Synthesis of 1,2,3,triazole modified analogues of hydrochlorothiazide via click chemistry approach and in-vitro α-glucosidase enzyme inhibition studies

Molecular Diversity - The current study was aimed to discover potent inhibitors of α-glucosidase enzyme. A 25 membered library of new 1,2,3-triazole derivatives of hydrochlorothiazide (1)...     

Production, Purification, and Characterization of Exoglucanase by Aspergillus fumigatus

Fungi are considered good producers of industrially valuable enzymes with higher enzymatic activities. Among these cellulases are group of extracellular enzymes commonly employed in many industries for the hydrolysis of cellulolytic material. Aspergillus fumigatus produced exoglucanase having high enzymatic activity (83 U/gds) during the solid-state fermentation of wheat straw under optimum physical and nutritional conditions. Maximum production was obtained after 72 h of fermentation, at 55 °C temperature, pH 5.5, 80 % moisture level, and 2 mL fungal inoculum. Production was further increased by the addition of fructose (0.3 %) as additional carbon source, peptone (0.4 %) as nitrogen source, Tween-80 (0.3 %) as surfactant, and ammonium sulfate (0.2 %) in media. Exoglucanase was 2.30-folds purified by adding 40 % ammonium sulfate with volumetric activity 95.4 U/gds and specific activity 14.74 U/mg. Further, it was 5.18-folds purified by gel filtration chromatography with volumetric activity 115.2 U/gds and specific activity 33.10 U/mg. Purified exoglucanase has maximum activity at 55 °C and pH 4.8 using 1 % Avicel aqueous solution as substrate. The K _m and V _max were 4.34 mM and 7.29 μM/min, respectively. Calcium, magnesium, and zinc ions have positive effect on exoglucanase activity.     

Osmium (VI) catalyzed chemoselective oxidation of allylic and benzylic alcohols

A mild and highly chemoselective approach to oxidation of allylic, electron rich/deficient benzylic, and heterocyclic alcohols employing catalytic quantities of K₂[OsO₂(OH)₄] (3 mol %) and chloramine-T (50 mol %) is described. The protocol offers short reaction times (25 min–2 h), controlled oxidation, and tolerance to a variety of substrates. A systematic mechanistic study based on the LC-ESI-MS/MS reveals the presence of imidotriooxoosmium species which further reacts with alcohol to give the oxidized product.     

Structure of bistramide A-actin complex at a 1.35 angstroms resolution

Bistramide A is a highly potent antiproliferative marine natural product from Lissoclinum bistratum. We have previously established actin as the primary cellular receptor of bistramide A. We report herein the X-ray structure of bistramide A bound to monomeric actin at a resolution of 1.35 A. The most notable aspect of the bistramide A-actin structure is an extensive hydrogen-bonding network established upon a deep penetration of the central segment of bistramide A into the actin-binding cleft between subdomains 1 and 3. The structure presents the first insight into the observed ability of bistramide A to modulate G-actin polymerization. The structural information combined with our ability to chemically modify the bistramide framework provides the basis for rational development of a series of new synthetic analogues as useful probes for studying actin cytoskeleton and as potential therapeutic leads.     

Selective Late‐Stage Oxygenation of Sulfides with Ground‐State Oxygen by Uranyl Photocatalysis

Oxygenation is a fundamental transformation in synthesis. Herein, we describe the selective late‐stage oxygenation of sulfur‐containing complex molecules with ground‐state oxygen under ambient conditions. The high oxidation potential of the active uranyl cation (UO₂²⁺) enabled the efficient synthesis of sulfones. The ligand‐to‐metal charge transfer process (LMCT) from O 2p to U 5f within the O=U=O group, which generates a U^V center and an oxygen radical, is assumed to be affected by the solvent and additives, and can be tuned to promote selective sulfoxidation. This tunable strategy enabled the batch synthesis of 32 pharmaceuticals and analogues by late‐stage oxygenation in an atom‐ and step‐efficient manner.     

Anionic photofragmentation of CO: a selective probe of core-level resonances

Anion-yield spectroscopy using x rays is shown to be a selective probe of molecular core-level processes, providing unique experimental verification of shape resonances. For CO, partial anion and cation yields are presented for photon energies near the C K edge. The O- yield exhibits features above threshold related only to doubly excited states, in contrast to cation yields which also exhibit pronounced structure due to the well-known sigma* shape resonance. Because the shape resonance is completely suppressed for O-, anion spectroscopy thus constitutes a highly selective probe, yielding information unobtainable with absorption or electron spectroscopy.     

Investigation of stimulated brillouin backscattering of nanosecond CO2 laser radiation from an extended underdense plasma

Stimulated Brillouin backscattering (SBS) of nanosecond CO₂ laser radiation is investigated from an homogeneous extended plasma for well defined interaction conditions. It is found that SBS saturates at the theoretical limit near 100% Growth of SBS ion-waves starts from near thermal-wave amplitudes. Theoretical and observed SBS threshold fluxes agree within the 50% error bounds of these values. It is pointed out that self focusing does not greatly affect SBS under the conditions investigated. SBS thresholds depend on plasma density and focal spot diameter. It is indicated that an equilibrium between inverse bremsstrahlung absorption and classical heat conduction can explain several aspects.     

Synthesis of optically active penems

A general synthesis for optically active penems is described. Penems undergo a novel thermal isomerisation reaction.