📚 BiometalDB

Metallodrugs represent a combination of multifunctionalities that are present concomitantly and can act differently on diverse biotargets. Their efficacy is often related to the lipophilic features exhibited both by long carbo-chains and the phosphine ligands. Three Ru(II) complexes containing hydroxy stearic acids (HSAs) were successfully synthesized in order to evaluate possible synergistic effects between the known antitumor activity of HSA bio-ligands and the metal center. HSAs were reacted with [Ru(H)₂CO(PPh₃)₃] selectively affording O,O-carboxy bidentate complexes. The organometallic species were fully characterized spectroscopically using ESI-MS, IR, UV-Vis, and NMR techniques. The structure of the compound Ru-12-HSA was also determined using single crystal X-ray diffraction. The biological potency of ruthenium complexes (Ru-7-HSA, Ru-9-HSA, and Ru-12-HSA) was studied on human primary cell lines (HT29, HeLa, and IGROV1). To obtain detailed information about anticancer properties, tests for cytotoxicity, cell proliferation, and DNA damage were performed. The results demonstrate that the new ruthenium complexes, Ru-7-HSA and Ru-9-HSA, possess biological activity. Furthermore, we observed that the Ru-9-HSA complex shows increased antitumor activity on colon cancer cells, HT29. Show less

A novel ligand BOPIP (BOPIP = {2-(4-(benzyloxy)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline}) and its mononuclear Ru(II) polypyridyl complexes [Ru(phen)₂ BOPIP]²⁺(1) (phen = 1,10-Phenanthrolene), [Ru(bpy)₂ BOPIP]²⁺(2) (bpy = 2,2' bipyridyl), [Ru(dmb)₂ BOPIP]²⁺(3) (dmb = 4, 4' -dimethyl 2, 2' -bipyridine), [Ru(Hdpa)₂ BOPIP]²⁺(4) (Hdpa = 2,2'dipyridylamine) have been synthesized successfully and characterized by elemental analysis, UV-vis, IR, ¹H, ¹³ C-NMR, and ESI-MS Spectroscopy. The interaction of these complexes with CT-DNA was studied using absorption, emission techniques, viscosity measurements and molecular docking studies. The docking study also supports the binding ability of complexes obtained through the absorption and emission techniques. These studies reveal that the Four Ru(II) polypyridyl complexes bind to DNA predominantly by intercalation. The Antimicrobial activity and cytotoxicity of these complexes are also reported. Show less

The binding properties of [Ru(bpy)(2)(H(2)IIP)](2+) (1) {bpy=2,2'-bipyridine, H(2)IIP=2-(indole-3-yl)-imidazolo[4,5-f][1,10]phenanthroline} with calf thymus DNA (CT-DNA) and yeast tRNA have been investigated comparatively by different spectroscopic and viscosity measurements. The results suggest that the affinity of complex 1 binding with yeast tRNA is stronger than that of complex 1 binding with CT-DNA, and complex 1 is a better enantioselective binder to yeast tRNA than to CT-DNA. The toxicity of complex 1 was concentration dependent, and HL-60 cells are more sensitive to complex 1 than Hep-G2 cells; complex 1 could induce Hep-G2 cell apoptosis. Show less

The reactions of [Ru(NO)Cl5](2-) with glycine (Gly), L-alanine (L-Ala), L-valine (L-Val), L-proline (L-Pro), D-proline (D-Pro), L-serine (L-Ser), L-threonine (L-Thr), and L-tyrosine (L-Tyr) in n-butanol or n-propanol afforded eight new complexes (1-8) of the general formula [RuCl3(AA-H)(NO)](-), where AA = Gly, L-Ala, L-Val, L-Pro, D-Pro, L-Ser, L-Thr, and L-Tyr, respectively. The compounds were characterized by elemental analysis, electrospray ionization mass spectrometry (ESI-MS), (1)H NMR, UV-visible and ATR IR spectroscopy, cyclic voltammetry, and X-ray crystallography. X-ray crystallography studies have revealed that in all cases the same isomer type (from three theoretically possible) was isolated, namely mer(Cl),trans(NO,O)-[RuCl3(AA-H)(NO)], as was also recently reported for osmium analogues with Gly, L-Pro, and D-Pro (see Z. Anorg. Allg. Chem. 2013, 639, 1590-1597). Compounds 1, 4, 5, and 8 were investigated by ESI-MS with regard to their stability in aqueous solution and reactivity toward sodium ascorbate. In addition, cell culture experiments in three human cancer cell lines, namely, A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon carcinoma), were performed, and the results are discussed in conjunction with the lipophilicity of compounds. Show less

Two new Ru(II) complexes, mononuclear [RuCl₂(η⁶-p-cymene)(3,4-dmph-κN)] (1) and the binuclear complex [{RuCl(η⁶-p-cymene)}₂(μ-Cl)(μ-3,4-dmph-κ²N,N')]Cl (2; 3,4-dmph = 3,4-dimethylphenylhydrazine), are synthesized and experimentally and theoretically structurally characterized utilizing ¹H and ¹³C NMR and FTIR spectroscopy, as well as DFT calculations. Degradation product of 2, thus ([{RuCl(η⁶-p-cymene)}₂(μ-Cl)(μ-3,4-dmph-κ²N,N')][RuCl₃(η⁶-p-cymene)] (2b) was characterized with SC-XRD. In the crystals of 2b, the cationic and anionic parts interact through N-H^...Cl hydrogen bridges. The spectrofluorimetric measurements proved the spontaneity of the binding processes of both complexes and HSA. Spin probing EPR measurements implied that 1 and 2 decreased the amount of bound 16-doxylstearate and implicated their potential to bind to HSA more strongly than the spin probe. The cytotoxicity assessment of both complexes against the MDA-MB-231 and MIA PaCa-2 cancer cell lines demonstrated a clear dose-dependent decrease in cell viability and no effect on healthy HS-5 cells. Determination of the malondialdehyde and protein carbonyl concentrations indicated that new complexes could offer protective antioxidant benefits in specific cancer contexts. Gel electrophoresis measurements showed the reduction in MMP9 activity and indicated the potential of 1 in limiting the cancer cells' invasion. The annexin V/PI apoptotic assay results showed that 1 and 2 exhibit different selectivity towards MIA PaCa-2 and MDA-MB-231 cancer cells. A comparative molecular docking analysis of protein binding, specifically targeting acetylcholinesterase (ACHE), matrix metalloproteinase-9 (MMP-9), and human serum albumin (HSA), demonstrated distinct binding interactions for each complex. Show less

A series of mono and bimetallic ruthenium(II) arene complexes bearing diamine (Ru_1-6) were prepared and fully characterized by ¹H, ¹³C, ¹⁹F, and ³¹P NMR spectroscopy and elemental analysis. The crystal structure of the bimetallic complex (Ru₅) was determined by X-ray crystallography. Monometallic analogues (Ru_1-3) were synthesized to investigate the contributions of ruthenium and the other organic groups (aren, ethylenediamine, butyl) to the activity. The electrochemical behaviors of mono and bimetallic complexes were obtained from the relationship between cyclic voltammetry (CV) and the biological activities of the compounds. The cytotoxic activities of the complexes (Ru_1-6) were tested against wide-scale cancer cell lines, namely HeLa, MDA-MB-231, DU-145, LNCaP, Hep-G2, Saos-2, PC-3, and MCF-7, and normal cell lines 3T3-L1 and Vero. Diamine Ru(II) arene complexes have unique biological characteristics and they are promising models for new anticancer drug development. MTT analysis reveals that each synthesized Ru complex showed cytotoxic activity towards the different cancer cells. In particular, three Ru complexes (Ru₃, Ru₅ and Ru₆) showed less toxic effects on the cancer cells than the others. These novel Ru complexes affected both cancer and normal cell lines. As they had a toxic effect on the cells, the dosage applied should be tested before being used for in vivo applications. Cytotoxicity tests have shown that the bimetallic complex Ru₆ was effective on all cancer cells. The effect of bimetallic enhancement on cancer cell lines, the systematic variation of the intermetallic distance and the ligand donor properties of the mono and bimetallic complexes were explored based on the cytotoxic activity. The interaction with FS-DNA and the stability/aquation of the complexes (Ru₃ and Ru₆) were investigated with ¹H NMR spectroscopy. The binding modes between the complexes (Ru₃ and Ru₆) and DNA were investigated via UV-Vis spectroscopy. Show less

A Ru(ii) arene complex with a NO-releasing 4-nitrooxymethyl-pyridine ligand shows increased cytotoxicity against the non-small cell lung cancer cell line A549 as compared to either the free ligand or the unfunctionalized complex. EPR spin-trapping studies show that NO release is selective, being limited in phosphate buffered saline or human serum, but promoted by glutathione. Show less

We report on the synthesis of novel Ru(II) compounds (Ru-1 to Ru-8) bearing R-pdc, 4-Cl-pbinh ligands (where R=4-CF3, 4-F, 4-OH pdc=3-phenyl-5-(1H-pyrrol-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide, pbinh=phenoxybenzylidene isonicotinyl hydrazides) and their in vitro antitumor activity toward the cell lines murine leukemia L1210, human lymphocyte CEM, human epithelial cervical carcinoma HeLa, BEL-7402 and Molt4/C8. Some of the complexes exhibited more potent antiproliferative activity against cell lines than the standard drug cisplatin. Ruthenium complex Ru-2 displayed potent cytotoxicity with than that of cisplatin. DNA-binding, DNA cleavage and protein binding properties of ruthenium complexes with these ligands are reported. Interactions of these ruthenium complexes with DNA revealed an intercalative mode of binding between them. Synchronous fluorescence spectra proved that the interaction of ruthenium complexes with bovine serum albumin (BSA) resulted in a conformational change of the latter. Show less

Thirteen new ruthenium amino acid complexes were synthesized and characterized. They were obtained by the reaction of α-amino acids (AA) with [RuCl₂(P-P)(N-N)], where P-P=1,4-bis(diphenylphosphino)butane (dppb) or 1,3-bis(diphenylphosphino)propane (dppp) and N-N=4,4'-dimethyl-2,2'-bipyridine (4'-Mebipy), 5,5'-dimethyl-2,2'-bipyridine (5'-Mebipy) or 4,4'-Methoxy-2-2'-bipyridine (4'-MeObipy). This afforded a family of complexes formulated as [Ru(AA-H)(P-P)(N-N)]PF₆, where AA=glycine (Gly), L-alanine (Ala), L-valine (Val), L-tyrosine (Tyr), L-tryptophan (Trp), L-histidine (His) and L-methionine (Met). All compounds were characterized by elemental analysis, spectroscopic and electrochemical techniques. The [Ru(AA-H)(P-P)(N-N)]PF₆ complexes are octahedral (the AA-H ligand binding involves N-amine and O-carboxylate), diamagnetic (low-spin d⁶, S=0) and present bands due to electronic transitions in the visible region. ¹H, ¹³C{¹H} and ³¹P{¹H} NMR spectra of the complexes indicate the presence of C₂ symmetry, and the identification of diastereoisomers. In vitro cytotoxicity assays of the compounds and cisplatin were carried out using MDA-MB-231 (human breast) tumor cell line and a non-tumor breast cell line (MCF-10A). Most complexes present promising results with IC₅₀ values comparable with the reference drug cisplatin and high selectivity indexes were found for the complexes containing L-Trp. The binding of two Ru-precursors of the type [RuCl₂(dppb)(NN)] (N-N=4'-MeObipy or 4'-Mebipy) to the blood transporter protein human serum albumin (HSA) was evaluated by fluorescence and circular dichroism spectroscopy. Both complexes bind HSA, probably in the hydrophobic pocket near Trp214, and the Ru-complex containing 4'-MeObipy shows higher affinity for HSA than the 4'-Mebipy one. Show less

The new ruthenium (III) complex has been synthesized and characterized by elemental analysis, FT-IR, UV-Vis, EI-Mass, EPR spectroscopy, and magnetic susceptibility measurement. Cytotoxic effects of organoruthenium (II/III) complexes 1a, 1b, and 2a, and their ligands (TSC¹ and TSC²) in cultured human ovarian (A2780, SKOV-3, and OVCAR-3) and colon (DLD, CCD18Co, and Caco-2) cells have been investigated comparing reactivity of the Ru (II/III) complexes and their free TSC ligands. The complexes exhibit higher cytotoxicity in three cancer cell lines than in normal cells. The binding with CT-DNA and BSA of the all complexes were weak compared with their ligand in spite of the cellular uptake of these complexes into the cytoplasm and then nucleus while their cytotoxic effects were vice versa. All the results showed that Complex 1b has more efficient cytotoxicity on the colon cancer cells than ovarian cancer cells. However, Complex 2a is a better drug candidate especially for antitumor therapy of metastasized ovarian cancer. Show less

Two new Ru(II) complexes, [Ru(Htip)3]Cl2 (1) and [Ru(Htip)2(dppz)]Cl2 (2), were synthesised and were characterised. The ground- and excited-state acid-base properties of 1 and 2 were studied and demonstrated that 1 acted as a pH-induced "on-off-on" luminescence switch. The binding behaviours of 1 and 2 to calf thymus DNA were studied with absorption and emission spectroscopy, DNA viscosities and density functional theory calculations. 2 was found to act as a DNA molecular light switch and as an efficient photocleaver of pUC 18 DNA. The cytotoxicities of the complexes were evaluated with the MTT method and it was found that 1 displayed apparent anticancer activity against MCF-7 cell, whereas 2 exhibited more potent and wider-spectrum antitumor activities against all cancer cell lines tested. Show less

We introduce ruthenosomes, a fusion of liposomal and reactive oxygen species (ROS)-generating properties meticulously engineered as potent ferroptosis inducers (FINs), marking a significant advancement in metallodrug design for cancer therapy. Formed through the self-assembly of oleate-conjugated ruthenium complexes, these ruthenosomes exhibit exceptional cellular uptake, selectively accumulating in mitochondria and causing substantial disruption. This targeted mitochondrial damage significantly elevates ROS levels, triggering autophagy and selectively activating ferritinophagy. Together, these processes sensitize cancer cells to ferroptosis. In vivo, ruthenosomes effectively suppress colorectal tumor growth, underscoring their therapeutic potential. Our study pioneers a design strategy that transforms ruthenium complexes into liposome-like structures capable of inducing ferroptosis independent of light activation. By leveraging ruthenosomes as multifunctional nanocarriers, this research offers a versatile and powerful platform for ROS-mediated, ferroptosis-driven cancer cell eradication. Show less

Title: Modulating Excited State Properties and Ligand Ejection Kinetics in Ruthenium Polypyridyl Complexes Designed to Mimic Photochemotherapeutics. Abstract: Ruthenium(II) polypyridyl complexes have gained significant interest as photochemotherapeutics (PCTs) due to their synthetic viability, strong light absorption, well understood excited state properties, and high phototoxicity indexes. Herein, we report the synthesis, characterization, electrochemical, spectrochemical, and preliminary cytotoxicity analyses of three series of ruthenium(II) polypyridyl complexes designed to mimic PCTs. The three series have the general structure of [Ru(bpy)2(N-N)]2+ (Series 1), [Ru(bpy)(dmb)(N-N)]2+ (Series 2), and [Ru(dmb)2(N-N)]2+ (Series 3, where N-N is a bidentate polypyridyl ligand, bpy = 2,2'-bipyridine, and dmb = 6,6'-dimethyl-2,2'-bipyridine). In the three series, the N-N ligand was systematically modified to incorporate increased conjugation and/or electronegative heteroatoms to increase dπ-π* backbonding, red-shifting the lowest energy metal-to-ligand charge transfer (MLCT) absorptions from λmax = 454 to λmax = 580 nm, nearing the therapeutic window for PCTs (600-1100 nm). In addition, steric bulk was systematically introduced through the series, distorting the Ru(II) octahedra, making the dissociative 3dd* state thermally accessible at room and body temperatures. This resulted in a 4 orders of magnitude increase in photoinduced ligand ejection kinetics, and demonstrates the ability to modulate both the MLCT* and dd* manifolds in the complexes, which is critical in PCT drug design. Preliminary cell viability assays suggest that the increased steric bulk to lower the 3dd* states may interfere with the cytotoxicity mechanism, limiting photoinitiated toxicity of the complexes. This work demonstrates the importance of understanding both the MLCT* and dd* manifolds and how they impact the ability of a complex to act as a PCT agent. Show less

Light-activated treatments, such as photodynamic therapy (PDT), provide temporal and spatial control over a specific cytotoxic response by exploiting toxicity differences between irradiated and dark conditions. In this work, a novel strategy for developing near infrared (NIR)-activatable Ru(II) polypyridyl-based photosensitizers (PSs) was successfully developed through the incorporation of symmetric heptamethine cyanine dyes in the metal complex via a phenanthrimidazole ligand. Owing to their strong absorption in the NIR region, the PSs could be efficiently photoactivated with highly penetrating NIR light (770 nm), leading to high photocytotoxicities towards several cancer cell lines under both normoxic and hypoxic conditions. Notably, our lead PS (Ru-Cyn-1), which accumulated in the mitochondria, exhibited a good photocytotoxic activity under challenging low-oxygen concentration (2 % O₂ ) upon NIR light irradiation conditions (770 nm), owing to a combination of type I and II PDT mechanisms. The fact that the PS Protoporphyrin IX (PpIX), the metabolite of the clinically approved 5-ALA PS, was found inactive under the same challenging conditions positions Ru-Cyn-1 complex as a promising PDT agent for the treatment of deep-seated hypoxic tumours. Show less

Photodynamic therapy (PDT) is a medical technique for the treatment of cancer. It is based on the use of non-toxic molecules, called photosensitizers (PSs), that become toxic when irradiated with light and produce reactive oxygen specious (ROS) such as singlet oxygen (¹O₂). This light-induced toxicity is rather selective since the physician only targets a specific area of the body, leading to minimal side effects. Yet, a strategy to improve further the selectivity of this medical technique is to confine the delivery of the PS to cancer cells only instead of spreading it randomly throughout the body prior to light irradiation. To address this problem, we present here novel sulfonamide-based monopodal and dipodal ruthenium and osmium polypyridyl complexes capable of targeting carbonic anhydrases (CAs) that are a major target in cancer therapy. CAs are overexpressed in the membrane or cytoplasm of various cancer cells. We therefore anticipated that the accumulation of our complexes in or outside the cell prior to irradiation would improve the selectivity of the PDT treatment. We show that our complexes have a high affinity for CAs, accumulate in cancer cells overexpressing CA cells and importantly kill cancer cells under both normoxic and hypoxic conditions upon irradiation at 540 nm. More importantly, Os(ii) compounds still exhibit some phototoxicity under 740 nm irradiation under normoxic conditions. To our knowledge, this is the first description of ruthenium/osmium-based PDT PSs that are CA inhibitors for the selective treatment of cancers. Show less

Title: A Ru(II) complex-based COX-2 targeting type I photosensitizer evokes ferroptosis and apoptosis. Abstract: Photodynamic therapy (PDT) often faces challenges such as oxygen dependence and limited tumour specificity. We report a tumour-targeting photosensitizer (PS), RuCXB, which enhances uptake by cancer cells by targeting overexpressed cyclooxygenase-2 enzyme in tumours. RuCXB also reduces oxygen dependence via a type I PDT mechanism and achieves a strong therapeutic effect through the synergistic induction of ferroptosis and apoptosis. This work presents a reliable strategy for developing potent PSs with enhanced PDT efficacy, tumour selectivity, and diminished oxygen dependence. Show less

Two novel strained ruthenium(II) polypyridyl complexes containing a 2,3-dihydro-1,4-dioxino[2,3-f]-1,10-phenanthroline (dop) ligand selectively ejected a methylated ligand when irradiated with >400 nm light. The best compound exhibited a 1880-fold increase in cytotoxicity in human cancer cells upon light-activation and was 19-fold more potent than the well-known chemotherapeutic, cisplatin. Show less

The combination of more than one bioactive moiety in a multitargeted anticancer agent may result in synergistic activity of its components. Using this concept, bioorganometallic compounds were designed to feature a metal center, a 2-pyridinecarbothioamide (PCA), and a hydroxamic acid, which is found in the anticancer drug vorinostat (SAHA). The organometallics showed inhibitory activity in the nanomolar range against histone deacetylases (HDACs) as the key target for SAHA. In particular, the Rh complex was a potent inhibitor of HDAC6 over HDAC1 and HDAC8. Whereas this complex was highly cytotoxic in human cancer cells, it showed low toxicity in hemolysis studies and zebrafish, demonstrating the role of the metal center. For this complex a slightly reduced expression of vascular endothelial growth factor receptor 2 (VEGFR2) was established, which was upregulated by SAHA. This finding indicates that the new organometallics display different modes of action than their bioactive components. Show less

The promise of the metal(arene) structure as an anticancer pharmacophore has prompted intensive exploration of this chemical space. While N-heterocyclic carbene (NHC) ligands are widely used in catalysis, they have only recently been considered in metal complexes for medicinal applications. Surprisingly, a comparatively small number of studies have been reported in which the NHC ligand was coordinated to the Ru^II(arene) pharmacophore and even less with an Os^II(arene) pharmacophore. Here, we present a systematic study in which we compared symmetrically substituted methyl and benzyl derivatives with the nonsymmetric methyl/benzyl analogues. Through variation of the metal center and the halido ligands, an in-depth study was conducted on ligand exchange properties of these complexes and their biomolecule binding, noting in particular the stability of the M-C_NHC bond. In addition, we demonstrated the ability of the complexes to inhibit the selenoenzyme thioredoxin reductase (TrxR), suggested as an important target for anticancer metal-NHC complexes, and their cytotoxicity in human tumor cells. It was found that the most potent TrxR inhibitor diiodido(1,3-dibenzylbenzimidazol-2-ylidene)(η⁶-p-cymene)ruthenium(II) 1b^I was also the most cytotoxic compound of the series, with the antiproliferative effects in general in the low to middle micromolar range. However, since there was no clear correlation between TrxR inhibition and antiproliferative potency across the compounds, TrxR inhibition is unlikely to be the main mode of action for the compound type and other target interactions must be considered in future. Show less

Two ruthenium(II) complexes [Ru(IP)2(PIP)](ClO4)2·2H2O (1) and [Ru(PIP)2(IP)](ClO4)2·2H2O (2) (IP=imidazole [4, 5-f] [1,10] phenanthroline, PIP=2-phenylimidazo-[4, 5-f][1,10] phenanthroline) have been synthesized and characterized. The quadruplex binding of the compounds was evaluated by emission spectrum, CD spectroscopy, Visual detection assay and FRET (fluorescence resonance energy transfer)-melting assay. The results show that both complexes can induce the stabilization of quadruplex DNA, while complex 1 is a better G-quadruplex binder than complex 2. Furthermore, polymerase chain reaction-stop assay, electrophoretic mobility shift assay, telomerase repeat amplification protocol and MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay demonstrate that complex 1 not only can stabilize dimer forms of the G-quadruplex at low concentrations but also exhibit better inhibitory activity for telomerase and cancer cells. Show less

Four new luminescent cyclometallated iridium(III) bis(quinolylbenzaldehyde) diimine complexes [Ir(qba)(2)(N⁁N)](PF(6)) (Hqba = 4-(2-quinolyl)benzaldehyde, N⁁N = 2,2'-bipyridine, bpy (1); 1,10-phenanthroline, phen (2); 3,4,7,8-tetramethyl-1,10-phenanthroline, Me(4)-phen (3); 4,7-diphenyl-1,10-phenanthroline, Ph(2)-phen (4)) have been synthesised and characterised, and their electronic absorption, emission and electrochemical properties investigated. The X-ray crystal structures of complexes 1 and 2 have been determined. Upon irradiation, complexes 1-4 exhibited intense and long-lived orange-yellow emission in fluid solutions at 298 K and in alcohol glass at 77 K. The emission has been assigned to a triplet intra-ligand ((3)IL) excited state associated with the qba ligand, probably with mixing of some triplet metal-to-ligand charge-transfer ((3)MLCT) (dπ(Ir) →π*(qba)) character. Reductive amination reactions of complexes 1-4 with the protein bovine serum albumin (BSA) afforded the bioconjugates 1-BSA-4-BSA, respectively. Upon photoexcitation, these bioconjugates displayed intense and long-lived (3)MLCT (dπ(Ir) →π*(N⁁C)) emission in aqueous buffer at 298 K. The cross-linked nature of the Ir-BSA bioconjugates has been verified by SDS-PAGE. Additionally, the cytotoxicity of the complexes towards human cervix epithelioid carcinoma (HeLa) cells has been examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays, and the cellular uptake of complex 4 has been investigated by laser-scanning confocal microscopy and flow cytometry. Show less

9-Anthracenecarboxylic acid (9-Ac) was reported early as a chloride channel inhibitor and was found to exhibit significant anti-proliferative activity on leukemic cells, but has not been researched in solid tumor cells. Herein, a 9-anthraceneic acid derivative was introduced into the cyclometalated Iridium (III) species to construct a novel Iridium (Ir) complex Ir-9-Ac, [Ir(ppy)₂(9-Ac-L)]PF₆ (ppy = 2-phenylpyridine, 9-Ac-L = N-((4'-methyl-[2,2'-bipyridin]-4-yl)methyl)anthracene-9-carboxamide), which could accumulated in lysosomes. Ir-9-Ac showed good cytotoxic activity against several tumor cell lines, notably on A549 cells. Besides Ir-9-Ac could inhibit the cell colony formation and growth of the 3D cell spheroids, demonstrating the potential to suppress tumors in vivo. This design provided a platform for the design of cyclometalated Iridium (III) anticancer complexes. Show less

Improvement of antineoplastic activity and selectivity is a main goal in the development of antineoplastic agents. Herein, we synthesized three new iridium (III) complexes: [Ir(ppy)₂(FTTP)](PF₆) (Ir1, ppy = 2-phenylpyridine, FTTP = 2-(3-fluoronaphthalen-2-yloxy)-1,4,8,9-tetraazatriphenylene), [Ir(bzq)₂(FTTP)](PF₆) (Ir2, bzq = benzo[h]quinolone), [Ir(piq)₂(FTTP)](PF₆) (Ir3, piq = 1-phenylisoquinoline). Ir1-3 exhibit excellent cytotoxicity against various cancer cells particularly towards human cervical carcinoma HeLa cells while remaining non-toxic to normal cell lines. Assays on 2D cell colony formation and 3D multicellular tumor spheroid model confirm that Ir1-3 can effectively inhibit the colony-forming and penetrate deeply into HeLa 3D multicellular tumor spheroid model exhibiting a notable cytotoxic effect, which was consistent with the results from the viability assays. Meanwhile, confocal microscopy shows a rapid uptake of Ir1-3 and co-localization experiments with subcellular markers reveal that Ir1-3 locate mainly at the mitochondria. Further investigation of the mechanism indicated the complexes Ir1-3 promote the excessive generation of ROS, inhibit glutathione and thioredoxin reductase that effectively interferes with the intracellular redox balance, induce oxidative stress and result in caspase-dependent apoptosis. Moreover, the ROS-mediated inactivation of the PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B)/mTOR (mammalian target of rapamycin) pathway, DNA damage combing with suppression of the cyclin D1/CDK4/6 activity arrested cell cycle in the G0/G1 phase are involved in complexes-induced cell apoptosis. Finally, assays on xenografted cervical carcinoma mouse model confirm the excellent biocompatibility and antineoplastic efficiency of Ir3 in vivo. Collectively, this work offers building blocks for developing iridium (III) complexes as clinical application potential. Show less

In this work, we report on the development of fluorescent half-sandwich iridium complexes using a fluorophore attachment strategy. These constructs consist of pentamethylcyclopentadienyl (Cp*) iridium units ligated by picolinamidate donors conjugated to green-emitting boron-dipyrromethene (bodipy) dyes. Reaction studies in H₂O/THF mixtures showed that the fluorescent Ir complexes were active as catalysts for transfer hydrogenation, with activities similar to that of their non-fluorescent counterparts. The iridium complexes were taken up by NIH-3T3 mouse fibroblast cells, with 50% inhibition concentrations ranging from ~20-70 μM after exposure for 3 h. Visualization of the bodipy-functionalized Ir complexes in cells using fluorescence microscopy revealed that they were localized in the mitochondria and lysosome but not the nucleus. These results indicate that our fluorescent iridium complexes could be useful for future biological studies requiring intracellular catalyst tracking. Show less

The synthesis and characterisation of iridium(III) bis(2-(2,4-difluorophenyl)pyridinato-N, C2')-2(4-carboxylphenyl)imidazo[4,5-f][1,10]phenanthroline perchlorate, [Ir(dfpp)(2)(picCOOH)](+) and its octaarginine conjugate [Ir(dfpp)(2)(picCONH-Arg(8))](9+) are reported. Both complex and conjugate exhibit intense and long-lived luminescence, which is O(2) and pH sensitive. Conjugation to the polyarginine peptide renders the complex very water soluble. The uptake of the parent iridium(III) complex and conjugate are compared in two mammalian cell lines; SP2 myeloma and Chinese hamster ovary (CHO). Both complexes internalise into the cytoplasm, however dye uptake rate and distribution vary with peptide conjugation and with cell identity. Whereas transmembrane transport is thought to have been facilitated by the dimethyl sulfoxide (DMSO) used as co-solvent (0.05% v/v) for the parent complex, the octaarginine, the dye-conjugate (iridium-R(8)) is membrane permeable in water only. Both complexes exhibit high cytotoxicity, evident through blebbing and vacuole formation within living cells, indicative of apoptosis, within 30min of exposure to the probe. The IC(50) recorded for the cells in the dark was independent, in the case of the parent complex, of the identity of the cell, with IC(50) of 84.8μM and 88μM respectively for SP2 and CHO cells. The IC(50) approximately doubled for the polyarginine conjugate and displayed a significant dependence on cell type with IC(50) of 35μM and 54.1μM respectively for SP2 and CHO cells. These IC(50) values were recorded in the dark. However under irradiation cell death is considerably faster. Evidence from imaging suggests that the conjugate penetrates the nucleus whereas the parent does not, indicating that nuclear penetration may play a role in cytotoxicity. Show less

Four neutral cyclometalated iridium(III) (Ir^III) dithioformic acid complexes ([(ppy)₂Ir(S^S)], Ir1-Ir4) were designed and synthesized. Toxicity assay revealed that these complexes showed favorable anticancer activity, especially for human non-small cell lung cancer cells (A549). Ir1 exhibited the best anticancer activity (11.0 ± 0.4 μM) was about twice that of cisplatin, meanwhile, which could availably restrain A549 cells migration. Complexes could target mitochondria, induce a decrease in mitochondrial membrane potential (MMP), result in an increase of intracellular reactive oxygen species (ROS) and disruption of the cell cycle, and ultimately generate apoptosis. Western blotting experiment indicated that complexes could inhibit the expression of B cell CLL/lymphoma-2 protein (Bcl-2), induce the expression of BCL2-associated X protein (Bax) and lead to a massive release of Cytochrome C (Cyt-c), which amplified apoptosis signals by activating downstream pathway to promote apoptosis. All these confirmed the existence of mitochondrial anticancer channels for these complexes. Above all, cyclometalated iridium(III) dithioformic acid complexes possess the prospect of becoming a multifunctional cancer therapeutic platform, including mitochondria-targeted imaging, anti-migration, and anticancer agents. Show less

In this paper, two new iridium(III) complexes [Ir(ppy)₂(CBIP)](PF₆) (ppy = 2-phenylpyridine, CBIP = 2-(4'-chloro-(1,1'-biphenyl))-1H-imidazo[4,5-f][1,10]phenanthroline) (Ir1) and [Ir(piq)₂(CBIP)](PF₆) (piq = 1-phenylisoquinoline) (Ir2) were synthesized and characterized. The anticancer activity of the complexes against cancer A549, HepG2, SGC-7901, BEL-7402, HeLa and LO2 cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Unexpectedly, the complexes exhibit no or low cytotoxic activity toward the selected cancer cells. To increase the anticancer activity, complexes Ir1 and Ir2 were encapsulated into the liposome to form Ir1lipo and Ir2lipo, while Ir1lipo and Ir2lipo show high cytotoxic efficacy against BEL-7402, SGC-7901 and HeLa cells and Ir2lipo displays moderate cytotoxic activity against A549 and HepG2. The anticancer mechanism was explored through wound healing, cell cycle arrest, apoptosis, the change of mitochondrial membrane potential and antitumor activity in vivo. The antitumor in vivo showed that Ir1Lipo (3.9 mg/kg) exhibited significant antitumor activity with an inhibitory rate of 62.16%. Additionally, the expression of B-cell lymphoma-2 family proteins was studies by western blotting analysis. The results demonstrate that Ir1lipo and Ir2lipo induce apoptosis in BEL-7402 cells via endoplasmic reticulum stress-mitochondrial pathway. Show less

Combining the ligand NPIP (2-(2-nitrophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) with piq (1-phenylisoquinoline) and bzq (benzo[h]quinolone) gave [Ir(piq)₂(NPIP)](PF₆) (Ir1), and [Ir(bzq)₂(NPIP)](PF₆) (Ir2). The newly synthesized complexes were characterized by high-resolution mass spectrometry (HRMS), ¹H NMR and ¹³C NMR. The complexes showed high antiproliferative activity against B16 cells. Three-dimensional (3D) cell model in vitro was used to evaluate the inhibitory effect of iridium (III) complex on B16 cells. The cellular uptake, mitochondrial localization, and intracellular distribution of the drugs confirmed that the iridium (III) complexes targeted the mitochondria, and the complexes can lead to the loss of mitochondrial membrane potential (MMP), increases the intracellular ROS content, further induces apoptosis. We also found that Ir1 and Ir2 can trigger the release of damage-associated molecular patterns (DAMPs) (cell surface calreticulin (CRT), heat-shock protein 70 (HSP70) and high mobility group box 1 (HMGB1)). In addition, Ir1 and Ir2 inhibited glutathione (GSH) synthesis and thus induced oxidative stress, Ir1 and Ir2 promoted malondialdehyde (MDA) production which is the stable metabolite of lipid peroxidation products. Finally, mice xenograft assay was performed to demonstrate that the complex shows higher antitumor activity in vivo than cisplatin. The inhibitory rates for cisplatin and Ir1 are 38.95% and 69.67%, respectively. Show less

Despite their outstanding properties as potential photosensitizers for photodynamic therapy (PDT), Ir(III) biscyclometalated complexes need both further developments to overcome remaining limitations and in-depth investigations into their mechanisms of action to reach clinic application in the treatment of cancer. This work describes the synthesis of a family of Ir(III) complexes of general formula [Ir(C^N)₂(N^N')]Cl (N^N' = thiabendazole-based ligands; C^N = ppy (2-phenylpyridinate) (Series A), or dfppy (2-(2,4-difluorophenyl)pyridinate) (Series B)) and their evaluation as potential PDT agents. These complexes are partially soluble in water and exhibit cytotoxic activity in the absence of light irradiation versus several cancer cell lines. Furthermore, the cytotoxic activity of derivatives of Series A is enhanced upon irradiation, particularly for complexes [1a]Cl and [3a]Cl, which show phototoxicity indexes (PI) above 20. Endocytosis was established as the uptake mechanism for [1a]Cl and [3a]Cl in prostate cancer cells by flow cytometry. These derivatives mainly accumulate in the mitochondria as shown by colocalization confocal microscopy experiments. Presumably, [1a]Cl and [3a]Cl induce death on cancer cells under irradiation through apoptosis triggered by a multimodal mechanism of action, which likely involves damage over mitochondrial DNA and mitochondrial membrane depolarization. Both processes seem to be the result of photocatalytic oxidation processes. Show less

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%. Show less