Copper(II/I) complexes of 5-pyridin-2-yl-[1,3]dioxolo[4,5-g]isoquinoline: Synthesis, crystal structure, antitumor activity and DNA interaction

Cycloplatinated (II) Complex Based on Isoquinoline Alkaloid Elicits Ferritinophagy-Dependent Ferroptosis in Triple-Negative Breast Cancer Cells

The development and optimization of metal-based anticancer drugs with novel cytotoxic mechanisms have emerged as key strategies to overcome chemotherapeutic resistance and side effects. Agents that simultaneously induce ferroptosis and autophagic death have received extensive attention as potential modalities for cancer therapy. However, only a limited set of drugs or treatment modalities can synergistically induce ferroptosis and autophagic tumor cell death. In this work, we designed and synthesized four new cycloplatinated (II) complexes harboring an isoquinoline alkaloid C∧N ligand. On screening the in vitro activity of these agents, we found that Pt-3 exhibited greater selectivity of cytotoxicity, decreased resistance factors, and improved anticancer activity compared to cisplatin. Furthermore, Pt-3, which we demonstrate can initiate potent ferritinophagy-dependent ferroptosis, exhibits less toxic and better therapeutic activity than cisplatin in vivo. Our results identify Pt-3 as a promising candidate or paradigm for further drug development in cancer treatment.

Copper(II) Complexes with 1-(Isoquinolin-3-yl)heteroalkyl-2-ones: Synthesis, Structure and Evaluation of Anticancer, Antimicrobial and Antioxidant Potential

Four copper(II) complexes, C1-4, derived from 1-(isoquinolin-3-yl)heteroalkyl-2-one ligands L1-4 were synthesized and characterized using an elemental analysis, IR spectroscopic data as well as single crystal X-ray diffraction data for complex C1. The stability of complexes C1-4 under conditions mimicking the physiological environment was estimated using UV-Vis spectrophotometry. The antiproliferative activity of both ligands L1-4 and copper(II) compounds C1-4 were evaluated using an MTT assay on four human cancer cell lines, A375 (melanoma), HepG2 (hepatoma), LS-180 (colon cancer) and T98G (glioblastoma), and a non-cancerous cell line, CCD-1059Sk (human normal skin fibroblasts). Complexes C1-4 showed greater potency against HepG2, LS180 and T98G cancer cell lines than etoposide (IC50 = 5.04-14.89 μg/mL vs. IC50 = 43.21->100 μg/mL), while free ligands L1-4 remained inactive in all cell lines. The prominent copper(II) compound C2 appeared to be more selective towards cancer cells compared with normal cells than compounds C1, C3 and C4. The treatment of HepG2 and T98G cells with complex C2 resulted in sub-G1 and G2/M cell cycle arrest, respectively, which was accompanied by DNA degradation. Moreover, the non-cytotoxic doses of C2 synergistically enhanced the cytotoxic effects of chemotherapeutic drugs, including etoposide, 5-fluorouracil and temozolomide, in HepG2 and T98G cells. The antimicrobial activities of ligands L2-4 and their copper(II) complexes C2-4 were evaluated using different types of Gram-positive bacteria, Gram-negative bacteria and yeast species. No correlation was found between the results of the antiproliferative and antimicrobial experiments. The antioxidant activities of all compounds were determined using the DPPH and ABTS radical scavenging methods. Antiradical tests revealed that among the investigated compounds, copper(II) complex C4 possessed the strongest antioxidant properties. Finally, the ADME technique was used to determine the physicochemical and drug-likeness properties of the obtained complexes.

Dimeric Drugs

This review intends to summarize the structures of an extensive number of symmetrical-dimeric drugs, having two monomers linked via a bridging entity while emphasizing the large versatility of biologically active substances reported to possess dimeric structures. The largest number of classes of these compounds consist of anticancer agents, antibiotics/antimicrobials, and anti-AIDS drugs. Other symmetrical-dimeric drugs include antidiabetics, antidepressants, analgesics, anti-inflammatories, drugs for the treatment of Alzheimer's disease, anticholesterolemics, estrogenics, antioxidants, enzyme inhibitors, anti-Parkisonians, laxatives, antiallergy compounds, cannabinoids, etc. Most of the articles reviewed do not compare the activity/potency of the dimers to that of their corresponding monomers. Only in limited cases, various suggestions have been made to justify unexpected higher activity of the dimers vs. the corresponding monomers. These suggestions include statistical effects, the presence of dimeric receptors, binding of a dimer to two receptors simultaneously, and others. It is virtually impossible to predict which dimers will be preferable to their respective monomers, or which linking bridges will lead to the most active compounds. It is expected that the extensive number of articles summarized, and the large variety of substances mentioned, which display various biological activities, should be of interest to many academic and industrial medicinal chemists.

The first copper(I) complex of anthrahydrazone with potential ROS scavenging activity showed significant in vitro anticancer activity by inducing apoptosis and autophagy

Based on the anticancer pharmacophore of anthrahydrazone and quinoline, a new quinolylanthrahydrazone ligand, 9-AQH (anthracene-9-quinolylhydrazone), was synthesized to further afford four metal complexes, [Co^II(9-AQH)(NO₃)₂(H₂O)] (1), [Ni^II(9-AQH)₂(H₂O)₂]·2NO₃ (2), [Cu^I(9-AQH)₂]·NO₃ (3), [Zn^II(9-AQH)₂(NO₃)]·NO₃ (4), determined by X-ray single crystal diffraction analysis. The reaction of Cu(NO₃)₂ with 9-AQH formed the stable and repeatable copper(I) complex 3. In vitro screening demonstrated only 3 showed significant and broad-spectrum anticancer activity, indicating that Cu(I) played a key role in exerting the anticancer activity. In solution, Cu(I) was not naturally oxidized to Cu(II) suggested by ¹H-NMR (Nuclear Magnetic Resonance) and EPR (Electron Paramagnetic Resonance) analysis. The presence of 3 could also catalyze the H₂O₂ system to give hydroxyl free radicals, suggested by further EPR and electrophoresis assay. At the cellular level, although no obvious Cu(II) signals were detected and the total ROS (Reactive Oxygen Species) scavenging in the tumor cells treated with 3, the potential redox property between Cu(I)/Cu(II), as a key role, should not be denied for the significant anticancer activity of 3, considering the much complicated circumstance and other reductive substances in cells. The anticancer mechanism of 3 on the most sensitive MGC-803 cells pointed to significant cell apoptosis through mitochondrial pathway, rather than cell cycle arrest. While the autophagy observed in tumor cells treated by 3 suggested its complicated anticancer mechanism, and whether there was an intrinsic correlation still needed to be further investigated.

Ni(ii), Cu(ii) and Zn(ii) complexes with the 1-trifluoroethoxyl-2,9,10-trimethoxy-7-oxoaporphine ligand simultaneously target microtubules and mitochondria for cancer therapy

Complexes 1–3 display potent anticancer activity against T-24 cell by disrupting mitochondria and microtubules. Furthermore, complex 1 exhibits almost same tumor growth inhibition activity in T-24 xenograft mouse model as cisplatin and paclitaxel.

Novel cyclometalated Ru(II) complexes containing isoquinoline ligands: Synthesis, characterization, cellular uptake and in vitro cytotoxicity

Two novel cyclometalated Ru(II) complexes containing isoquinoline ligand, [Ru(bpy)₂(1-Ph-IQ)](PF₆), (bpy = 2,2'-bipyridine; 1-Ph-IQ = 1-phenylisoquinoline; RuIQ-1) and [Ru(phen)₂(1-Ph-IQ)](PF₆) (phen = 1,10-phenanthroline; RuIQ-2) were found to show high cytotoxic activity against NCI-H460, A549, HeLa and MCF-7 cell lines. Notably, both of them exhibited IC₅₀ values that were an order of magnitude lower than those of clinical cisplatin and two structurally similar Ru(II)-isoquinoline complexes [Ru(bpy)₂(1-Py-IQ)](PF₆)₂ (Ru3) and [Ru(phen)₂(1-Py-IQ)](PF₆)₂ (Ru4) (1-Py-IQ = 1-pyridine-2-yl). The cellular uptake and intracellular localization displayed that the two cyclometalated Ru(II) complexes entered NCI-H460 cancer cells dominantly via endocytosis pathway, and preferentially distributed in the nucleus. Further investigations on the apoptosis-inducing mechanisms of RuIQ-1 and RuIQ-2 revealed that the two complexes could cause S, G2/M double-cycle arrest by regulating cell cycle related proteins. The two complexes also could reduce the mitochondrial membrane potential (MMP), promote the generation of intracellular ROS and trigger DNA damage, and then lead to apoptosis-mediated cell death. More importantly, RuIQ-2 exhibits low toxicity both towards normal HBE cells in vitro and zebrafish embryos in vivo. Accordingly, the developed complexes hold great potential to be developed as novel therapeutics for effective and low-toxic cancer treatment.

Antitumor effects of novel nickel–hydrazone complexes in lung cancer cells

Two novel nickel(ii) complexes [NiL^I]·CH₃CN (1·CH₃CN) and [Ni(H₂L^II)(NCS)₂]·0.5H₂O (2·0.5H₂O) were fabricated and in in vitro experiments they both showed the dose dependent cytotoxicity and killed A549 lung cancer cells via an apoptotic pathway.

Graphene quantum dots mediated electron transfer in DNA base pairs

Graphene quantum dots (GQDs) were connected to [Ru(bpy)3]2+ to sense DNA-mediated charge transfer. Interaction between abasic site double stranded DNA (Abasic-DNA) and [Ru(bpy)3-GQD]2+ was investigated by absorption spectroscopy, gel electrophoresis, circular dichroism, and melting temperature measurements. The results indicate that [Ru(bpy)3-GQD]2+ could be intercalated into double stranded DNA. Using [Ru(bpy)3-GQD]2+ as a signal molecule, the charge transfer performance of DNA-intercalated [Ru(bpy)3-GQD]2+ was determined using electrochemical and electrochemiluminescence measurements. Various DNA types were immobilized on Au electrodes via Au-S bonds. Electrochemiluminescence and electrochemical measurements indicate that [Ru(bpy)3-GQD]2+ could enhance DNA-mediated charge transfer when intercalated into an abasic site of double stranded DNA. And comparing with [Ru(bpy)3]2+, it can be concluded that GQDs intercalate into the DNA duplex by acting as a base analog, thus enhancing DNA charge transfer. These findings suggest that the DNA-GQD structure could aid the development of molecular devices and electric drivers, and broaden the application of DNA charge transfer.

Distinct supramolecular assemblies of Fe(iii) and Ni(ii) complexes constructed from the o-vanillin salicylhydrazone ligand: syntheses, crystal structures, DNA/protein interaction, and antioxidant and cytotoxic activity

A novel aroylhydrazone ligand-bridged Ni(ii) coordination polymer was reported and its DNA binding, protein interaction, radical scavenging and in vitro anticancer properties were evaluated.

New Platinum(II) agent induces bimodal death of apoptosis and autophagy against A549 cancer cell

Agents with multiple modes of tumor cell death can be effective chemotherapeutic drugs. One example of a bimodal chemotherapeutic approach is an agent that can induce both apoptosis and autophagic death. Thus far, no clinical anticancer drug has been shown to simultaneously induce both these pathways. Mono-functional platinum complexes are potent anticancer drug candidates which act through mechanisms distinct from cisplatin. Here, we describe the synthesis and characterize of two mono-functional platinum complexes containing 8-substituted quinoline derivatives as ligands. In comparison to cisplatin, n-Mon-Pt-1 exhibited a greater in vitro cytotoxicity, was more effective in resistant cells and elicited a better anticancer effect. Mechanistic experiments indicate that n-Mon-Pt-1 mainly accumulates in mitochondria, and stimulates significant TrxR inhibition, ROS release and an ER stress response, ultimately resulting in a simultaneous induction of apoptosis and autophagy. Importantly, compared to cisplatin, n-Mon-Pt-1 exhibits lower acute toxicity and better anticancer activity in a murine tumor model.

Mitochondria-targeted platinum(II) complexes induce apoptosis-dependent autophagic cell death mediated by ER-stress in A549 cancer cells

Agents with multiple modes of tumor cell death can be effective chemotherapeutic drugs. One example of a bimodal chemotherapeutic approach is an agent that can induce both apoptosis and autophagic death. Thus far, no clinical anticancer drug has been shown to simultaneously induce both these pathways. Mono-functional platinum complexes are potent anticancer drug candidates which act through mechanisms distinct from cisplatin. Here, we describe the synthesis and characterize of two mono-functional platinum complexes containing 8-substituted quinoline derivatives as ligands, [PtL₁Cl]Cl [L₁ = (Z)-1-(pyridin-2-yl)-N-(quinolin-8-ylmethylene) methanamine] (Mon-Pt-1) and [PtL₂Cl]Cl [L₂ = (Z)-2-(pyridin-2-yl)-N-(quinolin-8-ylmethylene) ethanamine] (Mon-Pt-2). In comparison to cisplatin, Mon-Pt-2 exhibited a greater in vitro cytotoxicity, was more effective in resistant cells and elicited a better anticancer effect. Mechanistic experiments indicate that Mon-Pt-2 mainly accumulates in mitochondria, and stimulates significant TrxR inhibition ROS release and an ER stress response, mediated by mitochondrial dysfunction, ultimately resulting in a simultaneous induction of apoptosis and autophagy. Importantly, compared to cisplatin, Mon-Pt-2 exhibits lower acute toxicity and better anticancer activity in a murine tumor model. To the best of our knowledge, Mon-Pt-2 is the first mono-functional platinum complex inducing pro-death autophagy and apoptosis of cancer cells.

Organometallic Gold(III) Complexes Similar to Tetrahydroisoquinoline Induce ER-Stress-Mediated Apoptosis and Pro-Death Autophagy in A549 Cancer Cells

Agents inducing both apoptosis and autophagic death can be effective chemotherapeutic drugs. In our present work, we synthesized two organometallic gold(III) complexes harboring C^N ligands that structurally resemble tetrahydroisoquinoline (THIQ): Cyc-Au-1 (AuL¹Cl₂, L¹ = 3,4-dimethoxyphenethylamine) and Cyc-Au-2 (AuL²Cl₂, L² = methylenedioxyphenethylamine). In screening their in vitro activity, we found both gold complexes exhibited lower toxicity, lower resistance factors, and better anticancer activity than those of cisplatin. The organometallic gold(III) complexes accumulate in mitochondria and induce elevated ROS and an ER stress response through mitochondrial dysfunction. These effects ultimately result in simultaneous apoptosis and autophagy. Importantly, compared to cisplatin, Cyc-Au-2 exhibits lower toxicity and better anticancer activity in a murine tumor model. To the best of our knowledge, Cyc-Au-2 is the first organometallic Au(III) compound that induces apoptosis and autophagic death. On the basis of our results, we believe Cyc-Au-2 to be a promising anticancer agent or lead compound for further anticancer drug development.

Studies on the interactions of 5-R-3-(2-pyridyl)-1,2,4-triazines with arynes: inverse demand aza-Diels–Alder reaction versus aryne-mediated domino process

The interactions between substituted 5-R-3-(pyridyl-2)-1,2,4-triazines with in situ generated substituted aryne intermediates have been studied.

Facile total synthesis of lysicamine and the anticancer activities of the RuII, RhIII, MnII and ZnII complexes of lysicamine

Lysicamine is a natural oxoaporphine alkaloid, which isolated from traditional Chinese medicine (TCM) herbs and has been shown to possess cytotoxicity to hepatocarcinoma cell lines. Reports on its antitumor activity are scarce because lysicamine occurs in plants at a low content. In this work, we demonstrate a facile concise total synthesis of lysicamine from simple raw materials under mild reaction conditions, and the preparation of the Ru(II), Rh(III), Mn(II) and Zn(II) complexes 1–4 of lysicamine (LY). All the compounds were fully characterized by elemental analysis, IR, ESI-MS, ¹H and ¹³C NMR, as well as single-crystal X-ray diffraction analysis. Compared with the free ligand LY, complexes 2 and 3 exhibited superior in vitro cytotoxicity against HepG2 and NCI-H460. Mechanistic studies indicated that 2 and 3 blocked the cell cycle in the S phase by decreasing of cyclins A2/B1/D1/E1, CDK 2/6, and PCNA levels and increasing levels of p21, p27, p53 and CDC25A proteins. In addition, 2 and 3 induced cell apoptosis via both the caspase-dependent mitochondrial pathway and the death receptor pathway. in vivo study showed that 2 inhibited HepG2 tumor growth at 1/3 maximum tolerated dose (MTD) and had a better safety profile than cisplatin.

Synthesis and crystal structure of new monometallic Ni(ii) and Co(ii) complexes with an asymmetrical aroylhydrazone: effects of the complexes on DNA/protein binding property, molecular docking, and in vitro anticancer activity

Cytotoxic nickel and cobalt complexes containing asymmetrical aroylhydrazone were synthesized and their interactions with HS–DNA and BSA protein were investigated, which was supported by molecular docking studies.

Synthesis, structural characterization, cytotoxic properties and DNA binding of a dinuclear copper(II) complex

In this study a novel dinuclear copper(II) complex with adenine and phenanthroline has been synthesized and its structure determined by single crystal X-ray diffraction. In the dinuclear complex [Cu₂(μ-adenine)₂(phen)₂(H2O)2](NO3)4·0.5H2O (phen=1,10-phenanthroline) (1) the two Cu(II) centres exhibit a distorted square pyramidal coordination geometry linked by two nitrogen donors from adenine bridges leading to a Cu-Cu distance of 3.242(3)Å. Intramolecular and intermolecular π⋯π interactions as well as an H-bonding network were observed. The antitumor capacity of the complex has been tested in vitro against human cancer cell lines, cervical carcinoma (HeLa) and colorectal adenocarcinoma (Caco-2), by metabolic tests, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide as reagent. The complex 1 has remarkable low IC50 values of 0.87±0.06μM (HeLa) and 0.44±0.06μM (Caco-2), when compared with values for cisplatin against the same cell lines. The interaction of complex 1 with calf thymus DNA (CT DNA) was further investigated by absorption and fluorescence spectroscopic methods. A binding constant of 5.09×10(5)M(-1) was obtained from UV-vis absorption studies.

DNA/protein interaction, cytotoxic activity and magnetic properties of amino-alcohol Schiff base derived Cu(ii)/Ni(ii) metal complexes: influence of the nuclearity and metal ions

The reactions of amino-alcohol derived Schiff-base ligands with Cu(ii) and Ni(ii) salts have afforded four novel polynuclear complexes, which exhibited interesting magnetic and cytotoxic properties.

Dihydroisoquinoline copper(ii) complexes: crystal structures, cytotoxicity, and action mechanism

Three new copper(ii) complexes with dihydroisoquinoline were synthesized. They exhibited considerable cytotoxicity, achieved through the induction of cell apoptosisviathe intrinsic pathways of caspase–mitochondria.

Synthesis, DNA interaction and anticancer activity of copper(II) complexes with 4'-phenyl-2,2':6',2″-terpyridine derivatives

Three novel copper(II) complexes CuL(1)Cl2 (1) (L(1)=4'-(3-methoxyphenyl)-2,2':6'- 2″-terpyridine), CuL(2)Cl2 (2) (L(2)=4'-(4-methoxyphenyl)-2,2':6'-2″-terpyridine) and CuL(3)Cl2 (3) (L(3)=4'-(3,5-dimethoxyphenyl)-2,2':6'-2″-terpyridine) have been synthesized and characterized. Absorption spectral titration experiments, ethidium bromide displacement assays, and cyclic voltammetric experiments were carried out and the results suggested that these complexes bound to DNA through an intercalative mode. Moreover, these complexes were found to cleave pBR322 DNA efficiently in the presence of glutathione (GSH), and exhibited good anticancer activity against HeLa, Hep-G2 and BEL-7402 cell lines. Nuclear chromatin cleavage was also observed by acridine orange/ethidium bromide (AO/EB) staining assays and comet assays. These results demonstrated that these three Cu(II) complexes caused DNA damage and induced the apoptosis of HeLa cells. Mechanistic investigations revealed the participation of reactive oxygen species which can be trapped by reactive oxygen species (ROS) radical scavengers and ROS sensors.