Electron transfer reduction of unactivated esters using SmI2-H2O

The reduction of unactivated esters using samarium diiodide is reported for the first time. The optimised protocol allows for the reduction of primary, secondary and tertiary alkyl esters in excellent yields and is competitive with reductions mediated by metal hydrides and alkali metals.     

Oxidizing metal ions with graphene oxide: the in situ formation of magnetic nanoparticles on self-reduced graphene sheets for multifunctional applications

Fe(2+) cations in FeCl(2) or FeSO(4) were oxidized by graphene oxide, leading to an in situ deposition of Fe(3)O(4) nanoparticles onto the self-reduced graphene oxide (rGO) sheets. The resultant Fe(3)O(4)/rGO sheets were demonstrated to possess interesting magnetic and electrochemical properties attractive for a large variety of potential applications.     

The role of adenosine receptor agonists in regulation of hematopoiesis

The review summarizes data evaluating the role of adenosine receptor signaling in murine hematopoietic functions. The studies carried out utilized either non-selective activation of adenosine receptors induced by elevation of extracellular adenosine or by administration of synthetic adenosine analogs having various proportions of selectivity for a particular receptor. Numerous studies have described stimulatory effects of non-selective activation of adenosine receptors, manifested as enhancement of proliferation of cells at various levels of the hematopoietic hierarchy. Subsequent experimental approaches, considering the hematopoiesis-modulating action of adenosine receptor agonists with a high level of selectivity to individual adenosine receptor subtypes, have revealed differential effects of various adenosine analogs. Whereas selective activation of A? receptors has resulted in suppression of proliferation of hematopoietic progenitor and precursor cells, that of A? receptors has led to stimulated cell proliferation in these cell compartments. Thus, A? and A? receptors have been found to play a homeostatic role in suppressed and regenerating hematopoiesis. Selective activation of adenosine A? receptors has been found to act curatively under conditions of drug- and radiation-induced myelosuppression. The findings in these and further research areas will be summarized and mechanisms of hematopoiesis-modulating action of adenosine receptor agonists will be discussed.     

Anodic oxidation of selenadiazoloquinolones in alkaline media

Newly synthesized derivatives of 6-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-h]quinoline variously substituted at position 7 (R = H, COOH, COCH(3), CN, COOC(2)H(5) and COOCH(3)) are established in strongly alkaline aqueous solutions (0.1 M NaOH; pH ～ 13) as N(9)-deprotonated structures, but in less alkaline solutions (0.001 M NaOH; pH ～ 11) the N(9)-protonated oxo tautomeric forms dominate. Upon their anodic oxidation in alkaline solutions, the selenadiazole ring is replaced, forming instead the paramagnetic species analogous to the ortho semiquinone radical anions as monitored by in situ EPR spectroscopy. The quantum chemical calculations for two representative selenadiazoloquinolones (R = H and COOH) and their anodic oxidation products presented are in agreement with experiments.     

Transferable scoring function based on semiempirical quantum mechanical PM6-DH2 method: CDK2 with 15 structurally diverse inhibitors

A semiempirical quantum mechanical PM6-DH2 method accurately covering the dispersion interaction and H-bonding was used to score fifteen structurally diverse CDK2 inhibitors. The geometries of all the complexes were taken from the X-ray structures and were reoptimised by the PM6-DH2 method in continuum water. The total scoring function was constructed as an estimate of the binding free energy, i.e., as a sum of the interaction enthalpy, interaction entropy and the corrections for the inhibitor desolvation and deformation energies. The applied scoring function contains a clear thermodynamical terms and does not involve any adjustable empirical parameter. The best correlations with the experimental inhibition constants (ln K _i) were found for bare interaction enthalpy (r ² = 0.87) and interaction enthalpy corrected for ligand desolvation and deformation energies (r ² = 0.77); when the entropic term was considered, however, the correlation becomes worse but still acceptable (r ² = 0.52). The resulting correlation based on the PM6-DH2 scoring function is better than previously published function based on various docking/scoring, SAR studies or advanced QM/MM approach, however, the robustness is limited by number of available experimental data used in the correlation. Since a very similar correlation between the experimental and theoretical results was found also for a different system of the HIV-1 protease, the suggested scoring function based on the PM6-DH2 method seems to be applicable in drug design, even if diverse protein–ligand complexes have to be ranked.     

Face-centered-cubic large-pore periodic mesoporous organosilicas with unsaturated and aromatic bridging groups

Large-pore ethenylene-bridged (-CH═CH-) and phenylene-bridged (-C(6)H(4)-) periodic mesoporous organosilicas (PMOs) with face-centered-cubic structure (Fm3m symmetry) of spherical mesopores were synthesized at 7 °C at low acid concentration (0.1 M HCl) using Pluronic F127 triblock copolymer surfactant in the presence of aromatic swelling agents (1,3,5-trimethylbenzene, xylenes-isomer mixture, and toluene). In particular, this work reports an unprecedented block-copolymer-templated well-ordered ethenylene-bridged PMO with cubic structure of spherical mesopores and an unprecedented block-copolymer-templated face-centered cubic phenylene-bridged PMO, which also has an exceptionally large unit-cell size and pore diameter. The unit-cell parameters of 30 and 25 nm and the mesopore diameters of 14 and 11 nm (nominal BJH-KJS pore diameters of 12-13 and 9 nm) were obtained for ethenylene-bridged and phenylene-bridged PMOs, respectively. Under the considered reaction conditions, the unit-cell parameters and pore diameters were found to be similar when the three different methyl-substituted benzene swelling agents were employed, although the degree of structural ordering appeared to improve for phenylene-bridged PMOs in the sequence of decreased number of methyl groups on the benzene ring.     

The influence of oxygen on radiation-induced structural and functional changes in glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase

Proteins are major targets for oxidative damage due to their abundance in cells and high reactivity with free radicals. In the present study we examined the influence of oxygen on radiation-induced inactivation and structural changes of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH). We chose these two enzymes because they occur at high concentrations and participate in the most important processes in organisms; furthermore, they show considerable similarity in their structure.Protein solutions were irradiated with X-rays in doses ranging from 0.1 to 0.7 kGy, in air and N₂O. The much higher radiation inactivation of GAPDH as compared to LDH is correlated with substantially greater structural changes in this protein, mainly involving the loss of free thiol groups (–SH). Of lesser importance in the differentiation of the radiosensitivity of the studied enzymes are tryptophan residues. Molecular oxygen, present during irradiation, increased to a significantly greater extent the inactivation and structural changes of GAPDH than that of LDH. The results suggest that the greater effect of oxygen on GAPDH is due to the higher efficiency of the superoxide radical, the higher amount of hydroperoxides generated, and the higher degree of unfolding of this protein.     

Determination of chloride, sulfate and nitrate in drinking water by microchip electrophoresis

We report on a method for simultaneous determination of chloride, sulfate and nitrate in drinking water by microchip electrophoresis. By adjusting a pH value of 4.2 in the aspartate background electrolyte, and by applying separation mechanisms via the ionic strength effect (bis-tris propane) and association equilibria (N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate), a complete resolution of analytes from other co-migrating constituents is accomplished. In addition, isotachophoretic preconcentration of nitrate was implemented directly on the microchip. The ions were detected via conductivity measurements after injecting 900-nL samples. The limits of detection range from 40 to 120?μg?L^-1. The method displays a high reproducibility of the migration velocities under suppressed hydrodynamic and electroosmotic flow and therefore allows for a precise quantitation of analytes. The total analysis time is <450?s, and the working range is up to 60?mg?L^-1 for chloride and sulfate, and of up to 20?mg?L^-1 for nitrate. Filtration and degassing are the only sample treatment steps prior to analysis. The use of an internal standard enabled an easy chip-to-chip transfer of the method.

Surface-modified protein nanospheres as potential antiviral agents

A novel application of surface-modified protein nanospheres as potential antiviral agents is illustrated. By using a single-step sonochemical process, bovine serum albumin nanospheres were generated, whose surface was covalently conjugated with mercaptoethane sulfonate to chemically and electrostatically mimic cellular heparan sulfate. The nanospheres effectively inhibited HSV-1 infection.