Synthesis, characterization of new copper (ii) Schiff base and 1,10 phenanthroline complexes and study of their bioproperties

Design, Synthesis, Structural Investigation and Photo Induced Biological Investigations of Co(II), Ni(II) and Cu(II) Complexes Derived from N,O Donor Schiff Bases

A series of chelated metal complexes, [Co(LI)2] (1), [Ni(LI)2] (2), [Cu(LI)2] (3) [Co(LII)2] (4), [Ni(LII)2] (5) and [Cu(LII)2] (6) were designed and synthesized from newly synthesized Schiff bases, LI = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-5-methylphenol and LII = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-4-chlorophenol. The synthesized compounds were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (NMR), electronic spectroscopy (UV-Vis), infrared spectroscopy (FT-IR), magnetic susceptibility (µeff), electron spin resonance spectroscopy (ESR), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and powder X-ray diffraction analysis (P-XRD). The spectral investigations have been clearly suggested 1:2 (metal: ligand) stoichiometric complexes with square planar geometrical arrangement around the metal ion. The thermal gravimmetric analysis (TGA) of these complexes indicates greater thermal stability and various steps involved in thermal decomposition of metal complexes. The binding ability between these metal complexes and calf thymus DNA (CT-DNA) was investigated by UV-Vis, fluorescence spectroscopy and viscometric experiments, which disclosed that, the complexes interacted to CT-DNA via an intercalation binding mode. The cleavage property of metal complexes against pBR322 DNA has been explored by gel electrophoresis technique mediated by UV-illumination and H2O2, showed momentous cleavage activity. Antioxidant activity of all complexes was determined by DPPH free radical scavenging experiment and showed prominent antioxidant activity. Further, the antibacterial and antifungal activities of all compounds were screened against bacterial and fungal strains via in-vitro disc diffusion method. These studies revealed that the complexes showed comparatively more antimicrobial activity than free ligands against tested microbial strains.

Antimicrobial and Antibiofilm Activity of Copper-Based Metallic Compounds Against Bacteria Related with Healthcare-Associated Infections

Health care-associated infections (HAIs) contribute to a significant rate of morbidity, mortality, and financial burden on health systems. These infections are caused by multidrug-resistant bacteria that produce biofilm as the main virulence factor. This study aimed to evaluate the effect of the copper-based metallic compounds [Cu(phen)(pz)NO₂]Cl (I), [Cu(bpy)(pz)(NO₂)]Cl (II), and [Cu(phen)(INA)NO₂]Cl (III), where phen = phenanthroline, bpy = bipyridine, pz = pyrazinamide, and INA = isonicotinic acid, against planktonic cells and biofilms formation of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. The susceptibility of the microorganisms was evaluated by minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), and time-kill curve assay on planktonic cells. The biofilm formation was evaluated by biomass quantification through staining with crystal violet (CV), colony-forming units (CFUs) quantification, and biofilm metabolic activity determination by XTT assay. The compounds showed bacteriostatic and bactericidal activity on all microorganisms analyzed. Regarding the antibiofilm activity, all metallic compounds were able to reduce significantly the biofilm biomass, colony-forming units, and the metabolic activity of remaining cells, varying the efficient concentration according to the strain analyzed. Interestingly, compounds (I), (II) and (III) did not exhibit DNA degradation activity even with up to 100 µM of these metal complexes. On the other hand, complexes (I) and (III) showed a remarkable capacity to cleave DNA upon addition of glutathione, a reducing agent (Cu^II/Cu^I) that leads to reactive oxygen species (ROS) formation. The results presented in this study showed promising antimicrobial and antibiofilm effects.

Bioactivity, molecular docking and anticancer behavior of pyrrolidine based Pt(II) complexes: Their kinetics, DNA and BSA binding study by spectroscopic methods

The complex [Pt(AEP)Cl₂]; C-1 (where, AEP = 1-(2-Aminoethyl) pyrrolidine) and its hydrolyzed diaqua form cis-[Pt(AEP)(H₂O)₂]²⁺; C-2 were synthesized for their bioactivity and in vitro kinetic study with bioactive thiol group (-SH) containing ligands (like; L- cysteine and N-ac-L- cysteine) for their biological importance for 'drug reservoir' activity. The Thermal Gravimetric Analysis (TGA) was executed to confirm about the weight loss due to coordinated water molecules at high temperature range. At pH 4.0, the substitution behavior of C-2 with the thiols was studied in pseudo-first order reaction condition. The interaction mechanism of thiols with complex C-2 to their corresponding thiol substituted C-3 [Pt(AEP)(L-cys)] and C-4 [Pt(AEP)(N-ac-L-cys)] (where L-cys = L-cysteine and N-ac-L-cys = N-ac-L- cysteine) were proposed from their thermodynamical activation parameters (ΔH^≠ and ΔS^≠), which were obtained from Eyring equation. DNA and BSA binding activity of the complexes C-1 to C-4 were investigated by gel electrophoresis technique, spectroscopic titration and viscosity methods. The binding activity of the complexes with DNA and BSA was evaluated using a theoretical approach molecular docking study. The drug-like nature of the complexes is supported by the prediction of activity spectra for substance (PASS) from 2D structure of the Pt(II) complexes. Structural optimization, HOMO-LUMO energy calculation, Molecular electrostatic potential surface, NBO and TD-DFT calculation were executed by using density functional theory (DFT) with Gaussian 09 software package to pre-assessment of biological activity of the complexes. DFT-based descriptors were determined from the HOMO-LUMA energy to be related with the ability of binding affinity of Pt(II) complexes towards DNA and BSA to the formation of their corresponding adducts. The anticancer property of the design complexes were examined on HCT116 (colorectal carcinoma) cancer cell lines and as well as human normal cell NKE (Normal Kidney Epithelial) and compared with the recognised anticancer drug cisplatin. The Reactive Oxygen Species (ROS) production was assessed by DCFDA assay in presence of the Pt(II) complexes.

Nickel-Metformin Ternary Complexes: Geometrical, Thermal, DNA Binding, and Molecular Docking Studies

Novel three nickel(II) complexes of type [Ni(metf)(o-phen)₂]Cl₂ (1), [Ni(metf)(opda)₂]Cl₂ (2), [Ni(metf)(2-2'bipy)₂]Cl₂ (3), (Metf = metformin, o-phen = ortho-phenanthroline, opda = ortho-phenylenediamine, 2-2' bipy = 2-2' bipyridyl) were synthesized and characterized by various analytical and spectral techniques. Based on these studies, octahedral geometry is assigned to these complexes. The DNA binding properties of these complexes were investigated by absorption, emission, and viscosity studies. From the spectral data, it was concluded that the complexes bind to DNA through groove mode of binding. The intrinsic binding constants (K_b) from absorption spectroscopy were 1.60 × 10⁴, 3.57 × 10⁴, and 5.70 × 10⁴ M^-1 for 1, 2, and 3, respectively, and Stern-Volmer quenching constants (K_sv) from emission spectroscopy were 0.11, 0.87, and 0.24, respectively. Thermal degradation pattern of the compounds was studied and Coats-Redfern method is used to determine kinetic parameters for complexes 1, 2, and 3 from thermal studies. The software Discovery Studio 2.1 was used to assess the binding affinity and interaction pattern of complexes with the B-DNA receptor protein and complex 1 has the highest dock score.

Metformin-Derived Water-Soluble Cobalt Complexes: Thermal, Spectroscopic, DNA Interaction, and Molecular Docking Studies

Novel three water-soluble cobalt (II) complexes of type [Co(metf)(o-phen)₂]Cl₂ (1), [Co(metf)(opda)₂]Cl₂ (2), and [Co(metf)(2-2'bipy)₂]Cl₂ (3) (Metf, metformin; o-phen, ortho-phenanthroline; opda, ortho-phenylenediamine; 2,2'-bipy, 2,2'-bipyridine) were synthesized and characterized by various analytical and spectral techniques. Based on these studies, octahedral geometry is assigned to these complexes. The stability of the complexes has been calculated from quantum chemical parameters using HOMO-LUMO energies. Thermal degradation pattern of the compounds was studied and Coats-Redfern method is used to determine kinetic parameters for complexes 1, 2, and 3 from thermal studies. The DNA interaction of these complexes was investigated by absorption, emission, and viscosity studies. From the spectral data, it was concluded that the complexes bind to DNA through groove mode of binding. The intrinsic binding constants (K_b) from absorption spectroscopy were 2.49 × 10⁴, 2.48 × 10⁴, and 2.64 × 10⁴ M^-1 for 1, 2, and 3, respectively, and Stern-Volmer quenching constants (K_sv) from emission spectroscopy were 0.21, 0.20, and 0.13, respectively. These complexes were screened for nuclease activity of pUC19 DNA, in the presence of H₂O₂. Discovery studio 2.1 software was used to evaluate binding affinity and interaction pattern of complexes with B-DNA receptor protein and the maximum dock score is seen for complex 2.

A turn-on bis-BODIPY chemosensor for copper recognition based on the in situ generation of a benzimidazole–triazole receptor and its applications in bioimaging

A bis-BODIPY-based fluorescent probe (BODIPY-NN) is developed for Cu2+ detection in aqueous solutions and living cells. The sensing mechanism is based on the in situ generation of a benzimidazole–triazole receptor induced by Cu2+ ions.

Synthesis, characterization, and crystal structure of RNA targeted l- and d-phenylalanine-(1,10-phen)–copper(ii) conjugate complexes: comparative in vitro RNA binding profile of enantiomers and their biological evaluation by morphological studies and antibacterial activity

Chiral Cu(ii) complexes targeting RNA showing morphological changes and Docking model.