Synthesis of of sterically encumbered biaryls based on a ‘copper(I)-catalyzed arylation/[3+3] cyclocondensation’ strategy

Sterically encumbered biaryls are prepared in two steps by combination of the CuI-proline-catalyzed arylation of acetylacetone with formal [3+3] cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-dienes. In addition, the synthesis of 4,6- and 5,6-diarylsalicylates based on [3+3] cyclizations is reported.     

Operator splitting for numerical solutions of the RLW Equation

In this study, the numerical behavior of the one-dimensional Regularized Long Wave (RLW) equation has been sought by the Strang splitting technique with respect to time. For this purpose, cubic B-spline functions are used with the finite element collocation method. Then, single solitary wave motion, the interaction of two solitary waves and undular bore problems have been studied and the effectiveness of the method has been investigated. The new results have been compared with those of some of the previous studies available in the literature. The stability analysis has also been taken into account by the von Neumann method.     

Antibacterial Activities and Molecular Docking of Novel Sulfone Biscompound Containing Bioactive 1,2,3-Triazole Moiety

In this study, a new synthetic 1,2,3-triazole-containing disulfone compound was derived from dapsone. Its chemical structure was confirmed using microchemical and analytical data, and it was tested for its in vitro antibacterial potential. Six different pathogenic bacteria were selected. MICs values and ATP levels were determined. Further, toxicity performance was measured using MicroTox Analyzer. In addition, a molecular docking study was performed against two vital enzymes: DNA gyrase and Dihydropteroate synthase. The results of antibacterial abilities showed that the studied synthetic compound had a strong bactericidal effect against all tested bacterial strains, as Gram-negative species were more susceptible to the compound than Gram-positive species. Toxicity results showed that the compound is biocompatible and safe without toxic impact. The molecular docking of the compound showed interactions within the pocket of two enzymes, which are able to stabilize the compound and reveal its antimicrobial activity. Hence, from these results, this study recommends that the established compound could be an outstanding candidate for fighting a broad spectrum of pathogenic bacterial strains, and it might therefore be used for biomedical and pharmaceutical applications.     

Patterned polymer brushes

This critical review summarizes recent developments in the fabrication of patterned polymer brushes. As top-down lithography reaches the length scale of a single macromolecule, the combination with the bottom-up synthesis of polymer brushes by surface-initiated polymerization becomes one main avenue to design new materials for nanotechnology. Recent developments in surface-initiated polymerizations are highlighted along with diverse strategies to create patterned polymer brushes on all length scales based on irradiation (photo- and interference lithography, electron-beam lithography), mechanical contact (scanning probe lithography, soft lithography, nanoimprinting lithography) and on surface forces (capillary force lithography, colloidal lithography, Langmuir-Blodgett lithography) (116 references).     

Combined effect of gamma irradiation and hot water dipping on the selected nutrients and shelf life of peach

Gamma irradiation in combination with hot water dipping treatment was tested for maintaining storage quality and extending the shelf life of peach fruit. The matured peaches fruits (local variety no, Tex-A-6-69) were first dipped in hot water having temperature of 0, 40 and 60 °C for 60 seconds and they were exposed to 0.5 and 1.0 kGy doses of gamma radiation and stored in paper cartons under ambient (temperature 25 ± 2 °C, RH 70 %) conditions for their physico-chemical evaluations on weekly basis. The combine effect of hot water dipping treatment and irradiation for peach was study for the first time in Pakistan. The parameters studied included % weight loss, % ash content, % moisture content, total soluble solids (TSS), titratable acidity and ascorbic acid. The sensory indices studied were size, shape, color and overall acceptability. The sensory evaluation values at 0 days for the controlled peach sample were recorded for comparison. Statistical analysis was performed to find determinates of irradiation alone and in combination with hot water dipping techniques on peaches. Studies revealed that irradiation treatment in combination with hot water treatments significantly (LSD at 5 %) maintained the storage quality of peach fruit under ambient conditions. Data obtained for weight loss, moisture, shape and overall acceptability showed significant results while non-significant values were recorded for ash, TSS and size. Overall, consumers rated the acceptability of treated peaches higher than untreated peaches. This particular type of research also helps in improving one’s country export quality of fruits.     

A Convenient New Method for Trapping Bicyclic Valence Tautomers of Cyclooctatetraene and 1,3,5-Cyclooctatriene with Singlet Oxygen

The bicyclic valence tautomers of cyclooctatetraene and 1,3,5-cyclooctatriene were prepared by MnO₂ oxidation of the appropriate hydrazo compounds at low temperatures and trapped with singlet oxygen to give the corresponding endoperoxides.     

Novel Triterpene Saponins from Zizyphus joazeiro

Two dammarane‐type saponins with a novel aglycone derived from the parent 16,22‐epoxy‐24‐methylidenedammarane and lotoside A, a new lotogenin derivative, were isolated from the MeOH extract of the stem bark of the Brazilian medicinal plant Zizyphus joazeiro, in addition to the known saponin 3β‐{{O‐[O‐[α‐L ‐arabinofuranosyl‐(1→2)]‐O‐[β‐D ‐glucopyranosyl‐(1→3)]]‐α‐L ‐arabinopyranosyl}oxy}jujubogenin ( 1 ). The structures of the new compounds were determined as 16,22‐epoxy‐3β‐[(β‐D ‐glucopyranosyl)oxy]‐24‐methylidenedammarane‐15α,16α,20β‐triol ( 2 ), 16,22‐epoxy‐3β‐{{O‐[O‐[β‐D ‐glucopyranosyl‐(1→2)]‐O‐[β‐D ‐apiofuranosyl‐(1→3)]]‐β‐D ‐glucopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl}oxy}‐24‐methylidenedammarane‐15α,16α,20β‐triol ( 3 ), and 3β‐{{O‐[O‐[β‐D ‐glucopyranosyl‐(1→2)]‐O‐[β‐D ‐apiofuranosyl‐(1→3)]]‐β‐D ‐glucopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl}oxy}lotogenin ( 4 ) by means of 1D‐ and 2D‐NMR spectroscopy, as well as FAB mass spectrometry. For the novel aglycone, we propose the name joazeirogenin and, for the new saponins, joazeiroside A ( 2 ) and B ( 3 ). Joazeirogenin was found to be 16,22‐epoxy‐24‐methylidenedammarane‐3β,15α,16α,20β‐tetrol.     

In Vitro Effects of Isoorientin,Forsythoside B,and Verbascoside on Bovine Kidney Cortex Glutathione Reductase

Glutathione reductase (GR; E.C 1.6.4.2) catalyzes the reduction of oxidized glutathione to reduced glutathione by the nicotinamide adenine dinucleotide phosphate (NADPH) dependent mechanism. GR participates in the protection of the cell from the toxic effects of free radicals. In this study, we have investigated in vitro effects of isoorientin (C‐glycosyl flavonoid), verbascoside, and forsythoside B (phenylethanoids) on purified bovine kidney cortex GR. These compounds present in many plant species that have been used as medicinal plants and have an interesting spectrum of biological activity. We have demonstrated that these compounds inhibit bovine kidney cortex GR in a concentration‐dependent manner. Kinetic characterization of the inhibition is also done. Isoorientin is a noncompetitive inhibitor with respect to both glutathione disulfide (GSSG) (Ki_GSSG 0.023 ± 0.001 mM) and NADPH (Ki_NADPH 0.032 ± 0.001 mM). Forsythoside B acts as an uncompetitive inhibitor with respect to GSSG (Ki_GSSG 0.20 ± 0.014 mM) and NADPH (Ki_NADPH 0.267 ± 0.028 mM). Verbascoside acts as an uncompetitive inhibitor with respect to both GSSG (Ki_GSSG 0.242 ± 0.024 mM) and NADPH (Ki_NADPH 0.175 ± 0.016 mM). Inhibition of GR causes accumulation of reactive oxygen species and depletion of the glutathione pool. Inhibition of this enzyme may be significant in drug resistance.     

Photooxygenation of the CN bond: a mild new method for oxidative CC cleavage

Upon photooxygenation in the presence of base, α-oximinocarbonyl compounds undergo clean oxidative CC cleavage giving rise to mixtures of esters and acids. The mechanism of these reactions involves some unusual peroxidic intermediates, including a 2,3,5-trioxapentanes.