Biological evaluation of organometallic palladium(II) complexes containing 4-hydroxybenzoic acid (3-ethoxy-2-hydroxybenzylidene)hydrazide: Synthesis, structure, DNA/protein binding, antioxidant activity and cytotoxicity

A Dual-Functional Fluorescent Chemosensor Derived from Naphthalene Dithiouryl for Cu2+: Applications in Water Analysis, Logic Gates, Swab Tests, and Pesticide Monitoring

A chemosensor (CNS) built on a naphthalene fluorophore was developed, featuring a disulfide-bridged dimer structure. The probe CNS was completely characterized by the usual spectral analysis methods like 1H NMR, 13C NMR, and HR-MS. The CNS probe selectively detects Cu2+ ions and subsequently recognizes the amino acid tryptophan in a semi-aqueous medium of DMF:H2O solution. The detection of Cu2+ ions occur via three distinct mechanisms: suppression of the photoinduced electron-transfer process (PET), arrested rotation of diuryl groups leading to conformational change, and a blue-shifted fluorescence enhancement through intramolecular charge-transfer (ICT). With a 1:1 complexation ratio and a detection limit of 2.14 x 10-4 M, the CNS probe has been successfully applied in various practical scenarios, including real water sample analysis, glyphosate detection, smartphone-based color detection, and Cu2+ ion testing using a cotton-swab method.

Experimental and theoretical studies of new Co(III) complexes of hydrazide derivatives proposed as multi-target inhibitors of SARS-CoV-2

Cobalt(III) complexes with Schiff base ligands derived from hydrazone, (HL 1  = (E)-N'-(3,5-dichloro-2-hydroxybenzylidene)-4-hydroxybenzohydrazide, HL 2  = (E)-N'-(3,5-dichloro-2-hydroxybenzylidene)-4-hydroxybenzohydrazide (3,5-dibromo-2-hydroxybenzylidene), and HL 3  = (E)-4-hydroxy-N'-(2-hydroxy-3-ethoxybenzylidene)benzohydrazide), were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, UV-Vis spectroscopy, and cyclic voltammetry. X-ray diffraction was used to determine the single crystal structure of the complex (1). Co(III) was formed in a distorted, very regular octahedral coordination in this complex; three pyridine moieties complete this geometry. Schiff base complexes' redox behaviors are represented by irreversible (1), quasi-reversible (2), and quasi-reversible (3) voltammograms. A density functional theory (DFT)/B3LYP method was used to optimize cobalt complexes with a base set of 6-311G. Furthermore, fragments occupying the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were investigated at the same theoretical level. Quantum theory of atoms in molecules (QTAIM) computations were also done to study the coordination bonds and non-covalent interactions in the investigated structures. Hirshfeld surface analysis was used to investigate the nature and types of intermolecular exchanges in the crystal structure of the complex (1). The capacity of cobalt complexes to bind to the major protease SARS-CoV-2 and the molecular targets of human angiotensin-converting enzyme-2 (ACE-2) was investigated using molecular docking. The molecular simulation methods used to assess the probable binding states of cobalt complexes revealed that all three complexes were stabilized in the active envelope of the enzyme by making distinct interactions with critical amino acid residues. Interestingly, compound (2) performed better with both molecular targets and the total energy of the system than the other complexes.

Experimental and Molecular Docking Studies on the Interaction of a Water-Soluble Pd(II) Complex Containing β-Amino Alcohol with Calf Thymus DNA

The interaction of water-soluble and fluorescent [Pd (HEAC) Cl₂] complex, in which HEAC is 2-((2-((2-hydroxyethyl)amino)ethyl)amino) cyclohexanol, with calf thymus DNA (ct-DNA) has been studied. This study was performed using electronic absorption and fluorescence emission spectroscopies, cyclic voltammetry and circular dichroism analyses, dynamic viscosity measurements, and molecular docking theory. From hypochromic effect observed in ct-DNA absorption spectra, it was found that the Pd(II) complex could form a conjugate with ct-DNA strands through the groove binding mode. The K_b values obtained from fluorescence measurements clearly assert the Pd(II) complex affinity to ct-DNA. The fluorescence quenching of the DNA-Hoechst compound following the successive additions of the Pd(II) complex to the solution revealed that the Pd(II) complex is located in the ct-DNA grooves, and Hoechst molecules have been released into solution; moreover, the resulting measurements from relative viscosity authenticate the Pd(II) complex binding to the grooves. Negative quantities of thermodynamic parameters imply that the Pd(II) complex binds to ct-DNA mainly by the hydrogen bonds and van der Waals forces; also, the Gibbs-free energy changes show the exothermic and spontaneous formation of the Pd(II) complex-DNA system. The electrochemical behavior of the Pd(II) complex in the attendance of ct-DNA was investigated using the cyclic voltammetry method (CV). Several quasi-reversible redox waves were observed along with increasing the anodic/cathodic peak currents, as well as a shift in anodic/cathodic peak potentials. Circular dichroism (CD) observations suggested that the Pd(II)-DNA interaction could alter ct-DNA conformation. The results of molecular modeling confirmed that groove mechanism is followed by the Pd(II) complex to interact with ct-DNA.

trans-Dichloro(triphenylarsino)(N,N-dialkylamino)platinum(II) Complexes: In Search of New Scaffolds to Circumvent Cisplatin Resistance

The high incidence of the resistance phenomenon represents one of the most important limitations to the clinical usefulness of cisplatin as an anticancer drug. Notwithstanding the considerable efforts to solve this problem, the circumvention of cisplatin resistance remains a challenge in the treatment of cancer. In this work, the synthesis and characterization of two trans-dichloro(triphenylarsino)(N,N-dialkylamino)platinum(II) complexes (1 and 2) were described. The trypan blue exclusion assay demonstrated an interesting antiproliferative effect for complex 1 in ovarian carcinoma-resistant cells, A2780cis. Quantitative analysis performed by ICP-AES demonstrated a scarce ability to platinate DNA, and a significant intracellular accumulation. The investigation of the mechanism of action highlighted the ability of 1 to inhibit the relaxation of supercoiled plasmid DNA mediated by topoisomerase II and to stabilize the cleavable complex. Cytofluorimetric analyses indicated the activation of the apoptotic pathway and the mitochondrial membrane depolarization. Therefore, topoisomerase II and mitochondria could represent possible intracellular targets. The biological properties of 1 and 2 were compared to those of the related trans-dichloro(triphenylphosphino)(N,N-dialkylamino)platinum(II) complexes in order to draw structure–activity relationships useful to face the resistance phenotype.