Low-dimensional compounds containing bioactive ligands. Part VI: Synthesis, structures, in vitro DNA binding, antimicrobial and anticancer properties of first row transition metal complexes with 5-chloro-quinolin-8-ol

8-hydroxyquinoline-N-oxide copper(II)- and zinc(II)-phenanthroline and bipyridine coordination compounds: Design, synthesis, structures, and antitumor evaluation

Fourteen novel tumor-targeting copper(II) and zinc(II) complexes, [Cu(ONQ)(QD1)(NO3)]·CH3OH (NQ3), [Cu(ONQ)(QD2)(NO3)] (NQ2), [Cu(NQ)(QD2)Cl] (NQ3), [Cu(ONQ)(QD1)Cl] (NQ4), [Cu(ONQ)(QD3)](NO3) (NQ5), [Cu(ONQ)(QD3)Cl] (NQ6), [Zn(ONQ)(QD4)Cl] (NQ7), [Zn(ONQ)(QD1)Cl] (NQ8), [Zn(ONQ)(QD5)Cl] (NQ9), [Zn(ONQ)(QD2)Cl] (NQ10), [Zn(ONQ)(QD6)Cl] (NQ11), [Zn(ONQ)(QD7)Cl] (NQ12), and [Zn(ONQ)(QD3)Cl] (NQ13) supported on 8-hydroxyquinoline-N-oxide (H-ONQ), 2,2'-dipyridyl (QD1), 5,5'-dimethyl-2,2'-bipyridyl (QD2), 1,10-phenanthroline (QD3), 4,4'-dimethoxy-2,2'-bipyridyl (QD4), 4,4'-dimethyl-2,2'-bipyridyl (QD5), 5-chloro-1,10-phenanthroline (QD6), and bathophenanthroline (QD7), were first synthesized and characterized using various spectroscopic techniques. Furthermore, NQ1-NQ13 exhibited higher antiproliferative activity and selectivity for cisplatin-resistant SK-OV-3/DDP tumor cells (CiSK3) compared to normal HL-7702 cells based on results obtained from the cell counting Kit-8 (CCK-8) assay. The complexation of copper(II) ion with QD2 and ONQ ligands resulted in an evident increase in the antiproliferation of NQ1-NQ6, with NQ6 exhibiting the highest antitumor potency against CiSK3 cells compared to NQ1-NQ5, H-ONQ, QD1-QD7, and NQ7-NQ13 as well as the reference cisplatin drug with an IC50 value of 0.17 ± 0.05 μM. Mechanistic studies revealed that NQ4 and NQ6 induced apoptosis of CiSK3 cells via mitophagy pathway regulation and adenosine triphosphate (ATP) depletion. Further, the differential induction of mitophagy decreased in the order of NQ6 > NQ4, which can be attributed to the major impact of the QD3 ligand with a large planar geometry and the Cl leaving group within the NQ6 complex. In summary, these results confirmed that the newly synthesized H-ONQ copper(II) and zinc(II) coordination metal compounds NQ1-NQ13 exhibit potential as anticancer drugs for cisplatin-resistant ovarian CiSK3 cancer treatment.

Biological and computational investigation of transition metal(II) complexes of 2-phenoxyaniline-based ligands

Aim: In the 21st century, we are witness of continuous onslaughts of various pathogen deformities which are a major cause of morbidity and mortality worldwide. Therefore, to investigate the grave for these deformities, antioxidant, anti-inflammatory and antimicrobial biological activities were carried out against newly synthesized Schiff base ligands and their transition metal complexes, which are based on newly synthesized 2-phenoxyaniline and salicylaldehyde derivatives. Materials & methods: The synthesized compounds were characterized by various physiochemical studies, demonstrating the octahedral stereochemistry of the complexes. Results: The biological assessments revealed that complex 6 (3.01 ± 0.01 μM) was found to be highly active for oxidant ailments whereas complex 14 (7.14 ± 0.05 μM, 0.0041-0.0082 μmol/ml) was observed as highly potent for inflammation and microbial diseases. Conclusion: Overall, the biological and computational studies demonstrate that the nickel(II) complex 14 can act as an excellent candidate for pathogen deformities.

Synthesis and anticancer mechanisms of zinc(II)-8-hydroxyquinoline complexes with 1,10-phenanthroline ancillary ligands

Twenty new zinc(II) complexes with 8-hydroxyquinoline (H-Q1-H-Q6) in the presence of 1,10-phenanthroline derivatives (D1-D10) were synthesized and formulated as [Zn(Q1)₂(D1)] (DQ1), [Zn(Q2)₂(D2)]·CH₃OH (DQ2), [Zn(Q1)₂(D3)] (DQ3), [Zn(Q1)₂(D4)] (DQ4), [Zn(Q3)₂(D5)] (DQ5), [Zn(Q3)₂(D4)] (DQ6), [Zn(Q4)₂(D5)]·CH₃OH (DQ7), [Zn(Q4)₂(D6)] (DQ8), [Zn(Q4)₂(D3)]·CH₃OH (DQ9), [Zn(Q4)₂(D1)]·H₂O (DQ10), [Zn(Q5)₂(D4)] (DQ11), [Zn(Q6)₂(D6)]·CH₃OH (DQ12), [Zn(Q5)₂(D2)]·5CH₃OH·H₂O (DQ13), [Zn(Q5)₂(D7)]·CH₃OH (DQ14), [Zn(Q5)₂(D8)]·CH₂Cl₂ (DQ15), [Zn(Q5)₂(D9)] (DQ16), [Zn(Q5)₂(D1)] (DQ17), [Zn(Q5)₂(D5)] (DQ18), [Zn(Q5)₂(D10)]·CH₂Cl₂ (DQ19) and [Zn(Q5)₂(D3)] (DQ20). They were characterized using multiple techniques. The cytotoxicity of DQ1-DQ20 was screened using human cisplatin-resistant SK-OV-3/DDP ovarian cancer (SK-OV-3CR) cells and normal hepatocyte (HL-7702) cells. Complex DQ6 showed low IC₅₀ values (2.25 ± 0.13 μM) on SK-OV-3CR cells, more than 3.0-8.0 times more cytotoxic than DQ1-DQ5 and DQ7-DQ20 (≥6.78 μM), and even 22.2 times more cytotoxic than the standard cisplatin, the corresponding free H-Q1-H-Q6 and D1-D10 alone (>50 μM). As a comparison, DQ1-DQ20 displayed nontoxic rates against healthy HL-7702 cells. Furthermore, DQ6 and DQ11 induced significant apoptosis via mitophagy pathways. DQ6 also significantly inhibited tumor growth in an in vivo SK-OV-3-xenograft model (ca. 49.7%). Thus, DQ6 may serve as a lead complex for the discovery of new antitumor agents.

Low-Dimensional Compounds Containing Bioactive Ligands. Part XIX: Crystal Structures and Biological Properties of Copper Complexes with Halogen and Nitro Derivatives of 8-Hydroxyquinoline

Six new copper(II) complexes were prepared: [Cu(ClBrQ)2] (1a, 1b), [Cu(ClBrQ)2]·1/2 diox (2) (diox = 1,4-dioxane), [Cu(BrQ)2] (3), [Cu(dNQ)2] (4), [Cu(dNQ)2(DMF)2] (5) and [Cu(ClNQ)2] (6), where HClBrQ is 5-chloro-7-bromo-8-hydroxyquinoline, HBrQ is 7-bromo-8-hydroxyquinoline, HClNQ is 5-chloro-7-nitro-8-hydroxyquinoline and HdNQ is 5,7-dinitro-8-hydroxyquinoline. Prepared compounds were characterised by infrared spectroscopy, elemental analysis and by X-ray structural analysis. Structural analysis revealed that all complexes are molecular. Square planar coordination of copper atoms in [Cu(XQ)2] (XQ = ClBrQ (1a, 1b), BrQ (3) and ClNQ (6)) and tetragonal bipyramidal coordination in [Cu(dNQ)2(DMF)2] (5) complexes were observed. In these four complexes, bidentate chelate coordination of XQ ligands via oxygen and nitrogen atoms was found. Hydrogen bonds stabilizing the structure were observed in [Cu(dNQ)2(DMF)2] (5) and [Cu(ClNQ)2] (6), no other nonbonding interactions were noticed in all five structures. The stability of the complexes in DMSO and DMSO/water was evaluated by UV-Vis spectroscopy. Cytotoxic activity of the complexes and ligands was tested against MCF-7, MDA-MB-231, HCT116, CaCo2, HeLa, A549 and Jurkat cancer cell lines. The selectivity of the complexes was verified on a noncancerous Cos-7 cell line. Antiproliferative activity of the prepared complexes was very low in comparison with cisplatin, except complex 3; however, its activity was not selective and was similar to the activity of its ligand HBrQ. Antibacterial potential was observed only with ligand HClNQ. Radical scavenging experiments revealed relatively high antioxidant activity of complex 3 against ABTS radical.

Antimicrobial Activities Along With Spectrophotometric Assessment of Stability Constants of Copper (II) and Cobalt (II) With 1,2-Bis(2,5-dimethoxybenzylidene) Hydrazine

The stability constants of 1,2-bis(2,5-dimethoxybenzylidene) hydrazine (DMBH) were determined using the modified Job’s method with the addition of the UV-Vis approach using salts of copper (II) (chloride and acetate) and salts of cobalt (II) (chloride and nitrate). Copper (II) chloride with a ligand at 1L:2M (stoichiometric ratio) was discovered to have a higher stability constant log value (6.995) than other metal salts. The stability constant log value (5.811) for cobalt (II) nitrate at 1L:2M (stoichiometric ratio) was found to be less stable than the other stability constants evaluated. Antimicrobial properties of the ligand were tested against Entamoeba coli, Candida albicans, and Staphylococcus aureus. The ligand was found to be effective against these strains, with positive results.

A new class of nickel(II) oxyquinoline-bipyridine complexes as potent anticancer agents induces apoptosis and autophagy in A549/DDP tumor cells through mitophagy pathways

A new class of nickel(II) oxyquinoline-bipyridine complexes, namely, [Ni(La1)2(Lb6)] (Ni1), [Ni(La1)2(Lb2)] CH3OH (Ni2), [Ni(La7)2(Lb11)]2H2O (Ni3), [Ni(La1)2(Lb9)] (Ni4), [Ni(La1)2(Lb8)] (Ni5), [Ni(La2)2(Lb1)] (Ni6), [Ni(La2)2(Lb6)]CH3OH (Ni7), [Ni(La2)2(Lb11)]CH3OH (Ni8), [Ni(La2)2(Lb3)] (Ni9), [Ni(La2)2(Lb2)]CH3OH (Ni10), [Ni(La2)2(Lb5)]CH3OH...

Antimicrobial and Anticancer Application of Silver(I) Dipeptide Complexes

Three silver(I) dipeptide complexes [Ag(GlyGly)]_n(NO₃)_n (AgGlyGly), [Ag₂(GlyAla)(NO₃)₂]_n (AgGlyAla) and [Ag₂(HGlyAsp)(NO₃)]_n (AgGlyAsp) were prepared, investigated and characterized by vibrational spectroscopy (mid-IR), elemental and thermogravimetric analysis and mass spectrometry. For AgGlyGly, X-ray crystallography was also performed. Their stability in biological testing media was verified by time-dependent NMR measurements. Their in vitro antimicrobial activity was evaluated against selected pathogenic microorganisms. Moreover, the influence of silver(I) dipeptide complexes on microbial film formation was described. Further, the cytotoxicity of the complexes against selected cancer cells (BLM, MDA-MB-231, HeLa, HCT116, MCF-7 and Jurkat) and fibroblasts (BJ-5ta) using a colorimetric MTS assay was tested, and the selectivity index (SI) was identified. The mechanism of action of Ag(I) dipeptide complexes was elucidated and discussed by the study in terms of their binding affinity toward the CT DNA, the ability to cleave the DNA and the ability to influence numbers of cells within each cell cycle phase. The new silver(I) dipeptide complexes are able to bind into DNA by noncovalent interaction, and the topoisomerase I inhibition study showed that the studied complexes inhibit its activity at a concentration of 15 μM.

An in vitro selective inhibitory effect of silver(i) aminoacidates against bacteria and intestinal cell lines and elucidation of the mechanism of action by means of DNA binding properties, DNA cleavage and cell cycle arrest

Novel silver(i) aminoacidate complexes {[Ag(HVal)(H₂O)(NO₃)]}_n (AgVal) and {[Ag₃(HAsp)₂(NO₃)]}_n·nH₂O (AgAsp) were prepared, investigated and fully characterized by vibrational spectroscopy (mid-IR), elemental analysis, thermogravimetric analysis, X-ray crystallography and mass spectrometry. Their stability in D₂O and PBS buffer was verified by time-dependent ¹H and ¹³C NMR measurements. Their in vitro antibacterial activity (against pathogenic Staphylococcus aureus CCM4223, Escherichia coli CCM4787) and that against probiotic bacteria Lactobacillus plantarum CCM7102 and Lactobacillus reuteri (L26) were determined and potential dosing concentration was evaluated. The cytotoxicity of both the complexes against intestinal porcine epithelial (IPEC-1) and human epithelial colorectal adenocarcinoma (CaCo-2) cell lines was determined using the colorimetric MTT assay and against human metastatic melanoma (A2058), human pancreatic adenocarcinoma (PaTu 8902), human cervical adenocarcinoma (HeLa), human colorectal carcinoma (HCT116), human leukaemic T cell lymphoma (Jurkat), and human dermal fibroblasts (HDF) using colorimetric MTS assay. The selectivity index (SI) was identified for intestinal cancer (CaCo-2) and healthy (IPEC-1) cells. The mechanism of action of AgVal and AgAsp was further elucidated and discussed by the study of their binding affinity toward the CT DNA, the ability to cleave the supercoiled form of pUC19 DNA and the ability to influence numbers of cells within each cell cycle.

Design, Synthesis, and Antifungal Evaluation of 8-Hydroxyquinoline Metal Complexes against Phytopathogenic Fungi

Phytopathogenic fungal infections have become a major threat to agricultural production, food security, and human health globally, and novel antifungal agents with simple chemical scaffolds and high efficiency are needed. In this study, we designed and synthesized 38 8-hydroxyquinoline metal complexes and evaluated their antifungal activities. The results showed that most of the tested compounds possessed remarkable in vitro antifungal activity. Especially, compound 1e exhibited the highest antifungal potency among all target compounds, with EC₅₀ values of 0.0940, 0.125, 2.95, and 5.96 μg/mL, respectively, against Sclerotinia sclerotiorum, Botrytis cinerea, Fusarium graminearum, and Magnaporthe oryzae. Preliminary mechanistic studies had shown that compound 1e might cause mycelial abnormalities of S. sclerotiorum, cell membrane permeability changes, leakage of cell contents, and inhibition of sclerotia formation and germination. Moreover, the results of in vivo antifungal activity of compound 1e against S. sclerotiorum showed that 1e possessed higher curative effects than that of the positive control azoxystrobin. Therefore, compound 1e is expected to be a novel leading structure for the development of new antifungal agents.

In vitro biological evaluation and consideration about structure-activity relationship of silver(I) aminoacidate complexes

Two silver(I) aminoacidate complexes {[Ag₄(L-HAla)₄(NO₃)₃]NO₃}_n (AgAla, complex 1, Ala = alanine) and {[Ag(L-Phe)]}_n (AgPhe, complex 2, Phe = phenylalanine) were prepared and characterized by elemental, spectral analysis (FT-IR, NMR techniques) and single crystal X-ray analysis in solid state and their solution stability was measured in biological testing time-scale by ¹H NMR. The bridging coordination modes of the zwitterionic Ala and deprotonated Phe ligands led to the formation of 1D polymeric chains of the complexes. The significant argentophilic interactions are presented in the structure of AgAla. Antimicrobial testing of prepared Ag(I) complexes was evaluated by IC₅₀ and MIC values and were compared with AgGly, silver(I) sulfadiazine and AgNO₃ samples. Moreover, MTS test was used to the testing of broad range antiproliferative activity of studied compounds against different cancer cell lines and also to the investigation of calf thymus DNA interactions by absorption spectroscopy, fluorescence spectroscopy, Ethidium bromide/Hoechst 33258 displacement experiments and circular dichroism spectroscopy. To evaluate the pUC19 DNA fragmentation by silver(I) complexes, the agarose gel electrophoresis was used. In addition to biological evaluation we used lipophilicity measurement results in the discussion about structure-activity relationship (SAR).

A Comparative Investigation of the Role of the Anchoring Group on Perylene Monoimide Dyes in NiO-Based Dye-Sensitized Solar Cells

The anchoring group of a sensitizer may strongly affect the overall properties and stability of the resulting dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthetic solar cells (DSPECs). The properties of seven perylene monoimide (PMI) dyes have been comprehensively studied for their immobilization on nanocrystalline NiO film. The PMI dyes differ only by the nature of the anchoring group, which are: carboxylic acid (PMI-CO₂ H), phosphonic acid (PMI-PO₃ H₂ ), acetyl acetone (PMI-acac), pyridine (PMI-Py), aniline (PMI-NH₂ ), hydroxyquinoline (PMI-HQ), and dipicolinic acid (PMI-DPA). The dyes are investigated by cyclic voltammetry and spectroelectrochemistry and modeled by TD-DFT quantum chemical calculations. The mode of binding of these anchoring groups is investigated by infrared spectroscopy and the stability of the binding to NiO surface is studied by desorption experiments in acidic and basic media. The phosphonic acid group is found to offer the strongest binding to the NiO surface in terms of stability and dye loading. Finally, a photophysical study by ultrafast transient absorption spectroscopy shows that all dyes inject a hole in NiO with rate constants on a subpicosecond timescale and display similar charge recombination kinetics. The photovoltaic properties of the dyes show that PMI-HQ and PMI-acac give the highest photovoltaic performances, owing to a lower degree of aggregation on the surface.

In vitro antiproliferative effect of vanadium complexes bearing 8-hydroxyquinoline-based ligands – the substituent effect

This is the first comprehensive study demonstrating the antiproliferative effect of vanadium complexes bearing 8-hydroxyquinoline (quinH) ligands, including the parent and –CH₃ (Me), –NO₂, –Cl and –I substituted ligands, on HCT116 and A2780 cancer cell lines.

Small Molecular Leads Differentially Active Against HER2 Positive and Triple Negative Breast Cancer Cell Lines

Background:

Breast cancer is the most prevalent cancer type in women globally. It is characterized by distinct subtypes depending on different gene expression patterns. Oncogene HER2 is expressed on the surface of cell and is responsible for cell growth regulation. Increase in HER2 receptor protein due to gene amplification, results in aggressive growth, and high metastasis in cancer cells.

Methods:

The current study evaluates and compares the anti-breast cancer effect of commercially available compounds against HER2 overexpressing BT-474, and triple negative MDA-MB-231 breast cancer cell lines.

Results:

Preliminary in vitro cell viability assays on these cell lines identified 6 lead molecules active against breast cancer. Convallatoxin (4), a steroidal lactone glycoside, showed the most potent activity with IC50 values of 0.63 ± 0.56, and 0.69 ± 0.59 µM against BT-474 and MDA-MB-231, respectively, whereas 4-[4-(Trifluoromethyl)-phenoxy] phenol (3) a phenol derivative, and Reserpine (5) an indole alkaloid selectively inhibited the growth of BT-474, and MDA-MB-231 breast cancer cells, respectively.

Conclusion:

These results exhibited the potential of small molecules in the treatment of HER2 amplified and triple negative breast cancers in vitro.

Silver pyridine-2-sulfonate complex - its characterization, DNA binding, topoisomerase I inhibition, antimicrobial and anticancer response

In the current study the ability of silver pyridine-2-sulfonate complex to exert multiple biological activities is compared with the pharmacological action of silver sulfadiazine (AgSD). Polymeric form of {[Ag(py-2-SO₃)]}_n (AgPS) was synthesized and characterized by analytical techniques (IR, CHN, TG/DTA, MS) and its molecular formula was established. The crystal structure was determined by X-ray diffraction method and the polymeric complex crystallizes in the triclinic P-1 space group. The stability of Ag(I) complex was verified by ¹H and ¹³C NMR measurements and the interaction with calf thymus DNA through UV-VIS and fluorescence quenching experiments was studied. The Ag(I) complex was able to interact with DNA by dual binding mode: partial intercalation along groove binding. The binding constants were calculated to be in the order of 10³ M^-1. Topoisomerase I inhibition study have shown that silver complex is inhibiting its activity at concentration of 30 μM. The cytotoxic activity of AgPS and AgSD against mouse leukaemia L1210 S, R and T cell line was also evaluated. AgPS showed higher cytotoxicity than AgSD after 48 h incubation. The results suggest that mechanism of cell death is necrosis with a contribution of late apoptosis. Antimicrobial testing indicates higher growth inhibition effect of AgPS with comparison to commercially available AgSD.