Experimental and Theoretical Approaches to Monitor the Behavior of Bovine Liver Catalase in Interaction with a Binuclear Bismuth Complex.

Here, the antioxidant potency of a binuclear Bi(III) complex {[Bi2(µ-ox)(dipic)2(H2O)2 (taa)2].H2O, where ox2- = oxalato, dipic2- = pyridine 2,6-dicarboxylato, and taa = thiourea} was evaluated using the •DPPH assay. It was demonstrated that the Bi complex exhibited a high ability to inhibit DPPH free radicals. The binding mechanism of the complex with bovine liver catalase (BLC) was also investigated, revealing structural and activity changes in the enzyme in the presence of the complex. The catalase activity in the decomposition of hydrogen peroxide increased in the presence of the Bi complex, reaching 39.8% higher than its initial activity at a concentration of 7.77 × 10-6 M. The complex exhibited a relatively high affinity for BLC, with K b values of 3.98, 0.13, and 0.09 × 105 M-1 at 303, 310, and 317 K, respectively. The mechanisms involved in the interaction were hydrogen bonding and van der Waals interactions, as validated through molecular docking simulations. Synchronous fluorescence showed that tryptophan was more affected by enzyme-complex interactions than tyrosine. In addition, a cell viability test using the MTT method revealed that at its highest concentration, the Bi complex caused a decrease in the number of cells below 50% compared to the control, while cisplatin showed negative effects at all concentrations. These findings suggest that the Bi complex has the potential to be developed as a promising candidate for BLC-related therapeutic target therapy.

Effect of Cu(II) compound containing dipicolinic acid on DNA damage: a study of antiproliferative activity and DNA interaction properties by spectroscopic, molecular docking and molecular dynamics approaches.

A polymeric compound formulized as [Cu(µ-dipic)2{Na2(µ-H2O)4]n.2nH2O (I), where dipic is 2,6-pyridine dicarboxylic acid (dipicolinic acid, H2dipic), was synthesized by sonochemical irradiation. The initial in-vitro cytotoxic activity of this complex compared with renowned anticancer drugs like cisplatin, versus HCT116 colon cell lines, shows promising results. This study investigated the interaction mode between compound (I) and calf-thymus DNA utilizing a range of analytical techniques including spectrophotometry, fluorimetry, partition coefficient analysis, viscometry, gel electrophoresis and molecular docking technique. The results obtained from experimental methods reveal complex (I) could bind to CT-DNA via hydrogen bonding and van der Waals forces and the theoretical methods support it. Also, complex (I) indicates nuclease activity in the attendance of H2O2 and can act as an artificial nuclease to cleave DNA with high efficiency.Communicated by Ramaswamy H. Sarma.

Probing the combination of erlotinib hydrochloride, an anticancer drug, and human serum albumin: Spectroscopic, molecular docking, and molecular dynamic analyses.

Human serum albumin (HSA) is a globular and monomeric protein in plasma that transports many drugs and compounds. Binding of some drugs to HSA can lead to changes in its stability and biological function. We investigated the binding interactions between erlotinib hydrochloride (Erlo) and HSA. Erlo is used to treat lung, pancreatic, and some other cancers. Experimental data showed that the fluorescence emission of the protein was quenched by Erlo using a static quenching mechanism. The calculation of the binding constant, Kb (1.57 × 105 M-1 at 300 K), confirmed the existence of a moderate binding interaction between Erlo and HSA. The interaction was enthalpy driven, spontaneous, and exothermic. The calculated thermodynamic parameters in agreement with simulation and molecular docking data showed that van der Waals and hydrogen bond forces played an important role in the interaction process. Molecular docking results indicated that Erlo has more affinity to bind to subdomain IIA (site I) of HSA. Molecular dynamics simulation analysis showed that the protein is stable in the presence of Erlo under simulation conditions.

Synthesis and crystal structure of a new heteronuclear complex of Fe(iii)-K designed to produce effective catalysts for CO hydrogenation.

A new paramagnetic heteronuclear complex formulated as [K3Fe(µ-ox)3(H2O)3]n (1), where ox2- is oxalate, has been synthesized under hydrothermal condition. The molecular structure of complex 1 was characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) and single-crystal X-ray diffraction (SCXRD). The results of SC-XRD analysis revealed that complex 1 crystallizes in the centrosymmetric space group P21/c of a monoclinic system with cell dimension a = 7.7175 (4) Å, b = 19.8009 (7) Å, c = 10.2623 (5) Å, and ß = 107.634 (5)° at 100 K. The thermal behavior of complex 1 was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The magnetic behavior of complex 1 was studied at room temperature by a vibration sample magnetometer (VSM). Thermal decomposition of the silica and alumina supports of complex 1 at 650 °C resulted in the main catalysts, Fe2O3-K2O/SiO2 and Fe2O3-K2O/Al2O3. The catalytic activity of the main catalysts was evaluated for CO hydrogenation. For comparative purposes, the reference catalysts of Fe2O3-K2O/SiO2 and Fe2O3-K2O/Al2O3 were prepared by the impregnation method. The structure and composition of the catalysts were investigated by FT-IR spectroscopy, powder X-ray diffraction (PXRD), N2 adsorption-desorption analysis, scanning electron microscopy (SEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive X-ray analysis (EDX). We tested all catalysts for hydrogenation of CO at 5 bar of pressure in the temperature range of 593-673 K. It was found that the main catalysts have better CO conversion and selectivity to desired products, such as light olefins, than the reference catalysts.

Comparative study on the anticancer activities and binding properties of a hetero metal binuclear complex [Co(dipic)2Ni(OH2)5]·2H2O (dipic=dipicolinate) with two carrier proteins.

Recognizing of binding mechanisms between drugs and carrier proteins is basic for us to understand the pharmacokinetics and pharmacodynamics of them. In this research, the anticancer activities of a binuclear complex [Co(dipic)2Ni(OH2)5]·2H2O (dipic=dipicolinate) against MDA-MB-231 cell lines were studied. Results of MTT assay and flow cytometry analysis revealed that above complex can induce the cytotoxicity and the apoptosis in breast cancer cell lines. So, this complex was selected to investigate its binding to human serum albumin (HSA) and bovine ß-lactoglobulin (ßLG) by spectroscopic methods (UV-visible, fluorescence and FT-IR) along with molecular docking technique. The fluorescence data showed Co-Ni complex quench the fluorescence of both proteins by a static quenching mechanism and HSA has stronger binding affinity toward Co-Ni complex than ßLG. The binding constant (Kb), number of binding sites (n) and thermodynamic parameters were calculated and showed that the Co-Ni complex binds to protein (HSA and ßLG) through hydrogen bonding and van der Waals forces with one binding site. The results of UV-visible measurements indicated that the binding of above complex to HSA and ßLG may induce conformational and micro-environmental changes of studied proteins. Protein-ligand docking analysis confirmed that the Co-Ni complex binds to residues located in the subdomain IIA of HSA and site II of ßLG.