Zinc Complexes with Nitrogen Donor Ligands as Anticancer Agents

Zinc(II) coordination compound with N'-(pyridin-2-ylmethylene)nicotinohydrazide: Synthesis, crystal structure, computational and cytotoxicity studies

In this work, we report on the synthesis of a novel zinc(II) coordination compound [ZnL2] (1), which was readily obtained from the reaction of Zn(OAc)·2H2O and N'-(pyridin-2-ylmethylene)nicotinohydrazide (HL) in methanol. Recrystallization of 1 from dimethylformamide under ambient conditions allowed to produce yellow block-like crystals of 1·H2O. Complex 1·H2O was characterized by FT-IR and 1H NMR spectroscopy, while its optical properties were studied by UV-vis and spectrofluorimetry in methanol. The crystal structure of the title complex was revealed by single crystal X-ray diffraction and further explored in detail by the Hirshfeld surface analysis. Theoretical investigations based on the DFT calculations have also been applied to show the electronic properties of complex 1. The antitumor activities of the parent ligand HL and complex 1 were studied using Dalton's lymphoma malignant cancer model. Both compounds were found to induce concentration-dependent cytotoxicity and apoptotic cell death, leading to a decrease in cell viability, body weight, and tumor volume in mice with the superior activity of complex 1 over HL. Mice treated with complex 1 demonstrated an increase in life span with a survival period of 23 days. Finally, using a molecular docking approach, we have probed complex 1 to inhibit the recombinant mouse tumor-necrosis factor alpha (mTNF).

In vitro and in vivo antiproliferative activity on lung cancer of two acylhydrazone based zinc(II) complexes

Two acylhydrazone based zinc(II) complexes [Zn(HL)2Cl2(CH3OH)2] (Zn1) and [ZnL(AC)]2 (Zn2) were synthesized from 3-(1-(salicyloylhydrazono)ethyl) pyridine (HL). Single crystal X-ray structure analyses showed that complexes Zn1 and Zn2 have a zero-dimensional monomer or dimer structure. Antiproliferative activity studies revealed that Zn1 and Zn2 are both more effective against A549 cells than cisplatin. The results of the reactive oxygen species (ROS) generation assay on A549 cells showed that both Zn1 and Zn2 induced apoptosis through ROS accumulation. The apoptosis-inducing and cell cycle arrest effects of Zn1 and Zn2 on A549 cells indicated that the antitumor effect was achieved through apoptosis induction and inhibition of DNA synthesis by blocking the G0/G1 phase of the cell cycle. What's more, the results of wound-healing assay showed that Zn1 and Zn2 could inhibit the migration of A549 cells. Western blot analysis further demonstrated that Zn1 and Zn2 induced cell apoptosis through the mitochondrial pathway, in which process, the expression level of cytochrome C, cleaved-PARP, cleaved-caspase 3 and cleaved-caspase 9 proteins increased while pro-caspase 3 and pro-caspase 9 expression decreased. In vivo anticancer evaluation demonstrated that both Zn1 and Zn2 complexes effectively inhibited tumor growth without causing significant toxicity in systemic organs.

Biomaterials in Cancer Therapy: Investigating the Interaction between Kaempferol and Zinc Ions through Computational, Spectroscopic and Biological Analyses

A complex of the natural flavonoid kaempferol with zinc (Kam-Zn) was synthesized, and its physicochemical properties were investigated using spectroscopic methods such as Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy and theoretical chemistry. Biological studies were conducted to evaluate the cytotoxic and antiproliferative effects of these complexes on MCF-7 breast cancer cells. Treatment with Kam 100 µM (84.86 ± 7.79%; 64.37 ± 8.24%) and Kam-Zn 100 µM (91.87 ± 3.80%; 87.04 ± 13.0%) showed no significant difference in proliferation between 16 h and 32 h, with the gap width remaining stable. Both Kam-Zn 100 μM and 200 μM demonstrated effective antiproliferative and cytotoxic activity, significantly decreasing cell viability and causing cell death and morphology changes. Antioxidant assays revealed that Kam (IC50 = 5.63 ± 0.06) exhibited higher antioxidant potential compared to Kam-Zn (IC50 = 6.80 ± 0.075), suggesting that zinc coordination impacts the flavonoid's radical scavenging activity by the coordination of metal ion to hydroxyl groups. Computational studies revealed significant modifications in the electronic structure and properties of Kam upon forming 1:1 complexes with Zn2+ ions. Spectroscopy analyses confirmed structural changes, highlighting shifts in absorption peaks and alterations in functional group vibrations indicative of metal-ligand interactions. FT-IR and UV-Vis spectra analysis suggested that Zn coordinates with the 3-OH and 4C=O groups of ligand. These findings suggest that the Kam-Zn complex exhibits interesting antiproliferative, cytotoxic and modified antioxidant effects on MCF-7 cells, providing valuable insights into their structural and anticancer properties.

Synthesis, characterization, biological potency, and molecular docking of Co2+, Ni2+ and Cu2+ complexes of a benzoyl isothiocyanate based ligand

The primary objective of the present study was to produce metal complexes of H4DAP ligand (N,N'-((pyridine-2,6-diylbis(azanediyl))bis(carbonothioyl))dibenzamide) derived from 2,6-diaminopyridine and benzoyl isothiocyanate with either ML or M2L stoichiometry. There are three distinct coordination complexes obtained with the formulas [Co(H2DAP)]·H2O, [Ni2(H2DAP)Cl2(H2O)2]·H2O, and [Cu(H4DAP)Cl2]·3H2O. The confirmation of the structures of all derivatives was achieved through the utilization of several analytical techniques, including FT-IR, UV-Vis, NMR, GC-MS, PXRD, SEM, TEM analysis, and QM calculations. Aiming to analyze various noncovalent interactions, topological methods such as QTAIM, NCI, ELF, and LOL were performed. Furthermore, the capacity of metal-ligand binding was examined by fluorescence emission spectroscopy. An in vitro investigation showed that the viability of MDA-MB-231 and HepG-2 cells was lower when exposed to the manufactured Cu2+ complex, in comparison to the normal cis-platin medication. The compounds were further evaluated for their in vitro antibacterial activity. The Ni2+ complex has shown promising activity against all tested pathogens, comparable to the reference drugs Gentamycin and Ketoconazole. Furthermore, a computational docking investigation was conducted to further examine the orientation, interaction, and conformation of the recently created compounds on the active site of the Bcl-2 protein.

Site-selective direct nitration of 2H-indazoles: easy access to 7-nitroindazoles

A new site-selective methodology for C-H nitration of 2H-indazoles has been accomplished at the C7 position using iron(III) nitrate. This strategy enables practical access to an array of 7-nitroindazoles with broad functional group tolerance in good yields. The synthesized products have been proven as valuable synthetic intermediates by demonstrating the synthetic utility. Mechanistic investigations indicate that the reaction goes through a radical pathway.

Liposomes Containing Zinc-Based Chemotherapeutic Drug Block Proliferation and Trigger Apoptosis in Breast Cancer Cells

Platinum-based chemotherapeutic drugs are effective in killing malignant cells but often trigger drug resistance or off-target side effects. Unlike platinum, zinc is used as an endogenous cofactor for several cellular enzymes and may, thus, display increased biocompatibility. In this present study, we have rationally designed and synthesized two substituted phenanthro[9,10-d]imidazole-based ligands L1 and L2 with pyridine and quinoline substitution at the 2 position and their corresponding Zn(II) complexes; (L1)2Zn and (L2)2Zn, which are characterized by standard analytical and spectroscopic methods. (L2)2Zn, but not (L1)2Zn has intrinsic fluorescence, indicating its potential utility in imaging applications. To facilitate cellular uptake, we generated liposomal formations with a phospholipid DMPC (1,2-Dimyristoyl-sn-glycero-3-phosphocholine) through molecular self-assembly. These liposomal formulations Lip-(L1)2Zn and Lip-(L2)2Zn were able to enter breast cancer cells, induce DNA fragmentation, arrest the cell cycle at the G0/G1 phase, decrease proliferation, and promote apoptosis by activating the DNA damage response. Importantly, both Lip-(L1)2Zn and Lip-(L2)2Zn decreased the size of breast cancer cell-based spheroids, indicating they may be capable of suppressing tumor growth. Our work represents an important proof-of-concept exercise demonstrating that successful liposomal formation of phenanthro[9,10-d]imidazole-based Zn(II) complexes with inherent optical properties have great promise for the development of imaging probes and efficient anticancer drugs.

Pyridyl-Isonicotinoyl Hydrazone-Bridged Zn(II) Coordination Framework with Thiophenedicarboxylato Link: Structure, Biological Activity, and Electrical Conductivity

Multidimensional applicability of functional materials is one of the focal attractions in today's scientific research. Highly stable and crystalline coordination polymers served as one of the active members in the club of multifunctional materials. Toward this concept, a 3-dimensional (3D) coordination framework, {[Zn2(tdc)2(pcih)2]n} (1) (tdc2-, 2,5-thiophene dicarboxylate; pcih, pyridine-4-carboxaldehyde isonicotinoyl hydrazine), is designed and has been structurally well characterized by single crystal X-ray crystallography. One of the carboxylate groups of tdc2- chelates to Zn(II), while the other carboxylato group (-COO) acts as bridging-O to neighboring Zn(II); the pcih serves as pyridyl-N bridging motif to two Zn(II) centers. The optical band gap, 3.83 eV (Tauc's plot), implies probable semiconducting ability of the material. Interestingly, the device fabricated using compound 1 measures the electrical conductivity, 2.21 × 10-5 S cm-1, and series resistance (Rs), 807 Ω, at the dark phase, which are improved significantly to 6.36 × 10-5 S cm-1 and 460 Ω, respectively, under illumination conditions. Isoniazid, used to synthesize pcih and hence the Zn(II) compound 1, is a medicine; so, the medicinal efficiency of 1 is checked by measuring the anticancer activity against MDA-MB-231, HeLa, HCT-116, and HepG2 cells. It is observed that drug efficacy is highest on MDA-MB-231 cells (IC50: 19.43 ± 1.36 μM) than other cancer cells [IC50: 24.43 ± 2.02 μM (HeLa), 26.06 ± 3.48 μM (HCT-116), and 44.28 ± 3.04 μM (HepG2)]. Therefore, the material has significant contribution in the area of energy and health toward the sustainable development goals.

An efficient one-pot synthesis of pyrazole complexes formed in situ: synthesis, crystal structure, Hirshfeld surface analysis and in vitro biological properties

The molecular crystals of monomeric and dimeric pyrazole complexes were prepared via one-pot syntheses. These are dichloridobis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.2/0.8), [Co0.20Zn0.80Cl2(C5H8N2)2] or [Co0.2Zn0.8Cl2(3,5-dmp)2] (1), and bis(μ-3,5-dimethyl-1H-pyrazole)-κ2N1:N2;κ2N2:N1-bis[bromido/chlorido(0.7/0.3)bis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.1/0.9)], [Co0.20Zn1.80Br1.40Cl0.60(C5H7N2)2(C5H8N2)2] or [Co0.1Zn0.9Br0.7Cl0.3(μ-3,5-dmp)(3,5-dmp)]2 (2). The isolated complexes contain 3,5-dimethylpyrazole (3,5-dmp) ligands formed in situ from the decomposition of 1-hydroxymethyl-3,5-dimethylpyrazole. In both isolated complexes, some positional disorder is observed at the metal ions and halogen ligands. The molecular crystals of 1 and 2 are centrosymmetric, with the space groups C2/c and P-1, respectively. Additionally, in the dinuclear complex, the pyrazole ring has a bridging coordination function with respect to the metal ions. Both complexes have good biological activities against cancer cells. The results of an in vitro cytotoxicity study indicated that compounds 1 and 2 showed significant cytotoxicity for cancer cell lines, including hepatic (HepG2 cells), lung (A549 cells) and colon cancer cells (SW 480 and SW 620). Based on the calculated IC50 values against human cancer cell lines, it was found that both complexes demonstrated potent antiproliferative activity combined with great selectivity towards cancer cells. Complex 2 was a more effective cytotoxic agent which, at the same time, exhibited high cytocompatibility. The obtained data are very encouraging and could be useful for anticancer drug discovery.

Homo- and heterometallic complexes of Zn(II), {Zn(II)Au(I)}, and {Zn(II)Ag(I)} with pentadentate Schiff base ligands as promising anticancer agents

Two families of homo- and heterometallic complexes, [Zn2L1(μ-OH)(H2O)2](ClO4)2, [Zn2L2(μ-OH)(H2O)2](ClO4)2, [Zn2L3(μ-OH)(H2O)2](ClO4)2, 1∞[{L1Zn2(μ-OH)}{μ-[Ag(CN)2]}](ClO4), [{L1Zn2(μ-OH)}2{μ-[Au(CN)2]}{[Au(CN)2]2}](ClO4)·H2O, 1∞[{L2Zn2(μ3-OH)}2(H2O){μ-[Ag(CN)2]}](ClO4)3·THF·0.5MeOH, 1∞[{L2Zn2(μ3-OH)}2(H2O){μ-[Au(CN)2]}](ClO4)3·THF·H2O, and 1∞[{L3Zn2(μ-OH)}{μ-[Ag(CN)2]}][Ag(CN)2]·H2O, respectively, have been synthesized and characterized. The Schiff bases used as ligands were obtained by condensation reactions of 2,6-diformyl-p-cresol with N,N-dimethyl-ethylenediamine (HL1), 2-aminomethyl-pyridine (HL2), and 2-aminoethyl-pyridine (HL3), respectively. The cytotoxic/cytostatic and genotoxic effects in cultured human MCF-7 (luminal type A breast cancer), MDA-MB-231 (triple negative breast cancer), HeLa (cervical carcinoma), and Lep-3 (non-tumor embryonal fibroblastoid cells) were studied. The investigations were performed by thiazolyl blue tetrazolium bromide test (MTT test), neutral red uptake cytotoxicity assay, crystal violet staining, hematoxylin and eosin staining, double staining with acridine orange and propidium iodide, AnnexinV/FITC, and Comet assay in short-term experiments (24-72 h, with monolayer cell cultures) as well as by 3D colony-forming method in long-term experiments (28 days, with 3D cancer cell colonies). The results obtained revealed that: (i) applied at a concentration range of 0.1-100 μg mL-1, the compounds investigated decrease in a time- and concentration-dependent manner the viability and/or proliferation of the treated cells; (ii) complexes of {Zn(II)Au(I)} show relatively higher cytotoxic/genotoxic activity and antitumor potential as compared to {Zn(II)Ag(I)}; (iii) some of the complexes demonstrate more pronounced cytotoxic potential than commercially available antitumor agents cisplatin, oxaliplatin, and epirubicin.

Anion-directed structural tuning of two azomethine-derived Zn2+ complexes with optoelectronic recognition of Cu2+ in aqueous medium with anti-cancer activities: from micromolar to femtomolar sensitivity with DFT revelation

Herein, two novel mononuclear transition metal Zn2+ complexes i.e. [Zn(HL)(N3)(OAc)] (NS-1) & [Zn(HL)2(ClO4)2] (NS-2) have been synthesised using a tridentate clickable Schiff base ligand, HL (2-methyl-2-((pyridin-2-ylmethyl)amino)propan-1-ol), and the polyatomic monoanions N3- and ClO4- for NS-1 and NS-2 respectively. Interestingly, NS-1 and NS-2 have been explored for the detection of Cu2+ with an LOD of 48.6 fM (response time ∼6 s) and 2.4 μM respectively through two mutually independent pathways that were studied using sophisticated methods like UV-Vis, cyclic voltammetry, ESI-MS etc. with theoretical DFT support. Herein, both chemosensors are equally responsive towards the detection of Cu2+ in aqueous as well as other targeted real field samples with appreciable recovery percentage (74.8-102%), demonstrating their practical applicability. Moreover, the detection of unbound Cu2+ in a human urine specimen was also analysed which may be helpful for the diagnosis of Cu2+-related disorders like Wilson's disease. Taking one step ahead, TLC strips have been employed for on-field detection of the targeted analytes by contact mode analysis. Additionally, the anti-cancer activity of these complexes has also been studied on breast cancer cells with the help of the MTT assay. It has been found that at a 0.5 mM dose, both NS-1 and NS-2 could kill 81.4% and 73.2% of cancer cells respectively. However, it has been found that NS-1 destroys normal cells together with cancer cells. Hence, NS-2 could be administered as a better anticancer drug for MDA-MB-231 cancer cells in comparison with NS-1. In a nutshell, the present work describes how anion-directed synthesis of two architecturally different metal complexes leads toward the detection of the same analyte via an independent chemodosimetric pathway along with their anti-cancer activities on breast cancer cells.

Anticancer activity of Ni(II) and Zn(II) complexes based on new unsymmetrical salophen-type ligands: synthesis, characterization and single-crystal X-ray diffraction

The discovery of new coordination compounds with anticancer properties is an active field of research due to the severe side effects of platinum-based compounds currently used in chemotherapy. In the search for new agents for the treatment of cancer, unsymmetrical N2O2-tetradentate ligand (H2L1 and H2L2) and their Ni(II) and Zn(II) asymmetric complexes (NiII-L1-2 and ZnII-L1-2) have been synthesized and fully characterized. 1H NMR studies revealed that the ligands and complexes were stable in mixtures of DMSO : D2O (9 : 1). Complementary UV-Vis studies confirmed that ZnII derivatives also exhibit high stability in mixtures DMSO : buffer (6 : 4) after 24 h. Single-crystal X-ray diffraction studies confirmed the molecular structures of H2L1, H2L2, NiII-L1, and NiII-L2. At the molecular level, complexes were completely planar without significant distortions of the square-planar geometry according to τ4 parameter. Furthermore, the crystalline structures revealed non-classical intermolecular interactions of the C-H⋯O and the Ni⋯Ni type. The ligands and complexes were screened against the human osteosarcoma (MG-63), human colon cancer (HCT-116), breast cancer (MDA-MB-231) cell lines, and non-cancerous cells (L929). H2L1 and H2L2 ligands not caused cytotoxic effects at a concentration of 100 μM, while NiII-L2, ZnII-L1, and ZnII-L2 complexes induce cytotoxic effects in all cell lines. NiII-L2 was a more active complex against MG-63 (3.9 ± 1.5) and HCT-116 (3.4 ± 1.7) cell lines with IC50 values in the low micromolar range. In addition, this compound was 10-, 5-, and 11-fold more potent than cisplatin in MG-63 (39 ± 1.8), HCT-116 (17.2), and MDA-MB-231 (131 ± 18), respectively. Three complexes exhibited great selectivity for tumoral cells with SI values ranging from 1.6 to 7.4.

Combining Copper and Zinc into a Biosensor for Anti-Chemoresistance and Achieving Osteosarcoma Therapeutic Efficacy

Due to its built-up chemoresistance after prolonged usage, the demand for replacing platinum in metal-based drugs (MBD) is rising. The first MBD approved by the FDA for cancer therapy was cisplatin in 1978. Even after nearly four and a half decades of trials, there has been no significant improvement in osteosarcoma (OS) therapy. In fact, many MBD have been developed, but the chemoresistance problem raised by platinum remains unresolved. This motivates us to elucidate the possibilities of the copper and zinc (CuZn) combination to replace platinum in MBD. Thus, the anti-chemoresistance properties of CuZn and their physiological functions for OS therapy are highlighted. Herein, we summarise their chelators, main organic solvents, and ligand functions in their structures that are involved in anti-chemoresistance properties. Through this review, it is rational to discuss their ligands' roles as biosensors in drug delivery systems. Hereafter, an in-depth understanding of their redox and photoactive function relationships is provided. The disadvantage is that the other functions of biosensors cannot be elaborated on here. As a result, this review is being developed, which is expected to intensify OS drugs with higher cure rates. Nonetheless, this advancement intends to solve the major chemoresistance obstacle towards clinical efficacy.

Coordination Compounds of Cu, Zn, and Ni with Dicarboxylic Acids and N Donor Ligands, and Their Biological Activity: A Review

Complexes of carboxylic acids are very often studied due to their interesting structural, spectral, and magnetic properties. This review is focused on complexes of four dicarboxylic acids, namely, 2,2'-thiodioacetic, 3,3'-thiodipropionic, 3,3'-dithiodipropionic, and fumaric acid. Many of the complexes were characterized by single crystal X-ray analyses. Without the analyses, it is very difficult to predict the coordination mode of carboxylate groups or nitrogen ligands on central atoms. Thus, structural properties are also discussed, as well as potential applications.

Antioxidant, Anti-Cancer Activity and Phytochemicals Profiling of Kigelia pinnata Fruits

Over the past few years, research studies on the therapeutic benefits of medicinal plants with potent antioxidant activity and few side effects have grown significantly. This has sparked interest in determining whether naturally occurring antioxidants could take the place of synthetic antioxidants, which are currently being constricted because of their toxic and carcinogenic properties. The identification and quantification of phytochemicals in the methanolic extract of Kigelia pinnata fruits was measured using gas chromatography–mass spectrometry (GC-MS) and ultra-high-performance liquid chromatography–mass spectrometry (UPLC-MS/MS) techniques. Additionally, the methanolic extract of fruits was used to determine antioxidant activity. Free radical-scavenging (DPPH) and ferric ion-reducing antioxidant power were measured using spectrophotometry, and total antioxidant capacity (TAC) was compared with two common antioxidants, vitamin C and α-tocopherol. Moreover, mature fruits have high DDPH, ferric ion-reducing antioxidant power and total antioxidant capacity. Furthermore, mature fruits have high levels of total phenolic, flavonoid, and tannin content; these compounds are thought to be the sources of the antioxidant activity. The major constituents of the methanolic extracts from the mature fruits of K. pinnata were found to be larixinic acid, 3,5-Dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one (DMDP), and 5-Hydrxoymethylfurfural. We performed the elemental analysis of the whole fruit. Huh-7 (liver cancer), PANC-1 (pancreatic cancer), Colo-205 (colorectal cancer), HT-29 (colorectal cancer), SNU-16 (gastric carcinoma), SW620 (colorectal adenocarcinoma) and HCT116 (colon carcinoma) were tested in vitro for anticancer activity. Both methanolic and ethyl acetate extracts of mature fruits had a positive effect on all cancer cell lines as compared to the doxorubicin drug. In addition, the methanolic extracts of mature fruits showed more potent cytotoxic effects than the ethyl acetate extracts. Moreover, the most pronounced cytotoxic effects of the methanolic extract were detected in SW620 (colorectal adenocarcinoma), with an IC50 value of 6.79 μg/mL, SNU-16 (gastric carcinoma), with and IC50 value of 8.69 μg/ ml, and in PANC-1 (pancreatic cancer) with an IC50 value of 10.34 μg/mL. Moreover, the results show that the water, ethyl acetate and methanolic extracts of mature fruits have antioxidant capacity, ferric ion-reducing antioxidant power, DPPH scavenging activity and also anticancer activity. Therefore, the present study suggests that the phytochemical profiles of mature fruits of K. pinnata may be used as potential natural antioxidants and anti-cancer cell lines.

Zinc Acts Synergistically with Berberine for Enhancing Its Efficacy as an Anti-cancer Agent by Inducing Clusterin-Dependent Apoptosis in HT-29 Colorectal Cancer Cells

It is now widely accepted that anti-cancer medications are most effective when administered in combination. Zinc is an essential micronutrient whilst berberine is a well-known natural phytochemical, both having multiple molecular mechanisms of action. The present study aimed to determine the combinatorial effect of zinc and berberine on the human adenocarcinoma HT-29 cancer cell line. The anti-proliferative activity of berberine and zinc was determined by cell viability and colony-forming assays. The combination index and drug reduction index values of zinc and berberine co-treatments were estimated by suitable software. Flow cytometry was used to analyse cell cycle distribution and Annexin V/PI staining. The expression of apoptosis and zinc signalling markers were analysed by RT-qPCR and immunoblot analysis. Berberine decreased the viability of colon cancer cells in a dose-dependent manner whilst zinc alone had no significant influence on it. However, zinc and berberine co-treatment resulted in a synergistic anti-cancer action which was demonstrated by G₂/M phase arrest of cell growth at a lower dose of berberine. Annexin V assay demonstrated that the synergistic impact of zinc and berberine boosted the number of apoptotic cells. Gene expression analysis at both transcriptional and translational levels showed the upregulation of apoptotic (caspase-3 and caspase-8) and a zinc-sensing receptor (GPR39) gene with concomitant downregulation of anti-apoptotic genes like proliferating cell nuclear antigen (PCNA) and clusterin. Our findings showed that the combination of zinc and berberine has synergistic anti-cancer efficacy and thus could be used as a potential chemopreventive option for colon cancer.

Dithiocarbazate-FeIII, -CoIII, -NiII, and -ZnII Complexes: Design, Synthesis, Structure, and Anticancer Evaluation

Non-platinum-metal complexes show great potential as anticancer agents. Herein, a series of dithiocarbazate non-Pt-metal complexes, including [Fe^III(L)₂]·Cl·2H₂O 1, [Co^III(L)₂]·NO₃·2.5H₂O 2, [Ni^II(L)₂] 3, and [Zn^II(L)₂] 4, have been designed and evaluated for their efficacy as antineoplastic agents. Among them, complex 2 exhibited higher anticancer efficacy than complexes 1, 3, 4, and cisplatin against several cancer cell lines. Hemolysis assays revealed that complex 2 showed comparable hemolysis with cisplatin. In vivo anticancer evaluations showed that complex 2 could retard tumor xenograft growth effectively with low systemic toxicity. Further studies revealed that complex 2 suppressed cancer cells by triggering multiple mechanisms involving the simultaneous inhibition of mitochondria and glycolytic bioenergetics. Overall, our study provides new insights into the anticancer mechanism of Co complexes, which can be used as a good strategy to overcome the flexibility of cancer cells to chemotherapy adaptation.

Novel 5-fluorouracil complexes of Zn(II) with pyridine-based ligands as potential anticancer agents

A series of novel Zn(II) complexes of 5-fluorouracilate (5-FU), namely [Zn(5-FU)₂(bpy)] (1), [Zn(5-FU)₂(phen)] (2), [Zn(5-FU)₂(dpya)]·H₂O (3), [Zn(5-FU)₂(bpyma)]·2H₂O (4) and [Zn(5-FU)₂(terpy)]·H₂O (5), were synthesized and structurally characterized by spectroscopic methods and X-ray crystallography. 5-FU was coordinated to Zn(II) via the deprotonated N3 site and also presented the N1 and N3 linkage isomerism in 4 and 5 due to its tautomerism. The antiproliferative activity of the complexes was studied against lung (A549), breast (MDA-MB-231), colon (HCT116) and prostate (DU145) cancer cell lines. Complexes 1, 4 and 5 except 2 and 3 showed potent growth inhibitory activity towards selected cancer cells. Remarkably, 4 was highly cytotoxic towards A549 and MDA-MB-231 cell lines, being more active than the clinical drugs cisplatin and 5-FU. In addition, 4 was not toxic to normal lung cells (BEAS-2B). The complex exhibited a significantly high affinity towards DNA as assessed by gel electrophoresis and DNA docking. The mechanistic studies of 4 in A549 cells indicated that the complex induced apoptotic cell death as evidenced via caspase 3/7 activity, Bcl2 inactivation, annexin V and DAPI/PI staining. 4 further elevated the levels of reactive oxygen species (ROS), depolarized mitochondria and enhanced the expression of γ-H2AX, thus contributing to its remarkable anticancer activity.

Syntheses, crystal structures and Hirshfeld surface analysis of (Z)-3-[(3-acetyl-2-hydroxyphenyl)amino]-2-bromoprop-2-enal and a novel ZnII complex

A novel zero-dimensional dinuclear zinc complex, di-μ-acetato-1:2κ4 O:O′-(μ-2-acetyl-6-{[(Z)-2-bromo-3-oxoprop-1-en-1-yl]azanidyl}phenolato-1κ2 O 1,O 2:2κ3 O 1,N,O 6)(N,N-dimethylacetamide-1κO)dizinc(II), [Zn2(C11H8BrNO3)(CH3COO)2(C4H9NO)] or [Zn2(L)(CH3COO)2(DMA)], 1, was synthesized using (Z)-3-[(3-acetyl-2-hydroxyphenyl)amino]-2-bromoprop-2-enal (H2 L), which was synthesized from 1-(3-amino-2-hydroxyphenyl)ethanone and 2-bromomalonaldehyde. H2 L and 1 were characterized by single-crystal X-ray diffraction, FT–IR spectroscopy and elemental analysis. Theoretical calculations of the bond orders and excited state of H2 L confirmed that there is extensive electron delocalization in the H2 L molecules. Single-crystal X-ray diffraction shows that the two Zn atoms are pentacoordinated in distorted trigonal bipyramidal configurations in the crystals of 1. The thermogravimetric analysis of 1 shows that the main frame of the complex remains stable to about 190 °C. Powder X-ray diffraction (PXRD) analysis shows that 1 possesses high purity and acid and alkali resistance. The intermolecular interactions of H2 L and 1 were analyzed using Hirshfeld surface analysis and the results indicate that the H...H and O...H interactions of H2 L and 1 play a considerable role in stabilizing the self-assembly process.

Insights into Structure and Biological Activity of Copper(II) and Zinc(II) Complexes with Triazolopyrimidine Ligands

In an attempt to increase the biological activity of the 1,2,4-triazolo[1,5-a]pyrimidine scaffold through complexation with essential metal ions, the complexes trans-[Cu(mptp)₂Cl₂] (1), [Zn(mptp)Cl₂(DMSO)] (2) (mptp: 5-methyl-7-phenyl-1,2,4-triazolo[1,5-a]pyrimidine), [Cu₂(dmtp)₄Cl₄]·2H₂O (3) and [Zn(dmtp)₂Cl₂] (4) (dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine), were synthesized and characterized as new antiproliferative and antimicrobial species. Both complexes (1) and (2) crystallize in the P2₁/n monoclinic space group, with the tetrahedral surroundings generating a square-planar stereochemistry in the Cu(II) complex and a tetrahedral stereochemistry in the Zn(II) species. The mononuclear units are interconnected in a supramolecular network through π–π interactions between the pyrimidine moiety and the phenyl ring in (1) while supramolecular chains resulting from C-H∙∙∙π interactions were observed in (2). All complexes exhibit an antiproliferative effect against B16 tumor cells and improved antibacterial and antifungal activities compared to the free ligands. Complex (3) displays the best antimicrobial activity against all four tested strains, both in the planktonic and biofilm-embedded states, which can be correlated to its stronger DNA-binding and nuclease-activity traits.

Zn(ii) complexes with thiazolyl–hydrazones: structure, intermolecular interactions, photophysical properties, computational study and anticancer activity

Title ligands and their symmetrical octahedral complexes are not photoluminescent, contrary to other synthesized asymmetrical complexes. In comparison to the ligands, the complexes showed improved antiproliferative activity and lower toxicity.

Zinc(ii) complexes of 3-bromo-5-chloro-salicylaldehyde: characterization and biological activity

Zinc(ii) complexes of 3-bromo-5-chloro-salicylaldehyde were isolated, and showed DNA- and albumin-binding affinity and antioxidant and antimicrobial properties.

hZIP1 Inhibits Progression of Clear Cell Renal Cell Carcinoma by Suppressing NF-kB/HIF-1α Pathway

Purpose

Accumulating literature has suggested that hZIP1 and HIF-1α play vital roles in the tumor process of clear cell renal cell carcinoma (ccRCC). However, the functional roles of hZIP1 and HIF-1α in ccRCC remain largely unknown.

Methods

HIF-1α protein level was evaluated by a western blot in ccRCC tissues and cell lines. ccRCC cell lines were transfected with HIF-1α-siRNA to downregulate the expression level of HIF-1α. Then the proliferative, migratory and invasive abilities of ccRCC cells in vitro were detected by real-time cell analysis (RTCA) assay, wound healing assay and transwell assay, respectively. The role of HIF-1α in vivo was explored by tumor implantation in nude mice. Then the effect on glycolysis‐related proteins was performed by western blot after hZIP1 knockdown (overexpression) or HIF-1α knockdown. The effect on NF‐kB pathway was detected after hZIP1 overexpression.

Results

HIF-1α was markedly downregulated in ccRCC tissues compared with normal areas. But HIF-1α presented almost no expression in HK-2 and ACHN cells. Immunofluorescence indicated HIF-1α and PDK1 expression in both the cytoplasm and nucleus in ccRCC cells. Downregulation of HIF-1α suppressed ccRCC cell proliferation, migration, and invasion and resulted in smaller implanted tumors in nude mice. Furthermore, hZIP1 knockdown elevated HIF-1α protein levels and PDK1 protein levels in ccRCC cells. Interestingly, a sharp downregulated expression of HIF-1α was observed after hZIP1 overexpression in OSRC-2 and 786-O cells, which resulted from a downtrend of NF-kB1 moving into the cell nucleus.

Conclusion

Our work has vital implications that hZIP1 suppresses ccRCC progression by inhibiting NF-kB/HIF-1α pathway.

Antiproliferative activity of two copper (II) complexes on colorectal cancer cell models: Impact on ROS production, apoptosis induction and NF-κB inhibition

The main goal of this work was to screen the antiproliferative activity and mechanism of actions of two copper complexes: [Cu(dmp)₂(CH₃CN)]²⁺ (1) and [Cu(phen)₂(CH₃CN)]²⁺ (2) on 2D and 3D colorectal cancer cells models. Cell viability studies on three colorectal cancer cell lines (HT-29, LS174T, Caco-2) displayed that 1 showed more robust antiproliferative activity than 2 and cisplatin. Intracellular copper content (63.24% and 48.06% for 1 and 2, respectively) can explain the differences in the cytotoxicity assay. ROS production is the primary mechanism of action involved in the antiproliferative activity of 1 showing 4-, 70- and 2.5- fold increased values of ROS level for HT-29, LS174T, Caco-2 cancer cell lines, respectively. This effect takes place along with the depolarization of the mitochondrial membrane at 2 µM. Besides, both complexes increased apoptosis on three cancer cell lines at low micromolar concentrations (0.5-2.5 μM). Moreover, 1 and 2 inhibited NF-κB pathway both in HT-29-NF-kB-hrGFP monolayer (0.5 to 1 μM) and spheroids HT-29 GFP (5 to 10 μM). This inhibitory effect leads to an inactivation of the MMP-9 expression on HT-29 cell line. Altogether, these results showed that 1 exhibits antiproliferative activity on human colorectal cancer cells in the monolayer and the 3D model.

Tris-(2-pyridyl)-pyrazolyl Borate Zinc(II) Complexes: Synthesis, DNA/Protein Binding and In Vitro Cytotoxicity Studies

Zn(II) complexes bearing tris[3-(2-pyridyl)-pyrazolyl] borate (Tppy) ligand (1-3) was synthesized and examined by spectroscopic and analytical tools. Mononuclear [TppyZnCl] (1) has a Zn(II) centre with one arm (pyrazolyl-pyridyl) dangling outside the coordination sphere which is a novel finding in TppyZn(II) chemistry. In complex [TppyZn(H2O)][BF4] (2) hydrogen bonding interaction of aqua moiety stabilizes the dangling arm. In addition, solution state behaviour of complex 1 confirms the tridentate binding mode and reactivity studies show the exogenous axial substituents used to form the [TppyZnN3] (3). The complexes (1-3) were tested for their ability to bind with Calf thymus (CT) DNA and Bovine serum albumin (BSA) wherein they revealed to exhibit good binding constant values with both the biomolecules in the order of 104-105 M-1. The intercalative binding mode with CT DNA was confirmed from the UV-Visible absorption, viscosity, and ethidium bromide (EB) DNA displacement studies. Further, the complexes were tested for in vitro cytotoxic ability on four triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, MDA-MB-468, HCC1937, and Hs 578T). All three complexes (1-3) exhibited good IC50 values (6.81 to 16.87 μM for 24 h as seen from the MTS assay) results which indicated that these complexes were found to be potential anticancer agents against the TNBC cells.

Zinc(II) complexes of 3,5-dibromo-salicylaldehyde and α-diimines: Synthesis, characterization and in vitro and in silico biological profile

The synthesis of five neutral zinc(II) complexes of 3,5-dibromo-salicyladehyde (3,5-diBr-saloH) in the presence of nitrogen-donor co-ligands 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neoc), or 2,2'-bipyridylamine (bipyam) was undertaken and complexes [Zn(3,5-diBr-salo)₂(H₂O)₂] (1), [Zn(3,5-diBr-salo)₂(bipy)] (2), [Zn(3,5-diBr-salo)₂(phen)]^.3,5-diBr-saloΗ (3), [Zn(3,5-diBr-salo)₂(neoc)] (4) and [Zn(3,5-diBr-salo)₂(bipyam)] (5) were characterized by various techniques. The crystal structures of complexes 3 and 5 were determined by X-ray crystallography, revealing the co-existence of two different coordination modes of 3,5-diBr-salo^- ligands. The new complexes show selective in vitro antibacterial activity against two Gram-positive and two Gram-negative bacterial strains. The complexes may scavenge 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radicals and reduce H₂O₂. The complexes may intercalate in-between the calf-thymus DNA-bases and have exhibited low-to-moderate ability to cleave supercoiled circular pBR322 plasmid DNA. The complexes may bind tightly and reversibly to bovine and human serum albumins. In order to explain the in vitro activity of the compounds, molecular docking studies were adopted on the crystal structure of calf-thymus DNA, human and bovine serum albumin, Escherichia coli and Staphylococcus aureus DNA-gyrase, 5-lipoxygenase, and 5-lipoxygenase activating protein. The employed in silico studies aimed to explore the ability of the compounds to bind to these target biomacromolecules, establishing a possible mechanism of action and were in accordance with the in vitro studies.

Synthesis and cytotoxicity against tumor cells of pincer N-heterocyclic ligands and their transition metal complexes

The complexes: [CoL₂](ClO₄)₂ (1), [FeL₂](ClO₄)₂ (2), [NiL₂](ClO₄)₂ (3) and [MnLCl₂] (4), with L = diethyl-1,1′-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazole-3-carboxylate), were synthesized and fully characterized. Structural analysis revealed two distinct patterns influenced by the counter ions where L acts as a tridentate chelating ligand. The in vitro antitumor activity of L and L′ (diethyl 2,2′-(pyridine-2,6-diylbis(5-methyl-1H-pyrazole-3,1-diyl)) diacetate) as well as their metal complexes, was tested by the measurement of their cytostatic and cytotoxic properties towards the blood cancer mastocytoma cell line P815. We have also investigated their interactions with the antioxidant enzyme system. As a result, [MnL′Cl₂] (1′) exhibited the strongest activity compared to reference cis-platin with no cytotoxicity towards normal cells PBMCs (Peripheral Blood Mononuclear Cells). On the other hand, the antioxidant enzyme activity showed that the efficiency of metal complex 1′ against P815 tumor cells was via the rise in the SOD activity and inhibition of CAT enzyme activity. This proof of concept study allows disclosure of a new class of molecules in cancer therapeutics.

The complexes: [CoL₂](ClO₄)₂ (1), [FeL₂](ClO₄)₂ (2), [NiL₂](ClO₄)₂ (3) and [MnLCl₂] (4), with L = diethyl-1,1′-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazole-3-carboxylate), were synthesized and fully characterized.

Effects of electroporation on anticancer activity of 5-FU and newly synthesized zinc(II) complex in chemotherapy-resistance human brain tumor cells

Zn(II) complex of Schiff base derived from the condensation of 4-aminopyrimidine-2(1H)-one with salicylaldehyde was prepared and characterized by various physico-chemical and spectral methods for structure determination. The cytotoxic activity of the Zn(II) complex was investigated in comparison with 5-fluorouracil (5-FU) against two different human brain tumor cell lines (T98G and U118), while primer human dermal fibroblast cells (HDF) was used as control for biocompatibility. Then, the effectiveness of electroporation (EP) on cytotoxic activities of these compounds has been examined. The cytotoxicities of the 5-FU and new Zn(II) complex, alone or in combination with electroporation, were determined by MTT assay. The Zn(II) complex showed good cytotoxicity against T98G and U118 brain tumor cell lines with IC₅₀ = 282.47 and 297.91 μM respectively, while it was safe on HDF healthy cells with IC₅₀ = 826.72 μM. The 5-FU exhibited less cytotoxicity compared to the Zn(II) complex against T98G (IC₅₀ = 382.35 μM) and U118 (IC₅₀ = 396.56 μM) tumor cell lines. The combined application of Zn (II) + EP decreased the IC₅₀ value by 5.96-fold in T98G cells and 4.76-fold in U118 cells. EP showed a similar effect in its combined application with 5-FU, resulting in a decrease of the IC₅₀ value of 4.22-fold in the T98G cells and 3.84-fold in the U118 cells. In a conclusion, the Zn(II) complex exhibited an anticancer potential against both brain tumor cell lines (T98G and U118) and EP greatly increased the cytotoxicity of Zn(II) complex and 5-FU on these chemotherapy-resistant cells.

The role of folic acid in inducing of apoptosis by zinc(II) complex in ovary and cervix cancer cells

Herein, the synthesis, structure, binding affinity, cytotoxicity, and apoptotic properties of the new Zn(II) complex composed of folic acid and bipyridine ligands are reported. Because folic acid has the ability to target cancer cells directly, so it can play a role in targeted drug delivery of the complex and be useful to distinguish normal cells from cancerous. After characterization of Zinc complex utilizing FTIR, EA, and NMR, the results of MTT assay were shown that viability levels of two FR-positive cell lines (HeLa and Ovcar-3) are dependent on time and concentration of [Zn(bpy)FA], whereas, did not show a significant effect on FR-negative cell lines (A549). Also, Real-time PCR revealed that the presence of FA can influence the expression of apoptosis in cervical carcinoma HeLa cells while cisplatin alone doesn't have the ability to trigger apoptosis. Furthermore, the experimental results were evaluated using pharmacophore modeling and molecular docking analysis. Finally, the stability of the Zn(II) complex was surveyed using quantum mechanical studies.

Biomimetic high performance artificial muscle built on sacrificial coordination network and mechanical training process

Artificial muscle materials promise incredible applications in actuators, robotics and medical apparatus, yet the ability to mimic the full characteristics of skeletal muscles into synthetic materials remains a huge challenge. Herein, inspired by the dynamic sacrificial bonds in biomaterials and the self-strengthening of skeletal muscles by physical exercise, high performance artificial muscle material is prepared by rearrangement of sacrificial coordination bonds in the polyolefin elastomer via a repetitive mechanical training process. Biomass lignin is incorporated as a green reinforcer for the construction of interfacial coordination bonds. The prepared artificial muscle material exhibits high actuation strain (>40%), high actuation stress (1.5 MPa) which can lift more than 10,000 times its own weight with 30% strain, characteristics of excellent self-strengthening by mechanical training, strain-adaptive stiffening, and heat/electric programmable actuation performance. In this work, we show a facile strategy for the fabrication of intelligent materials using easily available raw materials.