Pyridazine-based Schiff base ligands with N4OxS2 (x = 2, 4) donor set atoms: Synthesis,characterization, spectral studies and 13C chemical shifts computed by the GIAO-DFT and CSGT-DFT methodologies

Six pyridazine-based Schiff base ligands, H₂Lⁿ (n = 1–5) and H₄L, with N₄O₂S₂ and N₄O₄S₂ donor set atoms, respectively, were prepared by condensation reaction of 3,6-bis-((2-aminoethyl)thio)pyridazine with various salicyladehyde derivatives in ethanol and under solvent-free polyphosphate ester catalyzed conditions. The acid–base properties of H₂L² and H₂L³ in DMSO/water (1:1) solution have been studied by spectrophotometric method at 25 °C. Optimized geometries of all compounds were also obtained at the B3LYP level of theory. Additionally, the ¹³C chemical shielding of gas phase H₂L¹ and H₂L² were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) methods at the level of density functional theory (DFT). The 6-311++G* basis set was utilized for all of the atoms.     

Highly selective transport of lead cation through bulk liquid membrane by macrocyclic ligand of decyl-18-crown-6 as carrier

The liquid membrane transport of Pb²⁺ cation using decyl-18-crown-6 as selective ion carrier was studied. The transport of lead ion across the liquid membrane in the presence of S₂O ₃ ^2? , P₂O ₇ ^4? , CN^?, SCN^?, and DDC^? as stripping agents in the receiving phase shows that the nature and the concentration of the stripping agents affect on Pb²⁺ cation transport and the maximum transport occurs when the sodium thiosulfate (Na₂S₂O₃) was used. The effects of various parameters influencing the transport efficiency such as the pH of the source and receiving phases, the concentration of picrate ion as counter ion in the source phase were also studied. Five replicated experiments show that a value 82.12 ± 2.09% of the initial concentration of the Pb²⁺ cation in the source phase is extracted into the receiving phase after 4 hours. Also the selectivity and efficiency of lead ion transport from the source phase containing equimolar mixtures of Na⁺, K⁺, Ca²⁺, Ni²⁺, Cu²⁺, Cd²⁺ and Ag⁺ metal cations were investigated.     

Synthesis and cytotoxicity of 28-carboxymethoxy lupane triterpenoids.Preference of 28-O-acylation over 28-O-alkylation of betulm by ethyl bromoacetate

28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2- hydroxyethyl iodide followed by oxidation and reduction.Direct reaction of betulin(5) or betulone(10) with ethyl bromoacetate led to 28-O-acylation,instead of 28-O-alkylation.The targeted compounds 3 and 4 were not cytotoxic at the highest concentration tested(75μmol/L),suggesting that elongation of the chain length at the 28-position in both betulinic acid(1) and betulonic acid(2) was detrim...     

Nanostructure-based electrochemical sensor for determination of glutathione in hemolysed erythrocytes and urine

A sensitive and selective electrochemical method was developed for the determination of glutathione (GSH) in hemolysed erythrocyte using vinylferocene modified carbon nanotubes paste electrode (VFMCNTPE). The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of GSH, leading to a reduced overpotential by more than 470 mV. Also, the values of catalytic rate constant (k), and diffusion coefficient (D) for GSH were calculated. The electrocatalytic oxidation peak current of GSH showed two linear dynamic ranges with a detection limit of 0.09 μM GSH. The linear calibration ranges were obtained between 0.2–4.0 and 4.0–250.0 μM GSH using square wave voltammetry (SWV) method. The proposed method was also examined as a selective, simple and precise electrochemical sensor for the determination of GSH in real samples such as urine and hemolysed erythrocyte.     

A Cheap and Efficient Methodology for the Solvent‐Free,One‐pot and Multi‐component Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalyzed by Mesoporous NH4H2PO4/MCM‐48 and Comparison of Its Catalytic Efficacy with NH4H2PO4/MCM‐41

The catalytic efficiency of ammonium dihydrogenphosphate was evaluated in the two heterogeneous forms of NH₄H₂PO₄/MCM‐48 and NH₄H₂PO₄/MCM‐41, as mesoporous catalysts, in the solvent free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones through one‐pot three‐component condensation of ethyl acetoacetate, an aryl aldehyde and urea. Different reaction parameters including catalytic efficacy, solvent effect, and urea concentration are considered.     

An in silico approach to design peptide mimetics based on docking and molecular dynamics simulation of EGFR–matuzumab complex

Epidermal growth factor receptor (EGFR) plays an essential role in anticancer therapy. Matuzumab is an antibody for the treatment of colorectal, lung and stomach cancer. Matuzumab binds efficiently to EGFR and blocks its phosphorylation. The recent clinical successes have established application of peptides for cancer treatment. The present contribution introduces an in silico approach to design peptides based on molecular dynamics simulation (MDs) of the matuzumab-EGFR complex in water environment. Moreover, principal component analysis has been used to select multiple conformations of the complex in MDs for designing the peptides. The paratope and epitope in each conformation of the complex were determined, and the alanine scanning was used to identify the hot spots of EGFR conformers. The conformations of the peptides were optimized using PEP-FOLD server and MDs. The selected conformations were analyzed in a docking study to realize the binding site of the EGFR. Finally, pharmokinetics properties of the peptides were calculated. The designed oligopeptides were EWRSYYYWH, YYYWHNEWN, YYYWHNEWS and HNHSRNYGS with a higher affinity to the EGFR relative to the previously reported peptides. The newly designed peptides were investigated for their in vivo toxicities on rats, and all of them were non-toxic.