Tetranuclear Polypyridylruthenium(II) Complexes as Selective Nucleic Acid Stains for Flow Cytometric Analysis of Monocytic and Epithelial Lung Carcinoma Large Extracellular Vesicles.

Selective staining of extracellular vesicles (EVs) is a major challenge for diagnostic and therapeutic applications. Herein, the EV labeling properties of a new class of tetranuclear polypyridylruthenium(II) complexes, Rubb-TNL and Rubb-TL, as phosphorescent stains are described. These new stains have many advantages over standard stains to detect and characterize EVs, including: high specificity for EV staining versus cell staining; high phosphorescence yields; photostability; and a lack of leaching from EVs until incorporation with target cells.

Fluorescent, phosphorescent, magnetic resonance contrast and radioactive tracer labelling of extracellular vesicles.

This review focusses on the significance of fluorescent, phosphorescent labelling and tracking of extracellular vesicles (EVs) for unravelling their biology, pathophysiology, and potential diagnostic and therapeutic uses. Various labeling strategies, such as lipid membrane, surface protein, luminal, nucleic acid, radionuclide, quantum dot labels, and metal complex-based stains, are evaluated for visualizing and characterizing EVs. Direct labelling with fluorescent lipophilic dyes is simple but generally lacks specificity, while surface protein labelling offers selectivity but may affect EV-cell interactions.

Long-term stability and the physical and chemical factors predictive for antimicrobial activity in Australian honey.

The growing burden of expired medicines contributes to environmental contamination and landfill waste accumulation. Medicinal honey, with its non-toxic nature and potentially long shelf-life, represents a promising and underutilised therapeutic that avoids some of these issues. However, limited knowledge on how its antimicrobial properties change over time combined with a lack of reliable processes in the honey industry for measuring antimicrobial potential, hinder its clinical adoption.

Neutral rhenium(I) tricarbonyl complexes with sulfur-donor ligands: anti-proliferative activity and cellular localization.

Rhenium(I) tricarbonyl complexes are widely studied for their cell imaging properties and anti-cancer and anti-microbial activities, but the complexes with S-donor ligands remain relatively unexplored. A series of six -[Re(NN)(CO)(SR)] complexes, where (NN) is 2,2'-bipyridyl (bipy) or 1,10-phenanthroline (phen), and RSH is a series of thiocarboxylic acid methyl esters, have been synthesized and characterized. Cellular uptake and anti-proliferative activities of these complexes in human breast cancer cell lines (MDA-MB-231 and MCF-7) were generally lower than those of the previously described -[Re(NN)(CO)(OH)] complexes; however, one of the complexes, -[Re(CO)(phen)(SC(Ph)CHC(O)OMe)] (3b), was active (IC ∼ 10 μM at 72 h treatment) in thiol-depleted MDA-MB-231 cells.

Substitution Kinetics, Albumin and Transferrin Affinities, and Hypoxia All Affect the Biological Activities of Anticancer Vanadium(V) Complexes.

Limited stability of most transition-metal complexes in biological media has hampered their medicinal applications but also created a potential for novel cancer treatments, such as intratumoral injections of cytotoxic but short-lived anticancer drugs. Two related V(V) complexes, [VO(Hshed)(dtb)] () and [VO(Hshed)(cat)] (), where Hshed = -(salicylideneaminato)--(2-hydroxyethyl)-1,2-ethanediamine, Hdtb = 3,5-di--butylcatechol, and Hcat = 1,2-catechol, decomposed within minutes in cell culture medium at 310 K ( = 43 and 9 s for and , respectively). Despite this, both complexes showed high antiproliferative activities in triple-negative human breast cancer (MDA-MB-231) cells, but the mechanisms of their activities were radically different.

Anti-Migratory and Cytotoxic Activities of [Ga(8-hydroxyquinolinato) ]: Roles of Endogenous Cu(II) and Drug-Induced Phenotypic Changes.

As shown by IncuCyte Zoom imaging proliferation assays, invasive triple-negative human breast MDA-MB-231 cancer cells treated with sub-toxic doses (5.0-20 μM, 72 h) of [GaQ ] (Q=8-hydroxyquinolinato) caused profound morphological changes and inhibition of cell migration, which were likely due to terminal cell differentiation or similar phenotypical change. This is the first demonstration of potential use of a metal complex in differentiation anti-cancer therapy.

A tetranuclear polypyridylruthenium(II) complex as a selective stain for extracellular vesicle penetration through brain microvascular endothelium.

A new photoluminescent polypyridylruthenium(II) stain for extracellular vesicles (EVs) released from lipopolysaccharide-stimulated THP-1 monocytes enabled important new insights into how the bacteria-induced immune system affects the blood-brain barrier (BBB). These included previously unknown aspects of EV interactions with BBB microvascular endothelial cells and the extracellular matrix relevant to human brain diseases.

Synthesis and the photophysical and biological properties of tricarbonyl Re(I) diimine complexes bound to thiotetrazolato ligands.

Twelve Re(I) tricarbonyl diimine (2,2'-bipyridine and 1,10-phenanthroline) complexes with thiotetrazolato ligands have been synthesised and fully characterised. Structural characterisation revealed the capacity of the tetrazolato ligand to bind to the Re(I) centre through either the S atom or the N atom with crystallography revealing most complexes being bound to the N atom. However, an example where the Re(I) centre is linked the S atom has been identified.

Vanadium Chloro-Substituted Schiff Base Catecholate Complexes are Reducible, Lipophilic, Water Stable, and Have Anticancer Activities.

A hydrophobic Schiff base catecholate vanadium complex was recently discovered to have anticancer properties superior to cisplatin and suited for intratumoral administration. This [VO(HSHED)(DTB)] complex, where HSHED is -(salicylideneaminato)-'-(2-hydroxyethyl)-1,2-ethanediamine and the non-innocent catecholato ligand is di--butylcatecholato (DTB), has higher stability compared to simpler catecholato complexes. Three new chloro-substituted Schiff base complexes of vanadium(V) with substituted catecholates as co-ligands were synthesized for comparison with their non-chlorinated Schiff base vanadium complexes, and their properties were characterized.

Investigations of cellular copper metabolism in ovarian cancer cells using a ratiometric fluorescent copper dye.

Imbalances in metal homeostasis have been implicated in the progression and drug response of cancer cells. Understanding these changes will enable identification of new treatment regimes and precision medicine approaches to cancer treatment. In particular, there has been considerable interest in the interplay between copper homeostasis and response to platinum-based chemotherapeutic agents.

Tumour cell heterogeneity in triple-negative breast cancer cells affects response to cisplatin, but not doxorubicin.

Tumour cell heterogeneity affects cisplatin but not doxorubicin cytotoxicity in two phenotypes of the triple-negative breast cancer (TNBC) cell line, MDA-MB-231. A mesenchymal MDA-MB-231 phenotype was three times less sensitive to cisplatin than an epithelial-type phenotype from the same cell line, which has important implications in the success of TNBC chemotherapies.

Controversial Role of Transferrin in the Transport of Ruthenium Anticancer Drugs.

Ruthenium complexes are at the forefront of developments in metal-based anticancer drugs, but many questions remain open regarding their reactivity in biological media, including the role of transferrin (Tf) in their transport and cellular uptake. A well-known anticancer drug, KP1019 ((IndH)[RuCl(Ind)], where Ind = indazole) and a reference complex, [Ru(nta)] (nta = nitrilotriacetato(3-)) interacted differently with human apoTf, monoFeTf, or FeTf. These reactions were studied by biolayer interferometry (BLI) measurements of Ru-Fe-Tf binding to recombinant human transferrin receptor 1 (TfR1) in conjunction with UV-vis spectroscopy and particle size analysis.

Advantageous Reactivity of Unstable Metal Complexes: Potential Applications of Metal-Based Anticancer Drugs for Intratumoral Injections.

Injections of highly cytotoxic or immunomodulating drugs directly into the inoperable tumor is a procedure that is increasingly applied in the clinic and uses established Pt-based drugs. It is advantageous for less stable anticancer metal complexes that fail administration by the standard intravenous route. Such hydrophobic metal-containing complexes are rapidly taken up into cancer cells and cause cell death, while the release of their relatively non-toxic decomposition products into the blood has low systemic toxicity and, in some cases, may even be beneficial.

Urea Gel Electrophoresis in Studies of Conformational Changes of Transferrin on Binding and Transport of Non-Ferric Metal Ions.

Transferrin (Tf) is a crucial transporter protein for Fe(III), but its biological role in binding other metal ions and their delivery into cells remain highly controversial. The first systematic exploration of the effect of non-Fe(III) metal ion binding on Tf conformation has been performed by urea-polyacrylamide gel electrophoresis (urea-PAGE), which is commonly used for nucleic acids but rarely for proteins. Closed Tf conformation, similar to that caused by Fe(III)-Tf binding, was formed for In(III), V(III) or Cr(III) binding to Tf.

A Short-Lived but Highly Cytotoxic Vanadium(V) Complex as a Potential Drug Lead for Brain Cancer Treatment by Intratumoral Injections.

The chemistry and short lifetimes of metal-based anti-cancer drugs can be turned into an advantage for direct injections into tumors, which then allow the use of highly cytotoxic drugs. The release of their less toxic decomposition products into the blood will lead to decreased toxicity and can even have beneficial effects. We present a ternary V complex, 1 ([VOL L ], where L is N-(salicylideneaminato)-N'-(2-hydroxyethyl)ethane-1,2-diamine and L is 3,5-di-tert-butylcatechol), which enters cells intact to induce high cytotoxicity in a range of human cancer cells, including T98g (glioma multiforme), while its decomposition products in cell culture medium were ≈8-fold less toxic.

Vanadium(V/IV)-Transferrin Binding Disrupts the Transferrin Cycle and Reduces Vanadium Uptake and Antiproliferative Activity in Human Lung Cancer Cells.

The role of vanadium binding to transferrin (Tf) in the biological activities of vanadium-based drugs is a matter of considerable debate. In order to determine whether V(V) and/or V(IV) binding to Tf (in apo, monoferric(III), and diferric(III) forms) enhances or inhibits biological activities, cellular V uptake and in vitro antiproliferative activity were examined in the presence and absence of different forms of Tf and other biomolecules under normoxic conditions. These data were combined with studies on V-Tf binding in cell culture medium and its role in Tf interactions with transferrin receptor 1 (TfR1), using the biolayer interferometry (BLI) model of the Tf cycle that was developed in our group.

Ruthenium(II)-Arene Thiocarboxylates: Identification of a Stable Dimer Selectively Cytotoxic to Invasive Breast Cancer Cells.

Ru -arene complexes provide a versatile scaffold for novel anticancer drugs. Seven new Ru -arene-thiocarboxylato dimers were synthesized and characterized. Three of the complexes (2 a, b and 5) showed promising antiproliferative activities in MDA-MB-231 (human invasive breast cancer) cells, and were further tested in a panel of fifteen cancerous and noncancerous cell lines.

Vanadium(V) tris-3,5-di-tert-butylcatecholato complex: Links between speciation and anti-proliferative activity in human pancreatic cancer cells.

Vanadium complexes are intensively tested for anti-cancer activities, particularly for the novel treatment protocols involving injections of cytotoxic compounds directly into the tumor. This approach is increasingly applied to difficult-to-treat cancers, such as pancreatic cancer. The first study of in-vitro anti-cancer properties of a rare stable non-oxido V(V) complex, (NH)[V(dtbc)], where dtbcH is 3,5-di-tert-butylcatechol, was performed by a combination of end-point viability assays and real-time (IncuCyte) proliferation and cytotoxicity assays in human pancreatic cancer (PANC-1) cells.

Transferrin Cycle and Clinical Roles of Citrate and Ascorbate in Improved Iron Metabolism.

Fe(III) delivery from blood plasma to cells via the transferrin (Tf) cycle was studied intensively due to its crucial role in Fe homeostasis. Tf-cycle disruptions are linked to anemia, infections, immunodeficiency, and neurodegeneration. Biolayer interferometry (BLI) enabled direct kinetic and thermodynamic measurements for all Tf-cycle steps in a single in vitro experiment using Tf within blood serum or released into the medium by cultured liver cells.

Hydrophobicity may enhance membrane affinity and anti-cancer effects of Schiff base vanadium(v) catecholate complexes.

Anti-cancer activities of vanadium compounds have generated recent interest because of a combination of desirable properties for chemotherapy, i.e., strong cytotoxicities, anti-metastatic activities and relatively low systemic toxicities.

Reactivity and Transformation of Antimetastatic and Cytotoxic Rhodium(III)-Dimethyl Sulfoxide Complexes in Biological Fluids: An XAS Speciation Study.

Rhodium(III) anticancer drugs can exert preferential antimetastatic or cytotoxic activities, which are dependent on subtle structural changes. In order to delineate factors affecting the biotransformations and speciation, mer,cis-[RhCl( S-dmso)( O-dmso)] (A1) and mer,cis-[RhCl( S-dmso)(N-indazole)] (A2) have been studied by X-ray absorption spectroscopy (XAS). Interactions of these complexes with saline buffer, cell culture media, serum proteins (albumin and apo-transferrin), native and chemically degraded collagen gels, and A549 cells have been studied using linear combination fitting (LCF) and 3D scatter plots of XAS data.

Stabilities and Biological Activities of Vanadium Drugs: What is the Nature of the Active Species?

Diverse biological activities of vanadium(V) drugs mainly arise from their abilities to inhibit phosphatase enzymes and to alter cell signaling. Initial interest focused on anti-diabetic activities but has shifted to anti-cancer and anti-parasitic drugs. V-based anti-diabetics are pro-drugs that release active components (e.

High cytotoxicity of vanadium(IV) complexes with 1,10-phenanthroline and related ligands is due to decomposition in cell culture medium.

Cytotoxic effects of Metvan (cis-[VO(OSO)(Mephen)], where Mephen = 4,7-dimethyl-1,10-phenanthroline) and its analogues with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bpy) ligands in cultured human lung cancer (A549) cells have been re-investigated in conjunction with reactivity of the V(IV) complexes in neutral aerated aqueous solutions and in cell culture medium. All the V(IV) complexes underwent rapid oxidation to the corresponding V(V) species (cis-[V(O)L]), followed by release of free ligands (shown by electrospray mass spectrometry). Decomposition of V(IV) complexes in cell culture medium within minutes at 310 K was confirmed by UV-Vis and EPR spectroscopies.

Comparison of KP1019 and NAMI-A in tumour-mimetic environments.

NAMI-A and KP1019 are Ru(III)-based anti-metastatic and cytotoxic anti-cancer drugs, respectively, and have been proposed to be activated by reduction to Ru(II). The potential reduction of NAMI-A and KP1019 in the hypoxic environment of a tumour model of neuroblastoma was examined. Normoxic, hypoxic and necrotic tumour tissues were modelled by multicellular spheroids of SH-SY5Y human neuroblastoma cells of various diameters (50-800 μm).