Oxandrastins: Antibacterial Meroterpenes from an Australian Mud Dauber Wasp Nest-Associated Fungus,Penicillium sp. CMB-MD14

The ethyl acetate extract of an ISP-2 agar cultivation of the wasp nest-associated fungus Penicillium sp. CMB-MD14 exhibited promising antibacterial activity against vancomycin-resistant enterococci (VRE), with a bioassay guided chemical investigation yielding the new meroterpene, oxandrastin A (1), the first andrastin-like metabolite with an extra oxygenation at C-2. A culture media optimisation strategy informed a scaled-up rice cultivation that yielded 1, together with three new oxandrastins B–D (2–4), two known andrastins C (5) and F (6), and a new meroterpene of the austalide family, isoaustalide F (7). Structures of 1–7 were assigned based on detailed spectroscopic analysis and chemical interconversion. A GNPS molecular networking analysis of the rice cultivation extract detected the known austalides B (8), H (9), and H acid (10), tentatively identified based on molecular formulae and co-clustering with 7. That the anti-VRE properties of the CMB-MD14 extract were exclusively attributed to 1 (IC₅₀ 6.0 µM, MIC₉₉ 13.9 µM), highlights the importance of the 2-OAc and 3-OAc moieties to the oxandrastin anti-VRE pharmacophore.     

Antioxidant and Antisteatotic Activities of Fucoidan Fractions from Marine and Terrestrial Sources

Fucoidan is a fucose-rich sulfated polysaccharide typically found in the cell wall of marine algae but also recently isolated from terrestrial sources. Due to a variety of biological activities, including antioxidant properties, fucoidan exhibits an attractive therapeutic potential against a wide array of metabolic diseases associated with oxidative stress. We used FTIR, ¹H NMR and ¹³C NMR spectroscopy to investigate the structural features of a fucoidan fraction extracted from the brown alga Cystoseira compressa (CYS). The antioxidant potential of CYS was measured by DPPH, ABTS and FRAP assays, which revealed a radical scavenging capacity that was confirmed in in vitro cellular models of hepatic and endothelial cells. The same antioxidant effects were observed for another fucoidan fraction previously identified in the terrestrial tree Eucalyptus globulus (EUC). Moreover, in hepatic cells, CYS and EUC exhibited a significant antisteatotic action, being able to reduce intracellular triglyceride content through the regulation of key genes of hepatic lipid metabolism. EUC exerted stronger antioxidant and antisteatotic effects as compared to CYS, suggesting that both marine and terrestrial sources should be considered for fucoidan extraction and therapeutic applications.     

Can be Azo Dyes Obtained by Grinding under Solvent‐Free Conditions?

The solid‐solid reactions of some electron‐donors with sulfanilic acid in the presence of solid sodium nitrite afford azo dyes by self‐catalyzed diazotization of sulfanilic acid (2) under solvent‐free conditions with moderate yields. Also the reactions of some electron‐donors with diazotization of o‐nitroaniline (5), m‐nitroaniline (6) and p‐nitroaniline (7) in the presence of solid sodium nitrite catalyzed by p‐toluenesulfonic acid (PTSA) afford azo dyes under solvent‐free conditions in good yields. This new method totally avoids the use of acids, alkalies, and toxic and/or expensive solvents in diazotization and diazo coupling reactions.     

Spectrophotometric determination of acyclovir and ribavirin in their dosage forms

Two simple, accurate, and reliable spectrophotometric methods have been developed for the determination of 2 antiviral drugs, acyclovir (ACV) and ribavirin (RBV), in their pharmaceutical formulations. These methods are based on oxidation of the 2 drugs with either cerium (IV) ammonium sulfate (Method A) or potassium persulfate (Method B). The products of oxidation in both methods are coupled with 3-methylbenzothiazolin 2-one hydrazone, producing a deep blue color with a maximum absorption wavelength at 630 nm. In Method A, the absorbance-concentration plots were linear over the ranges of 5-50 and 10-60 microg/mL with detection limits of 0.18 microg/mL (8 x 10(-7) M) and 0.63 microg/mL (2.58 x 10(-6) M) for ACV and RBV, respectively. In Method B, the ranges were 5-45 and 20-50 microg/mL with detection limits of 0.11 microg/mL (4.88 x 10(-7) M) and 1.40 microg/mL (5.73 x 10(-6) M) for the 2 drugs, respectively. The molar absorptivities were 4.1 x 10(3) and 3.65 x 10(3) L/mol/cm in Method A and 5.03 x 10(3) and 3.97 x 10(3) L/mol/cm in Method B for the 2 drugs, respectively. The proposed methods were applied successfully for the determination of the 2 drugs in their pharmaceutical formulations. The percentage recoveries +/- standard deviation were 99.57 +/- 0.86 and 100.82 +/- 0.46 for ACV; 99.41 +/- 1.08 and 100.35 +/- 1.03 for RBV. The results obtained were compared statistically with those given by official methods and showed no significant differences regarding accuracy and precision.     

Output feedback controller for hysteretic time-delayed MIMO nonlinear systems

In this paper, an H ^?? output feedback controller is developed for a class of time-delayed MIMO nonlinear systems, containing backlash as an input nonlinearity. Particularly, a state observer is proposed to estimate unmeasurable states. The control law can be divided into two elements: An adaptive interval type-2 fuzzy part which approximates the uncertain model. The second part is an H ^??-based controller, which attenuates the effects of external disturbances and approximation errors to a prescribed level. Furthermore, the Lyapunov theorem is used to prove stability of proposed controller and its robustness to external disturbance, hysteresis input nonlinearity, and time varying time-delay. As an example, the designed controller is applied to address the tracking problem of 2-DOF robotic manipulator. Simulation results not only verify the robust properties but also in comparison with an existing method reveal the ability of the proposed controller to exclude the effects of unknown time varying time-delays and hysteresis input nonlinearity.     

DNS Analysis of Wall Heat Transfer and Combustion Regimes in a Turbulent Non-premixed Wall-jet Flame

Understanding the heat-release effects on the wall heat transfer in turbulent reacting flows, i.e. heat transfer with or without significant density variation, is essential for a wide variety of industrial flows, especially combustion problems. The present study focuses on the wall heat transfer and the near-wall reaction characteristics. The heat-release effects on the wall heat transfer and skin-friction coefficients are investigated using three-dimensional direct numerical simulations of a turbulent reacting wall-jet flow with and without heat release. Reductions in the skin-friction coefficient are observed in the exothermic case, compared to the isothermal one, and the underlying mechanism is explained. The absolute wall heat flux also increases, while the corresponding Nusselt number decreases with increasing heat release. Furthermore, the wall effects on the near-wall average burning rate are assessed. It is found that the isothermal cold wall results in an appreciable decrease of the burning rate in the exothermic cases. We observed indications that the wall increases the chances for the development of the premixed mode and its occurrence is very fast in the wall-normal direction.     

Immobilized Vanadium Histidine and Tryptophan Schiff Base Complexes on Modified Magnetite Nanoparticles as Epoxidation Catalyst

In this study, magnetically recoverable vanadium complexs designated as VO(Sal-Tryp)/AmpSCMNPs and VO(Sal-His)/AmpSCMNPs were prepared through immobilization of Schiff bases of histidine or tryptophan with salicylaldehyde on the surface of modified silica coated iron oxide magnetite nanoparticles with (3-aminopropyl) trimethoxysilane as aminopropyl (Amp) spacer followed by complexation with VOSO₄. Characterization was carried out by chemical analysis, Fourier transform infrared spectroscopy, XRD, scanning electron microscopy and vibrating sample magnetometry techniques. VO(Sal-Tryp)/AmpSCMNPs and VO(Sal-His)/AmpSCMNP were found to catalyze the epoxidation of allyl alcohols and olefins with tert-butyl hydroperoxide with excellent conversions and selectivities. Investigation of the stability and reusability revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, easily catalyst separation and recyclability of the solid catalyst are some advantages of this method.     

CO2 reforming of methane over nickel catalysts supported on nanocrystalline MgAl2O4 with high surface area

In this paper dry reforming of methane (DRM) was carried out over nanocrystalline MgAl2O4-supported Ni catalysts with various Ni loadings. Nanocrystalline MgAl2O4 spinel with high specific surface area was synthesized by a co-precipitation method with the addition of pluronic P123 triblock copolymer as surfactant, and employed as catalyst support. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption, H2 chemisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), temperature- programmed desorption (TPD) and transmission and scanning electron microscopies (TEM, SEM) techniques. The obtained results showed that the catalyst support has a nanocrystalline structure (crystal size: about 5 nm) with a high specific surface area (175 m2 g-1) and a mesoporous structure. Increasing in nickel content decreased the specific surface area and nickel dispersion. The prepared catalysts showed high catalytic activity and stability during the reaction. SEM analysis revealed that whisker type carbon deposited over the spent catalysts and increasing in nickel loading increased the amount of deposited carbon. The nickel catalyst with 7 wt% of nickel showed the highest catalytic activity.     

Lamellarins as Inhibitors of P‐Glycoprotein‐Mediated Multidrug Resistance in a Human Colon Cancer Cell Line

Chemical analysis of a Didemnum sp. (CMB‐01656) collected during scientific Scuba operations off Wasp Island, New South Wales, yielded five new lamellarins A1 ( 1 ), A2 ( 2 ), A3 ( 3 ), A4 ( 4 ) and A5 ( 5 ) and eight known lamellarins C ( 6 ), E ( 7 ), K ( 8 ), M ( 9 ), S ( 10 ), T ( 11 ), X ( 12 ) and χ ( 13 ). Analysis of a second Didemnum sp. (CMB‐02127) collected during scientific trawling operations along the Northern Rottnest Shelf, Western Australia, yielded the new lamellarin A6 ( 14 ) and two known lamellarins G ( 15 ) and Z ( 16 ). Structures were assigned to 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 on the basis of detailed spectroscopic analysis with comparison to literature data and authentic samples. Access to this unique library of natural lamellarins ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ) provided a rare opportunity for structure–activity relationship (SAR) investigations, probing interactions between lamellarins and the ABC transporter efflux pump P‐glycoprotein (P‐gp) with a view to reversing multidrug resistance in a human colon cancer cell line (SW620 Ad300). These SAR studies, which were expanded to include the permethylated lamellarin derivative ( 17 ) and a series of lamellarin‐inspired synthetic coumarins ( 19 , 20 , 21 , 22 , 23 , 24 ) and isoquinolines ( 25 , 26 ), successfully revealed 17 as a promising new non‐cytotoxic P‐gp inhibitor pharmacophore.     

Photochromism of dihydroindolizines. Part XVIII: palladium-catalyzed Negishi coupling for the synthesis of photochromic dihydro 5-azaindolizine-linker-conjugates with a terminal ethylene anchoring group

Eight new photochromic dihydro 5-azaindolizine-linker-conjugates with a terminal ethylene anchoring group have been synthesized via palladium-catalyzed Negishi coupling. Polychromatic light irradiation of the photochromic dihydro 5-azaindolizines (DHAIs) led to ring-opened colored betaines which underwent reversible thermal 1,5-electrocyclization into their corresponding DHAIs in the second domain. The noteworthy multiaddressable photochromic properties are useful for a plethora of new applications for these materials such as anchoring the ethylene group to metal-oxide nanoparticles.