Liposomes encapsulated iridium(III) polypyridyl complexes enhance anticancer activity in vitro and in vivo

Evaluation of Efficiency of Liposome-Entrapped Iridium(III) Complexes Inhibiting Tumor Growth In Vitro and In Vivo

In this paper, three new iridium(III) complexes: [Ir(piq)2(DFIPP)]PF6 (piq = deprotonated 1-phenylisoquinoline, DFIPP = 3,4-difluoro-2-(1H-imidazo[4,5-f][1,10]phenenthrolin-2-yl)phenol, 3a), [Ir(bzq)2(DFIPP)]PF6 (bzq = deprotonated benzo[h]quinoline, 3b), and [Ir(ppy)2(DFIPP)]PF6 (ppy = deprotonated 1-phenylpyridine, 3c), were synthesized and characterized. The complexes were found to be nontoxic to tumor cells via 3-(4,5-dimethylthiazole-2-yl)-diphenyltetrazolium bromide (MTT) assay. Surprisingly, its liposome-entrapped complexes 3alip, 3blip, and 3clip on B16 cells showed strong cytotoxicity (IC50 = 13.6 ± 2.8, 9.6 ± 1.1, and 18.9 ± 2.1 μM). Entry of 3alip, 3blip, and 3clip into B16 cells decreases mitochondrial membrane potential, regulates Bcl-2 family proteins, releases cytochrome c, triggers caspase family cascade reaction, and induces apoptosis. In addition, we also found that 3alip, 3blip, and 3clip triggered ferroptosis and autophagy. In vivo studies demonstrated that 3blip inhibited melanoma growth in C57 mice with a high inhibitory rate of 83.95%, and no organic damage was found in C57 mice.

Liposomal Formulations of Metallodrugs for Cancer Therapy

The search for new antineoplastic agents is imperative, as cancer remains one of the most preeminent causes of death worldwide. Since the discovery of the therapeutic potential of cisplatin, the study of metallodrugs in cancer chemotherapy acquired increasing interest. Starting from cisplatin derivatives, such as oxaliplatin and carboplatin, in the last years, different compounds were explored, employing different metal centers such as iron, ruthenium, gold, and palladium. Nonetheless, metallodrugs face several drawbacks, such as low water solubility, rapid clearance, and possible side toxicity. Encapsulation has emerged as a promising strategy to overcome these issues, providing both improved biocompatibility and protection of the payload from possible degradation in the biological environment. In this respect, liposomes, which are spherical vesicles characterized by an aqueous core surrounded by lipid bilayers, have proven to be ideal candidates due to their versatility. In fact, they can encapsulate both hydrophilic and hydrophobic drugs, are biocompatible, and their properties can be tuned to improve the selective delivery to tumour sites exploiting both passive and active targeting. In this review, we report the most recent findings on liposomal formulations of metallodrugs, with a focus on encapsulation techniques and the obtained biological results.

Nanoliposomes a future based delivery vehicle of cyanidin-3-O-glucoside against major chronic disease

BACKGROUND

Cyanidin-3-O-glucoside (C3G), is an anthocyanin mainly found in berries, and can also be produced by microorganisms. It has been traditionally used as a natural coloring agent for decades. Recently, it has been investigated for its high antioxidant activity and anti-cancer attributes. C3G has low bioavailability and is sensitive to oxidation and gastric pH; therefore, it is encapsulated in nanoliposomes to enhance its bio-availability, targeted delivery- and efficacy against chronic disease.

SCOPE AND APPROACH

In this review, the role of C3G nanoliposomes against major chronic diseases has been discussed. The focus was on research findings and the mechanism of action to affect the proliferation of cancer, neuro disease and cardiovascular problems. It also discussed the formulation of nanoliposomes, their role in nutraceutical delivery and enhancement in C3G bioavailability.

KEY FINDINGS AND CONCLUSIONS

Data suggested that nanoliposomes safeguard C3G, enhance bioavailability, and ensure safe, adequate and targeted delivery. It can reduce the impact of cancer and inflammation by inhibiting the ß-catenin/O6-methylguanine-DNA methyltransferase (MGMT) pathway and upregulating miR-214-5p. Formation of C3G nanoliposomes significantly enhances the nutraceutical efficacy of C3G against major chronic disease therefore, C3G nanoliposomes might be a future-based nutraceutical to treat major chronic diseases, including cancer, neuro problems and CVD, but challenges remain in finding correct dose and techniques to maximize its efficacy.

Synthesis and mitochondria-localized iridium (III) complexes induce cell death through pyroptosis and ferroptosis pathways

This paper introduces a new ligand, 4,6-dichloro-5-(1H-imidazo [4,5-f]phenanthroline-2-yl)pyrimidin-2-amine (DPPA), and its corresponding new iridium(III) complexes: [Ir(ppy)2(DPPA)](PF6) (2a) (where ppy represents deprotonated 2-phenylpyridine), [Ir(bzq)2(DPPA)](PF6) (2b) (with bzq indicating deprotonated benzo[h]quinoline), and [Ir(piq)2(DPPA)](PF6) (2c) (piq denoting deprotonated 1-phenylisoquinoline). The cytotoxic effects of both DPPA and 2a, 2b, and 2c were evaluated against human lung carcinoma A549, melanoma B16, colorectal cancer HCT116, human hepatocellular carcinoma HepG2 cancer cell lines, as well as the non-cancerous LO2 cell line using the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. While DPPA exhibited moderate anticancer activity toward A549, B16, HCT116 and HepG2 cells, complexes 2a, 2b, and 2c displayed remarkable efficacy against A549, B16, and HCT116 cells. The cell colonies and wound healing were investigated. Moreover, various aspects of the anticancer mechanisms were explored. The cell cycle analyses revealed that the complexes block cell proliferation of A549 cells during the S phase. Complex 2c induce an early apoptosis, while 2a and 2b cause a late apoptosis. The interaction of 2a, 2b and 2c with endoplasmic reticulum and mitochondria was identified, leading to elevated ROS and Ca2+ amounts. This resulted in a reduced mitochondrial membrane potential, mitochondrial permeability transition pore opening, and an increase of cytochrome c. Also, ferroptosis was investigated through measurements of intracellular glutathione (GSH), malondialdehyde (MDA), and recombinant glutathione peroxidase (GPX4) protein expression. The pyroptosis was explored via cell morphology, release of lactate dehydrogenase (LDH) and expression of pyroptosis-related proteins. RNA sequencing was applied to examine the signaling pathways. Western blot analyses illuminated that the complexes regulate the expression of Bcl-2 family proteins. Additionally, an in vivo antitumor study demonstrated that complex 2c exhibited a remarkable inhibitory rate of 58.58% in restraining tumor growth. In summary, the findings collectively suggest that the iridium(III) complexes induce cell death via ferroptosis, apoptosis by a ROS-mediated mitochondrial dysfunction pathway and GSDMD-mediated pyroptosis.

Mitochondria-targeted iridium(III) complexes encapsulated in liposome induce cell death through ferroptosis and gasdermin-mediated pyroptosis

This paper unveils a novel perspective on synthesis and characterization of the ligand 5-bromo-2-amino-2'-(phenyl-1H-imidazo[4,5-f][1,10]phenanthroline) (BAPIP), and its iridium(III) complexes [Ir(PPY-)2(BAPIP)](PF6) (1a, with PPY- as deprotonated 2-phenylpyridine), [Ir(PIQ-)2(BAPIP)](PF6) (1b, piq- denoting deprotonated 1-phenylisoquinoline), and [Ir(BZQ-)2(BAPIP)](PF6) (1c, bzq- signifying deprotonated benzo[h]quinoline). Systematic evaluation of the cytotoxicity of 1a, 1b, and 1c across diverse cell lines encompassing B16, HCT116, HepG2, A549, HeLa, and LO2 using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Unexpectedly, compounds 1b and 1c demonstrated no cytotoxicity against the above cell lines. Motivated by the pursuit of heightened anti-proliferative potential, a strategic encapsulation approach yielded liposomes 1alip, 1blip, and 1clip. As expectation, 1alip, 1blip, and 1clip displayed remarkable anti-proliferative efficacy, particularly noteworthy in A549 cells, exhibiting IC50 values of 4.9 ± 1.0, 5.9 ± 0.1, and 7.6 ± 0.2 μM, respectively. Moreover, our investigation illuminated the mitochondrial accumulation of these liposomal entities, 1alip, 1blip, and 1clip, evoking apoptosis through the mitochondrial dysfunction mediated by reactive oxygen species (ROS). The ferroptosis was confirmed by decrease in glutathione (GSH) concentrations, the downregulation of glutathione peroxidase 4 (GPX4), increase of high mobility group protein 1 (HMGB1), and lipid peroxidation. Simultaneously, pyroptosis as another mode of cell death was undertaken. RNA-sequencing was employed to investigate intricate signalling pathways. In vivo examination provided tangible evidence of 1alip in effectively curbing tumor growth. Collectively, this study provides a multifaceted mode of cellular demise orchestrated by 1a, 1alip, 1blip, and 1clip, involving pathways encompassing apoptosis, ferroptosis, and pyroptosis.

A review on metal complexes and its anti-cancer activities: Recent updates from in vivo studies

Research into cancer therapeutics has uncovered various potential medications based on metal-containing scaffolds after the discovery and clinical applications of cisplatin as an anti-cancer agent. This has resulted in many metallodrugs that can be put into medical applications. These metallodrugs have a wider variety of functions and mechanisms of action than pure organic molecules. Although platinum-based medicines are very efficient anti-cancer agents, they are often accompanied by significant side effects and toxicity and are limited by resistance. Some of the most studied and developed alternatives to platinum-based anti-cancer medications include metallodrugs based on ruthenium, gold, copper, iridium, and osmium, which showed effectiveness against many cancer cell lines. These metal-based medicines represent an exciting new category of potential cancer treatments and sparked a renewed interest in the search for effective anti-cancer therapies. Despite the widespread development of metal complexes touted as powerful and promising in vitro anti-cancer therapeutics, only a small percentage of these compounds have shown their worth in vivo models. Metallodrugs, which are more effective and less toxic than platinum-based drugs and can treat drug-resistant cancer cells, are the focus of this review. Here, we highlighted some of the most recently developed Pt, Ru, Au, Cu, Ir, and Os complexes that have shown significant in vivo antitumor properties between 2017 and 2023.

Mitochondria-targeted cyclometalated iridium (III) complexes: Dual induction of A549 cells apoptosis and autophagy

In this study, we synthesized 4 cyclometalated iridium complexes using N-(1,10-phenanthrolin-5-yl)picolinamide (PPA) as the main ligand, denoted as [Ir(ppy)2PPA]PF6 (ppy = 2-phenylpyridine, Ir1), [Ir(bzq)2PPA]PF6 (bzq = benzo[h]quinoline, Ir2), [Ir(dfppy)2PPA]PF6 (dfppy = 2-(3,5-difluorophenyl)pyridine, Ir3), and [Ir(thpy)2PPA]PF6 (thpy = 2-(thiophene-2-yl)pyridine, Ir4). Compared to cisplatin and oxaliplatin, all four complexes exhibited significant anti-tumor activity. Among them, Ir2 demonstrated higher cytotoxicity against A549 cells, with an IC50 value of 1.6 ± 0.2 μM. The experimental results indicated that Ir2 primarily localized in the mitochondria, inducing a large amount of reactive oxygen species (ROS) generation, that decreased in mitochondrial membrane potential (MMP), reduced ATP production, and further impaired mitochondrial function, leading to cytochrome c release. Additionally, Ir2 caused cell cycle arrest at the S phase and induced apoptosis through the AKT-mediated signaling pathway. Further investigations revealed that Ir2 could simultaneously induce both apoptosis and autophagy in A549 cells, with the latter acting as a non-protective mechanism that promoted cell death. More importantly, Ir2 exhibited low toxicity to both normal LO2 cells in vitro and zebrafish embryos in vivo. Consequently, these newly developed Ir(III) complexes show great potential in the development of novel and low-toxicity anticancer agents.

Synthesis, characterization, molecular docking, RNA-sequence and anticancer efficacy evaluation in vitro of ruthenium(II) complexes on B16 cells

In recent years, the studies of the ruthenium(II) complexes on anticancer activity have been paid great attention, many Ru(II) complexes possess high anticancer efficiency. In this paper, three ligands CPIP (2-(4-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline), DCPIP (2-(3,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline), TCPIP (2-(2,3,5-trichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and their three ruthenium (II) complexes [Ru(dip)2(CPIP)](PF6)2 (1, dip = 4,7-diphenyl-1,10-phenanthroline), [Ru(dip)2(DCPIP)](PF6)2 (2) and [Ru(dip)2(TCPIP)](PF6)2 (3) were synthesized and characterized. 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) assay was used to investigate in vitro cytotoxicity of complexes against various cancer cells. The results showed that complexes 1-3 exhibited pronounced cytotoxic effect on B16 cells with low IC50 values of 7.2 ± 0.1, 11.7 ± 0.6 and 1.2 ± 0.2 μM, respectively. The 3D model demonstrated that the complexes can validly prevent the cell proliferation. Apoptosis determined using Annexin V-FITC/PI double staining revealed that complexes 1-3 can effectively induce apoptosis in B16 cells. The intracellular localization of 1-3 in the mitochondria, the levels of intracellular reactive oxygen species (ROS), the opening of mitochondrial permeability transition pore as well as the decline of mitochondrial membrane potential were investigated, which demonstrated that the complexes 1-3 led to apoptosis via a ROS-mediated mitochondrial dysfunction pathway. The RNA-sequence indicated that the complexes upregulate the expression of 74 genes and downregulate the expression of 81 genes. The molecular docking showed that the complexes interact with the proteins through hydrogen bond, π-cation and π-π interaction. The results show that ruthenium(II) complexes 1, 2 and 3 can block tumor cell growth and induce cell death through autophagy and ROS-mediated mitochondrial dysfunction pathways.

Synthesis, characterization, anticancer efficacy evaluation of ruthenium(II) and iridium(III) polypyridyl complexes toward A549 cells

A new ligand DFIP (2-(dibenzo[b,d]furan-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its two complexes iridium(III) [Ir(ppy)₂(DFIP)](PF₆) (ppy = 2-phenylpyridine, Ir1) and ruthenium(II) [Ru(bpy)₂(DFIP)](PF₆)₂ (bpy = 2,2'-bipyridine, Ru1) were synthesized and characterized. The anticancer effects of the two complexes on A549, BEL-7402, HepG2, SGC-7901, HCT116 and normal LO2 cells were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complex Ir1 shows high cytotoxic activity on A549, BEL-7402, SGC-7901 and HepG2, Ru1 exhibits moderate anticancer activity toward A549, BEL-7402 and SGC-7901 cells. The IC₅₀ values of Ir1 and Ru1 toward A549 are 7.2 ± 0.1 and 22.6 ± 1.4 μM, respectively. The localization of complexes Ir1 and Ru1 in the mitochondrial, intracellular accumulation of reactive oxygen species (ROS) levels, and the changes of mitochondrial membrane potential (MMP) and cytochrome c (cyto-c) were investigated. Apoptosis and cell cycle were detected by flow cytometry. Immunogenic cell death (ICD) was used to detect the effects of Ir1 and Ru1 on the A549 using a confocal laser scanning microscope. The expression of apoptosis-related proteins was detected by western blotting. Ir1 and Ru1 can increase the intracellular ROS levels and release cyto-c, reduce the MMP, leading to the apoptosis of A549 cells and blocking the A549 cells at the G0/G1 phase. Additionally, the complexes caused a decrease of the expression of polyADP-ribose polymerase (PARP), caspase 3, Bcl-2 (B-cell lymphoma-2), PI3K (phosphoinositide-3 kinase) and upregulated the expression of Bax. All these findings indicated that the complexes exert anticancer efficacy to induce cell death through immunogenic cell death, apoptosis, and autophagy.

Design, synthesis and biological evaluation of liposome entrapped iridium(III) complexes toward SGC-7901 cells

In this study, two new iridium(III) polypyridyl complexes [Ir(bzq)₂(DIPH)](PF₆) (bzq = deprotonated benzo[h]quinoline, DIPH = 4-(2,5-dibromo-4-(1H-imidazo[4,5-f][1,10]phenanthrolim-2-yl)-4-hydroxybutan-2-one) (Ir1) and [Ir(piq)₂(DIPH)](PF₆) (piq = deprotonated 1-phenylisoquinoline) (Ir2) were synthesized and characterized by elemental analysis, HRMS, ¹H and ¹³C NMR. The cytotoxic activity of Ir1, Ir2, Ir1lipo and Ir2lipo against cancer cells SGC-7901, HepG2, A549, HeLa, B16 and normal NIH3T3 cells in vitro was evaluated using 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. Ir1 and Ir2 showed no cytotoxic activity, but their liposome-entrapped Ir1 (Ir1lipo) and Ir2 (Ir2lipo) showed significant cellular activity, especially sensitive to SGC-7901 with IC₅₀ values of 4.7 ± 0.2 and 12.4 ± 0.5 μM, respectively. The cellular uptake, endoplasmic reticulum (ER) localization, autophagy, tubulin polymerization, glutathione (GSH), malondialdehyde (MDA) and release of cytochrome c were investigated to explore the mechanisms of apoptosis. The calreticulin (CRT), heat shock protein 70 (HSP70), high mobility group box 1 (HMGB1) were also explored. Western blotting showed that Ir1lipo and Ir2lipo inhibited PI3K (phosphoinositide-3 kinase), AKT (protein kinase B), p-AKT and activated Bcl-2 (B-cell lymphoma-2) protein and apoptosis-regulated factor caspase 3 (cysteinyl aspartate specific proteinase-3) and cleaving PARP (poly ADP-ribose polymerase). The results demonstrated that Ir1lipo and Ir2lipo induce cell apoptosis through targeting the endoplasmic reticulum (ER), cause oxidative stress damage, inhibiting PI3K/AKT signaling pathway, immunogenic cell death (ICD) and inhibit the cell growth at G2/M phase.

Synthesis, biological evaluation of novel iridium(III) complexes targeting mitochondria toward melanoma B16 cells

A new ligand 2-(1E,3E,5E,7E)-2,6-dimethyl-8-(2,6,6-trimethylcyclohex-1-yl)octa-1,2,5,7-tetraen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (DTOIP) was synthesized and combined with [Ir(ppy)₂Cl]₂·2H₂O (ppy = deprotonated Hppy: 2-phenylpyridine), [Ir(piq)₂Cl]₂·2H₂O (piq = deprotonated Hpiq: 1-phenylisoquinoline) and [Ir(bzq)₂Cl]₂·2H₂O (bzq = deprotonated Hbzq: benzo[h]quinolone) to form [Ir(ppy)₂(DTOIP)](PF₆) (Ir1), [Ir(piq)₂(DTOIP)](PF₆) (Ir2), and [Ir(bzq)₂(DTOIP)](PF₆) (Ir3), respectively. The complexes were characterized by elemental analysis, high-resolution mass spectrometry (HRMS), ¹H NMR and ¹³C NMR. The antiproliferative activity of the complexes toward B16, BEL-7402, Eca-109 and normal LO2 cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complexes Ir1, Ir2 and Ir3 showed high antiproliferative activity against B16 cells with a low IC₅₀ values of 0.4 ± 0.1, 2.0 ± 0.1 and 1.4 ± 0.09 μM, respectively. Three-dimensional (3D) in vitro cell models also demonstrated that the iridium(III) complexes have a remarkable cytotoxicity to B16 cells. The experiments of cellular uptake, mitochondrial localization, and intracellular distribution of the drugs proved that the three iridium(III) complexes can enter the mitochondria, leading to the loss of mitochondrial membrane potential (MMP), decreased glutathione (GSH) levels, causing an increase of intracellular ROS content, and DNA damage, finally inducing apoptosis. RNA-sequence and bioinformatics analyses were used to analyze the differentially expressed genes and enriched biology processes. Antitumor in vivo demonstrated that complex Ir1 (5 mg/kg) exhibits a high efficacy to inhibit the tumor growth with an inhibitory rate of 71.67%. These results show that the complexes may be potent anticancer candidate drugs.

Trends in Drug Delivery Systems for Natural Bioactive Molecules to Treat Health Disorders: The Importance of Nano-Liposomes

Drug delivery systems are believed to increase pharmaceutical efficacy and the therapeutic index by protecting and stabilizing bioactive molecules, such as protein and peptides, against body fluids' enzymes and/or unsuitable physicochemical conditions while preserving the surrounding healthy tissues from toxicity. Liposomes are biocompatible and biodegradable and do not cause immunogenicity following intravenous or topical administration. Still, their most important characteristic is the ability to load any drug or complex molecule uncommitted to its hydrophobic or hydrophilic character. Selecting lipid components, ratios and thermo-sensitivity is critical to achieve a suitable nano-liposomal formulation. Nano-liposomal surfaces can be tailored to interact successfully with target cells, avoiding undesirable associations with plasma proteins and enhancing their half-life in the bloodstream. Macropinocytosis-dynamin-independent, cell-membrane-cholesterol-dependent processes, clathrin, and caveolae-independent mechanisms are involved in liposome internalization and trafficking within target cells to deliver the loaded drugs to modulate cell function. A successful translation from animal studies to clinical trials is still an important challenge surrounding the approval of new nano-liposomal drugs that have been the focus of investigations. Precision medicine based on the design of functionalized nano-delivery systems bearing highly specific molecules to drive therapies is a promising strategy to treat degenerative diseases.

An N-heterocyclic carbene iridium(III) complex as a potent anti-cancer stem cell therapeutic

Cancer stem cells (CSCs) represent a difficult to treat cellular niche within tumours due to their unique characteristics, which give them a high propensity for resistance to classical anti-cancer treatments and the ability to repopulate the tumour mass. An attribute that may be implicated in the high rates of recurrence of certain tumours. However, other characteristics specific to these cells, such as their high dependence on mitochondria, may be exploited for the development of new therapeutic agents that are effective against the niche. As such, a previously described phosphorescent N-heterocyclic carbene iridium(III) compound which showed a high level of cytotoxicity against classical tumour cell lines with mitochondria-specific effects was studied for its potential against CSCs. The results showed a significantly higher level of activity against several CSC lines compared to non-CSCs. Mitochondrial localisation and superoxide production were confirmed. Although the cell death involved caspase activation, their role in cell death was not definitive, with a potential implication of other, non-apoptotic pathways shown. A cytostatic effect of the compound was also displayed at low mortality doses. This study thus provides important insights into the mechanisms and the potential for this class of molecule in the domain of anti-CSC therapeutics.

Metal complex-based liposomes: Applications and prospects in cancer diagnostics and therapeutics

Metal complexes are of increasing interest as pharmaceutical agents in cancer diagnostics and therapeutics, while some of them suffer from issues such as limited water solubility and severe systemic toxicity. These drawbacks severely hampered their efficacy and clinical applications. Liposomes hold promise as delivery vehicles for constructing metal complex-based liposomes to maximize the therapeutic efficacy and minimize the side effects of metal complexes. This review provides an overview on the latest advances of metal complex-based liposomal delivery systems. First, the development of metal complex-mediated liposomal encapsulation is briefly introduced. Next, applications of metal complex-based liposomes in a variety of fields are overviewed, where drug delivery, cancer imaging (single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI)), and cancer therapy (chemotherapy, phototherapy, and radiotherapy) were involved. Moreover, the potential toxicity, action of toxic mechanisms, immunological effects of metal complexes as well as the advantages of metal complex-liposomes in this content are also discussed. In the end, the future expectations and challenges of metal complex-based liposomes in clinical cancer therapy are tentatively proposed.

Induction of apoptosis in SGC-7901 cells by iridium(III) complexes via endoplasmic reticulum stress-mitochondrial dysfunction pathway

This study was intended to evaluate the anticancer activity of three newly synthesized iridium(III) complexes [Ir(ppy)₂(PEIP)](PF₆) (1) (ppy = 2-phenylpyridine, PEIP = 2-phenethyl-1H-imidazo[4,5-f][1,10]phenanthroline), [Ir(ppy)₂(SIP)](PF₆) (2) (SIP = (E)-2-styryl-1H-imidazo[4,5-f][1,10]phenanthroline) and [Ir(ppy)₂(PEYIP)](PF₆) (3) (PEYIP = 2-phenethynyl-1H-imidazo[4,5-f][1,10]phenanthroline). The cytotoxic activity in vitro against A549, SGC-7901, HepG2, HeLa and normal NIH3T3 cells was investigated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. We found that the complexes 1, 2 and 3 significantly inhibited cell proliferation, in particular, complexes 2 and 3 show high cytotoxic effect on SGC-7901 cells with an IC₅₀ value of 5.8 ± 0.7 and 4.4 ± 0.1 μM. Moreover, cell cycle assay revealed that the complexes could block G2/M phase of the cell cycle. Apoptotic evaluation by Annexin V/PI staining indicated that complexes 1-3 can induce apoptosis in SGC-7901 cells. In addition, microscopy detection suggested that disruption of mitochondrial functions, characterized by increased generation of intracellular ROS and Ca²⁺ as well as decrease of mitochondrial membrane potential. Western blot analysis shows that the complexes upregulate the expression of pro-apoptotic Bax and downregulate the expression of anti-apoptotic Bcl-2, which further activates caspase-3 and prompts the cleavage of PARP. Taken together, these results demonstrated that complexes 1-3 exert a potent anticancer effect on SGC-7901 cells via ROS-mediated endoplasmic reticulum stress-mitochondrial apoptotic pathway and have a potential to be developed as novel chemotherapeutic agents for human gastric cancer. Three new iridium(III) complexes [Ir(ppy)₂(PEIP)](PF₆) (1) (ppy = 2-phenylpyridine, PEIP = 2-phenethyl-1H-imidazo[4,5-f][1,10]phenanthroline), [Ir(ppy)₂(SIP)](PF₆) (2) (SIP = 2-styryl-1H-imidazo[4,5-f][1,10]phenanthroline) and [Ir(ppy)₂(PEYIP)](PF₆) (3) (PEYIP = 2-phenethynyl-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized. The anticancer activity in vitro was investigated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The results show that the complexes induce apoptosis via ROS-mediated endoplasmic reticulum stress-mitochondrial dysfunction pathway.

A Comprehensive Review on Novel Liposomal Methodologies, Commercial Formulations, Clinical Trials and Patents

Liposomes are well-recognized and essential nano-sized drug delivery systems. Liposomes are phospholipid vesicles comprised of cell membrane components and have been employed as artificial cell models to mimic structure and functions of cells and are of immense use in various biological analyses. Liposomes acquire great advantages and provide wide range of applications as useful drug carriers in pre-clinical and clinical trials. This review summarizes exclusively on scalable techniques for liposome preparation and focuses on the strengths and limitations with respect to industrial applicability. Also, this review discusses the updated recent advancements in biomedical applications with a mention of key highlights of commercially available formulations, clinical trials and patents in recent past. Furthermore, this review also provides brief information of the classification, composition and characterization of liposomes.

Iridium(III) complexes entrapped in liposomes trigger mitochondria-mediated apoptosis and GSDME-mediated pyroptosis

In this report, a new ligand TFBIP (TFBIP = 2-(4'-trifluoromethyl)-[1,1'-biphenyl]-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its three iridium (III) complexes [Ir(ppy)₂(TFBIP)](PF₆) (Ir1, ppy = 2-phenylpyridine), [Ir(bzq)₂(TFBIP)](PF₆) (Ir2, bzq = benzo[h]quinolone) and [Ir(piq)₂(TFBIP)](PF₆) (Ir3, piq = 1-phenylisoquinoline) were synthesized and characterized. The cytotoxicity in vitro of the complexes toward several cancer cells was evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) methods. The complexes show no cytotoxicity (IC₅₀ > 100 μM) against these cancer cells. To enhance anticancer activity, these complexes were trapped in liposomes to form Ir1Lipo, Ir2Lipo and Ir3Lipo. The liposomes Ir1Lipo, Ir2Lipo and Ir3Lipo exhibit high or moderate cytotoxic activity. In particular, Ir1Lipo can effectively inhibit the cell growth with a low IC₅₀ value (< 10 μM) toward A549, HepG2, BEL-7402, B16, HeLa and SGC-7901 cells. Surprisingly, Ir1Lipo has no cytotoxic activity against the normal cell LO2 (IC₅₀ > 100 μM). The apoptosis and pyroptosis were investigated. Ir3Lipo induces apoptosis with a high early apoptotic number of 37%. The reactive oxygen species (ROS) levels, mitochondrial permeability transition pore open and mitochondrial membrane potential were detected. The intracellular Ca²⁺ concentration and release of cytochrome c were investigated. The expression of Bcl-2 (B-cell lymphoma-2) family proteins was explored by western blot. The antitumor activity in vivo of Ir1Lipo was evaluated with an inhibitory rate of 53%.

Increasing anticancer effect in vitro and vivo of liposome-encapsulated iridium(III) complexes on BEL-7402 cells

The studies of iridium (III) complexes as potent anticancer reagents have attracted great attention. Here, a new iridium (III) complex [Ir(bzq)₂(PYIP)](PF₆) (Ir1, bzq = benzo[h]quinoline, PYIP = 2-(pyren-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) was synthesized and its liposomes (Ir1Lipo) was prepared. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method was used to detect the cytotoxic activity of Ir1 and Ir1Lipo on HepG2, SGC-7901, BEL-7402, HeLa, B16, A549 and normal NIH3T3 cells. The complex Ir1 displays no obvious inhibitory effect on the growth of BEL-7402 cells, while the Ir1Lipo shows significant cytotoxic activity on BEL-7402 cells (IC₅₀ = 2.6 ± 0.03 μM). In further studies, Ir1Lipo induced apoptosis by the mitochondrial pathways, such as increasing intracellular reactive oxygen species (ROS) content and intracellular Ca²⁺ level, decreasing the mitochondrial membrane potential (MMP). In addition, after incubation with Ir1Lipo, the colony formation of BEL-7402 cells was significantly inhibited. Moreover, flow cytometry was used to detect the impact of Ir1Lipo on cell cycle distribution, and western blot was used to detect the expression of caspases and Bcl-2 (B-cell lymphoma-2) family proteins. Furthermore, Ir1Lipo exhibited significant antitumor activity in vivo with an inhibitory rate of 65.8%. These results indicated that Ir1Lipo induces apoptosis in BEL-7402 cells through intrinsic mitochondrial pathway.

Iridium(III)-BBIP complexes induce apoptosis via PI3K/AKT/mTOR pathway and inhibit A549 lung tumor growth in vivo

The new ligand BBIP (BBIP = 2-(7-bromo-2H-benzo[d]imidazole-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) with its iridium(III) complexes: [Ir(ppy)2(BBIP)](PF6) (ppy = 2-phenylpyridine, Ir1), [Ir(bzq)2(BBIP)](PF6) (bzq = benzo[h]quinolone, Ir2) and [Ir(piq)2(BBIP)](PF6) (piq = 1-phenylisoquinoline, Ir3) were synthesized and characterized by elemental analysis, High Resolution Mass Spectrometer (HRMS), 1H NMR and 13C{1H} NMR. The cytotoxicity of the complexes against A549, HepG2, SGC-7901, BEL-7402, HeLa and normal LO2 was evaluated through 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. The results show that Ir1 exhibits high cytotoxic activity against A549 cells with a low IC50 value of 4.9 ± 0.5 μM. A series of biological activities such as cell cycle arrest, endoplasmic reticulum localization assay, apoptosis, western blotting, cellular uptake determination and in vivo antitumor activity were investigated. The assays implied that the complexes inhibit cancer cell migration through blocking mitotic progress. Cell cycle distribution stated that the complexes depress cell growth at G0/G1 phase. Additionally, the complexes acted on the endoplasmic reticulum and induce apoptosis through endoplasmic reticulum stress pathway. Especially, the western blotting showed that the complexes activated Bcl-2 (B-cell lymphoma-2) family and decreased PI3K (phosphoinositide-3 kinase) and AKT (protein kinase B), up-regulated the expression of mTOR (mammalian target of rapamycin) and p-mTOR (phosphorylated mammalian target of rapamycin). Therefore, the complexes induce apoptosis through activating PI3K-AKT-mTOR pathway. Antitumor in vivo demonstrated that Ir1 can effectively prevent the tumor growth with an inhibitory rate of 48.89%.

Antitumor activity studies of iridium (III) polypyridine complexes-loaded liposomes against gastric tumor cell in vitro

Two iridium (III) polypyridine complexes [Ir(ppy)₂(BIP)]PF₆ (ppy = 2-phenylpyridine, BIP = 2-biphenyl-1H-imidazo[4,5-f][1,10]phenanthroline, Ir1), [Ir(piq)₂(BIP)]PF₆ (piq = 1-phenylisoquinoline, Ir2) and their liposomes Ir1lipo and Ir2lipo were synthesized and characterized. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cytotoxic activity against several cancer cells (A549, HepG2, SGC-7901, Bel-7402, HeLa) and non-cancer cell (mouse embryonic fibroblast, NIH3T3). The results showed that Ir1lipo displays the high cytotoxicity toward SGC-7901 with IC₅₀ value of 5.8 ± 0.2 μM, while the complexes have no cytotoxicity toward A549, HepG2, Bel-7402 and HeLa cells. The cell colony demonstrated that the iridium (III) complexes-loaded liposomes can inhibit cell proliferation, induce cell cycle arrest at G0/G1 phase. Moreover, they also cause autophagy, induce a decrease of mitochondrial membrane potential and increase intracellular reactive oxygen species (ROS) content. These results suggest that the complexes encapsulated liposomes Ir1lipo and Ir2lipo inhibit the growth of SGC-7901 cells through a ROS-mediated mitochondrial dysfunction and activating the PI3K (phosphoinositide-3 kinase)/ AKT (protein kinase B) signaling pathways.

Synthesis and evaluation of iridium(III) complexes on antineoplastic activity against human gastric carcinoma SGC-7901 cells

The study was intended to determine the antineoplastic effects of two new iridium(III) complexes [Ir(ppy)₂(PTTP)](PF₆) (1) (ppy = 2-phenylpyridine) and [Ir(piq)₂(PTTP)](PF₆) (2) (piq = 1-phenylisoquinoline, PTTP = 2-phenoxy-1,4,8,9-tetraazatriphenylene). In MTT assay, the ligand PTTP displayed ineffective inhibition on cell growth in SGC-7901, BEL-7402, HepG2 as well as NIH3T3 cell lines, while complexes 1 and 2 showed high cytotoxic activity on SGC-7901 cells with an IC₅₀ value of 0.5 ± 0.1 µM and 4.4 ± 0.6 µM, respectively. Cellular uptake, cell cloning experiments, wound healing assay and cell cycle arrest indicated that the two complexes can inhibit the cell proliferation in SGC-7901 and induce cell cycle arrest at G0/G1 phase. Additionally, reactive oxygen species (ROS) and mitochondrial membrane potential suggested that the two complexes induced cell apoptosis through disrupting mitochondrial functions. Further, western blot analysis illustrated that the two complexes caused apoptosis via regulating expression levels of Bcl-2 family proteins. Moreover, complex 1 could suppress tumor growth in vivo with an inhibitory rate of 49.41%. Altogether, these results demonstrated that complexes 1 and 2 exert a potent anticancer effect against SGC-7901 cells via mitochondrial apoptotic pathway and have a potential to be developed as antineoplastic drug candidates for human gastric cancer.

Ru(ii), Ir(iii), Re(i) and Rh(iii) based complexes as next generation anticancer metallopharmaceuticals

Several anticancer drugs such as cisplatin, and its analogues, epirubicin, and doxorubicin are well known for their anticancer activity but the therapeutic value of these drugs comes with certain side effects and they cannot distinguish between normal and cancer cells. Thus, a major challenge for researchers around the world is to develop an anticancer drug with the least toxicity and more target specificity. With the successful reporting of NAMI-A and KP1019, a new path has emerged in the anticancer field. Recently, several Ru(ii) complexes have been reported for their anticancer activity due to their enhanced cellular uptake and selectivity towards cancer cells. Apart from the Ru(ii) complexes, a large amount of research has been carried out with Ir(iii), Re(i), and Rh(iii) based complexes, which exhibited promising anticancer activity. The present review reports various Ru(ii), Ir(iii), Re(i), and Rh(iii) based complexes for their anticancer activity based on their cytotoxicity profiles, biological targets and mechanism of action.

Anticancer effect evaluation in vitro and in vivo of iridium(III) polypyridyl complexes targeting DNA and mitochondria

To investigate the antitumor effect of iridium complexes, three iridium (III) complexes [Ir(ppy)₂(dcdppz)]PF₆ (ppy = 2-phenylpyridine, dcdppz = 11,12-dichlorodipyrido[3,2-a:2',3'-c]phenazine) (Ir1), [Ir(bzq)₂(dcdppz)]PF₆ (bzq = benzo[h]quinoline) (Ir2) and [Ir(piq)₂(dcdppz)]PF₆ (piq = 1-phenylisoquinoline) (Ir3) were synthesized and characterized. Geometry optimization, molecular dynamics simulation and docking studies have been performed to further explore the antitumor mechanism. The cytotoxicity of Ir1-3 toward cancer cells was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The localization of complexes Ir1-3 in the mitochondria, intracellular accumulation of reactive oxygen species (ROS) levels, the changes of mitochondrial membrane potential and morphological changes in apoptosis were investigated. Flow cytometry was applied to quantify fluorescence intensity and determine cell cycle distribution. Western blotting was used to detect the expression of apoptosis-related proteins. The anti-tumor effect of Ir1 in vivo was evaluated. The results showed that Ir1-3 had high cytotoxicity to most tumor cells, especially to SGC-7901 cells with a low IC₅₀ value. Ir1-3 can increase the intracellular ROS levels, reduce the mitochondrial membrane potential. Additionally, the complexes induce an increase of apoptosis-related protein expression, enhance the percentage of apoptosis. The complexes inhibit the cell proliferation at G0/G1 phase. The results obtained from antitumor in vivo indicate that Ir1 can significantly inhibit the growth of tumors with an inhibitory rate of 54.08%. The docking studies show that complexes Ir1-3 interact with DNA through minor-groove intercalation, which increases the distance of DNA base pairs, leading to a change of DNA helix structure. These experimental and theoretical findings indicate that complexes Ir1-3 can induce apoptosis in SGC-7901 cells through the mitochondrial dysfunction and DNA damage pathways, and then exerting anti-tumor activity in vitro and vivo.

Evaluation of anticancer effects in vitro of new iridium(III) complexes targeting the mitochondria

Iridium(III) complexes have the potential to serve as novel therapeutic drugs for treating tumor. In this work, three new complexes [Ir(ppy)₂(cdppz)](PF₆) (1) (ppy = 2-phenylpyridine, cdppz = 11-chlorodipyrido[3,2-a,2',3'-c]phenazine), [Ir(bzq)₂(cdppz)](PF₆) (2) (bzq = benzo[h]quinolone) and [Ir(piq)₂(cdppz)](PF₆) (3) (piq = 1-phenylisoquinoline) were prepared as well as characterized. MTT (3-(4,5-dimethylthiazole)-2,5-diphenyltetraazolium bromide) assay revealed that the complex 2 exerted potent cytotoxicity against to various cancer cells lines and particularly for SGC-7901 cells. Meanwhile, the complexes could suppress cell colonies formation and migration ability. Apoptosis assays of AO/EB staining as well as flow cytometry revealed that the synthesized complexes may cause apoptosis of SGC-7901 cells. Moreover, the decline of mitochondrial membrane potential (MMP), elevation of intracellular reactive oxygen species (ROS) levels and release of cytochrome c demonstrated the complexes could cause apoptosis mainly through the mitochondrial death pathway and arrest cell at G0/G1 phase. Additionally, the complexes have significant influence on the expression of proteins which is interrelated to cell apoptosis. In summary, our studies provided fundamental information regarding the further study of the possible anticancer mechanisms of iridium (III) complexes.

Evaluation of the Synthesized Novel Iridium (III) Complexes Against HeLa Cell Lines Through In-Silico, In-Vitro and DNA Nicking

Globally, the pharmaceutical industry is continuously driven in search of new anticancer drugs due to increasing rate of cancer patients. Clinical trials of Cisplatin has been explored, however, usage of Cisplatin as a drug is limited due to its various side effects, hence, alternative to platinum based complex drugs and its analogues are needed. Iridium complexes have been attracted widespread interests by virtue of their pharmacological and photo-physical properties; however the less number of complexes was reported in the literature. In this article, a new series of novel Iridium (III) complexes were synthesized using substituted quinoline Schiff Base (SB) ligands and characterized by spectroscopic techniques. The in- vitro cyto-toxicity assay showed that the Iridium (III) complex activity is equal to standard Cisplatin. In addition, computational docking studies have shown that the prominent binding sites for synthesized complexes against HeLa cell lines, which is comparable with standard Cisplatin drugs and other Ruthenium complexes.

Studies of anticancer activity in vivo and in vitro behaviors of liposomes encapsulated iridium(III) complex

Iridium(III) complexes have gained great attention in cancer treatment in recent years. In this paper, we designed and synthesized a new iridium(III) complex [Ir(piq)₂(DQTT)](PF₆) Ir1 (piq = 1-phenylisoquinoline, DQTT = 12-(1,4-dihydroquinoxalin-6-yl)-4,5,9,14-tetraazabenzo[b]triphenylene). The Ir1-loaded PEGylated liposomes (Lipo-Ir1) were prepared using the ethanol injection method. The anticancer activity of the complex and Lipo-Ir1 against SGC-7901 (human gastric adenocarcinoma), A549 (human lung carcinoma), HeLa (human cervical carcinoma), HepG2 (human hepatocellular carcinoma), BEL-7402 (human hepatocellular carcinoma), and normal NIH3T3 (mouse embryonic fibroblasts) was tested by the MTT method. The complex Ir1 shows moderate or low cytotoxicity against the selected cancer cells, whereas the Lipo-Ir1 exhibits high anticancer activity toward the same cancer cells. The apoptosis induced by Lipo-Ir1 was assayed by flow cytometry and Lipo-Ir1 induced apoptosis through increasing intracellular reactive-oxygen species levels, decreasing mitochondrial membrane potential, further promoting cytochrome c release and causing the increase of level of intracellular Ca²⁺. Western blot was used to detect the changes in Bcl-2 family protein and PI3K/AKT pathway proteins. The cloning experiments demonstrated that the Lipo-Ir1 can effectively inhibit cell proliferation. In vivo experiments, Lipo-Ir1 inhibited tumor growth in xenograft nude mice, and the percentage of tumor growth inhibition in vivo was 75.70%. Overall, the liposomes Lipo-Ir1 exhibits higher anticancer activity than Ir1 under the same conditions. These results indicated that Lipo-Ir1 may be a valuable resource for cancer therapy.

Three new cadmium(II) coordination compounds based on 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline: syntheses, structures and luminescence

Three cadmium(II) coordination compounds, [Cd(pyip)2(CH3COO)2] (1), [Cd(pyip)2(cis-OH)2]·H2O (2) and [Cd(pyip)2(trans-OH)2]·3H2O (3), based on 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (pyip) have been synthesized by a hydrothermal method and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1, 2 and 3 all appear as monomeric entities, which are further assembled into supramolecular networks by hydrogen bonding interactions. The Cd(II) centers in compounds 2 and 3 lie in distinct octahedral environments with the hydroxyl groups in cis- and trans-positions, respectively, leading to the generation of different structures . Photoluminescence studies of compounds 1–3 were also carried out.

Liposome as drug delivery system enhance anticancer activity of iridium (III) complex

Herein an Ir(III) complex [Ir(Hppy)₂(HMNPIP)](PF₆) (Ir1, Hppy = 2-phenylpyridine, HMNPIP = 2-(1H-imidazo[4,5-f][1, 10]phenanthroline-3-yl)-6-methoxy-4-nitrophenol) was prepared and characterized. Due to the low anticancer activity of Ir1 when administered free drug, we prepared a liposome Ir1Lipo encapsulated form of Ir1 to improve the antitumor effect, furthermore, we explored the antitumor mechanism of both forms in vitro experiments on HepG2 cells. We investigated the inhibitory efficiency of Ir1 and Ir1Lipo on cell viability and proliferation using MTT (MTT = 3-(4,5-dimethylthiazole)-2,5-diphenltetraazolium bromide) and colony-forming assay. Intracellular accumulation of reactive oxygen species (ROS) was examined using a fluorescence microscope (High Content Screening System, ImageXpress Micro XLS System, Molecular Devices LLC, Sunnyvale, CA), programmed cell death cells stained with acridine orange/ethidium bromide (AO/EB) using flow cytometry detection and western blot have been performed. An in vivo study where HepG2 cells were transplanted into nude nice as xenografts. Tumour volume and body weight were monitored during the 10 days of administration. After encapsulation in liposomes Ir1Lipo displayed high potency against a variety of tumour cells in vitro, especially against HepG2 (IC₅₀ = 4.6 ± 0.5 μM). Mechanism studies indicated that Ir1Lipo initiated apoptosis by generating intracellular ROS that regulate lysosomal-mitochondrial dysfunction, followed by microtubule disruption that subsequently leads to a G0/G1 phase of cell cycle arrest. Additionally, Ir1Lipo significantly curbed tumour growth in nude mice. The tumour inhibitory rate was 51.2% (5.6 mg/kg). Therefore, liposome as a drug delivery system greatly enhances anticancer activity of Ir1 by a factor of relatively minor side effects.