Novel carotenoids genetically engineered in a heterologous host

Carotenoids are commercially important pigments that are essential for human health. Diverse carotenoids have been identified, but availability has impeded evaluation of their pharmaceutical potential. Molecular techniques have been developed to produce specific and novel carotenoids with improved biological activities.     

Isolation, biological activity evaluation, structure elucidation, and total synthesis of eliamid: a novel complex i inhibitor

Eliamid is a secondary metabolite isolated from two bacterial strains. This molecule features a linear polyketide backbone terminated by a tetramic acid amide moiety. Among other biological activities, eliamid shows a high and specific cytostatic action on human lymphoma and cervix carcinoma cell lines. The 2,4-anti relative configuration of the C-2,C-4-dimethyl substituted amide fragment was assigned by means of Breit's rule. The absolute configuration of all stereocenters was determined by a combination of degradation methods, structural similarity analysis and total synthesis. The stereogenic centers were introduced by vinylogous Mukaiyama aldol reaction and two consecutive Myers alkylations. The use of pentafluorophenyl ester as acylation agent allowed the efficient formation of tetramic acid amide. The longest linear sequence in the synthesis consist of 13?steps and proceeds with 12?% overall yield. Differential spectroscopy experiments with beef heart submitochondrial particles established that eliamid is a potent inhibitor of the NADH-ubiquinone oxidoreductase complex. Additionally, biosynthesis of eliamid was investigated by feeding experiments with (13) C-labeled precursors.     

Organocatalytic, asymmetric synthesis of 3-sulfenylated N-boc-protected oxindoles

Sulfenylated oxindoles: The first asymmetric sulfenylation of N-Boc-protected oxindoles has been developed to provide products containing a tetrasubstituted stereogenic center in high to excellent yields (86-98?%) and, in most cases, excellent enantioselectivities (up to 96?%?ee; see scheme).     

A benchmark library and a comparison of heuristic methods for the linear ordering problem

The linear ordering problem consists of finding an acyclic tournament in a complete weighted digraph of maximum weight. It is one of the classical NP-hard combinatorial optimization problems. This paper surveys a collection of heuristics and metaheuristic algorithms for finding near-optimal solutions and reports about extensive computational experiments with them. We also present the new benchmark library LOLIB which includes all instances previously used for this problem as well as new ones.     

Preussianone, a new flavanone-chromone biflavonoid from Garcinia preussii Engl

A new flavanone-chromone biflavonoid, preussianone (1), has been isolated from the leaves of Garcinia preussii, along with four known biflavonoids. The absolute stereostructures were elucidated by chemical, spectroscopic, and chiroptical methods. The biological properties of the new biflavonoid against several bacterial strains were evaluated.     

Dimethyl(2-oxo-2-ferrocenylethyl)sulfonium iodide—a useful synthetic equivalent of ferrocenoylcarbene in the synthesis of ferrocene-containing cyclopropanes

The reaction of 1-ferrocenyl-3-thiabutan-1-one with methyl iodide in acetonitrile at room temperature gave dimethyl(2-oxo-2-ferrocenylethyl)sulfonium iodide, which was characterized by spectral data (¹H NMR, ¹³C NMR, IR) and X-ray crystallographic analysis. This salt reacted with a base (sodium hydride) in acetonitrile yielding a stabilized ylide—dimethylsulfonium ferrocenoylmethylide, which was in turn, submitted to reactions with seven conjugated enones. The obtained results showed that this methodology is potentially a new and useful approach to ferrocene-containing cyclopropanes.     

A two-dimensional domain decomposition technique for the simulation of quantum-scale devices

The simulation of realistically sized devices under the Non-Equilibrium Greens Function (NEGF) formalism typically requires prohibitive amounts of memory and computation time. In order to meet the rising computational challenges associated with quantum-scale device simulation we offer a 2-D domain decomposition technique. This technique is applicable to a large class of atomistic and spatial simulation problems. Considering a decomposition along both the cross section and length of the device, the framework presented in this work ensures efficient distribution of both memory and computation based upon the underlying device structure. As an illustration we stably generate the density of states and transmission, under the NEGF formalism, for the atomistic-based simulation of square 5 nm cross section silicon nanowires consisting of over one million atomic orbitals.     

Pair diffusion, hydrodynamic interactions, and available volume in dense fluids

We calculate the pair diffusion coefficient D(r) as a function of the distance r between two hard sphere particles in a dense monodisperse fluid. The distance-dependent pair diffusion coefficient describes the hydrodynamic interactions between particles in a fluid that are central to theories of polymer and colloid dynamics. We determine D(r) from the propagators (Green's functions) of particle pairs obtained from molecular dynamics simulations. At distances exceeding ~3 molecular diameters, the calculated pair diffusion coefficients are in excellent agreement with predictions from exact macroscopic hydrodynamic theory for large Brownian particles suspended in a solvent bath, as well as the Oseen approximation. However, the asymptotic 1/r distance dependence of D(r) associated with hydrodynamic effects emerges only after the pair distance dynamics has been followed for relatively long times, indicating non-negligible memory effects in the pair diffusion at short times. Deviations of the calculated D(r) from the hydrodynamic models at short distances r reflect the underlying many-body fluid structure, and are found to be correlated to differences in the local available volume. The procedure used here to determine the pair diffusion coefficients can also be used for single-particle diffusion in confinement with spherical symmetry.     

Indirubin Derivatives Modulate TGFβ/BMP Signaling at Different Levels and Trigger Ubiquitin-Mediated Depletion of Nonactivated R-Smads

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Highlights? Inhibition of TGFβ/BMP signaling by degradation of nonactivated R-Smads ? Total R-Smad pools are regulated through the ubiquitin-proteasome pathway ? Ubiquitin proteases USP9x and USP34 interact directly with R-Smads ? Indirubin derivative E738 controls BMP/TGFβ signaling though R-Smad depletion