A novel water-soluble Cu(II) gluconate complex inhibits cancer cell growth by triggering apoptosis and ferroptosis related mechanisms.

Metal copper complexes have attracted extensive attention as potential alternatives to platinum-based anticancer drugs due to their possible different modes of action. Herein, a new copper(II) gluconate complex, namely [Cu(DPQ)(Gluc)]·2H2O (CuGluc, DPQ = pyrazino[2,3-f][1,10]phenanthroline), with good water-solubility and high anticancer activity was synthesized by using D-gluconic acid (Gluc-2H) as an auxiliary ligand. The complex was well characterized by single-crystal X-ray diffraction analysis, elemental analysis, molar conductivity, and Fourier transform infrared spectroscopy (FTIR). The DNA-binding experiments revealed that CuGluc was bound to DNA by intercalation with end-stacking binding. CuGluc could oxidatively cleave DNA, in which 1O2 and H2O2 were involved. In addition, CuGluc was bound to the IIA subdomain of human serum albumin (HSA) through hydrophobic interaction and hydrogen bonding, showing a good affinity for HSA. The complex showed superior anticancer activity toward several cancer cells than cisplatin in vitro. Further studies indicated that CuGluc caused apoptotic cell death in human liver cancer (HepG2) cells through elevated intracellular reactive oxygen species (ROS) levels, mitochondrial dysfunction, cell cycle arrest, and caspase activation. Interestingly, CuGluc also triggered the ferroptosis mechanism through lipid peroxide accumulation and inhibition of glutathione peroxidase 4 (GPX4) activity. More importantly, CuGluc significantly inhibited tumor growth in vivo, which may benefit from the combined effects of apoptosis and ferroptosis. This work provides a promising strategy to develop highly effective antitumor copper complexes by coordinating with the glucose metabolite D-gluconic acid and exploiting the synergistic effects of apoptosis and ferroptosis mechanisms.

Synthesis, structural studies, interaction with DNA/HSA and antitumor evaluation of new Cu(II) complexes containing 2-(1H-imidazol-2-yl)pyridine and amino acids.

Copper complexes are considered as potential candidates for anticancer therapy and medical applications. In this paper, three new Cu(II) complexes, [Cu(IPY)2](ClO4)2·H2O (CuI1), [Cu(IPY)(L-Phe)H2O]ClO4·0.5H2O (CuI2) and [Cu(IPY)(L-Val)H2O]ClO4 (CuI3) (where IPY = 2-(1H-imidazol-2-yl)pyridine, L-Phe = L-phenylalanine, and L-Val = L-valine), with good amphipathic properties were synthesized and characterized. Their single crystal X-ray diffraction results revealed that CuI1 was four-coordinated, while CuI2 and CuI3 both adopted a five-coordinated tetragonal pyramidal configuration. Multi-spectral methods, viscosity experiment and molecular docking technique showed that the three complexes interacted with DNA through insertion. The results of the gel electrophoresis experiments indicated that DNA was oxidatively cleaved by all the complexes in a concentration-dependent manner. Moreover, singlet oxygen (1O2), hydrogen peroxide (H2O2) and superoxide anion radicals (˙O2-) were associated with the oxidative cleavage of DNA. All the complexes also had good binding affinity with human serum albumin (HSA). The MB degradation assay revealed that all complexes could react with H2O2 to form ˙OH through Fenton-like processes. The complexes displayed good antiproliferative activity against the tested human cancer cells in vitro, including cervical carcinoma cells (HeLa), liver cancer cells (HepG2 and BEL-7402) and gastric adenocarcinoma cells (SGC-7901), but showed lower toxicity to normal liver cells (LO2). The anticancer mechanism research revealed that CuI1, CuI2 and CuI3 arrested the cell cycle at the S phase, elevated intracellular reactive oxygen species (ROS) levels and induced loss of mitochondrial membrane potential (MMP). The results indicated that these Cu(II) complexes could induce DNA damage and ROS-mediated mitochondrial dysfunction, leading to cancer cell apoptosis. Our work provides a theoretical basis for the design of new low-toxicity and highly efficient anticancer Cu(II) complexes by incorporating biological metabolites and aromatic heterocyclic ligands.

Sparfloxacin - Cu(II) - aromatic heterocyclic complexes: synthesis, characterization and in vitro anticancer evaluation.

Two new copper(II) complexes of sparfloxacin (sf), [Cu(Hsf)(HPB)(H2O)](ClO4)2 (1) and [Cu(Hsf)(PBT)(H2O)](ClO4)2 (2) (where HPB = 2-(2'-pyridyl)benzimidazole and PBT = 2-(4'-pyridyl) benzothiazole), have been synthesized and characterized by physicochemical and spectroscopic techniques. The oil-water partition coefficient (log P) values of complexes 1 and 2 were 1.47 and 1.71, respectively. By studying the interaction between the complexes and DNA, it was found that the complexes could bind to DNA through an intercalation mode. Moreover, both complexes were evaluated for antitumor activity, revealing that the complexes displayed good inhibitory activity toward the tested cancer cell lines (human lung carcinoma A549 cells, human hepatocellular carcinoma Bel-7402 cells and human esophageal carcinoma Eca-109 cells), but showed relatively low toxicity against normal human hepatic LO2 cells. In particular, the antitumor mechanism of the complexes on Eca-109 cells was investigated by morphological analysis, apoptosis analysis and determination of cell cycle arrest, mitochondrial membrane potential, reactive oxygen species (ROS) levels, and release of cytochrome c and Ca2+. The results demonstrated that the complexes could induce loss of intracellular mitochondrial functions and increase of ROS levels, which led to an increase of Ca2+ levels and the release of cytochrome c into the cytoplasm. In addition, the cell cycle was arrested in the G2/M phase, and western blot analysis showed that the caspase family was activated. These results fully proved that the complexes could induce apoptosis through DNA damage and loss of mitochondrial functions, accompanied by the regulation of endogenous proteins.

Synthesis, DNA binding, antibacterial and anticancer properties of two novel water-soluble copper(II) complexes containing gluconate.

In this paper, two new Cu(II) complexes, [Cu(Gluc)(HPB)(H2O)]Gluc (CuG1) and [Cu(Gluc)(HPBC)(H2O)]Gluc (CuG2) (where HPB = 2-(2'-pyridyl)benzimidazole, HPBC = 5-chloro-2-(2'-pyridyl)benzimidazole, Gluc = d-Gluconic acid), with good water solubility were synthesized and characterized. These complexes exhibited a five-coordinated tetragonal pyramidal geometry. The DNA binding and cleavage properties of the complexes were investigated using multi-spectroscopy, viscosity measurement, molecular docking and gel electrophoresis analysis methods. The results showed that the complexes could interact with DNA by insertion and groove binding, and cleave CT-DNA through a singlet oxygen-dependent pathway in the presence of ascorbic acid. The studies on antibacterial and anticancer activities in vitro demonstrated that both complexes had good inhibitory activity against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes) and one Gram-negative bacterium (Escherichia coli) and good cytotoxic activity toward the tested cancer cells (A549, HeLa and SGC-7901). CuG2 showed higher antimicrobial and cytotoxic activities than CuG1, which was consistent with their binding strength and cleavage ability to DNA, indicating that their antimicrobial and cytotoxic activities may be related to the DNA interaction. Moreover, the cell-based mechanism studies have indicated that CuG1 and CuG2 could arrest the cell cycle at G2/M phase, elevate the levels of intracellular reactive oxygen species (ROS) and decrease the mitochondrial membrane potential (MMP). The results showed that the complexes could induce apoptosis through DNA-damaged and ROS-mediated mitochondrial dysfunction pathways. Finally, the in vivo antitumor study revealed that CuG2 inhibited tumor growth by 50.44%, which is better than that of cisplatin (40.94%).

Synthesis, characterization, DNA/HSA interactions and in vitro cytotoxic activities of two novel water-soluble copper(II) complexes with 1,3,5-triazine derivative ligand and amino acids.

Two water-soluble copper(II) complexes of 6-(pyrazin-2-yl)-1,3,5-triazine-2,4-diamine (pzta) and amino acids, [Cu(pzta)(L-ArgH)(H2O)](ClO4)2 (1) and [Cu(pzta)(L-Met)(H2O)]ClO4·3H2O (2) (L-ArgH: protonated L-Argininate; L-Met: L-Methioninate), were synthesized and characterized. The determined X-ray crystallographic structures of 1 and 2 exhibited distorted square-pyramidal coordination geometries. Their binding properties toward calf thymus DNA (CT-DNA) and human serum protein (HSA) were measured by spectroscopic (UV-Vis, fluorescence, circular dichroism (CD)), calorimetric (isothermal titration calorimetry (ITC)) and molecular docking technology. DNA binding experiments showed that the complexes bound to DNA through a groove binding mode, the positive ΔH and ΔS values indicated that the hydrophobic interaction was the main force in the binding between the complexes and DNA. Besides, the complexes caused the fluorescence quenching of HSA through a static quenching procedure, changed the secondary structure and microenvironment of the Trp-214 residue, and preferably bound to subdomain IIA of HSA driven by hydrophobic and hydrogen-bond interactions. These results were further verified by the molecular docking technology. Furthermore, the in vitro cytotoxicities of the complexes against three human carcinoma cell lines (A549, PC-3 and HeLa) were evaluated, which confirmed that the complexation improved the anticancer activity of the pzta ligand significantly.

Two new Cu(II) dipeptide complexes based on 5-methyl-2-(2'-pyridyl)benzimidazole as potential antimicrobial and anticancer drugs: Special exploration of their possible anticancer mechanism.

In the search for more effective anticancer drugs with less toxic side effects, dipeptides were introduced into the Cu(II) complex of 5-methyl-2-(2'-pyridyl)benzimidazole (HPBM). Analytical and spectroscopic techniques were employed to thoroughly characterize complexes [Cu(Gly-gly)(HPBM)(H2O)]ClO4·0.5H2O (1) and [Cu(Gly-L-leu)(HPBM)(H2O)]ClO4 (2) (where Gly-gly = Glycyl-glycine anion, Gly-L-leu = Glycyl-l-leucine anion). The solution stability studies performed by ultraviolet-visible (UV-Vis) spectroscopy confirmed the stability of the complexes in the buffer solutions. The DNA binding affinity was evaluated using multi-spectroscopy, viscosity measurement and molecular docking methods and further quantified by Kb and Kapp values, revealing an intercalative mode. Moreover, gel electrophoresis analysis revealed that the complexes could damage CT DNA through a hydroxyl radical pathway in the presence of ascorbic acid. All the complexes displayed favorable antimicrobial and cytotoxic activities toward the tested microorganisms (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and cancer cells (A549, HeLa and PC-3). Most importantly, the possible anticancer mechanism of the complexes was explored by determining the cells morphological changes, intracellular reactive oxygen species (ROS) levels, location in mitochondria, mitochondrial membrane potentials and the expression of Bcl-2 family proteins. The results showed that the complexes could induce apoptosis in HeLa cells through an ROS-mediated mitochondrial dysfunction pathway, which was accompanied by the regulation of Bcl-2 family proteins.

Dual-Enzyme Characteristics of Polyvinylpyrrolidone-Capped Iridium Nanoparticles and Their Cellular Protective Effect against H2O2-Induced Oxidative Damage.

Polyvinylpyrrolidone-stabilized iridium nanoparticles (PVP-IrNPs), synthesized by the facile alcoholic reduction method using abundantly available PVP as protecting agents, were first reported as enzyme mimics showing intrinsic catalase- and peroxidase-like activities. The preparation procedure was much easier and more importantly, kinetic studies found that the catalytic activity of PVP-IrNPs was comparable to previously reported platinum nanoparticles. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterization indicated that PVP-IrNPs had the average size of approximately 1.5 nm and mainly consisted of Ir(0) chemical state. The mechanism of PVP-IrNPs' dual-enzyme activities was investigated using XPS, Electron spin resonance (ESR) and cytochrome C-based electron transfer methods. The catalase-like activity was related to the formation of oxidized species Ir(0)@IrO2 upon reaction with H2O2. The peroxidase-like activity originated from their ability acting as electron transfer mediators during the catalysis cycle, without the production of hydroxyl radicals. Interestingly, the protective effect of PVP-IrNPs against H2O2-induced cellular oxidative damage was investigated in an A549 lung cancer cell model and PVP-IrNPs displayed excellent biocompatibility and antioxidant activity. Upon pretreatment of cells with PVP-IrNPs, the intracellular reactive oxygen species (ROS) level in response to H2O2 was decreased and the cell viability increased. This work will facilitate studies on the mechanism and biomedical application of nanomaterials-based enzyme mimic.

Cu(II)-dipeptide complexes of 2-(4'-thiazolyl)benzimidazole: synthesis, DNA oxidative damage, antioxidant and in vitro antitumor activity.

Two new Cu(II)-dipeptide complexes of 2-(4'-thiazolyl)benzimidazole, [Cu(Gly-Gly)(TBZ)(Cl)]·4H2O (1) and [Cu(Gly-l-Leu)(TBZ)(Cl)]·H2O (2) (Gly-Gly=glycyl-glycine anion, Gly-l-Leu=glycyl-l-leucine anion and TBZ=2-(4'-thiazolyl)benzimidazole) have been synthesized and characterized by elemental analyses, molar conductance measurements and spectroscopy methods (IR, UV-visible, electrospray ionization mass spectra (ESI-MS) and EPR). The DNA binding and cleavage properties of the complexes monitored by multi-spectroscopic techniques (UV absorption, fluorescence and circular dichroism), viscosity determination and agarose gel electrophoresis indicated that the complexes bound to calf thymus (CT)-DNA via a partial intercalative mode with considerable intrinsic binding constants (Kb=1.64×10(5)M(-1) for 1 and 2.59×10(5)M(-1) for 2), and cleaved pBR322 DNA efficiently in the mediation of ascorbic acid (AA), probably via an oxidative damage mechanism induced by OH. The antioxidant activities of the complexes have been evaluated by means of modified nitroblue tetrazolium (NBT) photoreduction and cellular antioxidant activity (CAA) assays using HepG2 cells as a model, and it was found that IC50 values of 1 and 2 for dismutation of O2(-) were 0.172 and 0.247µM, respectively, and the CAA50 values were 10.57 and 10.74µM. In addition, the complexes were subjected to in vitro cytotoxicity against three human carcinoma cell lines (HeLa, A549 and HepG2), which revealed that the complexes exhibited effective cytotoxicity (IC50 values varying from 33.17 to 100µM) and selective inhibition toward HeLa cell lines. These findings indicate that the complexes have the potential to act as effective metallopeptide chemotherapeutic agents.

Water-soluble DNA minor groove binders as potential chemotherapeutic agents: synthesis, characterization, DNA binding and cleavage, antioxidation, cytotoxicity and HSA interactions.

Two new water-soluble copper(ii)-dipeptide complexes: [Cu(glygly)(PyTA)]ClO4·1.5H2O (1) and [Cu(glygly)(PzTA)]ClO4·1.5H2O (2) (glygly = glycylglycine anion, PyTA = 2,4-diamino-6-(2'-pyridyl)-1,3,5-triazine and PzTA = 2,4-diamino-6-(2'-pyrazino)-1,3,5-triazine), utilizing two interrelated DNA base-like ligands (PyTA and PzTA), have been synthesized and characterized. The structure elucidation for 1 performed by single crystal X-ray diffraction showed a one dimensional chain conformation in which the central copper ions arrange in a five-coordinate distorted square-pyramidal geometry. Spectroscopic titration, viscosity and electrophoresis measurements revealed that the complexes bound to DNA via an outside groove binding mode, and cleaved pBR322 DNA efficiently in the presence of ascorbate, probably via an oxidative mechanism with the involvement of ˙OH and ˙O2(-). Notably, the complexes exhibited considerable in vitro cytotoxicity against four human carcinoma cell lines (HepG2, HeLa, A549 and U87) with IC50 values ranging from 41.68 to 159.17 µM, in addition to their excellent SOD mimics (IC50 ~ 0.091 and 0.114 µM). Besides, multispectroscopic evidence suggested their HSA-binding at the cavity containing Trp-214 in subdomain IIA with moderate affinity, mainly via hydrophobic interaction. Further, the molecular docking technique utilized for ascertaining the mechanism and mode of action towards DNA and HSA theoretically verified the experimental results.

A new ternary copper(II) complex derived from 2-(2'-pyridyl)benzimidazole and glycylglycine: synthesis, characterization, DNA binding and cleavage, antioxidation and HSA interaction.

A new ternary copper(II)-dipeptide complex [Cu(glygly)(HPB)(Cl)]⋅2H2O (glygly=glycylglycine anion, HPB=2-(2'-pyridyl)benzimidazole) has been synthesized and characterized. The DNA interaction of the complex was studied by spectroscopic methods, viscosity, and electrophoresis measurements. The antioxidant activity was also investigated using the pyrogallol autoxidation assay. Besides, the interaction of the complex with human serum albumin (HSA) in vitro was examined by multispectroscopic techniques. The complex partially intercalated to CT-DNA with a high binding constant (Kb=7.28×10(5) M(-1)), and cleaved pBR322 DNA efficiently via an oxidative mechanism in the presence of Vc, with the HO· and O2(-) as the active species, and the SOD as a promoter. Furthermore, the complex shows a considerable SOD-like activity with the IC50 value of 3.8386 µM. The complex exhibits desired binding affinity to HSA, in which hydrogen bond or vander Waals force played a major role. The alterations of HSA secondary structure induced by the complex were confirmed by UV-visible, CD, synchronous fluorescence and 3D fluorescence spectroscopy.

Multifunctional QD-based co-delivery of siRNA and doxorubicin to HeLa cells for reversal of multidrug resistance and real-time tracking.

Co-delivery of siRNA and chemotherapeutic agents has been developed to combat multidrug resistance in cancer therapy. Recently, we developed a series of quantum dots (QDs) functionalized by ß-cyclodextrin (ß-CD) coupled to amino acids, some of which can be used to facilitate the delivery of siRNA. In this study, two CdSe/ZnSe QDs modified with ß-CD coupled to L-Arg or L-His were used to simultaneously deliver doxorubicin (Dox) and siRNA targeting the MDR1 gene to reverse the multidrug resistance of HeLa cells. In this co-delivery system, Dox was firstly encapsulated into the hydrophobic cavities of ß-CD, resulting in bypass of P-glycoprotein (P-gp)-mediated drug efflux. After complex formation of the mdr1 siRNA with Dox-loaded QDs via electrostatic interaction, significant down-regulation of mdr1 mRNA levels and P-gp expression was achieved as shown by RT-PCR and Western blotting experiments, respectively. The number of apoptotic HeLa cells after treatment with the complexes substantially exceeded the number of apoptotic cells induced by free Dox only. The intrinsic fluorescence of the QDs provided an approach to track the system by laser confocal microscopy. These multifunctional QDs are promising vehicles for the co-delivery of nucleic acids and chemotherapeutics and for real-time tracking of treatment.

catena-Poly[[[[2-(2-pyridyl-κN)-1H-benzimidazole-κN]copper(II)]-µ-l-methio-ninato-κN,O:O'] perchlorate].

The structure of the title compound, {[Cu(C(5)H(10)NO(2)S)(C(12)H(9)N(3))]ClO(4)}(n), has ortho-rhom-bic symmetry. The chain structure is constructed from square-pyramidally coordinated Cu(II) atoms linked through l-methio-nate ligands. The chains propagate along the a-axis direction and are linked to perchlorate anions via N-H⋯O hydrogen bonds.

DNA-binding and cleavage studies of novel copper(II) complex with L-phenylalaninate and 1,4,8,9-tetra-aza-triphenylene ligands.

DNA-binding properties of novel copper(II) complex [Cu(l-Phe)(TATP)(H(2)O)](+), where L-Phe=L-phenylalaninate and TATP=1,4,8,9-tetra-aza-triphenylene are investigated using electronic absorption spectroscopy, fluorescence spectroscopy, voltammetry and viscosity measurement. It is found that the presence of calf thymus DNA results in a hypochromism and red shift in the electronic absorption, a quenching effect on fluorescence nature of ethidium bromide-DNA system, an enhanced response on voltammograms of [Co(phen)(3)](3+/2+)-DNA system, and an obvious change in viscosity of DNA. From absorption titration, fluorescence analysis and voltammetric measurement, the binding constant of the complex with DNA is calculated. The latter two methods reveal the stronger binding of [Cu(l-Phe)(TATP)(H(2)O)](+) complex to double strand DNA by the moderate intercalation than [Co(phen)(3)](3+). Such a binding induces the cleavage of plasmid pBR322 DNA in the presence of H(2)O(2).