👤 Zhu H

Title: Rhodium(III)-Picolinamide Complexes Act as Anticancer and Antimetastasis Agents via Inducing Apoptosis and Autophagy. Abstract: As a continuation of our endeavors in discovering metal-based drugs with cytotoxic and antimetastatic activities, herein, we reported the syntheses of 11 new rhodium(III)-picolinamide complexes and the exploration of their potential anticancer activities. These Rh(III) complexes showed high antiproliferative activity against the tested cancer cell lines in vitro. The mechanism study indicated that Rh1 ([Rh(3a)(CH3CN)Cl2]) and Rh2 ([Rh(3b)(CH3CN)Cl2]) inhibited cell proliferation by multiple modes of action via cell cycle arrest, apoptosis, and autophagy and inhibited cell metastasis via FAK-regulated integrin β1-mediated suppression of EGFR expression. Furthermore, Rh1 and Rh2 significantly inhibited bladder cancer growth and breast cancer metastasis in a xenograft model. These rhodium(III) complexes could be developed as potential anticancer agents with antitumor growth and antimetastasis activity. Show less

The curative effect of sorafenib in hepatocellular carcinoma (HCC) is limited and sorafenib resistance remains a major obstacle for HCC. To overcome this obstacle, a new photoactive sorafenib-Ru(II) complex Ru-Sora has been designed. Upon irradiation (λ = 465 nm), Ru-Sora rapidly releases sorafenib and generates reactive oxygen species, which can oxidize intracellular substances such as GSH. Cellular experiments show that irradiated Ru-Sora is highly cytotoxic toward Hep-G2 cells, including sorafenib-resistant Hep-G2-SR cells. Compared to sorafenib, Ru-Sora has a significant photoactivated chemotherapeutic effect against Hep-G2-SR cancer cells and 3D Hep-G2 multicellular tumor spheroids. Furthermore, Ru-Sora inducing apoptosis and ferroptosis is proved by GSH depletion, GPX4 downregulation, and lipid peroxide accumulation. Metabolomics results suggest that Ru-Sora exerts photocytotoxicity by disrupting the purine metabolism, which is expected to inhibit tumor development. This study provides a promising strategy for enhancing chemotherapy and combating drug-resistant HCC disease. Show less

(1) Background: Ruthenium and osmium complexes attract increasing interest as next generation anticancer drugs. Focusing on structure-activity-relationships of this class of compounds, we report on 17 different ruthenium(II) complexes and four promising osmium(II) analogues with cinnamic acid derivatives as O,S bidentate ligands. The aim of this study was to determine the anticancer activity and the ability to evade platin resistance mechanisms for these compounds. (2) Methods: Structural characterizations and stability determinations have been carried out with standard techniques, including NMR spectroscopy and X-ray crystallography. All complexes and single ligands have been tested for cytotoxic activity on two ovarian cancer cell lines (A2780, SKOV3) and their cisplatin-resistant isogenic cell cultures, a lung carcinoma cell line (A549) as well as selected compounds on three non-cancerous cell cultures in vitro. FACS analyses and histone γH2AX staining were carried out for cell cycle distribution and cell death or DNA damage analyses, respectively. (3) Results: IC50 values show promising results, specifically a high cancer selective cytotoxicity and evasion of resistance mechanisms for Ru(II) and Os(II) compounds. Histone γH2AX foci and FACS experiments validated the high cytotoxicity but revealed diminished DNA damage-inducing activity and an absence of cell cycle disturbance thus pointing to another mode of action. (4) Conclusion: Ru(II) and Os(II) compounds with O,S-bidentate ligands show high cytotoxicity without strong effects on DNA damage and cell cycle, and this seems to be the basis to circumvent resistance mechanisms and for the high cancer cell specificity. Show less

In this article, ligand IPP (IPP = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline) and its three Ru(II) complexes: [Ru(bpy)₂(IPP)](ClO₄)₂ (1) (bpy = 2,2'-bipyridine), [Ru(dmbpy)₂(IPP)](ClO₄)₂ (2) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine), and [Ru(phen)₂(IPP)](ClO₄)₂ (3) (phen = 1,10-phenanthroline) were synthesized and characterized. The anticancer activity in vitro of the complexes was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The scratching and colony-forming experiments confirmed the complexes 1, 2, 3 interfered with the proliferation and migration ability of cells. The accumulation of the complexes in cells was researched and we found that these complexes directly accumulated in mitochondria, then the complexes cause a decline of the mitochondrial membrane potential and induce an increase of intracellular reactive oxygen species (ROS) levels. The growth of B16 cells were inhibited by 1, 2 and 3 at G0/G1 phase. Apoptosis was induced through mitochondrial pathway and the expression of apoptosis-related factors was regulated. In addition, the complexes promoted the transition of poly(ADP-ribose)polymerase (PARP) into the cleaved form (Cleaved PARP), downregulated the anti-apoptotic proteins, and upregulated the pro-apoptotic proteins. Consequently, complexes 1, 2 and 3 exerted their anticancer activity by regulating B-cell lymphoma-2 (Bcl-2) family proteins. Complex 2 showed excellent antitumor effects with a high inhibitory rate of 65.95% in vivo. Taken together, the complexes cause apoptosis in B16 cells through a ROS-mediated mitochondrial dysfunction pathway. Show less

To study the antitumor activity and action mechanism of Ru(II) polypyridyl plumbagin (PLN) complexes, four complexes [Ru(PLN)(DMSO)₂]Cl (Ru1), [Ru(bpy)₂(PLN)](PF₆) (bpy is bipyridine) (Ru2), [Ru(phen)₂(PLN)](PF₆) (phen is 1,10-phenanthroline) (Ru3), and [Ru(DIP)₂(PLN)](PF₆) (DIP is 4,7-diphenyl-1,10-phenanthroline) (Ru4) were obtained and fully characterized. Lipophilicity, cellular uptake and cytotoxicity of these Ru(II) complexes are in the order of: Ru1Show less

Novel bipyridine-based heterocyclic building block, 3,10-dichloro-benzo[f][1,10]phenanthroline and its Ruthenium(II) complex have been synthesized and fully characterized. The synthesized Ru(II)-complex is highly luminescent displaying emission at 590 nm with quantum yield of ∼0.8 in methanol. Ru(II) complex showed photocytotoxicity upon 400 nm blue light irradiation. Mechanistic study revealed that photoactivated Ru(II) complex generates reactive radical species which can damage the protein inside the cells and induce cell death even with short irradiation time. Show less

Title: Ursolic acid-piperazine-dithiocarbamate ruthenium(II) polypyridyl complexes induced necroptosis in MGC-803 cells. Abstract: Three ursolic acid-piperazine-dithiocarbamate ruthenium(II) polypyridyl complexes Ru1-Ru3 were designed and synthesized for evaluating antitumor activity. All the complexes exhibited high in vitro cytotoxicity against MGC-803, T24, HepG2, CNE2, MDA-MB-231, MCF-7, A549, and A549/DDP cell lines. Ru1, Ru2, and Ru3 were 11, 8 and 10 times, respectively, more active than cisplatin against A549/DDP. An in vivo study on MGC-803 xenograft mouse models demonstrated that representative Ru2 exhibited an effective inhibitory effect on tumor growth, showing stronger antitumor activity than cisplatin. Biological investigations suggested that Ru2 entered MGC-803 cells by a clathrin-mediated endocytic pathway, initially localizing in the lysosomes and subsequently escaping and localizing in the mitochondria. Mitochondrial swelling resulted in vacuolization, which induced vacuolation-associated cell death and necroptosis with the formation of necrosomes (RIP1-RIP3) and the uptake of propidium iodide. These results demonstrate that the potential of Ru2 as a chemotherapeutic agent to kill cancer cells via a dual mechanism represents an alternative way to eradicate apoptosis-resistant forms of cancer. Show less

The main purpose of this study was to synthesize a new set of naphthoquinone-based ruthenium(II) arene complexes and to develop an understanding of their mode of action. This study systematically reviews the steps of synthesis, aiming to provide a simplified approach using microwave irradiation. The chemical structures and the physicochemical properties of this novel group of compounds were examined by ¹H-NMR and ¹³C-NMR spectroscopy, X-ray diffractometry, HPLC-MS and supporting DFT calculations. Several aspects of the biological activity were investigated in vitro, including short- and long-term cytotoxicity tests, cellular accumulation studies, detection of reactive oxygen species generation, apoptosis induction and NAD(P)H:quinone oxidoreductase 1 (NQO1) activity as well as cell cycle analysis in A549, CH1/PA-1, and SW480 cancer cells. Furthermore, the DNA interaction ability was studied in a cell-free assay. A positive correlation was found between cytotoxicity, lipophilicity and cellular accumulation of the tested complexes, and the results offer some important insights into the effects of the arene. The most obvious finding to emerge from this study is that the usually very chemosensitive CH1/PA-1 teratocarcinoma cells showed resistance to these phthiocol-based organometallics in comparison to the usually less chemosensitive SW480 colon carcinoma cells, which pilot experiments suggest as being related to NQO1 activity. Show less

Ru(II) polypyridyl complexes are widely used in biological fields, due to their physico-chemical and photophysical properties. In this paper, a series of new chiral Ru(II) polypyridyl complexes (1-5) with the general formula {Δ/Λ-[Ru(bpy)₂(X,Y-sal)]BF₄} (bpy = 2,2'-bipyridyl; X,Y-sal = 5-bromosalicylaldehyde (1), 3,5-dibromosalicylaldehyde (2), 5-chlorosalicylaldehyde (3), 3,5-dichlorosalicylaldehyde (4) and 3-bromo-5-chlorosalicylaldehy (5)) were synthesized and characterized by elemental analysis, FT-IR, and ¹H/¹³C NMR spectroscopy. Also, the structures of complexes 1 and 5 were determined by X-ray crystallography; these results showed that the central Ru atom adopts a distorted octahedral coordination sphere with two bpy and one halogen-substituted salicylaldehyde. DFT and TD-DFT calculations have been performed to explain the excited states of these complexes. The singlet states with higher oscillator strength are correlated with the absorption signals and are mainly described as ¹MLCT from the ruthenium centre to the bpy ligands. The lowest triplet states (T₁) are described as ³MLCT from the ruthenium center to the salicylaldehyde ligand. The theoretical results are in good agreement with the observed unstructured band at around 520 nm for complexes 2, 4 and 5. Biological studies on human cancer cells revealed that dihalogenated ligands endow the Ru(II) complexes with enhanced cytotoxicity compared to monohalogenated ligands. In addition, as far as the type of halogen is concerned, bromine is the halogen that provides the highest cytotoxicity to the synthesized complexes. All complexes induce cell cycle arrest in G0/G1 and apoptosis, but only complexes bearing Br are able to provoke an increase in intracellular ROS levels and mitochondrial dysfunction. 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 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

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

Targeted therapy showed broad application prospects in the treatment of various types of cancer. Through carriers such as aptamers, antibodies, proteins and peptides, targeted therapy can selectively deliver drugs into tumor cells. Compared with traditional treatment methods such as chemo- and radiotherapy, targeted drug delivery systems can reduce the toxic effects of drugs on normal cells and avoid adverse reactions. Herein, an aptamer-cyclometalated iridium(III) complex conjugate (ApIrC) has been designed and developed as a targeted anticancer agent. Owing to the targeting ability of aptamers, ApIrC specifically bound to nucleolin over-expressed on the surface of cancer cells and showed strong fluorescence signal for tumor imaging and diagnosis. ApIrC had more substantial cellular uptake in cancer cells than the iridium complex alone and exhibited favorable low toxicity to normal cells. After uptake by cells through endocytosis, ApIrC can selectively accumulated in mitochondria and induced caspase-3/7-dependent cell death. Remarkably, ApIrC can also specifically target 3D multicellular spheroids (MCSs) and show excellent tumor permeability. So, it can effectively reach the interior of MCSs and cause cell damage. To our knowledge, this is the first report of the aptamer-cyclometalated iridium(III) complex conjugate which studied for cancer targeted therapy. The developed conjugate has great potential to be developed as novel therapeutics for effective and low-toxic cancer treatment. Show less

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. Show less

Ligand HMSPIP (2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its iridium(III) complexes [Ir(ppy)₂(HMSPIP)]PF₆ (ppy = 2-phenylpyridine, Ir1) and [Ir(bzq)₂(HMSPIP)]PF₆ (bzq = benzo[h]quinoline, Ir2) were synthesized. The complexes were characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectra. The cytotoxicity of the complexes toward cancer cells were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, the scratch wound healing and colony-forming were also investigated. MTT assay certificated that the complexes show high toxic effect on the HeLa cells. The cell cycle assay illustrated that the complexes blocked cell growth at G₀/G₁ phase in HeLa cells. A series of subsequent experiments showed that the complexes first enter the endoplasmic reticulum (ER) and then enter the mitochondria, leading to an increase in intracellular Ca²⁺ and reactive oxygen species (ROS) content, depolarizing mitochondrial membrane potential (MMP), and ultimately resulting in apoptosis. In addition, the experimental results revealed that the complexes not only increase the level of ROS but also inhibit the production of GSH and eventually produce large amounts of MDA and further leading to cell death. Taken together, we consider that the complexes can be used as potential candidate drugs for HeLa cancer treatment. Show less

Title: Light activation of iridium(III) complexes driving ROS production and DNA damage enhances anticancer activity in A549 cells. Abstract: The work aimed to synthesize and characterize two iridium(III) complexes [Ir(ppy)2(IPPH)](PF6) (Ir1, IPPH = (2S,3R,5S,6R)-2-(2-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenoxy)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol, ppy = 2-phenylpyridine), [Ir(piq)2(IPPH)](PF6) (Ir2, piq = 1-phenylisoquinoline). The cytotoxicity of the complexes against BEL-7402, A549, HCT-116, B16 cancer cells and normal LO2 was evaluated through 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. The complexes show no cytotoxic activity (IC50 > 100 μM) against these cancer cells, while their cytotoxicity can significantly be elevated upon illumination. The IC50 values range from 0.2 ± 0.05 to 35.5 ± 3.5 μM. The cellular uptake, endoplasmic reticulum and mitochondria localization, reactive oxygen species, the change of mitochondrial membrane potential, γ-H2AX levels, cycle arrest, apoptosis and the expression of B-cell lymphoma-2 were investigated. The calreticulin (CRT), heat shock protein 70 (HSP70), high mobility group box 1 (HMGB1) were explored. This study demonstrates that photoactivatable complexes induce cell death in A549 through ROS-mediated endoplasmic reticulum stress-mitochondrial pathway, DNA damage pathways, immunogenic cell death (ICD), activation of PI3K/AKT signaling pathway and inhibit the cell growth at S phase. Show less

Title: Synthesis, biological evaluation of novel iridium(III) complexes targeting mitochondria toward melanoma B16 cells. Abstract: 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. Show less

We disclose novel amphiphilic ruthenium and osmium complexes that auto-assemble into nanomedicines with potent antiproliferative activity by inhibition of mitochondrial respiration. The self-assembling units were rationally designed from the [M(p-cymene)(1,10-phenanthroline)Cl]PF₆ motif (where M is either Ru^II or Os^II) with an appended C₁₆ fatty chain to achieve high cellular activity, nano-assembling and mitochondrial targeting. These amphiphilic complexes block cell proliferation at the sub-micromolar range and are particularly potent towards glioblastoma neurospheres made from patient-derived cancer stem cells. A subcutaneous mouse model using these glioblastoma stem cells highlights one of our C₁₆ Os^II nanomedicines as highly successful in vivo. Mechanistically, we show that they act as metabolic poisons, strongly impairing mitochondrial respiration, corroborated by morphological changes and damage to the mitochondria. A genetic strategy based on RNAi gave further insight on the potential involvement of microtubules as part of the induced cell death. In parallel, we examined the structural properties of these new amphiphilic metal-based constructs, their reactivity and mechanism. Show less

Title: Formation of Iridium(III) and Rhodium(III) Amine, Imine, and Amido Complexes Based on Pyridine-Amine Ligands: Structural Diversity Arising from Reaction Conditions, Substituent Variation, and Metal Centers. Abstract: Herein, we present the different coordination modes of half-sandwich iridium(III) and rhodium(III) complexes based on pyridine-amine ligands. The pyridyl-amine iridium(III) and rhodium(III) complexes, the corresponding oxidation pyridyl-imine products, and 16-electron pyridyl-amido complexes can be obtained through the change in reaction conditions (nitrogen/adventitious oxygen atmosphere, reaction time, and solvents) and structural variations in the metal and ligand. Overall, the reaction of pyridine-amine ligands with [(η5-C5(CH3)5)MCl2]2 (M = Ir or Rh) in the presence of adventitious oxygen afforded the oxidized pyridyl-imine complexes. The possible mechanism for the oxidation of iridium(III) and rhodium(III) amine complexes was confirmed by the detection of the byproduct hydrogen peroxide. Moreover, the formation of pyridyl-amine complexes was favored when nonpolar solvent CH2Cl2 was used instead of CH3OH. The rarely reported complex with [(η5-Cp*)IrCl3] anions can also be obtained without the addition of NH4PF6. The introduction of the sterically bulky i-Bu group on the bridge carbon of the ligand led to the formation of stable 16-electron pyridyl-amido complexes. The pyridyl-amine iridium(III) and rhodium(III) complexes were also synthesized under a N2 atmosphere, and no H2O2 was detected in the whole process. In particular, the aqueous solution stability and in vitro cytotoxicity toward A549 and HeLa human cancer cells of these complexes were also evaluated. No obvious selectivity was observed for cancer cells versus normal cells with these complexes. Notably, the represented complex 5a can promote an increase in the reactive oxygen species level and induce cell death via apoptosis. Show less

Iron-sulfur (FeS) proteins are ancient and fundamental to life, being involved in electron transfer and CO2 fixation. FeS clusters have structures similar to the unit-cell of FeS minerals such as greigite, found in hydrothermal systems linked with the origin of life. However, the prebiotic pathway from mineral surfaces to biological clusters is unknown. Here we show that FeS clusters form spontaneously through interactions of inorganic Fe2+/Fe3+ and S2- with micromolar concentrations of the amino acid cysteine in water at alkaline pH. Bicarbonate ions stabilize the clusters and even promote cluster formation alone at concentrations >10 mM, probably through salting-out effects. We demonstrate robust, concentration-dependent formation of [4Fe4S], [2Fe2S] and mononuclear iron clusters using UV-Vis spectroscopy, 57Fe-Mössbauer spectroscopy and 1H-NMR. Cyclic voltammetry shows that the clusters are redox-active. Our findings reveal that the structures responsible for biological electron transfer and CO2 reduction could have formed spontaneously from monomers at the origin of life. Show less

The vascular endothelial glycocalyx is a dense, bush-like structure that is synthesized and secreted by endothelial cells and evenly distributed on the surface of vascular endothelial cells. The blood-brain barrier (BBB) is mainly composed of pericytes endothelial cells, glycocalyx, basement membranes, and astrocytes. The glycocalyx in the BBB plays an indispensable role in many important physiological functions, including vascular permeability, inflammation, blood coagulation, and the synthesis of nitric oxide. Damage to the fragile glycocalyx can lead to increased permeability of the BBB, tissue edema, glial cell activation, up-regulation of inflammatory chemokines expression, and ultimately brain tissue damage, leading to increased mortality. This article reviews the important role that glycocalyx plays in the physiological function of the BBB. The review may provide some basis for the research direction of neurological diseases and a theoretical basis for the diagnosis and treatment of neurological diseases. Show less

As a basic structure of most polypyridinal metal complexes, [Ru(bpy)₃]²⁺, has the advantages of simple structure, facile synthesis and high yield, which has great potential for scientific research and application. However, sonodynamic therapy (SDT) performance of [Ru(bpy)₃]²⁺ has not been investigated so far. SDT can overcome the tissue-penetration and phototoxicity problems compared to photodynamic therapy. Here, we report that [Ru(bpy)₃]²⁺ is a highly potent sonosensitizer and sonocatalyst for sonotherapy in vitro and in vivo. [Ru(bpy)₃]²⁺ can produce singlet oxygen (¹O₂) and sono-oxidize endogenous 1,4-dihydronicotinamide adenine dinucleotide (NADH) under ultrasound (US) stimulation in cancer cells. Furthermore, [Ru(bpy)₃]²⁺ enables effective destruction of mice tumors, and the therapeutic effect can reach deep tissues over 10 cm under US irradiation. This work paves a way for polypyridinal metal complexes to be applied to the noninvasive precise sonotherapy of cancer. Show less

Four bipyridine-type ligands variably derivatized with two bioactive groups (taken from ethacrynic acid, flurbiprofen, biotin, and benzylpenicillin) were prepared via sequential esterification steps from commercial 2,2'-bipyridine-4,4'-dicarboxylic acid and subsequently coordinated to ruthenium(II) p-cymene and iridium(III) pentamethylcyclopentadienyl scaffolds. The resulting complexes were isolated as nitrate salts in high yields and fully characterized by analytical and spectroscopic methods. NMR and MS studies in aqueous solution and in cell culture medium highlighted a substantial stability of ligand coordination and a slow release of the bioactive fragments in the latter case. The complexes were assessed for their antiproliferative activity on four cancer cell lines, showing cytotoxicity to the low micromolar level (equipotent with cisplatin). Additional biological experiments revealed a multimodal mechanism of action of the investigated compounds, involving DNA metalation and enzyme inhibition. Synergic effects provided by specific combinations of metal and bioactive fragments were identified, pointing toward an optimal ethacrynic acid/flurbiprofen combination for both Ru(II) and Ir(III) complexes. Show less

Ruthenium (Ru) and osmium (Os) complexes are of sustained interest in cancer research and may be alternative to platinum-based therapy. We detail here three new series of ruthenium and osmium complexes, supported by physico-chemical characterizations, including time-dependent density functional theory, a combined experimental and computational study on the aquation reactions and the nature of the metal-arene bond. Cytotoxic profiles were then evaluated on several cancer cell lines although with limited success. Further investigations were, however, performed on the most active series using a genetic approach based on RNA interference and highlighted a potential multi-target mechanism of action through topoisomerase II, mitotic spindle, HDAC and DNMT inhibition. Show less

The ruthenium polypyridyl complex [Ru(dppz)₂PIP]²⁺ (dppz: dipyridophenazine, PIP: (2-(phenyl)-imidazo[4,5-f ][1,10]phenanthroline), or Ru-PIP, is a potential anticancer drug that acts by inhibiting DNA replication. Due to the poor dissolution of Ru-PIP in aqueous media, a drug delivery agent would be a useful approach to overcome its limited bioavailability. Mesoporous silica nanoparticles (MSNs) were synthesized via a co-condensation method by using a phenanthrolinium salt with a 16 carbon length chain (Phen-C₁₆) as the template. Optimization of the synthesis conditions by Box-Behnken design (BBD) generated MSNs with high surface area response at 833.9 m²g^-1. Ru-PIP was effectively entrapped in MSNs at 18.84%. Drug release profile analysis showed that Ru-PIP is gradually released, with a cumulative release percentage of approximately 50% at 72 h. The release kinetic profile implied that Ru-PIP was released from MSN by diffusion. The in vitro cytotoxicity of Ru-PIP, both free and MSN-encapsulated, was studied in Hela, A549, and T24 cancer cell lines. While treatment of Ru-PIP alone is moderately cytotoxic, encapsulated Ru-PIP exerted significant cytotoxicity upon all the cell lines, with half maximal inhibitory concentration (IC₅₀) values determined by MTT (([3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide]) assay at 48 h exposure substantially decreasing from >30 µM to <10 µM as a result of MSN encapsulation. The mechanistic potential of cytotoxicity on cell cycle distribution showed an increase in G1/S phase populations in all three cell lines. The findings indicate that MSN is an ideal drug delivery agent, as it is able to sustainably release Ru-PIP by diffusion in a prolonged treatment period. Show less

A series of nine Ru^II arene complexes bearing tridentate naphthoquinone-based N,O,O-ligands was synthesized and characterized. Aqueous stability and their hydrolysis mechanism were investigated via UV/vis photometry, HPLC-MS, and density functional theory calculations. Substituents with a positive inductive effect improved their stability at physiological pH (7.4) intensely, whereas substituents such as halogens accelerated hydrolysis and formation of dimeric pyrazolate and hydroxido bridged dimers. The observed cytotoxic profile is unusual, as complexes exhibited much higher cytotoxicity in SW480 colon cancer cells than in the broadly chemo- (incl. platinum-) sensitive CH1/PA-1 teratocarcinoma cells. This activity pattern as well as reduced or slightly enhanced ROS generation and the lack of DNA interactions indicate a mode of action different from established or previously investigated classes of metallodrugs. Show less

The use of cisplatin is severely limited by its toxic side-effects, which has spurred chemists to employ different strategies in the development of new metal-based anticancer agents. Here, three novel dehydroabietyl piperazine dithiocarbamate ruthenium (II) polypyridyl complexes (6a-6c) were synthesized as antitumor agents. Compounds 6a and 6c exhibited better in vitro antiproliferative activity against seven tumor cell lines than cisplatin, they displayed no evident resistance in the cisplatin-resistant cell line A549/DPP. Importantly, 6a effectively inhibited tumor growth in the T-24 xenograft mouse model in comparison with cisplatin. Gel electrophoresis assay indicated that DNA was the potential targets of 6a and 6c, and the upregulation of p-H2AX confirmed this result. Cell cycle arrest studies demonstrated that 6a and 6c arrested the cell cycle at G1 phase, accompanied by the upregulation of the expression levels of the antioncogene p27 and the down-regulation of the expression levels of cyclin E. In addition, 6a and 6c caused the apoptosis of tumor cells along with the upregulation of the expression of Bax, caspase-9, cytochrome c, intracellular Ca²⁺ release, reactive oxygen species (ROS) generation and the downregulation of Bcl-2. These mechanistic study results suggested that 6a and 6c exerted their antitumor activity by inducing DNA damage, and consequently causing G1 stage arrest and the induction of apoptosis. Show less

Two new cyclometalated Ru(II)-β-carboline complexes, [Ru(dmb)₂(Cl-Ph-βC)](PF₆) (dmb = 4,4'-dimethyl-2,2'-bipyridine; Cl-Ph-βC = Cl-phenyl-9H-pyrido[3,4-b]indole; RuβC-3) and [Ru(bpy)₂(Cl-Ph-βC)](PF₆) (bpy = 2,2'-bipyridine; RuβC-4) were synthesized and characterized. The Ru(II) complexes display high cytotoxicity against HeLa cells, the stabilized human cervical cancer cell, with IC₅₀ values of 3.2 ± 0.4 μM (RuβC-3) and 4.1 ± 0.6 μM (RuβC-4), which were considerably lower than that of non-cyclometalated Ru(II)-β-carboline complex [Ru(bpy)₂(1-Py-βC)] (PF₆)₂ (61.2 ± 3.9 μM) by 19- and 15-folds, respectively. The mechanism studies indicated that both Ru(II) complexes could significantly inhibit HeLa cell migration and invasion, and effectively induce G0/G1 cell cycle arrest. The new Ru(II) complexes could also trigger apoptosis through activating caspase-3 and poly (ADP-ribose) polymerase (PARP), increasing the Bax/Bcl-2 ratio, enhancing reactive oxygen species (ROS) generation, decreasing mitochondrial membrane potential (MMP), and inducing cytochrome c release from mitochondria. Further research revealed that RuβC-3 could deactivate the ERK/Akt signaling pathway thus inhibiting HeLa cell invasion and migration, and inducing apoptosis. In addition, RuβC-3-induced apoptosis in HeLa cells was closely associated with the increase of intracellular ROS levels, which may act as upstream factors to regulate ERK and Akt pathways. More importantly, RuβC-3 exhibited low toxicity on both normal BEAS-2B cells in vitro and zebrafish embryos in vivo. Consequently, the developed Ru(II) complexes have great potential on developing novel low-toxic anticancer drugs. Show less

Drug resistance to existing anticancer agents is a growing clinical concern, with many first line treatments showing poor efficacy in treatment plans of some cancers. Resistance to platinum agents, such as cisplatin, is particularly prevalent in the treatment of ovarian cancer, one of the most common cancers amongst women in the developing world. Therefore, there is an urgent need to develop next generation of anticancer agents which can overcome resistance to existing therapies. We report a new series of organoruthenium(II) complexes bearing structurally modified pyrithione ligands with extended aromatic scaffold, which overcome platinum and adriamycin resistance in human ovarian cancer cells. The mechanism of action of such complexes appears to be unique from that of cisplatin, involving G₁ cell cycle arrest without generation of cellular ROS, as is typically associated with similar ruthenium complexes. The complexes inhibit the enzyme thioredoxin reductase (TrxR) in a model system and reduce cell motility towards wound healing. Importantly, this work highlights further development in our understanding of the multi-targeting mechanism of action exhibited by transition metal complexes. Show less

The synthesis and the evaluation of the efficacy of a cycloruthenated complex, RuZ, is reported, to overcome multi-drug resistance (MDR) in cancer cells. RuZ can self-assemble into nanoaggregates in the cell culture medium, resulting in a high intracellular concentration of RuZ in MDR cancer cells. The self-assembly significantly decreases oxygen consumption and inhibits glycolysis, which decreases cellular adenosine triphosphate (ATP) levels. The decrease in ATP levels and its low affinity for the ABCB1 and ABCG2 transporters (which mediate MDR) significantly increase the retention of RuZ by MDR cancer cells. Furthermore, RuZ increases cellular oxidative stress, inducing DNA damage, and, in combination with the aforementioned effects of RuZ, increases the apoptosis of cancer cells. Proteomic profiling analysis suggests that the RuZ primarily decreases the expression of proteins that mediate glycolysis and aerobic mitochondrial respiration and increases the expression of proteins involved in apoptosis. RuZ inhibits the proliferation of 35 cancer cell lines, of which 7 cell lines are resistant to clinical drugs. It is also active in doxorubicin-resistant MDA-MB-231/Adr mouse tumor xenografts. To the best of our knowledge, the results are the first to show that self-assembled cycloruthenated complexes are efficacious in inhibiting the growth of MDR cancer cells. Show less