Vol 66, No 1 (2017)

The intravenous administration of bienzyme superoxide dismutase–chondroitin sulfate–catalase (SOD–CHS–CAT) conjugate in rats with endotoxic shock induced by a lipopolysac-charide bolus in the preventive and therapeutic regimens demonstrated the possible effective use of antioxidant agents not only for preventing the oxidative stress damage (as was considered previously), but also for its therapy. The results confirmed the importance of investigations of pathogenesis of vascular injury and the role of oxidative stress in it. The intravenous administration of the SOD–CHS–CAT conjugate in the therapeutic regimen during endotoxic shock development in rats was found to induce a variety of effects on the pathological process, besides preserving NO from conversion to peroxynitrite via reaction with the superoxide radical. These results, together with literature data, indicate good prospects of the research into NO-independent therapeutic effect of the SOD–CHS–CAT conjugate and the importance of studying the mechanism of its action using cardiovascular injury models associated with vasoactive agents other than NO.

The preparation, physicochemical properties, and cytotoxicity of zinc-containing hydroxyapatites (HAP) were considered for further using HAP as carriers for zinc-containing drugs and radiopharmaceuticals.

Density functional calculations of the geometries, electronic structures, and spectral properties of a series of iron(II) and ruthenium(II) complexes with 4,4´,4´,4´´-substituted 2,2´:6´2´´:6´´,2´´´-quaterpyridines were carried out. A high-spin state is characteristic of the iron(II) complexes with Cl^–, NO^–, CNS^–, and I^– as axial ligands while a low-spin state is characteristic of the iron(II) complex with a CN^– axial ligand. Calculations of the complexes with the nitroxide ligand predict intense absorption in a wide wavelength range up to the IR region.

The activity of supported nickel catalysts (5–20% Ni) in the hydrogenation of p-dinitrobenzene to p-phenylenediamine was investigated. The catalysts were obtained by ureainduced precipitation. Activated carbon, alumina, titania, and silica gel were evaluated as supports. The most active catalysts, 5%Ni/TiO₂ and 20%Ni/SiO₂, provided 50–54% yields of p-phenylenediamine at complete dinitrobenzene conversion.

Photophysical processes and photochemical reactions in the N-ammonioalkyl derivatives of the azacrown-containing styryl dyes and their complexes with lead and barium perchlorates in MeCN and CH₂Cl₂ were studied by ¹Н NMR spectroscopy, absorption spectroscopy, luminescence spectroscopy, laser kinetic spectroscopy, and quantum chemistry. Molecules of the styryl dyes and their complexes are able to undergo normal (fast) and delayed fluorescence and trans–cis-photoisomerization. The molecules in the triplet state participate in degradation processes of the electron excitation energy.

The structures of crystalline hydrates of calix[4]arene-para-sulfonic acid with n (n = 6–16) water molecules and the activation barriers to surface proton migration were calculated within the framework of the density functional theory (DFT) using the PBE gradient-corrected functional, the "hard" basis set of projector-augmented waves (PAW), a corresponding pseudopotential, periodic boundary conditions, and the VASP program package. The energies of formation of crystalline hydrates from calix[4]arene-para-sulfonic acid and n water molecules calculated per water molecule are in the range of 0.4–0.9 eV and depend on n. The adsorption energy of water on the surface is in the range of 0.5–0.7 eV. The activation barriers to proton transfer across the surface calculated for the most stable crystal (n = 8) are close to experimental data and depend on the number of superstoihiometric water molecules, being equal to ~0.2 eV provided three superstoihiometric water molecules per surface SO₃H group.

The ability of nitrobenzoxadiazoles to induce the SOX-operon from a genetically engineered biosensor based on E. coli MG 1655 (pSoxS-lux) was confirmed by the fact of producing nitric oxide. The NO-donating properties of three nitrobenzoxadiazole derivatives bearing π-excessive carbo- and heterocycles were found by the ESR method using spin trapping. The yield of nitrogen(II) oxide was 17, 0.3, and 1.6%. Sodium sulfide accelerates the thiol-dependent transformation and increases the yield of nitric oxide to 27, 16, and 12%, respectively.

A versatile synthetic approach towards 4-oxo-4,5-dihydro-1H-imidazol-5-ylacetanilides was elaborated. The target compounds result from recyclization of substituted N-aryl maleimides with carboximide amides in aprotic solvents.

New derivatives of the drug riluzole, 6-(trifluoromethoxy)benzothiazol-2-ylamine, modified at the endo- and exocyclic nitrogen atoms with trifluoromethyl-containing heterocycles were synthesized via transformations of methyltrifluoropyruvate and hexafluoroacetone N-6-(trifluoromethoxy)benzothiazol-2-ylimines by meams of cycloaddition and cyclocondensation reactions, respectively. The influence of the resulting compounds on neuronal NMDA receptors, as well as on the release and reuptake of the neurotransmitter glutamate was investigated.

3-Aminopropyl glycosides of di-, tri-, and tetrasaccharide structurally related to fragments of Streptococcus pneumoniae type 3 bacteria capsular polysaccharide were synthesized.

Glycyrrhizic acid, arabinogalactan, and β-cyclodextrin are capable of forming complexes with various drug compounds significantly enhancing their solubility and bioavailability. To elucidate the mechanism of action of oligo- and polysaccharides, the exchange time of transporting formate ions through the membrane of myeloblastic leukemia cells (K562) was measured by NMR spectroscopy with the addition of paramagnetic ions. It was found that glycyrrhizic acid and arabinogalactan substantially increased the membrane permeability.

Humic substances isolated from curative mud, brown coal, and shale of the Mongolian deposits were used for the synthesis of water-soluble silver-containing nanocomposites. The humic substances from curative mud have the highest reducing and stabilizing ability among the studied objects. The compositions and structures of the obtained nanocomposites were characterized in detail by a complex of modern physicochemical methods. The humic substances and related nanocomposites were found to exhibit high antioxidant activity comparable with that of the known antioxidants.

A method for radiolabeling the water-soluble N-vinylpyrrolidone copolymers with N-vinyl- and N-allylamine containing bifunctional chelation unit 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetate by the radioactive isotope gallium-68 (⁶⁸Ga) was developed. Radiotracers were obtained in the yield about 65%. A method of liquid chromatography for the micropreparative isolation of the metal-polymeric complexes with a radiochemical purity of ~98% was developed. The data on the stability of the complexes in blood serum and the results on the biodistribution of the synthesized complexes in organs and tissues of laboratory animals (rats) with transplantable tumor are presented.

A selective one-pot procedure to access 8-, 9-, and 10-membered polyoxacycles bearing ester functions was elaborated. The procedure involved the copper-promoted reactions of cyclic acetals with ethyl 2-diazo-3-oxobutanoate to give the target compounds in yields up to 99%.