Biosynthesis of Bromoroquefortines in a High Saline Medium by Penicillium chrysogenum,a Terrestrial Endophyte Collected from Coffea arabica

Roquefortine C ( 1 ) and 11‐bromoroquefortine C ( 4 ) were isolated from Penicillium chrysogenum, an endophyte obtained from green leaves of Coffea arabica, during induction experiments by adding halide salts to the culture media. In our studies, 11‐bromoroquefortine D and 11‐bromo‐17‐hydroxybromoroquefortine C were identified by LC/HR‐MS. It is the first time that bromoroquefortine C and D are described as halogenated natural products. These halo alkaloids were shown to be biosynthesized from brominated tryptophan as the biosynthetic precursor. Cytotoxic and antibiotic assays using roquefortine C and 11‐bromoroquefortine C showed that the presence of the 11‐Br substituent impairs some biological activities of this alkaloid.     

A Theorem of DoCarmo–Zhou Type: Oscillations and Estimates for the First Eigenvalue of the p-Laplacian

It is shown that the estimates, obtained by DoCarmo and Zhou (Trans. Amer. Math. Soc. 351(4):1391–1401, 1999) for the first eigenvalue of the Laplace–Beltrami operator on open manifolds via an oscillation theorem, can be naturally extended to the semi-elliptic singular operator, the p-Laplacian on manifolds, defined by ${\Delta_p(u) := -div (||\nabla u||^{p-2}\nabla u)}$ .     

Experiments with LAGRASP heuristic for set k-covering

The set k-covering problem (SC _k P) is a variant of the classical set covering problem, in which each object is required to be covered at least k times. We describe a hybrid Lagrangean heuristic, named LAGRASP, which combines subgradient optimization and GRASP with path-relinking to solve the SC _k P. Computational experiments carried out on 135 test instances show experimentally that by properly tuning the parameters of LAGRASP, it is possible to obtain a good trade-off between solution quality and running times. Furthermore, LAGRASP makes better use of the dual information provided by subgradient optimization and is able to discover better solutions and to escape from locally optimal solutions even after the stabilization of the lower bounds, whereas other strategies fail to find new improving solutions.     

Fed-Batch production of glucose 6-Phosphate dehydrogenase using recombinant saccharomyces cerevisiae

The strain Saccharomyces cerevisiae W303-181, having the plasmid YEpPGK-G6P (built by coupling the vector YEPLAC 181 with the promoter phosphoglycerate kinase 1), was cultured by fed-batch process in order to evaluate its capability in the formation of glucose 6-phosphate dehydrogenase (EC.1.1.1.49). Two liters of culture medium (10.0 g/L glucose, 3.7 g/L yeast nitrogen broth (YNB), 0.02 g/L L-tryptophan, 0.02 g/L L-histidine, 0.02 g/L uracil, and 0.02 g/L adenine) were inoculated with 1.5 g dry cell/L and left fermenting in the batch mode at pH 5.7, aeration of 2.2 vvm, 30 degrees C, and agitation of 400 rpm. After glucose concentration in the medium was lower than 1.0 g/L, the cell culture was fed with a solution of glucose (10.0 g/L) or micronutrients (L-tryptophan, L-histidine, uracil, and adenine each one at a concentration of 0.02 g/L) following the constant, linear, or exponential mode. The volume of the culture medium in the fed-batch process was varied from 2 L up to 3 L during 5 h. The highest glucose 6-phosphate dehydrogenase activity (350 U/L; 1 U=1 micromol of NADP/min) occurred when the glucose solution was fed into the fermenter through the decreasing linear mode.     

Oxidovanadium(IV) Schiff base complex derived from vitamin B6: synthesis, characterization, and insulin enhancing properties

A new Schiff base, [H(4)pydmedpt](2+)·2Cl(-), derived from one of the forms of vitamin B(6) has been synthesized by condensation of pyridoxal hydrochloride with N,N-bis[3-aminopropyl]-methylamine (medpt) and characterized by analytical and spectroscopic methods. The molecular structure is calculated by density functional theory (DFT) procedures, and the donor properties of each individual donor atom are evaluated by calculation of the Fukui function. One pot reaction of pyridoxal and medpt with vanadyl acetylacetonate yields the brown complex [V(IV)O(H(2)pydmedpt)](2+)·2Cl(-)1, which upon recrystallization from water crystallizes as [V(IV)O(pydmedpt)]·5H(2)O 2. The compounds are characterized by analytical and spectroscopic methods, 2 being also characterized by single crystal X-ray diffraction. It displays a slightly distorted octahedral geometry around the vanadium atom involving the coordination of N(amine), two N(imine), and O(phenolato) donors of the ligand. One of the phenolato oxygen donors is positioned trans to the terminal O-oxido atom with relatively short V-O(phenolate) {2.041(3) ?} and long V-O(oxido) {1.625(4) ?} bond distances when compared to other known compounds. The two different pK(a) values (6.0 and 7.9) obtained for 1 are due to protonation of the pyridine ring nitrogen atoms having different basic characters, this being also substantiated by theoretical calculation of the proton affinity of the O- and N- atoms of the molecule. The spin Hamiltonian parameters are obtained from the electron paramagnetic resonance (EPR) spectra, but the A(z) value (ca. 155 × 10(-4) cm(-1)) is lower than expected by applying the additivity rule for the present set of equatorial donor atoms (ca. 162-163 × 10(-4) cm(-1)), this being attributed to the strong trans V-O(phenolate) bond. The UV-vis transitions and EPR spectral parameters are calculated by DFT procedures, and both the calculated electronic transitions and the hyperfine coupling constants agree well with those experimentally observed. The inhibitory effect of 1 on FFA release and % glucose uptake determined with isolated rat adipocyte cells gave IC(50) and EC(50) values lower than for V(IV)OSO(4) and of the same order of magnitude of other reported insulin enhancing vanadium compounds.     

Polymer-bound metal complexes as catalysts: Synthesis, characterization, reactivity and catalytic activity in E-H bond activation

An account of recent research of our groups is presented, focusing on the preparation of several polystyrene anchored complexes and their use as catalysts in functionalization of alkenes. The procedures for covalently binding the ligands or ligand precursors are outlined, as well as for coordination of the metal ions. Instrumental techniques used for the characterization of the polymer-bound complexes have been highlighted. The heterogenized complexes are used as catalysts for the functionalization of alkenes, namely for oxidative aminations, hydroaminations and several types of oxidations, and results obtained using the catalysts prepared are presented. The main advantages of the use of the prepared supported catalyst are specified, namely their recyclability and their higher activity, also confirmed in many cases by comparison with their homogeneous counterparts. An account of the success in the use of EPR to characterize the V^IVO- and Cu^II-systems is also given.     

Synthesis of new 9-hydroxy-α- and 7-hydroxy-β-pyran naphthoquinones and cytotoxicity against cancer cell lines

A synthetic method to obtain α- and β-pyran naphthoquinones 10 and 11 with a hydroxyl substituent on the aromatic ring was developed. Two series of α- and β-pyran naphthoquinones were obtained from the 8-hydroxy-lawsone, and their anticancer properties were evaluated against four tumor cell lines. In general, the new compounds displayed good activity, possibly indicating that these compounds have increased pro-oxidant capacity. The 9-hydroxy-α-lapachone and 7-hydroxy-β-lapachone analogues of the natural products α-lapachone and β-lapachone were successfully produced by this methodology.     

Assessment of dispersion map impact on the digital back propagation of long-haul fibre-optic links

The back propagation algorithm is one of the best methods known for simultaneous linear and nonlinear impairment mitigation in long-haul fibre-optic links. Better understanding the full potential of such algorithm is key to improve the capacity of future links, whose design is likely to depend on the algorithm performance under different link configurations. In this paper, we carry out a novel and pertinent comparison in terms of the computational complexity requirements of both symmetric and asymmetric back-propagation implementation approaches for different dispersion map configurations, using simple single channel transmission, which results in the proposal of several design rules for the optimized deployment of ultra-long haul optical transport systems. In particular, it is concluded that dispersion unmanaged transmission is preferable in the sense of compatibility with different link design configurations as well as computational complexity requirements and maximum performance that can be achieved.     

Dzhuraev’s Formulas and Poly-Bergman Kernels on Domains Möbius Equivalent to a Disk

Let ${U\subset\mathbb{C}}$ be a domain Möbius equivalent to the unit disk. For every non-zero integer j, the poly-Bergman projection B _{U, j} is explicitly represented in terms of the singular integral operator S _{U, j} . If Ω is the complement of a disk, then the action of the Beurling operator S _Ω and its adjoint ${S_\Omega^*}$ on the true poly-Bergman spaces is described. The poly-Bergman kernels of U are explicitly given.     

The method of variation of the domain for poly‐Bergman spaces

If , is an increasing sequence (well ordered by inclusion) of domains then the sequence of poly‐Bergman projections on the domains strongly converges to the poly‐Bergman projection on the limit domain. As a corollary some properties of the poly‐Bergman spaces on the half‐planes are deduced from the corresponding ones in the unit disk. We obtain explicit representation of the poly‐Bergman projections in terms of the two‐dimensional singular integral operators , likewise explicit formulas for the poly‐Bergman kernels. We prove that the poly‐Bergman projections on the sectors with a non‐smooth boundary do not admit the usual representations by the two‐dimensional singular integral operators. The variation of the domain and the latter peculiarity of the poly‐Bergman projections allow us to furnish a larger class of domains not admitting Dzhuraev's formulas.