane interactions. This research underscores PdTCEP's selective cytotoxicity and structural effects on membranes, suggesting its promise for more in-depth biological and pharmacological studies.

Biotin functionalization of 8-hydroxyquinoline anticancer organometallics: low in vivo toxicity but potent in vitro activity

[M(arene)(HQ)Cl] complexes (M = RuII/OsII/RhIII/IrIII; HQ = 8-hydroxyquinoline) have shown promise as anticancer agents. To assess the effect of conjugating biotin (vitamin B7) to such compounds and improve their tumor-targeting ability through interaction with the sodium-dependent multivitamin transporter (SMVT), the chlorido co-ligand was exchanged with biotinylated 6-aminoindazole. The complexes were characterized by NMR spectroscopy and mass spectrometry, and purity was determined by elemental analysis. The compounds were shown to be stable in aqueous solution but reacted in particular with biologically relevant nitrogen-donor ligands. The biotinylated organometallics were shown to be able to interact with the high-affinity biotin-binding protein streptavidin using molecular modelling. High antiproliferative activity of the biotinylated Rh complex (IC50 = 1.1-10 μM) and its chlorido precursor (IC50 = 2.1-7.0 μM) was demonstrated in human HCT116, NCI-H460, COLO 205, SW620, A2780 and A2780cis cancer cells, which feature differing levels of SMVT expression. While there was no clear relationship between the anticancer activity in cells and SMVT expression, the complexes showed similar activity in cisplatin-sensitive and -resistant cells. The most potent was the biotinylated Rh derivative which displayed low toxicity toward zebrafish embryos with >75% survival up to day 4 and after treatment with up to 32 μM complex.

Two novel SNS-donor palladium(II) complexes of benzoxazole and benzothiazole derivatives as potential anticancer agents

Two novel mononuclear palladium(II) complexes, [PdL1Cl]Cl (1) and [PdL2Cl]Cl (2) with SNS-donor ligands [where L1 = N-(4-(benzo[d]oxazol-2-yl)phenyl)-2-(bis(2-ethylthioethyl)amino)acetamide, L2 = N-(4-(benzo[d]thiazol-2-yl)phenyl)-2-(bis(2-ethylthioethyl)amino)acetamide], were synthesized and characterized. In vitro antiproliferative activity tests showed that the two palladium(II) complexes displayed excellent antiproliferative activity against all tested cancer cell lines, especially human colon cancer HCT-116, human liver cancer HepG-2, and human breast cancer MDA-MB-231 cells. Spectacularly, complexes 1 and 2 exhibited approximately 8.49- and 6.88-fold higher antiproliferative activity, as compared with cisplatin, against HCT-116, respectively, but were less toxic to human normal colon fibroblast CCD-18Co cell lines with selectivity index (SI = IC50(CCD-18Co)/IC50(HCT-116)) values of 22.43 and 21.48 for 1 and 2, respectively, compared to that of cisplatin (SI, 1.74). These results suggested that the two palladium complexes have the potential to act as candidates for the treatment of colorectal cancer. The interaction of the complexes with CT-DNA and pUC19 plasmid DNA illustrated that both 1 and 2 could strongly bind to the DNA helix via an intercalative mode and covalent interaction and perturb the tertiary structure of DNA, where the DNA binding affinity of 1 was slightly higher than that of 2. Additionally, investigations of the reaction of the two complexes with 5'-GMP and glutathione (GSH) showed that both 1 and 2 could readily react with 5'-GMP and GSH to form Pd-GMP adducts and Pd-GS adducts, respectively, and when 5'-GMP and GSH coexisted, the coordination binding of the complexes with GSH did not prevent the formation of the Pd-GMP adducts. Moreover, Hoechst 33342 staining and flow cytometry analysis demonstrated that the two palladium(II) complexes arrested HCT-116 cells mainly at the G2/M phase, induced mitochondrial-membrane depolarization, increased ROS generation, and triggered obvious cell apoptosis.

DNA or not DNA -that is the question determining the design of platinum anticancer drugs

Platinum drugs are the most widely used chemotherapeutics to treat various tumors. Their primary mode of action is supposed to be inducing apoptosis of cancer cells via covalent binding to DNA. This mechanism has shackled the design of new platinum drugs for many years. Mounting evidence shows that many platinum complexes form non-covalent adducts with DNA or interact with proteins to exhibit significant antitumor activity, thus implying some distinct mechanisms from that of traditional platinum drugs. These unconventional examples indicate that covalent DNA binding is not the precondition for the antitumor activity of platinum complexes, and diversified reactions or interactions with biomolecules, organelles, signal pathways, or immune system could lead to the antitumor activity of platinum complexes. The atypical mechanisms break the classical DNA-only paradigm and structure-activity relationships, thus opening a wide avenue for the design of innovative platinum anticancer drugs.

Synthesis and Evaluation of Cytotoxic Activity of RuCp(II) Complexes Bearing (Iso)nicotinic Acid Based Ligands

BACKGROUND/OBJECTIVES

Cancer remains one of the major challenges of our century. Organometallic ruthenium complexes are gaining recognition as a highly promising group of compounds in the development of cancer treatments.

METHODS

Building on the auspicious results obtained for [Ru(η5-C5H5)(PPh3)(bipy)][CF3SO3] (TM34), our focus has shifted to examining the effects of incorporating bioactive ligands into the TM34 framework, particularly within the cyclopentadienyl ring.

RESULTS

In this study, we report the synthesis and characterization of two new ruthenium(II) complexes with the general formula [Ru(η5-C5H4CCH3=R)(PPh3)(bipy)][CF3SO3], where R represents a nicotinic acid derivative (NNHCO(py-3-yl)) (1) or an isoniazid derivative (NNHCO(py-4-yl)) (2). The complexes were fully characterized using a combination of spectroscopic techniques and computational analysis, revealing the presence of E/Z-hydrazone isomerism. Stability studies confirmed the robustness of both complexes in biological media, with compound 1 maintaining good stability in buffer solutions mimicking physiological (pH 7.4) and tumor-like (pH 6.8) environments. The cytotoxicity of the complexes was evaluated in vitro in several human cancer cell lines, namely melanoma (A375), alveolar adenocarcinoma (A549), epidermoid carcinoma (A431), and breast cancer (MDA-MB 231).

CONCLUSIONS

Both compounds exhibited moderate to high cytotoxic activity, with complex 1 showing a greater propensity to induce cell death, particularly in the A431 and MDA-MB 231 cell lines.

Necrosis inducing tetranuclear Ru(II)-Re(I) metal complex for anticancer therapy

Chemotherapy is one of the most widely used anticancer treatments worldwide. However, despite its clinical effectiveness, most chemotherapeutic agents are associated with severe side effects. To address this limitation, there is an urgent need for the development of novel anticancer agents. Among the promising alternatives, Ruthenium and Rhenium complexes have garnered significant attention in the scientific literature. This study proposes combining these two metal moieties into a single tetranuclear complex, bridged by a 2,2'-bipyrimidine ligand. Cytotoxicity tests revealed broad activity of the novel metal complex against multiple cancer cell lines. Mechanistic studies suggested that the complex induces cell death by necrosis. Further analyses demonstrated its ability to eradicate colon carcinoma tumor spheroids at micromolar concentrations. To the best of our knowledge, this represents the first example of a Ru(II)-Re(I) tetranuclear metal complex as an anticancer agent.

Ruthenium complexes with abiraterone acetate as antiproliferative agents

This study is dedicated to the development of multimodal anticancer agents. We have obtained ruthenium complexes conjugated with the steroid-type antitumor drug abiraterone acetate in order to take advantage of the dual antitumor properties of both ruthenium and abiraterone. The compounds exhibit good antiproliferative activity against cancer cells, with selectivity over primary fibroblasts. Real-time cell analysis revealed that compound dichlorido(η6-p-cymene)(abiraterone acetate)ruthenium(II) had pronounced antiproliferation activity compared to abiraterone acetate. Flow cytometric studies on the mechanism of cell death have revealed that the most active compound induces apoptosis more effectively than abiraterone acetate. Our findings demonstrate the potential of this novel dual-action compound as promising candidates for further development as anticancer agents.

TTFA-Platin Conjugate: Deciphering the Therapeutic Roles of Combo-Prodrug through Evaluating Stability-Activity Relationship

This work introduces a novel Pt(II) based prodrug TTFA-Platin that integrates a β-diketonate ligand TTFA with a platinum scaffold to structurally resemble carboplatin and offers intermediate kinetic lability between cisplatin and carboplatin, striking a balance between therapeutic efficacy and safety. A comprehensive stability and speciation study was conducted in various biological media, mapping the therapeutic effects of TTFA-Platin. A control molecule, TMK-Platin, was synthesized to further validate the structural-stability relationship, which displayed poor activatable features in biological systems. In vitro studies against a panel of cancer cell lines revealed that TTFA-Platin exhibited significantly higher potency compared to TMK-Platin. In vivo studies revealed that TTFA-Platin exhibited significantly lower toxicity than the reference platinum compounds. Thus, leveraging ligands that fine-tune kinetic lability and offer therapeutic benefits can help develop more effective and safer cancer treatments, addressing the limitations of existing therapies.

Multi-functional biotinylated platinum(IV)-SAHA conjugate for tumor-targeted chemotherapy

The development of multi-functional Pt(IV) complexes as chemotherapeutic agents has gained growing attention in medical oncology. However, the design of multi-functional tumor-targeted Pt(IV) complexes with high hydrolytic stability remains challenging. Herein, we have developed a Pt(IV) prodrug conjugated with vorinostat as a multi-functional cancer therapeutic. In this design, the octahedral Pt(IV) prodrug of a DNA damaging anticancer drug cisplatin is tethered to the cancer cell targeting biotin ligand through one of the axial sites and the other axial site of the Pt(IV) center is attached to the anticancer drug vorinostat (also known as SAHA), a histone deacetylase inhibitor (HDACi) approved by the Food and Drug Administration (FDA) for treatment of cutaneous T-cell lymphoma. The designed biotinylated Pt(iv)-SAHA (Biotin-Pt(iv)-SAHA) conjugate is hydrolytically stable but reduced to Pt(II) species under intracellularly relevant conditions and concomitantly releases cisplatin and two of its axial ligands such as SAHA and biotin. The anticancer activity of the conjugate is investigated against a panel of cisplatin-sensitive human cancer cells, including cisplatin-resistant cells. Interestingly, the conjugate exhibited significantly higher cytotoxicity than the clinically approved anticancer drug cisplatin and slightly more cytotoxicity than the HDACi SAHA in all the tested cell lines. By combining the Pt(IV) prodrug of cisplatin with SAHA in the conjugate, synergistic cytotoxicity is achieved. The imaging studies revealed that the conjugate is taken up by cancer cells and shows dose-dependent cell death. The studies on our designed multi-pronged conjugate can be further optimized to enhance its efficacy, paving the way for developing a new class of clinically relevant chemotherapeutic agents.

Optical detection strategies for Ni(II) ion using metal-organic chemosensors: from molecular design to environmental applications

Nickel is an important element utilized in various industrial/metallurgical processes, such as surgical and dental prostheses, Ni-Cd batteries, paint pigments, electroplating, ceramics, computer magnetic tapes, catalysis, and alloy manufacturing. However, its extensive use and associated waste production have led to increased nickel pollution in soils and water bodies, which adversely affects human health, animals and plants. This issue has prompted researchers to develop various optical probes, hereafter luminescent/colorimetric sensors, for the facile, sensitive and selective detection of nickel, particularly in biological and environmental contexts. In recent years, numerous functionalized chemosensors have been reported for imaging Ni2+, both in vivo and in vitro. In this context, metal-based receptors offer clear advantages over conventional organic sensors (viz., organic ligands, polymers, and membranes) in terms of cost, durability, stability, water solubility, recyclability, chemical flexibility and scope. This review highlights recent advancements in the design and fabrication of hybrid receptors (i.e., metal complexes and MOFs) for the specific detection of Ni2+ ions in complex environmental and biological mixtures.

Copper Sulfide Nanorod-Embedded Urinary Catheter with Hydrophobicity and Photothermal Sterilization

The high prevalence of catheter-associated urinary tract infections (CAUTIs) is causing significant concern in healthcare systems. Antibacterial urinary catheters have been developed to prevent CAUTIs in clinical application. In this work, a copper sulfide nanorod (CuS NR)-embedded urinary catheter (CuS/UC) was designed as an antibacterial urinary catheter with photothermal sterilization. The CuS NRs with low cytotoxicity were synthesized via the hydrothermal method. The CuS NRs were embedded into urinary catheters at different weight percentages. The CuS/UC exhibited homogenous surface roughness, low wettability, hydrophobicity, and low adhesiveness, promoting minimal interaction with bacteria and healthy cells. Under near-infrared (NIR) laser irradiation, the 0.8 weight percentage of CuS NRs in the urinary catheter (0.8CuS/UC) reached a temperature of 67.4 °C, demonstrating its photothermal antibacterial activity and suitability for catheter sterilization. Agar plate test verified that CuS/UCs exhibited a superior photothermal antibacterial activity against both Gram-negative Escherichia coli (E. coli) and Gram-positive Streptococcus aureus (S. aureus). Moreover, the 0.8CuS/UC exhibited excellent biocompatibility and anti-cell adhesion properties. The 0.8CuS/UC with photothermal performance, excellent biocompatibility, and anti-cell adhesion properties demonstrated its potential as a photothermal antibacterial catheter for clinical applications.

Tailored Metal-Based Catalysts: A New Platform for Targeted Anticancer Therapies

Innovative strategies for targeted anticancer therapies have gained significant momentum, with metal complexes emerging as tunable catalysts for more effective and safer treatments. Rational design and engineering of metal complexes enable the development of tailored molecular structures optimized for precision oncology. The strategic incorporation of metal complex catalysts within combinatorial therapies amplifies their anticancer properties. This perspective highlights the advancements in synthetic strategies and rational design since 2019, showing how tailored metal catalysts are optimized by designing structures to release or in situ synthesize active drugs, leveraging the target-specific characteristics to develop more precise cancer therapies. This review explores metal-based catalysts, including those conjugated with biomolecules, nanostructures, and metal-organic frameworks (MOFs), highlighting their catalytic activity in biological environments and their in vitro/in vivo performance. To sum up, the potential of metal complexes as catalysts to reshape the landscape of anticancer therapies and foster novel avenues for therapeutic advancement is emphasized.

Co-targeting CDK 4/6 and C-MYC/STAT3/CCND1 axis and inhibition of tumorigenesis and epithelial-mesenchymal-transition in triple negative breast cancer by Pt(II) complexes bearing NH3 as trans-co-ligand

In search of potential anticancer agents, we synthesized SNO-donor salicylaldimine main ligand-based Pt(II) complexes bearing NH3 as co-ligand at trans-position (C1-C6). These complexes showed similarity in structure with transplatin as the two N donor atoms of the main ligand and NH3 co-ligand were coordinated to Pt in trans position to each other. Each complex with different substituents on the main ligand was characterized thoroughly by detailed spectroscopic and spectrophotometric methods. Four of these complexes were studied in solid state by single crystal X-ray analysis. The stability of reference complex C1 was measured in solution state in DMSO‑d6 or its mixture with D2O using 1H NMR methods. These complexes were further investigated for their anticancer activity in triple-negative-breast (TNBC) cells including MDA-MB-231, MDA-MB-468 and MDA-MB-436 cells. All these complexes showed satisfactory cytotoxic effect as revealed by the MTT results. Importantly, the highly active complex C4 anticancer effect was compared to the standard chemotherapeutic agents including cisplatin, oxaliplatin and 5-fluorouracil (5-FU). Functionally, C4 suppressed invasion, spheroids formation ability and clonogenic potential of cancer cells. C4 showed synergistic anticancer effect when used in combination with palbociclib, JQ1 and paclitaxel in TNBC cells. Mechanistically, C4 inhibited cyclin-dependent kinase (CDK)4/6 pathway and targeted the expressions of MYC/STAT3/CCND1/CNNE1 axis. Furthermore, C4 suppressed the EMT signaling pathway that suggested a role of C4 in the inhibition of TNBC metastasis. Our findings may pave further in detailed mechanistic study on these complexes as potential chemotherapeutic agents in different types of human cancers.

Biotin-Pt(IV)-Ru(II)-Boron-Dipyrromethene Prodrug as "Platin Bullet" for Targeted Chemo- and Photodynamic Therapy

Using the principle of "Magic Bullet", a cisplatin-derived platinum(IV) prodrug heterobimetallic Pt(IV)-Ru(II) complex, cis,cis,trans-[Pt(NH3)2Cl2{Ru(tpy-BODIPY)(tpy-COO)}(biotin)]Cl2 (Pt-Ru-B, 2), having two axial ligands, namely, biotin as water-soluble B-vitamin for enhanced cellular uptake and a BODIPY-ruthenium(II) (Ru-B, 1) photosensitizer having N,N,N-donor tpy (4'-phenyl-2,2':6',2″-terpyridine) bonded to boron-dipyrromethene (BODIPY), is developed as a "Platin Bullet" for targeted photodynamic therapy (PDT). Pt-Ru-B exhibited intense absorption near 500 nm and emission near 513 nm (λex = 488 nm) in a 10% dimethyl sulfoxide-Dulbecco's phosphate-buffered saline medium (pH 7.2). The BODIPY complex on light activation generates singlet oxygen as the reactive oxygen species (ROS) giving a quantum yield (ΦΔ) of ∼0.64 from 1,3-diphenylisobenzofuran experiments. Pt-Ru-B exhibited preferential cellular uptake in cancer cells over noncancerous cells. The dichlorodihydrofluorescein diacetate assay confirmed the generation of cellular ROS. Confocal images revealed its mitochondrial internalization. Pt-Ru-B showed submicromolar photocytotoxicity in visible light (400-700 nm) in A549 and multidrug-resistant MDA-MB-231 cancer cells. It remained nontoxic in the dark and less toxic in nontumorigenic cells. Cellular apoptosis and alteration of the mitochondrial membrane potential were evidenced from the respective Annexin V-FITC/propidium iodide assay and JC-1 dye assay. A wound healing assay using A549 cells and Pt-Ru-B revealed inhibition of cancer cell migration, highlighting its potential as an antimetastatic agent.

Recent Advancements in Polymeric N-Nitrosamine-Based Nitric Oxide (NO) Donors and their Therapeutic Applications

Nitric oxide (NO), a gasotransmitter, is known for its wide range of effects in vasodilation, cardiac relaxation, and angiogenesis. This diatomic free radical also plays a pivotal role in reducing the risk of platelet aggregation and thrombosis. Furthermore, NO demonstrates promising potential in cancer therapy as well as in antibacterial and antibiofilm activities at higher concentrations. To leverage their biomedical activities, numerous NO donors have been developed. Among these, N-nitrosamines are emerging as a notable class, capable of releasing NO under suitable photoirradiation and finding a broad range of therapeutic applications. This review discusses the design, synthesis, and biological applications of polymeric N-nitrosamines, highlighting their advantages over small molecular NO donors in terms of stability, NO payload, and target-specific delivery. Additionally, various small-molecule N-nitrosamines are explored to provide a comprehensive overview of this burgeoning field. We anticipate that this review will aid in developing next-generation polymeric N-nitrosamines with improved physicochemical properties.

Masking the Bioactivity of Hydroxamic Acids by Coordination to Cobalt: Towards Bioreductive Anticancer Agents

The clinical use of many potent anticancer agents is limited by their non-selective toxicity to healthy tissue. One of these examples is vorinostat (SAHA), a pan histone deacetylase inhibitor, which shows high cytotoxicity with limited discrimination for cancerous over healthy cells. In an attempt to improve tumor selectivity, we exploited the properties of cobalt(III) as a redox-active metal center through stabilization with cyclen and cyclam tetraazamacrocycles, masking the anticancer activity of SAHA and other hydroxamic acid derivatives to allow for the complex to reach the hypoxic microenvironment of the tumor. Biological assays demonstrated the desired low in vitro anticancer activity of the complexes, suggesting effective masking of the activity of SAHA. Once in the tumor, the bioactive moiety may be released through the reduction of the CoIII center. Investigations revealed long-term stability of the complexes, with cyclic voltammetry and chemical reduction experiments supporting the design hypothesis of SAHA release through the reduction of the CoIII prodrug. The results highlight the potential for further developing this complex class as novel anticancer agents by masking the high cytotoxicity of a given drug, however, the cellular uptake needs to be improved.

Exploring the effect of the axial ligands on the anticancer activity of [C,N,N'] Pt(IV) cyclometallated compounds

The synthesis of three novel [C,N,N'] Pt(IV) cyclometallated compounds containing hydroxo, dichloroacetato or trifluoroacetato axial ligands is reported. Compound [PtCl(OH)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (3) was prepared by the oxidative addition of hydrogen peroxide to [C,N,N'] Pt(II) cyclometallated compound [PtCl{(CH3)2N(CH2)2NCH(4-FC6H3)}] (1) and further the reaction of compound 3 with dichloroacetate or trifluoroacetate anhydrides led to the formation of the corresponding compounds [PtCl(CHCl2COO)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (4) and [PtCl(CF3COO)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (5). The properties of the new compounds along with those of the compound [PtCl3{(CH3)2N(CH2)2NCH(4-FC6H3)}] (2), including stability in aqueous media, reduction potential using cyclic voltammetry, cytotoxic activity against the HCT116 CRC cell line, DNA interaction, topoisomerase I and cathepsin inhibition, and computational studies involving reduction of the Pt(IV) compounds and molecular docking studies, are presented. Interestingly, the antiproliferative activity of these compounds against the HCT116 CRC cell line, which is in all cases higher than that of cisplatin, follows the same trend as the reduction potentials so that the most easily reduced compound 2 is the most potent. In contrast, according to the electrophoretic mobility and molecular docking studies, the efficacy of these compounds in binding to DNA is not related to their cytotoxicity. The most active compound 2 does not modify the DNA electrophoretic mobility while the less potent compound 3 is the most efficient in binding to DNA. Although compounds 2 and 3 have only a slight effect on cell cycle distribution and apoptosis induction, generation of ROS to a higher extent for the most easily reduced compound 2 was observed.

Design, synthesis and mechanistic studies of novel arylformylhydrazone butylphenyltin complexes as potential anticancer agents

Many diorganotin complexes with various alkyl groups exhibit excellent in vitro anticancer activity. However, most diorganotin is the same alkyl group, and the asymmetric alkyl R group has been rarely reported. Hence, in this paper, twenty butylphenyl mixed dialkyltin arylformylhydrazone complexes have been synthesized by microwave "one-pot" reaction with arylformylhydrazine, substituted α-keto acid or its sodium salt and butylphenyltin dichloride. The crystal structures of nine complexes were determined, indicating that the complexes C1, C2, C11, C12, and C16 ∼ C19 possessed a central symmetric structure of a dinuclear Sn2O2 tetrahedral ring; while the complex C9 is a trinuclear tin-oxygen cluster with a 6-membered ring encased in a 12-membered macrocyclic structure. The inhibiting activity of complexes was tested against the human cell lines NCI-H460, MCF-7, HepG2, Huh-7 and HL-7702. Complex C2 demonstrated the optimal inhibitory effect on HepG2 cells, with an IC50 value of 0.82 ± 0.03 μM. Cellular biology experiments revealed that complex C2 could induce apoptosis and G2/M phase cell cycle arrest in HepG2 and Huh-7 cells. The complex also caused the collapse of the mitochondrial membrane potential and increased intracellular reactive oxygen species in HepG2 and Huh-7 cells. Western blot analysis further clarified that complex C2 could induce cell apoptosis through the mitochondrial pathway along with the release of reactive oxygen species.

Unraveling Novel Strategies in Mesothelioma Treatments Using a Newly Synthetized Platinum(IV) Compound

Malignant mesothelioma is a rare tumor associated with asbestos exposure. Mesothelioma carcinogenesis is related to enhanced reactive oxygen species (ROS) production and iron overload. Despite the recent advances in biomedical sciences, to date the only available treatments include surgery in a small fraction of patients and platinum-based chemotherapy in combination with pemetrexed. In this view, the purpose of this study was to evaluate the therapeutic potential of the newly synthetized platinum prodrug Pt(IV)Ac-POA compared to cisplatin (CDDP) on human biphasic mesothelioma cell line MSTO-211H using different complementary techniques, such as flow-cytometry, transmission electron microscopy (TEM), and immunocytochemistry. Healthy mesothelial cell lines Met-5A were also employed to assess the cytotoxicity of the above-mentioned compounds. Our in vitro results showed that Pt(IV)Ac-POA significantly interfere with iron metabolisms and more importantly is able to trigger cell death, through different pathways, including ferroptosis, necroptosis, and apoptosis, in neoplastic cells. On the other hand, CDDP triggers mainly apoptotic and necrotic cell death. In conclusion, Pt(IV)Ac-POA may represent a new promising pharmacological agent in the treatment of malignant mesothelioma.

An engineered POSS drug delivery system for copper(II) anticancer metallodrugs in a selective application toward melanoma cells

In this work, a polyhedral silsesquioxane (POSS) was used as an engineered drug delivery system for two oxindolimine-copper(II) anticancer complexes, [Cu(isaepy)]+ and [Cu(isapn)]+. The interest in hybrid POSS comes from the necessity of developing materials that can act as adjuvants to improve the cytotoxicity of non-soluble metallodrugs. Functionalization of POSS with a triazole ligand (POSS-atzac) permitted the anchorage of such copper complexes, producing hybrid materials with efficient cytotoxic effects. Structural and morphological characterizations of these copper-POSS systems were performed by using different techniques (IR, NMR, thermogravimetric analysis). A combination of continuous-wave (CW) and pulsed EPR (HYSCORE) spectroscopies conducted at the X-band have enabled the complete characterization of the coordination environment of the copper ion in the POSS-atzac matrix. Additionally, the cytotoxic effects of the loaded materials, [Cu(isapn)]@POSS-atzac and [Cu(isaepy)]@POSS-atzac, were assessed toward melanomas (SK-MEL), in comparison to non-tumorigenic cells (fibroblast P4). Evaluation of their nuclease activity or ability to facilitate cleavage of DNA indicated concentrations as low as 0.6 μg mL-1, while complete DNA fragmentation was observed at 25 μg mL-1. By using adequate scavengers, investigations on active intermediates responsible for their cytotoxicity were performed, both in the absence and in the presence of ascorbate as a reducing agent. Based on the observed selective cytotoxicity of these materials toward melanomas, investigations on the reactivity of these complexes and corresponding POSS-materials with melanin, a molecule that contributes to melanoma resistance to chemotherapy, were carried out. Results indicated the main role of the binuclear copper species, formed at the surface of the silica matrix, in the observed reactivity and selectivity of these copper-POSS systems.

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Multifunctional Organometallic Compounds Active against Infective Trypanosomes: Ru(II) Ferrocenyl Derivatives with Two Different Bioactive Ligands

Human African trypanosomiasis (HAT, sleeping sickness) and American trypanosomiasis (Chagas disease) are endemic zoonotic diseases caused by genomically related trypanosomatid protozoan parasites (Trypanosoma brucei and Trypanosoma cruzi, respectively). Just a few old drugs are available for their treatment, with most of them sharing poor safety, efficacy, and pharmacokinetic profiles. Only fexinidazole has been recently incorporated into the arsenal for the treatment of HAT. In this work, new multifunctional Ru(II) ferrocenyl compounds were rationally designed as potential agents against these pathogens by including in a single molecule 1,1'-bis(diphenylphosphino)ferrocene (dppf) and two bioactive bidentate ligands: pyridine-2-thiolato-1-oxide ligand (mpo) and polypyridyl ligands (NN). Three [Ru(mpo)(dppf)(NN)](PF6) compounds and their derivatives with chloride as a counterion were synthesized and fully characterized in solid state and solution. They showed in vitro activity on bloodstream T. brucei (EC50 = 31-160 nM) and on T. cruzi trypomastigotes (EC50 = 190-410 nM). Compounds showed the lowest EC50 values on T. brucei when compared to the whole set of metal-based compounds previously developed by us. In addition, several of the Ru compounds showed good selectivity toward the parasites, particularly against the highly proliferative bloodstream form of T. brucei. Interaction with DNA and generation of reactive oxygen species (ROS) were ruled out as potential targets and modes of action of the Ru compounds. Biochemical assays and in silico analysis led to the insight that they are able to inhibit the NADH-dependent fumarate reductase from T. cruzi. One representative hit induced a mild oxidation of low molecular weight thiols in T. brucei. The compounds were stable for at least 72 h in two different media and more lipophilic than both bioactive ligands, mpo and NN. An initial assessment of the therapeutic efficacy of one of the most potent and selective candidates, [Ru(mpo)(dppf)(bipy)]Cl, was performed using a murine infection model of acute African trypanosomiasis. This hit compound lacks acute toxicity when applied to animals in the dose/regimen described, but was unable to control parasite proliferation in vivo, probably because of its rapid clearance or low biodistribution in the extracellular fluids. Future studies should investigate the pharmacokinetics of this compound in vivo and involve further research to gain deeper insight into the mechanism of action of the compounds.

Discovery of Novel p53-MDM2 Inhibitor (RG7388)-Conjugated PlatinumIV Complexes as Potent Antitumor Agents

While a number of p53-MDM2 inhibitors have progressed into clinical trials for the treatment of cancer, their progression has been hampered by a variety of problems, including acquired drug resistance, dose-dependent toxicity, and limited clinical efficiency. To make more progress, we integrated the advantages of MDM2 inhibitors and platinum drugs to construct novel PtIV-RG7388 (a selective MDM2 inhibitor) complexes. Most complexes, especially 5a and 5b, displayed greatly improved antiproliferative activity against both wild-type and mutated p53 cancer cells. Remarkably, 5a exhibited potent in vivo tumor growth inhibition in the A549 xenograft model (66.5%) without apparent toxicity. It arrested the cell cycle at both the S phase and the G2/M phase and efficiently induced apoptosis via the synergistic effects of RG7388 and cisplatin. Altogether, PtIV-RG7388 complex 5a exhibited excellent in vitro and in vivo antitumor activities, highlighting the therapeutic potential of PtIV-RG7388 complexes as antitumor agents.

Effects induced by η6-p-cymene ruthenium(II) complexes on Langmuir monolayers mimicking cancer and healthy cell membranes do not correlate with their toxicity

The mechanism of chemotherapeutic action of Ru-based drugs involves plasma membrane disruption and valuable insights into this process may be gained using cell membrane models. The interactions of a series of cytotoxic η6-p-cymene ruthenium(II) complexes, [Ru(η6-p-cymene)P(3,5-C(CH3)3-C6H3)3Cl2] (1), [Ru(η6-p-cymene)P(3,5-CH3-C6H3)3Cl2] (2), [Ru(η6-p-cymene)P(4-CH3O-3,5-CH3-C6H2)3Cl2] (3), and [Ru(η6-p-cymene)P(4-CH3O-C6H4)3Cl2] (4), were examined using Langmuir monolayers as simplified healthy and cancerous outer leaflet plasma membrane models. The cancerous membrane (CM1 and CM2) models contained either 40 % 1,2- dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 30 % cholesterol (Chol), 20 % 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 10 % 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine (DPPS). Meanwhile, the healthy membrane (HM1 and HM2) models were composed of 60 % DPPC or DOPC, 30 % Chol and 10 % DPPE. The complexes affected surface pressure isotherms and decreased compressional moduli of cancerous and healthy membrane models, interacting with the monolayers headgroup and tails according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). However, the effects did not correlate with the toxicity of the complexes to cancerous and healthy cells. Multidimensional projection technique showed that the complex (1) induced significant changes in the CM1 and HM1 monolayers, though it had the lowest cytotoxicity against cancer cells and is not toxic to healthy cells. Moreover, the most toxic complexes (2) and (4) were those that least affected CM2 and HM2 monolayers. The findings here support that the ruthenium complexes interact with lipids and cholesterol in cell membrane models, and their cytotoxic activities involve a multifaceted mode of action beyond membrane disruption.

L-Citrullinato-Bipyridine and L-Citrullinato-Phenanthroline Mixed Copper Complexes: Synthesis, Characterization and Potential Anticancer Activity

Citrulline (C6H13N3O3) is an amino acid found in the body as a zwitterion. This means its carboxylic and amine groups can act as Lewis donors to chelate metal cations. In addition, citrulline possesses a terminal ureido group on its aliphatic chain, which also appears to coordinate. Here, two new mixed complexes of citrulline were made with 1,10-phenanthroline and 2,2'-bipyridine. These compounds, once dissolved in water, gave aquo-complexes that were subject to DFT studies and in vitro toxicity studies on cancer cell lines (HeLa, MDA-MB-231, HCT 15, and MCF7) showed promising results. Docking studies with DNA were also conducted, indicating potential anticancer properties.

Glycyrrhetinic Acid as a Hepatocyte Targeting Ligand-Functionalized Platinum(IV) Complexes for Hepatocellular Carcinoma Therapy and Overcoming Multidrug Resistance

Promising targeted therapy options to overcome drug resistance and side effects caused by platinum(II) drugs for treatment in hepatocellular carcinoma are urgently needed. Herein, six novel multifunctional platinum(IV) complexes through linking platinum(II) agents and glycyrrhetinic acid (GA) were designed and synthesized. Among them, complex 20 showed superior antitumor activity against tested cancer cells including cisplatin resistance cells than cisplatin and simultaneously displayed good liver-targeting ability. Moreover, complex 20 can significantly cause DNA damage and mitochondrial dysfunction, promote reactive oxygen species generation, activate endoplasmic reticulum stress, and eventually induce apoptosis. Additionally, complex 20 can effectively inhibit cell migration and invasion and trigger autophagy and ferroptosis in HepG-2 cells. More importantly, complex 20 demonstrated stronger tumor inhibition ability than cisplatin or the combo of cisplatin/GA with almost no systemic toxicity in HepG-2 or A549 xenograft models. Collectively, complex 20 could be developed as a potential anti-HCC agent for cancer treatment.

Antimicrobial properties of triazolato terpyridine Pd(II) and Pt(II) complexes formed by [3+2] cycloaddition coupling reaction

Modern classes of antimicrobials are crucial because most drugs in development today are basically antibiotic derivatives. Even though a large number of metal-based compounds have been studied as antimicrobial agents, relatively few studies have examined the antimicrobial properties of Pd(II) and Pt(II) compounds. The [3+2] cycloaddition reactions of [M(N3)L]PF6 (M = Pd(II) and Pt(II); L = 4'-(2-pyridyl)-2,2':6',2″-terpyridine) with 4,4,4-trifluoro-2-butynoic acid ethyl ester gave the corresponding triazolate complexes. The reaction products were fully characterized with a variety of analytical and spectroscopic tools including X-ray crystallographic analysis. The crystal structure of [Pd(triazolatoCF3,COOCH2CH3)L]PF6 provided cut-off evidence that the kinetically formed N1-triazolato isomer favoured the isomerization to the thermodynamically stable N2-analogue. The experimental work was complemented with computational work to get an insight into the nature of the predominant triazolate isomer. The lysozyme binding affinity of the triazolate complexes was examined by mass spectrometry. An analysis of the lysozyme Pd(II) adducts suggests a coordinative covalent mode of binding via the loss of the triazolato ligand. The free ligand and its triazolate complexes displayed selective toxicity against Candida albicans and Cryptococcus neoformans, while no cytotoxicity was observed against the normal human embryonic kidney cell line.

Novel NF-κB Inhibitor-Conjugated Pt(IV) Prodrug to Enable Cancer Therapy through ROS/ER Stress and Mitochondrial Dysfunction and Overcome Multidrug Resistance

Although cisplatin has been widely used for clinical purposes, its application is limited due to its obvious side effects. To mitigate the defects of cisplatin, here, six "multitarget prodrugs" were synthesized by linking cisplatin and NF-κB inhibitors. Notably, complex 9 demonstrated a 63-fold enhancement in the activity against A549/CDDP cells with lower toxicity toward normal LO2 cells compared to cisplatin. Additionally, complex 9 could effectively cause DNA damage, induce mitochondrial dysfunction, generate reactive oxygen species, and induce cell apoptosis through the mitochondrial pathway and ER stress. Remarkably, complex 9 effectively inhibited the NF-κB/MAPK signaling pathway and disrupted the PI3K/AKT signaling transduction. Importantly, complex 9 showed superior in vivo antitumor efficiency compared to cisplatin or the combination of cisplatin/4, without obvious systemic toxicity in A549 or A549/CDDP xenograft models. Our results demonstrated that the dual-acting mechanism endowed the complexes with high efficiency and low toxicity, which may represent an efficient strategy for cancer therapy.

Inhibition of NF-κB-Mediated Proinflammatory Transcription by Ru(II) Complexes of Anti-Angiogenic Ligands in Triple-Negative Breast Cancer

Nuclear factor kappa beta (NF-κB) plays a pivotal role in breast cancer, particularly triple-negative breast cancer, by promoting inflammation, proliferation, epithelial-mesenchymal transition, metastasis, and drug resistance. Upregulation of NF-κB boosts vascular endothelial growth factor (VEGF) expression, assisting angiogenesis. The Ru(II) complexes of methyl- and dimethylpyrazolyl-benzimidazole N,N donors inhibit phosphorylation of ser536 in p65 and translocation of the NF-κB heterodimer (p50/p65) to the nucleus, disabling transcription to upregulate inflammatory signaling. The methyl- and dimethylpyrazolyl-benzimidazole inhibit VEGFR2 phosphorylation at Y1175, disrupting downstream signaling through PLC-γ and ERK1/2, ultimately suppressing Ca(II)-signaling. Partial release of the antiangiogenic ligand in a reactive oxygen species-rich environment is possible as per our observation to inhibit both NF-κB and VEGFR2 by the complexes. The complexes are nontoxic to zebrafish embryos up to 50 μM, but the ligands show strong in vivo antiangiogenic activity at 3 μM during embryonic growth in Tg(fli1:GFP) zebrafish but no visible effect on the adult phase.