Antitumor Effects of Ir(III)-2H-Indazole Complexes for Triple Negative Breast Cancer

Triphenylphosphine-modified cyclometalated iridiumIII complexes as mitochondria-targeting anticancer agents with enhanced selectivity

This study presents the development and evaluation of triphenylphosphine-modified cyclometalated iridiumIII complexes as selective anticancer agents targeting mitochondria. By leveraging the mitochondrial localization capability of the triphenylphosphine group, these complexes displayed promising cytotoxicity in the micromolar range (3.12-7.24 μM) against A549 and HeLa cancer cells, these complexes exhibit significantly higher activity compared to their unmodified counterparts lacking the triphenylphosphine moiety. Moreover, they demonstrate improved specificity for cancer cells over normal cells, achieving selectivity index in the range of 5.46-14.83. Mechanistic studies confirmed that these complexes selectively target mitochondria rather than DNA, as shown by confocal microscopy and flow cytometry, where they accumulate to induce mitochondrial dysfunction. This disruption leads to mitochondrial membrane depolarization (MMP), elevated reactive oxygen species (ROS) levels, and activation of intrinsic apoptosis pathways. Furthermore, the complexes induce cell cycle arrest at the G2/M phase and suppress the migration of A549 cells.

Anticancer behavior of cyclometallated iridium(III)-tributyltin(IV) carboxylate schiff base complexes with aggregation-induced emission

Cyclometallated iridium(III) and organotin(IV) carboxylate complexes have shown potential application value in the field of anticancer. However, the widespread aggregation-caused quenching (ACQ) effect of these complexes is not conducive to the exploration of their targeting and anticancer mechanism, and the idea of aggregation-induced emission (AIE) effect can effectively solve this problem. Then, AIE-activated cyclometallated iridium(III)-tributyltin(IV) carboxylate Schiff base complexes were designed and prepared in this study. Complexes exhibited AIE effect in highly concentrated solution or aggregative state, which facilitated the investigation of subcellular tissue targeting (mitochondria) and cell morphology. Compared with cyclometallated iridium(III) complex and tributyltin(IV) carboxylate monomers, these complexes showed the better in-vitro anti-proliferative activity toward A549 cells, confirming the favorable synergistic anticancer activity. Even for A549/DDP (cisplatin-resistance) cells, these complexes also exhibited the better activity. In addition, complexes showed a mitochondrial apoptotic pathway. Therefore, cyclometallated iridium(III)-tributyltin(IV) carboxylate Schiff base complexes can be used as the potential substitutes for platinum-based drugs and gain further application.

Triphenylphosphine-Modified IridiumIII, RhodiumIII, and RutheniumII Complexes to Achieve Enhanced Anticancer Selectivity by Targeting Mitochondria

The incorporation of an organelle-targeting moiety into compounds has proven to be an effective strategy in the development of targeted anticancer drugs. We herein report the synthesis, characterization, and biological evaluation of novel triphenylphosphine-modified half-sandwich iridiumIII, rhodiumIII, and rutheniumII complexes. The primary goal was to enhance anticancer selectivity through mitochondrial targeting. All these triphenylphosphine-modified complexes exhibited promising cytotoxicity in the micromolar range (5.13-23.22) against A549 and HeLa cancer cell lines, surpassing the activity of comparative complexes that lack the triphenylphosphine moiety. Noteworthy is their good selectivity toward cancer cells compared to normal BEAS-2B cells, underscored by selectivity index ranging from 7.3 to >19.5. Mechanistically, these complexes primarily target mitochondria rather than interacting with DNA. The targeting of mitochondria and triggering mitochondrial dysfunction were confirmed using both confocal microscopy and flow cytometry. Their ability to depolarize mitochondrial membrane potential (MMP) and enhance reactive oxygen species (ROS) was observed, thereby leading to intrinsic apoptotic pathways. Moreover, these complexes lead to cell cycle arrest in the G2/M phase and demonstrated antimigration effects, significantly inhibiting the migration of A549 cells in wound-healing assays.

Design, synthesis, in-vitro, in-silico, DFT and POM studies of a novel family of sulfonamides as potent anti-triple-negative breast cancer agents

In this study, a new family of ethacrynic acid-sulfonamides and indazole-sulfonamides was synthesized and tested in vitro against MDA-MB-468 triple-negative breast cancer cells and PBMCs human peripheral blood mononuclear cells, using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The aim of this research is to discover novel compounds with potential therapeutic effects on breast cancer. The antiproliferative activity of these compounds showed a significant dose-dependent activity, with IC50 values ranging between 2.83 and 7.52 µM. The lead compounds 8 and 9 displayed similar IC50 values to paclitaxel with 2.83, 3.84 and 2.72 µM, respectively. This highlights the novelty and potential of these compounds as alternatives to current treatments. The binding properties of 8, 9, and paclitaxel with the active sites of the PARP1(Poly(ADP-ribose) polymérase 1) and EGFR (Epidermal growth factor receptor) proteins were analyzed by molecular docking methods showing, for PARP1 protein, binding affinities of -9.8 Kcal /mol, -10 Kcal /mol, and -9.4 Kcal /mol, respectively. While their binding affinities for EGFR protein are -7.5 Kcal/mol, -7.2 Kcal/mol and -6.9 Kcal/mol, respectively. Moreover, drug-likeness and ADMET (Absorption-distribution-metabolism-excretion-toxicity) analyses demonstrated that both molecules are orally bioavailable and have good pharmacokinetic and non-toxic profiles. DFT (Density functional theory) was also carried out on both compounds 8 and 9 additionally to POM (Petra/Osiris/Molinspiration) studies on all compounds. The outcomes of this study suggest that compounds 8 and 9 are promising candidates for further development as therapeutic agents against triple-negative breast cancer.

Anti-cancer property and DNA binding interaction of first row transition metal complexes: A decade update

Metal ions carry out a wide variety of functions, including acid-base/redox catalysis, structural functions, signaling, and electron transport. Understanding the interactions of transition metal complexes with biomacromolecules is essential for biology, medicinal chemistry, and the production of synthetic metalloenzymes. After the coincidental discovery of cisplatin, importance of the metal complexes in biochemistry became a top priority for inquiry. In this review, a decade update on various synthetic strategies to first row transition metal complex and their interaction with DNA through non-covalent binding are explored. Moreover, this effort provides an excellent analysis on the efficacy of theoretical and practical approaches to the systematic generation of new non-platinum based metallodrugs for anti-cancer therapeutics.

Iminoamido chelated iridium(III) and ruthenium(II) anticancer complexes with mitochondria-targeting ability and potential to overcome cisplatin resistance

A diverse set of neutral half-sandwich iminoamido iridium and ruthenium organometallic complexes is synthesized through the utilization of Schiff base pro-ligands with N˄N donors. Notably, these metal complexes with varying leaving groups (Cl- or OAc-) are formed by employing different quantities of the deprotonating agent NaOAc, and exhibit promising cytotoxicity against various cancer cell lines such as A549 and cisplatin-resistant A549/DDP lung cancer cells, as well as HeLa cells, with IC50 values spanning from 9.26 to 15.98 μM. Cytotoxicity and anticancer selectivity (SI: 1.9-2.4) of these metal complexes remain unaffected by variations in the metal center, leaving group, and ligand substitution. Further investigations reveal that these metal complexes specifically target mitochondria, leading to the depolarization of the mitochondrial membrane and instigating the production of intracellular reactive oxygen species. Furthermore, the metal complexes are found to induce late apoptosis and disrupt the cell cycle, leading to G2/M cell cycle arrest specifically in A549 cancer cells. In light of these findings, it is evident that the primary mechanism contributing to the anticancer effectiveness of these metal complexes is the redox pathway.

Studies of Anticancer Activities In Vitro and In Vivo for Butyltin(IV)-Iridium(III) Imidazole-Phenanthroline Complexes with Aggregation-Induced Emission Properties

Organotin(IV) and iridium(III) complexes have shown good application potential in the field of anticancer; however, the aggregation-caused quenching (ACQ) effect induced by high concentration or dose has limited the research on their targeting and anticancer mechanism. Then, a series of aggregation-induced emission (AIE)-activated butyltin(IV)-iridium(III) imidazole-phenanthroline complexes were prepared in this study. Complexes exhibited significant fluorescence improvement in the aggregated state because of the restricted intramolecular rotation (RIR), accompanied by an absolute fluorescence quantum yield of up to 29.2% (IrSn9). Complexes demonstrated potential in vitro antiproliferative and antimigration activity against A549 cells, following a lysosomal-mitochondrial apoptotic pathway. Nude mouse models further confirmed that complexes had favorable in vivo antitumor and antimigration activity in comparison to cisplatin. Therefore, butyltin(IV)-iridium(III) imidazole-phenanthroline complexes possess the potential as potential substitutes for platinum-based drugs.

Synthetic access to diverse thiazetidines via a one-pot microwave assisted telescopic approach and their interaction with biomolecules

A one-pot microwave assisted telescopic approach is reported for the chemo-selective synthesis of substituted 1,3-thiazetidines using readily available 2-aminopyridines/pyrazines/pyrimidine, substituted isothiocyanates and 1,2-dihalomethanes. The procedure involves thiourea formation from 2-aminopyridines/pyrazines/pyrimidine with the substituted isothiocyanates followed by a base catalysed nucleophilic attack of the CS bond on the 1,2-dihalomethane. Subsequently, a cyclization reaction occurs to yield substituted 1,3-thiazetidines. These four membered strained ring systems are reported to possess broad substrate scope with high functional group tolerance. The above synthetic sequence for the formation of four membered heterocycles is proven to be a modular and straightforward approach. Further the mechanistic pathway for the formation of 1,3-thiazetidines was supported by computational evaluations and X-ray crystallography analyses. The relevance of these thiazetidines in biological applications is evaluated by studying their ability to bind bio-macromolecules like proteins and nucleic acids.

Mitochondria-targeted neutral and cationic iridium(III) anticancer complexes chelating simple hybrid sp2-N/sp3-N donor ligands

Most platinum group-based cyclometalated neutral and cationic anticancer complexes with the general formula [(C^N)2Ir(XY)]0/+ (neutral complex: XY = bidentate anionic ligand; cationic complex: XY = bidentate neutral ligand) are notable owing to their intrinsic luminescence properties, good cell permeability, interaction with some biomolecular targets and unique mechanisms of action (MoAs). We herein synthesized a series of neutral and cationic amine-imine cyclometalated iridium(III) complexes using Schiff base ligands with sp2-N/sp3-N N^NH2 chelating donors. The cyclometalated iridium(III) complexes were identified by various techniques. They were stable in aqueous media, displayed moderate fluorescence and exhibited affinity toward bovine serum albumin (BSA). The complexes demonstrated promising cytotoxicity against lung cancer A549 cells, cisplatin-resistant lung cancer A549/DDP cells, cervical carcinoma HeLa cells and human liver carcinoma HepG2 cells, with IC50 values ranging from 9.98 to 19.63 μM. Unfortunately, these complexes had a low selectivity (selectivity index: 1.62-1.98) towards A549 cells and BEAS-2B normal cells. The charge pattern of the metal center (neutral or cationic) and ligand substituents showed little influence on the cytotoxicity and selectivity of these complexes. The study revealed that these complexes could target mitochondria, cause depolarization of the mitochondrial membrane, and trigger the production of intracellular ROS. Additionally, the complexes were observed to induce late apoptosis and perturb the cell cycle in the G2/M or S phase in A549 cells. Based on these results, it appears that the anticancer efficacy of these complexes was predominantly attributed to the redox mechanism.

Potent Half-Sandwich 16-/18-Electron Iridium(III) and Ruthenium(II) Anticancer Complexes with Readily Available Amine-Imine Ligands

The synthesis and biological evaluation of stable 16-electron half-sandwich complexes have remained scarce. We herein present the different coordination modes (16-electron or 18-electron) between half-sandwich iridium(III) complexes and ruthenium(II) complexes derived from the same amine-imine ligands chelating hybrid sp3-N/sp2-N donors. The 16-electron iridium(III) and 18-electron ruthenium(II) complexes with different counteranions were obtained and identified by various techniques. The promising cytotoxicity of these complexes against A549 lung cancer cells, cisplatin-resistant A549/DPP cells, cervical carcinoma HeLa cells, and human hepatocellular liver carcinoma HepG2 cells was observed with IC50 values ranging from 5.4 to 16.3 μM. Moreover, these complexes showed a certain selectivity (selectivity index: 2.1-3.7) toward A549 cells and BEAS-2B normal cells. The variation of metal center, counteranion, 16/18-electron coordination mode, and ligand substituents showed little influence on the cytotoxicity and selectivity of these complexes. The mechanism of action study showed that these complexes could target mitochondria, induce the depolarization of the mitochondrial membrane, and promote the generation of intracellular reactive oxygen species (ROS). Further, the induction of cell apoptosis and the perturbation of the cell cycle in the G0/G1 phase were also observed for these complexes. Overall, it seems that the redox mechanism dominated the anticancer efficacy of these complexes.

Half-Sandwich Iridium(III), Rhodium(III), and Ruthenium(II) Complexes Chelating Hybrid sp2-N/sp3-N Donor Ligands to Achieve Improved Anticancer Selectivity

The biological efficacy of half-sandwich platinum group organometallic complexes of the formula [(η5-Cpx)/(η6-arene)M(XY)Cl]0/+ (XY = bidentate ligands; Cpx = functionalized cyclopentadienyl; M = Ir, Rh, Ru, Os) has received considerable attention due to the significance of the metal center, chelating ligand, and Cpx/arene moieties in defining their anticancer potency and selectivity. With a facile access to the BIAN-derived imine-amine ligands using alkylaluminum as the reductant, we herein described the preparation and characterization of 16 half-sandwich Ir(III), Rh(III), and Ru(II) complexes chelating the hybrid sp2-N/sp3-N donor ligand. A nonplanar five-member metallacycle was confirmed by X-ray single-crystal structures of Ir1-Ir3, Ir7, Rh1, Ru1, and Ru4. The attempt to prepare imine-amido complexes using a base as the deprotonating agent led to the mixture of imine-amine complexes, within which the leaving group Cl- was displaced, and 16-electron imine-amido complexes without Cl-. The half-sandwich imine-amine complexes in this system underwent rapid hydrolysis in aqueous solution, exhibited weak photoluminescence, and showed the ability of binding to CT-DNA and BSA. The cytotoxicity of all imine-amine complexes against A549 lung cancer cell lines, HeLa cervical cancer cell lines, and 4T1 mouse breast cancer cells was determined by an MTT assay. The IC50 values of these complexes were in a range of 5.71-67.28 μM. Notably, most of these complexes displayed improved selectivity toward A549 cancer cells versus noncancerous BEAS-2B cells in comparison with the corresponding α-diimine complexes chelating the sp2-N/sp2-N donor ligand, which have been shown no selectivity in our previous report. The anticancer selectivity of these complexes appeared to be related to the redox-based mechanism including the catalytic oxidation of NADH to NAD+, reactive oxygen species (ROS) generation, and depolarization of the mitochondrial membrane. Further, inducing apoptosis of these complexes in A549 cancer cells and BEAS-2B normal cells also correlated with their anticancer selectivity, indicating the apoptosis mode of cell death in this system. In addition, these complexes could enter A549 cells via energy-dependent pathway and were able to impede the in vitro migration of A549 cells.

Recent Advancements of Aptamers in Cancer Therapy

Aptamers are chemical antibodies possessing the capability of overcoming the limitations posed by conventional antibodies, particularly for diagnostic, therapeutic, and theranostic applications in cancer. The ease of chemical modifications or functionalization, including conjugations with nucleic acids, drug molecules, and nanoparticles, has made these aptamers to gain priorities in research. In this Mini-review, various reports on therapeutics with aptamer-functionalized nanomaterials for controlled or multistep drug release, targeted delivery, stimuli-responsive drug release, etc. are discussed. In the case of nucleic-acid-conjugated aptamers, DNA nanotrains and DNA beacons are discussed in terms of the possibility of multidrug loading for chemotherapy and gene therapy. Developments with electrochemical aptasensors and signal-enhanced immune aptasensors are also discussed. Further, the future scope of aptamer technology in cancer theranostics and the prevailing limitations are discussed.

Mitochondrial DNA-targeted therapy: A novel approach to combat cancer

Mitochondrial DNA (mtDNA) encodes proteins and RNAs that are essential for mitochondrial function and cellular homeostasis, and participates in important processes of cellular bioenergetics and metabolism. Alterations in mtDNA are associated with various diseases, especially cancers, and are considered as biomarkers for some types of tumors. Moreover, mtDNA alterations have been found to affect the proliferation, progression and metastasis of cancer cells, as well as their interactions with the immune system and the tumor microenvironment (TME). The important role of mtDNA in cancer development makes it a significant target for cancer treatment. In recent years, many novel therapeutic methods targeting mtDNA have emerged. In this study, we first discussed how cancerogenesis is triggered by mtDNA mutations, including alterations in gene copy number, aberrant gene expression and epigenetic modifications. Then, we described in detail the mechanisms underlying the interactions between mtDNA and the extramitochondrial environment, which are crucial for understanding the efficacy and safety of mtDNA-targeted therapy. Next, we provided a comprehensive overview of the recent progress in cancer therapy strategies that target mtDNA. We classified them into two categories based on their mechanisms of action: indirect and direct targeting strategies. Indirect targeting strategies aimed to induce mtDNA damage and dysfunction by modulating pathways that are involved in mtDNA stability and integrity, while direct targeting strategies utilized molecules that can selectively bind to or cleave mtDNA to achieve the therapeutic efficacy. This study highlights the importance of mtDNA-targeted therapy in cancer treatment, and will provide insights for future research and development of targeted drugs and therapeutic strategies.

In Vitro and In Vivo Antitumor Assay of Mitochondrially Targeted Fluorescent Half-Sandwich Iridium(III) Pyridine Complexes

Half-sandwich iridium(III) complexes show potential value in the anticancer field. However, complexes with favorable luminescence performance are rare, which limits further investigation of the anticancer mechanism. In this paper, 10 triphenylamine-modified fluorescent half-sandwich iridium(III) pyridine complexes {[(η⁵-Cp^x)Ir(L)Cl₂]} (Ir1-Ir10) were prepared and showed potential antiproliferative activity, effectively inhibiting the migration of A549 cells. Ir6, showing the best activity among these complexes, exhibited excellent fluorescence performance (absolute fluorescence quantum yield of 15.17%) in solution. Laser confocal detection showed that Ir6 followed an energy-dependent cellular uptake mechanism, specifically accumulating in mitochondria (Pearson co-localization coefficient of 0.95). A Western blot assay further confirmed the existence of a mitochondrial apoptotic channel. Additionally, Ir6 could arrest the cell cycle at the G₂/M phase, catalyze NADH oxidation, reduce the mitochondrial membrane potential, induce an increase in the level of intracellular reactive oxygen species, and exhibit a mechanism of oxidation. An in vivo antitumor assay confirmed that Ir6 can effectively inhibit tumor growth and is safer than cisplatin.

Synthetic approaches to potent heterocyclic inhibitors of tuberculosis: A decade review

Tuberculosis (TB) continues to be a significant global health concern with about 1.5 million deaths annually. Despite efforts to develop more efficient vaccines, reliable diagnostics, and chemotherapeutics, tuberculosis has become a concern to world health due to HIV, the rapid growth of bacteria that are resistant to treatment, and the recently introduced COVID-19 pandemic. As is well known, advances in synthetic organic chemistry have historically enabled the production of important life-saving medications that have had a tremendous impact on patients' lives and health all over the world. Small-molecule research as a novel chemical entity for a specific disease target offers in-depth knowledge and potential therapeutic targets. In this viewpoint, we concentrated on the synthesis of a number of heterocycles reported in the previous decade and the screening of their inhibitory action against diverse strains of Mycobacterium tuberculosis. These findings offer specific details on the structure-based activity of several heterocyclic scaffolds backed by their in vitro tests as a promising class of antitubercular medicines, which will be further useful to build effective treatments to prevent this terrible illness.

In-silico molecular modelling, MM/GBSA binding free energy and molecular dynamics simulation study of novel pyrido fused imidazo[4,5-c]quinolines as potential anti-tumor agents

With an alarming increase in the number of cancer patients and a variety of tumors, it is high time for intensive investigation on more efficient and potent anti-tumor agents. Though numerous agents have enriched the literature, still there exist challenges, with the availability of different targets and possible cross-reactivity. Herein we have chosen the phosphoinositide 3-kinase (PI3K) as the target of interest and investigated the potential of pyrido fused imidazo[4,5-c]quinoline derivatives to bind strongly to the active site, thereby inhibiting the progression of various types of tumors. The AutoDock, Glide and the Prime-MM/GBSA analysis are used to execute the molecular docking investigation and validation for the designed compounds. The anti-tumor property evaluations were carried out by using PASS algorithm. Based on the GLIDE score, the binding affinity of the designed molecules towards the target PI3K was evaluated. The energetics associated with static interactions revealed 1j as the most potential candidate and the dynamic investigations including RMSD, RMSF, Rg, SASA and hydrogen bonding also supported the same through relative stabilization induced through ligand interactions. Subsequently, the binding free energy of the Wortmannin and 1j complex calculated using MM-PBSA analysis. Further evaluations with PASS prediction algorithm also supported the above results. The studies reveal that there is evidence for considering appropriate pyrido fused imidazo[4,5-c]quinoline compounds as potential anti-tumor agents.

2-Aminopyridine - an unsung hero in drug discovery

2-Aminopyridine is a simple, low molecular weight and perfectly functionalised moiety known for the synthesis of diverse biological molecules. Many pharmaceutical companies across the globe aim to synthesise low-molecular weight molecules for use as pharmacophores against various biological targets. 2-Aminopyridine can serve as a perfect locomotive in the synthesis and pulling of such molecules towards respective pharmacological goals. The major advantage of this moiety is its simple design, which can be used to produce single products with minimum side reactions. Moreover, the exact weight of synthesised compounds is low, which enables facile identification of toxicity-causing metabolites in drug discovery programmes. This manuscript is a quick review of such pharmacophores derived from 2-aminopyridine.