A comparative analyses of bioactive Cu(II) complexes using Hirshfeld surface and density functional theory (DFT) methods: DNA binding studies, cleavage and antibiofilm activities

In-silico study for the screening and preparation of ionic liquid-AVDs conjugate to combat COVID-19 surge

The pandemic due to COVID-19 caused by SARS-CoV-2 has led to the recorded deaths worldwide and is still a matter of concern for scientists to find an effective counteragent. The combination therapy is always been a successful attempt in treating various threatful diseases. Recently, Ionic liquids (ILs) are known for their antiviral activity. Fascinating tunable properties of ILs make them a potential candidate for designing the therapeutic agent. The concern while using ILs in biomedical field remains is toxicity therefore, choline-based ILs were used in the study as they are considered to be greener as compared to other ILs. In the present study strategically, we performed the blind molecular docking of antiviral drug (Abacavir, Acyclovir, and Galidesivir)-choline based ILs conjugates with the target protein (M_pro protease). The molecules were screened on the basis of binding energy. The data suggested that the combination of AVDs-ILs have greater antiviral potential as compared to the drugs and ILs alone. Further, the ADME properties and toxicity analysis of the screened conjugates was done which revealed the non-toxicity of the conjugates. Additionally, the energetic profiling of the ILs drugs and their conjugates was done using DFT calculations which revealed the stability of the conjugates and have a better option to be developed as a therapeutic agent. Also, from molecular dynamic simulation was done and results showed the stability of the complex formed between target protein and the designed conjugates of AVDs and ILs.

Metal Complexes—A Promising Approach to Target Biofilm Associated Infections

Microbial biofilms are represented by sessile microbial communities with modified gene expression and phenotype, adhered to a surface and embedded in a matrix of self-produced extracellular polymeric substances (EPS). Microbial biofilms can develop on both prosthetic devices and tissues, generating chronic and persistent infections that cannot be eradicated with classical organic-based antimicrobials, because of their increased tolerance to antimicrobials and the host immune system. Several complexes based mostly on 3D ions have shown promising potential for fighting biofilm-associated infections, due to their large spectrum antimicrobial and anti-biofilm activity. The literature usually reports species containing Mn(II), Ni(II), Co(II), Cu(II) or Zn(II) and a large variety of multidentate ligands with chelating properties such as antibiotics, Schiff bases, biguanides, N-based macrocyclic and fused rings derivatives. This review presents the progress in the development of such species and their anti-biofilm activity, as well as the contribution of biomaterials science to incorporate these complexes in composite platforms for reducing the negative impact of medical biofilms.

New organosulfur metallic compounds as potent drugs: synthesis, molecular modeling, spectral, antimicrobial, drug likeness and DFT analysis

During the present investigation, two new sulfonamide-based Schiff base ligands, 4-{[(2-hydroxy-3-methoxyphenyl)methylidene]amino}-N-(1,3-thiazol-2-yl)benzene-1-sulfonamide (L¹) and 4-{[1-(2-hydroxyphenyl)ethylidene]amino}-N-(1,3-thiazol-2-yl)benzene-1-sulfonamide (L²), have been synthesized and coordinated with the transition metals (V, Fe, Co, Ni, Cu and Zn). The ligands were characterized by their physical (color, melting point, yield and solubility), spectral (UV-Vis, FT-IR, LC-MS, ¹H NMR and ¹³C NMR) and elemental data. The structures of the metal complexes (1)-(12) were evaluated through their physical (magnetic and conductance), spectral (UV-Vis, FT-IR and LC-MS) and elemental data. The molecular geometries of ligands and their selected metal complexes were optimized at their ground state energies by B3LYP level of density functional theory (DFT) utilizing 6-311+G (d, p) and LanL2DZ basis set. The first principle study has been discussed for the electronic properties, the molecular electrostatic possibilities as well as the quantum chemical identifiers. An obvious transition of intramolecular charge had been ascertained from the occupied to the unoccupied molecular orbitals. The UV-Vis analysis was performed through time-dependent density functional theory (TD-DFT) by CAM-B3LYP/6-311+G (d, p) function. The in vitro antimicrobial activity was studied against two fungal (Aspergillus niger and Aspergillus flavus) and four bacterial (Staphylococcus aureus, Klebsiela pneumoniae, Escherichia coli and Bacillus subtilis) species. The antioxidant activity was executed as antiradical DPPH scavenging activity (%), total iron reducing power (%) and total phenolic contents (mg GAE g^-1). Additionally, enzyme inhibition activity was done against four enzymes (Protease, α-Amylase, Acetylcholinesterase and Butyrylcholinesterase). All the synthetic products exhibited significant bioactivity which were found to enhance upon chelation due to phenomenon of charge transfer from metal to ligand.

Cytotoxic activity, molecular docking, pharmacokinetic properties and quantum mechanics calculations of the brown macroalga Cystoseira trinodis compounds

In this study, nine compounds were isolated, eight of them were isolated for the first time from Cystoseira trinodis. The biological activity of the extract, fractions and pure compounds was evaluated. The antimicrobial activity was investigated against 3 fungi species, 3 gram + ve and 3 gram -ve bacteria. The crude extract and fractions showed moderate inhibition against some of the tested microorganisms, especially the butanol fraction exhibited the maximum inhibition zone against Salmonella typhimurium (16 ± 0.60 mm). Cytotoxicity was evaluated against HepG-2 and MCF-7 cell lines. Hexane fraction exhibited the highest cytotoxic effect against HepG-2 and MCF-7 cell lines with an IC₅₀ value of 14.3 ± 0.8 and 19.2 ± 0.7 µg/ml, respectively with compared to other fractions. The isolates were identified as octacosanoic acid (1), glyceryl trilinoleate (2), oleic acid (3), and the epimeric mixture of saringosterols (4, 5), β-sitosterol (6), glycoglycerolipid (7) and a mixture of kjellmanianone and loliolide (8, 9) by spectroscopic analysis. Among the all tested compounds kjellmanianone and loliolide mixture exhibited significant cytotoxic activity with an IC₅₀ value of 7.27 µg/ml against HepG-2 cells. The major and minor constituents of the extract and fractions were identified using GC-MS analysis. Molecular docking analysis confirmed that most of the studied compounds especially compounds 8 and 9 strongly interact with TPK and VEGFR-2 with highest binding energies supported that the high cytotoxicity of these compounds against human hepatocellular cancer in the experimental part. The energetic, geometric and topological properties of compounds 8 and 9 binding with cytosine base were computed by DFT methods. Molecular properties descriptors, bioactivity score and ADMET analysis confirmed that most of the studied compounds especially compounds 8 and 9 exhibit significant biological activities and have a better chance to be developed as drug leads. Communicated by Ramaswamy H. Sarma.

Structural, Spectroscopic, and Chemical Bonding Analysis of Zn(II) Complex [Zn(sal)](H2O): Combined Experimental and Theoretical (NBO, QTAIM, and ELF) Investigation

The Zn(II) complex of salen-like scaffold [Zn(sal)](H2O) was synthesized and characterized by elemental analysis, IR, UV–Vis, and 1H-NMR spectroscopic techniques. The structure of complex was confirmed by single crystal X-ray diffraction studies. In the complex, Zn (II) was placed in the inner N2O2 compartment of the salen scaffold in square planar geometry and crystallized in the monoclinic space group P21/n. DFT and TDDFT calculations were performed to reproduce the experimentally observed structural and spectroscopic (IR and UV–vis) findings. The bonding of the Zn(II) framework in the [Zn(sal)](H2O) complex was explored in depth. The theoretical approaches employed were perturbation theory within the context of the natural bond orbital (NBO) framework, and quantum theory of atoms in molecule (QTAIM) and electron localization function (ELF) analysis. The study begins by delineating the difference between the NBO and QTAIM approaches. This paper thus exhibits the supportive nature of NBO theory and QTAIM in discussion of the bonding in the [Zn(sal)](H2O) complex, when both the methodologies are used in combination.

Structure elucidation {spectroscopic, single crystal X-ray diffraction and computational DFT studies} of new tailored benzenesulfonamide derived Schiff base copper(II) intercalating complexes: Comprehensive biological profile {DNA binding, pBR322 DNA cleavage, Topo I inhibition and cytotoxic activity}

New tailored copper(II)-based intercalating complexes [Cu(L1)2] (1) and [Cu(L2)2] (2) were synthesized from Schiff base scaffold HL1 and HL2(E)-4-(2-((2-hydroxy-3-methoxybenzylidene)amino)ethyl)benzenesulfonamide and (E)-4-(2-((2-hydroxybenzylidene)amino)ethyl)benzenesulfonamide, respectively. The structure elucidation of complexes 1 and 2 was carried out by employing various spectroscopic techniques viz., FT-IR, UV-vis, ESI-MS, EPR and single X-ray crystal diffraction studies. The complexes 1 and 2 were crystallized in monoclinic P21/n and triclinic P-1 space group, respectively possessing square planar geometry around Cu(II) coordinated with N,O-donor Schiff base ligands. An analysis of Hirshfeld surfaces of complexes 1 and 2 were performed to ascertain different intra and intermolecular non-covalent interactions (H-bonding, CH⋯ πetc.) responsible for the stabilization of crystal lattices. Calculations based on Density functional theory (B3LYP/DFT), have been carried out to obtain energies of Frontier molecular orbitals. Comparative in vitro binding profile of complexes 1 and 2 with ct-DNA was evaluated employing various biophysical techniques viz., UV-vis, fluorescence, circular dichroism and cyclic voltammetry which suggested non-covalent intercalative binding mode with more avid binding propensity of complex 1 compared to complex 2. The cleavage experiments of complex 1 was performed by gel electrophoretic assay which revealed efficient cleavage mediated via oxidative pathway. Furthermore, topoisomerase I enzymatic activity of complex 1 was carried out employing gel electrophoretic assay which demonstrated significant inhibitory effects at a low concentration of 25 µM. The cytotoxic potential of complex 1 was analyzed by SRB assay on a panel of selected human cancer cell lines which revealed selective activity for MCF-7 (breast cancer) cell line with GI50 = 16.21 µg/ml.

A palladium(II) complex with the Schiff base 4-chloro-2-(N-ethyliminomethyl)-phenol: Synthesis, structural characterization, and in vitro and in silico biological activity studies

The synthesis and characterization of the Pd(II) complex of the formula [Pd(L)₂] 1 with the Schiff base 4-chloro-2-(N-ethyliminomethyl)-phenol (HL) as derived in situ via the condensation reaction of 5-chloro-salicylaldehyde and ethylamine was undertaken. The structure of 1 was verified by single-crystal X-ray crystallography. The ability of 1 to interact with calf-thymus (CT) DNA was studied by UV-vis and viscosity experiments, and its ability to displace ethidium bromide (EB) from the DNA-EB conjugate was revealed by fluorescence spectroscopy. It was found that intercalation is the most possible mode of interaction with CT DNA. Additionally, DNA electrophoretic mobility experiments showed that 1 interacts with the plasmid pBluescript SK(+) (pDNA) as proved by the formation of unusual mobility DNA bands and degradation of relaxed pDNA at concentration of 5 mM. The interaction of 1 with human (HSA) and bovine serum albumin (BSA) was monitored revealing its reversible binding to albumins. The complex showed noteworthy antimicrobial activity against one (Bacillus subtilis) of the five tested bacteria. In order to explain the described in vitro activity of the compound, we adopted molecular docking studies on the crystal structure of HSA, BSA, CT DNA and DNA-gyrase. Furthermore, in silico predictive tools have been employed to study the properties of the complex. The in silico studies are adopted on a multitude of proteins involved in cancer growth, as well as prediction of drug-induced changes of gene expression profile, protein- and mRNA-based prediction results, prediction of sites of metabolism, cytotoxicity for cancer cell lines, etc.

Synthesis and characterization of heterobimetallic SnIV-CuII/ZnII complexes: DFT studies, cleavage potential and cytotoxic activity

Heterobimetallic complexes [Cu(L)Sn(CH₃)₂(H₂O)(Cl)] (3) and [Zn(L)Sn(CH₃)₂(H₂O)(Cl)] (4) have been synthesized from their monometallic analogs [Cu(L)(H₂O)(Cl)] (1) and [Zn(L)(H₂O)(Cl)] (2) of Schiff base ligand (L) which were characterized by various spectroscopic and analytical methods. DFT calculations were carried out to simulate the vibrational spectra to support the anticipated structures. The interaction studies of ligand (L) and complexes (1-4) with CT-DNA were performed by employing UV-vis, and fluorescence spectroscopic techniques which revealed that heterobimetallic complexes 3 and 4 showed higher affinity with DNA due to dual mode of action as compared to monometallic complexes 1 and 2. Further, validation of the interaction studies was accomplished by carrying out molecular docking studies with DNA. Gel assay displayed that both the complexes have ability to cleave DNA efficiently and are specific minor groove binders. Cu^II-Sn^IV complex 3 cleaved pBR322 DNA via oxidative mechanism, while Zn^II-Sn^IV complex 4 followed hydrolytic cleavage pathway. In vitro cytotoxicity evaluation of complex 3 was tested on a different cancer cell lines showing promising antitumor activity.Communicated by Ramaswamy H. Sarma.

Interference of phosphane copper (I) complexes of β-carboline with quorum sensing regulated virulence functions and biofilm in foodborne pathogenic bacteria: A first report

Foodborne pathogens are one of the major cause of food-related diseases and food poisoning. Bacterial biofilms and quorum sensing (QS) mechanism of cell–cell communication have also been found to be associated with several outbreaks of foodborne diseases and are great threat to food safety. Therefore, In the present study, we investigated the activity of three tetrahedrally coordinated copper(I) complexes against quorum sensing and biofilms of foodborne bacteria. All the three complexes demonstrated similar antimicrobial properties against the selected pathogens. Concentration below the MIC i.e. at sub-MICs all the three complexes interfered significantly with the quorum sensing regulated functions in C. violaceum (violacein), P. aeruginosa (elastase, pyocyanin and alginate production) and S. marcescens (prodigiosin). The complexes demonstrated potent broad-spectrum biofilm inhibition in Pseudomonas aeruginosa, E. coli, Chromobacterium violaceum, Serratia marcescens, Klebsiella pneumoniae and Listeria monocytogenes. Biofilm inhibition was visualized using SEM and CLSM images. Action of the copper(I) complexes on two key QS regulated functions contributing to biofilm formation i.e. EPS production and swarming motility was also studied and statistically significant reduction was recorded. These results could form the basis for development of safe anti-QS and anti-biofilm agents that can be utilized in the food industry as well as healthcare sector to prevent food-associated diseases.

Single X-ray crystal structure, DFT studies and topoisomerase I inhibition activity of a tailored ionic Ag(i) nalidixic acid–piperazinium drug entity specific for pancreatic cancer cells

DFT studies, Topo I inhibition assay and cytotoxic activity of novel ionic Ag(i) nalidixic acid–piperazinium molecular entity.

Biological evaluation of dinuclear copper complex/dichloroacetic acid cocrystal against human breast cancer: design, synthesis, characterization, DFT studies and cytotoxicity assays

Binuclear copper(ii) cocrystal “[Cu₂(valdien)₂⋯2Cl₂CHCOOH],” 1 was synthesized from H₂valdien scaffold and anticancer drug pharmacophore “dichloroacetic acid” embedded with two Cu(ii) connected via a hydrogen bonded network.

Coumarin centered copper(ii) complex with appended-imidazole as cancer chemotherapeutic agents against lung cancer: molecular insight via DFT-based vibrational analysis

Synthesis and structural characterization of the novel copper complex, DFT based vibrational analysis, DNA binding studies. In vitro cytotoxicity against A549 cancer cell lines and estimation of GSH, ROS, LPO levels, have been reported.