New zinc(II) N4 tetradentate Schiff base complex: A potential cytotoxic metallodrug and simple precursor for the preparation of ZnO nanoparticles

Amalgamation and Scrutinizing of Leucine Derivatives Schiff bases Complexes as Antimicrobial Agent

The enhanced applications of Schiff bases metal complexes of amino acid derivatives have captured the attention of researchers for the synthesis of leucine derivatives of Schiff bases metal complexes. Amino acids are considered to be essential part of food supplements as well as derivatives of Schiff bases in coordination chemistry due to their donor ability. The leucine derivatives Schiff bases ligand have been synthesized by condensation reaction between amine of leucine with aldehyde or ketone bearing molecules attached with them. These complexes were characterized by different spectroscopic tools in order to confirm their structural geometries. The structural geometries are considered to be very important in order to improve the antimicrobial potential of leucine derivative metal complexes. By taking into account the antimicrobial potential of titled compounds, a comprehensive review of leucine derivatives of Schiff bases metal complexes has been compiled.

A mechanistic explanation of two novel Zn(II) dithiocarbamate complexes with β-lactoglobulin

The synthesis, characterization, antioxidant activity and β-LG interaction of two Zn(II) complexes formulated as [(N-N)Zn(µ-pr-dtc)Zn(N-N)](NO₃)₂] (where pr-dtc is propylenbisdithiocarbamate, N-N are 2,2'-bipyridine for complex a, and 1,10 phenanthroline for complex b) were reported. The in vitro antioxidant activity of the Zn complexes was evaluated against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH). Both complexes presented moderate antioxidant activity (IC₅₀ = 231.0 ± 5.7 mg L^-1 for complex a and 250.0 ± 6.1 mg L^-1 for complex b). Fluorescence studies showed that the intrinsic fluorescence of β-LG was statically quenched by the prepared complexes mainly through Van der Waals interaction and hydrogen bond. The fluorescence results showed that the above complexes could bind with β-LG with a relatively strong affinity (complex a: K_b(27 °C) = 0.16 × 10⁴ M^-1, K_b(37 °C) = 0.06 × 10⁴ M^-1, complex b: K_b(27 °C) = 1.94 × 10⁴ M^-1, K_b(37 °C) = 0.11 × 10⁴ M^-1). The secondary structure of β-LG was changed in the presence of these Zn complexes and the decrease in α-helix (0.41% and 0.55% for complex a and complex b, respectively) and β-sheet (1.19% and 1.44% for complex a and complex b, respectively) contents confirmed the protein instability during the interaction. Molecular dynamics simulation was used during the preparation of the protein receptor before docking to find the best fit of the complexes to β-LG. Some details about molecular docking simulations describe Van der Waals interactions and hydrogen bonding, and this is in agreement with the thermodynamics data derived from fluorescence spectroscopy experiment.Communicated by Ramaswamy H. Sarma.

Preparation, characterization and comparison of biological potency in two new Zn(II) and Pd(II) complexes of butanedione monoxime derivatives

A novel Schiff base ligand (2-iminothiophenol-2,3-butanedione monoxime, ITBM) and its complexes with Pd(II) and Zn(II) metal ions ([M(ITBM)₂]Cl₂) were synthesized and characterized in the present study. The formulated complexes were evaluated for in vitro antioxidant activity as radical scavengers against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH^•). According to the results, antioxidant activity of Pd complex (IC₅₀=36 mg L^-1) was more effective than that of Zn(II) complex (IC₅₀=72 mg L^-1). Biophysical techniques along with computational modeling were employed to examine the binding of these complexes with human serum albumin (HSA) as the model protein. The trial findings revealed an interaction between Schiff base complexes and HSA with a modest binding affinity [K_b=6.31(±0.11)×10⁴ M^-1 for Zn(II) complex and 0.71(±0.05)×10⁴ M^-1 for Pd(II) complex at 310 K]. An intense fluorescence quenching of protein through a static quenching mechanism was occurred due to the binding of both complexes to HSA. Hydrogen bonds and van der Waals forces in both examined systems were the main stabilizing forces in the development of drug-protein complex. Based on far-UV-CD observations, the content of α-helical structure in the protein was reduced through induction by both complexes. Analysis of protein-ligand docking demonstrated binding of the two Schiff base complexes to residues placed in the IIA subdomain of HSA. In addition, Zn complex with HSA showed a stronger binding ability than that of Pd complex.Communicated by Ramaswamy H. Sarma.