Bio-affinity of copper(II) complexes with nitrogen and oxygen donor ligands: Synthesis, structural studies and in vitro DNA and HSA interaction of copper(II) complexes

Functionalization of a porous copper(ii) metal-organic framework and its capacity for loading and delivery of ibuprofen

A porous copper(ii) metal-organic framework (MOF) of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine(N3ttb) and 5-nitroisophthalic acid (npd) formulated as [Cu(npd)(N3ttb)]·(DMF)(H2O) 1 (DMF = dimethylformamide) was synthesized and characterized by elemental analyses, spectroscopic techniques, single crystal X-ray crystallography, and scanning electron microscopy. Single crystal X-ray crystallographic analysis of the copper(ii) metal-organic framework reveals a monoclinic crystal system with space group P21/c. The copper(ii) ion is in a five-coordinate geometry consisting of three meridional nitrogen atoms of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine and two oxygen atoms of 5-nitroisophthalic acid to form a square pyramidal structure. The compound was functionalized with ethylenediamine (ED) to form [Cu(npd)(N3ttb)]-ED 2 that was characterized by FT-IR, PXRD, SEM-EDX and BET and the drug loading capacity was investigated and compared with that of as-synthesized MOFs. The amount of ibuprofen loaded was 916.44 mg g-1 (15.27%) & 1530.20 mg g-1 (25.50%) over 1 and 2, respectively. The results indicate that the functionalized MOFs 2 have a higher loading capacity for ibuprofen than 1 by 613.76 mg g-1 (10.23%), which could be ascribed to the acid-base interactions in the functionalized molecules. The results show that [Cu(npd)(N3ttb)]-ED 2 is a better drug transporter than [Cu(npd)(N3ttb)]·(DMF)(H2O) 1 due to the presence of an amine functional group that interacts with the acid group on the ibuprofen through non-covalent bonds interactions.

Fe(II) complexes of 2,2':6',2''-terpyridine ligands functionalized with substituted-phenyl groups: synthesis, crystal structures and anticancer potential

With the aim of developing potential anticancer drug candidates, a series of Fe(II) complexes were synthesized using nine 2,2':6',2''-terpyridine ligands functionalized with substituted-phenyl groups, and their biological activities were systematically investigated. Their bis-terpyridine sandwich-like structures were determined by single crystal X-ray crystallography. In vitro antiproliferative experiments based on three human cancer cell lines, including human hepatoma cancer cell line (Bel-7402), human esophageal cancer cell line (Eca-109), and human cervical squamous cancer cell line (SiHa), indicate the high antiproliferation activities of these complexes compared with commercial cisplatin. And their toxicity to normal cells was estimated based on human normal hepatocyte (HL-7702) cell line. In particular, when the phenyl in terpyridine ligand was modified by a carboxyl group, the corresponding complex 3 exhibited much higher antiproliferation to cancer Bel-7402 cells (IC50 = 3.653 μmol L-1) than cisplatin and low toxicity to normal HL-7702 cells (IC50 = 99.92 μmol L-1), implying a significant selectivity for 3 in killing hepatoma cancer cells. Combined with the fact that iron element is more accessible than platin, this series of Fe(II) complexes comprises potential candidates for anticancer drugs with specific inhibition of hepatoma cancer. UV titration experiments and circular dichroism (CD) showed a strong binding affinity between these nine complexes and CT-DNA. However, molecular docking simulation revealed the competitive binding of DNA and protein to these complexes. Further, the interactions between these complexes and bovine serum albumin (BSA) have been studied by fluorescence titration and CD spectroscopy.

An Integrated Analysis of Mechanistic Insights into Biomolecular Interactions and Molecular Dynamics of Bio-Inspired Cu(II) and Zn(II) Complexes towards DNA/BSA/SARS-CoV-2 3CLpro by Molecular Docking-Based Virtual Screening and FRET Detection

Novel constructed bioactive mixed-ligand complexes (1b) [Cu^II(L)₂(phen)] and (2b) [Zn^II(L)₂(phen)] {where, L = 2-(4-morpholinobenzylideneamino)phenol), phen = 1,10-phenanthroline} have been structurally analysed by various analytical and spectroscopic techniques, including, magnetic moments, thermogravimetric analysis, and X-ray crystallography. Various analytical and spectral measurements assigned showed that all complexes appear to have an octahedral geometry. Agar gel electrophoresis's output demonstrated that the Cu(II) complex (1b) had efficient deoxyribonucleic cleavage and complex (2b) demonstrated the partial cleavage accomplished with an oxidation agent, which generates spreadable OH^● through the Fenton type mechanism. The DNA binding constants observed from viscosity, UV-Vis spectral, fluorometric, and electrochemical titrations were in the following sequence: (1b) > (2b) > (HL), which suggests that the complexes (1b-2b) might intercalate DNA, a possibility that is supported by the biothermodynamic measurements. In addition, the observed binding constant results of BSA by electronic absorption and fluorometric titrations indicate that complex (1b) revealed the best binding efficacy as compared to complex (2b) and free ligand. Interestingly, all compounds are found to interact with BSA through a static approach, as further attested by FRET detection. The DFT and molecular docking calculations were also performed to realize the electronic structure, reactivity, and binding capability of all test samples with CT-DNA, BSA, and the SARS-CoV-2 3CL^Pro, which revealed the binding energies were in a range of -8.1 to -8.9, -7.5 to -10.5 and -6.7--8.8 kcal/mol, respectively. The higher reactivity of the complexes than the free ligand is supported by the FMO theory. Among all the observed data for antioxidant properties against DPPH^᛫, ^᛫OH, O₂^-• and NO^᛫ free radicals, complex (1a) had the best biological efficacy. The antimicrobial and cytotoxic characteristics of all test compounds have been studied by screening against certain selected microorganisms as well as against A549, HepG2, MCF-7, and NHDF cell lines, respectively. The observed findings revealed that the activity enhances coordination as compared to free ligand via Overtone's and Tweedy's chelation mechanisms. This is especially encouraging given that in every case, the experimental findings and theoretical detections were in perfect accord.

Design and Syntheses of Ruthenium ENE (E = S, Se) Pincer Complexes: A Versatile System for Catalytic and Biological Applications

This report describes synthesis of two ruthenium(II) ENE pincer complexes (E = S, C1 and E = Se, C2 ) by the reaction of bis(2-(phenylchalcogenyl)ethyl)amine ( L1 , L2 ) with RuCl 2 (PPh 3 ) 3 . The complexes were characterized with the help of 1 H and 13 C{ 1 H} NMR, FTIR, HRMS, cyclic voltammetry and elemental analysis techniques. The structure and bonding mode of ligand with ruthenium in C2 was established with the help of single crystal X-ray diffraction. The complex showed distorted octahedral geometry with two chlorine atoms trans to each other. The Ru-Se bond distances (Å) are 2.4564(3)-2.4630(3), Ru-N distance is 2.181(2), Ru-P distance is 2.2999(6), and Ru-Cl distances are 2.4078(6)-2.4314(6). The complexes showed good to excellent catalytic activity for the N -alkylation of 1,2-phenylenediamine with benzyl alcohol derivatives to synthesize 1,2-disubstituted benzimidazole derivatives. The complexes were also found to be efficient for aerobic oxidation of benzyl alcohols to corresponding aldehydes which are precursors to the bisimines generated in situ during the synthesis of 1,2-disubstituted benzimidazole derivatives. Complex C2 where selenium is coordinated with ruthenium was found to be more efficient as compared to sulfur coordinated ruthenium complex C1 . Since ruthenium complexes are getting increasing attention for developing new anticancer agents, the preliminary studies like binding behavior of both the complexes towards CT-DNA were studied by competitive binding with ethidium bromide (EthBr) using emission spectroscopy. In addition, the interactions of C1-C2 were also studied with bovine serum albumin (BSA) using steady state fluorescence quenching and synchronous fluorescence studies. A good stability of Ru(II) state was observed by cyclic voltammetric studies of C1-C2 . Overall these molecules are good examples of bio-organometallic systems for catalytic and biological applications.

Polydopamine-Coated Copper-Substituted Mesoporous Silica Nanoparticles for Dual Cancer Therapy

Combinational therapy using chemodynamictherapy (CDT) and photothermal therapy (PTT) is known to enhance the therapeutic outcome for cancer treatment. In this study, a biocompatible nano formulation was developed by coating polydopamine (PDA) over doxorubicin (DOX)-loaded copper-substituted mesoporous silica (CuMSN) nanoparticles. PDA coating not only allowed selective photothermal properties with an extended DOX release but also enhanced the water solubility and biocompatibility of the nanocomposites. The nanocomposites displayed a monodispersed shape and pH-dependent release characteristics, with an outstanding photothermal conversion and excellent tumor cell inhibition. The cellular-uptake experiments of CuMSN@DOX@PDA in A549 cells indicated that nanoparticles (NPs) aided in the enhanced DOX uptake in tumor cells compared to free DOX with synergistic anti-cancer effects. Moreover, the cell-viability studies displayed remarkable tumor inhibition in combinational therapy over monotherapy. Thus, the synthesized CuMSN@DOX@PDA NPs can serve as a promising platform for dual cancer therapy.

Copper Adsorption to Microplastics and Natural Particles in Seawater: A Comparison of Kinetics, Isotherms, and Bioavailability

The growing use of plastics has led to microplastics (MPs) being ubiquitously distributed in marine environments. Although previous studies have emphasized MPs as important metal-transport vectors, few have considered the differences between these anthropogenic particles and their coexisting natural counterparts in sequestering metals in seawater. Here, we compared Cu adsorption to pristine and naturally aged MPs (polystyrene and polyethylene) with that to algae particles and sediments and assessed the bioavailability of the adsorbed Cu by a gut juice extraction assay. Adsorption kinetics and isotherms consistently showed that natural particles bound far more Cu to their surfaces than MPs. The rougher surfaces, greater specific surface areas, and lower ζ-potentials of natural particles contributed to their stronger Cu adsorption capacity than pristine or aged MPs. Natural particles also contained more diverse functional groups for binding Cu, with oxygen-containing groups playing a dominant role. Adsorbed Cu on natural particles was less extractable by sipunculan gut juice than that on MPs, indicating their higher Cu affinity. Overall, our study suggests that natural particles outcompete MPs in carrying metals in the water column and transferring them to marine organisms in today's environmental context. This work provides new insights for assessing the risks of MPs in marine environments.

Synthesis, Characterization, Photoluminescence, Molecular Docking and Bioactivity of Zinc (II) Compounds Based on Different Substituents

Six new zinc(II) complexes were prepared by the reaction of ZnBr₂ or ZnI₂ with 4′-(substituted-phenyl)-2,2′:6′,2′′-terpyridine compounds, bearing p-methylsulfonyl (L¹), p-methoxy (L²) and p-methyl (L³), which were characterized by elemental analysis, FT-IR, NMR and single crystal X-ray diffraction. The antiproliferative properties against Eca-109, A549 and Bel-7402 cell lines and the cytotoxicity test on RAW-264.7 of these compounds were monitored using a CCK-8 assay, and the studies indicate that the complexes show higher antiproliferative activities than cisplatin. The interactions of these complexes with CT-DNA and proteins (BSA) were studied by UV-Vis, circular dichroism (CD) and fluorescent spectroscopy, respectively. The results indicate that the interaction of these zinc(II) complexes with CT-DNA is achieved through intercalative binding, and their strong binding affinity to BSA is fulfilled through a static quenching mechanism. The simulation of the complexes with the CT-DNA fragment and BSA was studied by using molecular docking software. It further validates that the complexes interact with DNA through intercalative binding mode and that they have a strong interaction with BSA.

Structural-Dependent N,O-Donor Imine-Appended Cu(II)/Zn(II) Complexes: Synthesis, Spectral, and in Vitro Pharmacological Assessment

Four mononuclear bioefficient imine-based coordination complexes, [(L ¹ ) ₂ Cu], [(L ¹ ) ₂ Zn], [(L ² )Cu(H ₂ O)], and [(L ² )Zn(H ₂ O)], were synthesized using ligands [L ¹ = 2-(((3-hydroxynaphthalen-2-yl)methylene)amino)-2-methylpropane-1,3-diol and L ² = 4-(1-((1,3-dihydroxy-2-methylpropan-2-yl)imino)ethyl)benzene-1,3-diol]. The formation of the complexes was ascertained by elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, electrospray ionization-mass spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The comparative binding propensity profiles of the above-synthesized complexes with the DNA/human serum albumin (HSA) were investigated via UV absorption, fluorescence, and Förster resonance energy-transfer studies. On the basis of extended conjugation and planarity, L ¹ complexes exhibited superior bioactivity with greater calculated DNA binding constant values, (K _b) 2.9444 × 10³ [(L ¹ ) ₂ Cu] and 2.2693 × 10³ [(L ¹ ) ₂ Zn], as compared to L ² complexes, 1.793 × 10³ [(L ² )Cu(H ₂ O)] and 9.801 × 10² [(L ² )Zn(H ₂ O)]. The competitive displacement assay of complexes was performed by means of fluorogenic dyes (EtBr and Hoechst), which corroborates the occurrence of minor groove binding because of the enhanced displacement activity with Hoechst 33258. The minor groove binding of the [(L ¹ ) ₂ Cu] complex is further confirmed by the molecular docking study. Moreover, the HSA study demonstrated effective static quenching of complexes with substantial K _sv values. The [(L ¹ ) ₂ Cu] complex was found to have pronounced cleavage efficiency as evaluated from sodium dodecyl sulfate polyacrylamide gel electrophoresis electrophoresis. Furthermore, in vitro antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals further proclaimed the remarkable bioefficiency of compounds, which make them promising as active chemotherapeutic agents.

Design, synthesis, characterization and evaluation of the anticancer activity of water-soluble half-sandwich ruthenium(ii) arene halido complexes

Synthesis, crystal structure determination, DFT studies, experimental and theoretical evaluation of DNA/BSA interactions and cytotoxicity studies of three piano-stool Ru(ii)(p-cymene)chloride complexes (1–3) are presented herein.

Synthesis and spectral characterizations of water soluble Cu(ii) complexes containing N-heterocyclic chelates: cell-proliferation, antioxidant and nucleic acid/serum albumin interactions

Water soluble N-heterocyclic copper(ii) complexes were synthesized, characterized and studied their DNA/protein binding interactions, antioxidation and antiproliferative potentials. The complex 4 found to be better than other complexes.

Homo- and heteroleptic trimethoxy terpyridine–Cu(ii) complexes: synthesis, characterization, DNA/BSA binding, DNA cleavage and cytotoxicity studies

In the current study, four novel mononuclear Cu(ii) complexes with terpyridine (L) and different co-ligands (phen, bipy, and imd) were synthesized and characterized in detail, whereLis 4′-(3,4,5-trimethoxyphenyl)-2,2′:6′,2′′-terpyridine.

Characterization by Potentiometric Procedures of the Stability Constants of the Binary and Ternary Complexes of Cu(II) and Duloxetine Drug with Amino Acids

Potentiometric titration method has been used to define stoichiometries and stability constants of ternary complexes of Cu(II) with duloxetine (D) and some selected amino acids (L). The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the HYPERQUAD program. The formation constants of the complexes formed in aqueous solutions and their concentration distributions as a function of pH were evaluated at 25°C and ionic strength 0.10 mol·L−1 NaNO3. Respective stabilities of ternary complexes have been determined compared with the corresponding binary complexes in terms of Δlog  K and %R.S. values. A novel binary and ternary duloxetine (D) drug with glycine and its Cu(II) complexes has been synthesized and characterized by several spectroscopic methods. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for both complexes. The elemental analyses and mass spectral data have justified the [Cu(D)(Gly)] and [Cu(D)Cl(H2O)] composition of complexes, where D = duloxetine and Gly = glycine. The EPR spectra of Cu(II) complexes support the mononuclear structures. Thermal properties and decomposition kinetics of Cu(II) complexes are investigated.