Separation of hypoviral double-stranded RNA on monolithic chromatographic supports

A procedure based on BIA Separations CIM DEAE anion-exchange chromatography was developed to separate double-stranded (ds) RNA of hypovirus infecting phytopathogenic fungus Cryphonectria parasitica. Using a linear gradient of 25 mM 4-morpholinepropanesulfonic acid (MOPS), pH 7.0 as a binding buffer, and 25 mM MOPS, 1.5 M NaCl, 0.1 mM EDTA, 15% isopropanol (v/v), pH 7.0 as an elution buffer, hypoviral dsRNA was additionally purified from nucleic acid species present in preparations partially purified by standard CF-11 cellulose chromatography. Moreover, crude phenol/chloroform extracts of the fungal tissue were also applied to monolithic supports and CIM DEAE chromatograms revealed clear evidence for hypoviral presence without CF-11 chromatography, nucleic acid precipitation, and electrophoresis.     

Determination of triazines and dinitroanilines in waters by high-performance liquid chromatography after solid-phase extraction

A rapid and selective method for the simultaneous determination of triazines and dinitroanilines in real water matrices is suggested based on a preliminary adsorption on an RP-18 cartridge, an elution step using acetonitrile and HPLC separation with a Lichrosorb RP- Select B column and UV detection. The washing step cartridge is critical for triazines: terbutryn is eluted with quantitative recovery only after washing with an NH₃ solution. The degree of enrichment of the compounds studied has been determined: triazine recoveries are quantitative, while dinitroaniline recoveries are between 66% and 78% at the lowest fortification level. The detection limits for the ten herbicides are in the range 0.03-0.1 μg/l. The analysis time is 2 h.     

Synthesis of 6-phenanthridinones and their heterocyclic analogues through palladium-catalyzed sequential aryl-aryl and N-aryl coupling

[reaction: see text] 6-Phenanthridinones and their heterocyclic analogues were synthesized through a one-pot procedure based on consecutive Pd-catalyzed aryl-aryl and N-aryl coupling from iodoarenes ortho-substituted by electron-releasing substituents and amides of o-bromoarene- and heteroarenecarboxylic acids.     

Optical Limiting Devices Based on C60 Derivatives in Sol-Gel Hybrid Organic-Inorganic Materials

A guest-host solid state device based on hybrid organic-inorganic materials and fullerene derivatives has been fabricated for optical limiting applications. Different 3-glycidoxypropyltrimethoxysilane derived hybrid matrices have been synthesized to increase the optical limiting performances. These matrices have shown high laser damage fluences, low light scattering, good transmittance in the visible range and allowed to deposit 10–100 m thick films per single layer. The C₆₀ derivatives have been functionalized with Si tri-alkoxide terminal groups and have reached a final concentration in the solid matrix up to 2 × 10^–2 M·l^–1. A multilayer system with a bottleneck structure has been developed to optimize a laser protection device.     

Toward the identification of the cardiac cGMP inhibited-phosphodiesterase catalytic site

Cyclic nucleotide phosphodiesterases (PDEs) comprise a complex group of enzymes; five major PDE families or classes with distinctive properties have been identified. Among these a great deal of interest has recently been focused on the so called cGMP-inhibited low K_m cAMP phosphodiesterase (cGI PDE) or PDE III. A number of positive inotropic agents, including the well-known milrinone, display a specific inhibition of PDE III as primary mechanism of action. Recent studies have been carried out to develop a pharmacophore model of the PDE III active site. We therefore performed molecular modelling and 3D-SAR studies so as to better define structural requirements for potent and selective enzymatic inhibition. The DISCO (DIStance COmparison) strategy has been applied on a set of compounds taken from literature and a milrinone analogue previously synthesized by us, all of which are characterized by a marked inotropic effect but with varying degrees of enzyme selectivity. A common pharmacophoric model was derived, validated and considered as starting point to perform a 3D-SAR study using the GRID force field and PCA (Principal Component Analysis) with the aim of rationally designing more selective inhibitors. This paper presents the results of this theoretical approach.     

Metmyoglobin-catalyzed exogenous and endogenous tyrosine nitration by nitrite and hydrogen peroxide

Metmyoglobin catalyzes the nitration of various phenolic compounds in the presence of nitrite and hydrogen peroxide. The reaction rate depends on the reactant concentrations and shows saturation behavior. Two competing paths are responsible for the reaction. In the first, myoglobin reacts according to a peroxidase-like cycle forming two active intermediates, which can induce one-electron oxidation of the substrates. The MbFe(IV)==O intermediate oxidizes nitrite to nitrogen dioxide, which, after reaction with the phenol or with a phenoxy radical, yields the nitrophenol. In the second mechanism, hydrogen peroxide reacts with iron-bound nitrite to produce an active nitrating species, which we assume to be a protein-bound peroxynitrite species, MbFe(III)--N(O)OO. The high nitrating power of the active species is shown by the fact that the catalytic rate constant is essentially independent of the redox properties of the phenol. The occurrence of one or other of these mechanisms depends on the nitrite concentration: at low [NO(2) (-)] the nitrating agent is nitrogen dioxide, whereas at high [NO(2) (-)] the peroxynitrite path is dominant. The myoglobin derivative that accumulates during turnover depends on the mechanism. When the path involving NO(2) (.) is dominant, the spectrum of the MbFe(IV)==O intermediate is observed. At high nitrite concentration, the Soret band appears at 416 nm, which we attribute to an iron-peroxynitrite species. The metMb/NO(2) (-)/H(2)O(2) system competitively nitrates the heme and the endogenous tyrosine at position 146 of the protein. Phenolic substrates protect Tyr146 from nitration by scavenging the active nitrating species. The exposed Tyr103 residue is not nitrated under the same conditions.     

The fungal metabolite austdiol

The title compound, (7R,8S)‐7,8‐di­hydroxy‐3,7‐di­methyl‐6‐oxo‐7,8‐di­hydro‐6H‐isochromene‐5‐carb­aldehyde, C₁₂H₁₂O₅, is a trans‐vicinal diol. Of the two fused rings, which lie approximately in the same plane, the pyran ring is almost perfectly planar, while the cyclo­hexenone ring adopts a slightly distorted half‐chair conformation. The crystal packing is dictated by two strong intermolecular O—H⃛O interactions, one involving hydroxy and keto groups, the other involving two hydroxy groups. Molecules are linked together through twofold axes, forming zigzag ribbons extended along the a axis.     

A new norkaurane‐γ‐lactone from Parinari sprucei

The title tetracyclic diterpenoid, 10,13,16,17‐tetra­hydroxy‐9‐methyl‐15‐oxo‐20‐norkaurane‐18,10‐carbolactone hemihydrate, C₂₀H₂₈O₆·0.5H₂O, is a plant metabolite from Parinari sprucei, part of the Venezuelan Amazon flora. The asymmetric unit consists of two nearly identical mol­ecules of the diterpenoid and one mol­ecule of water. Some of the geometric parameters reflect steric strain in the mol­ecule. The extended structure is characterized by hydrogen bonds and weaker hydrogen‐mediated interactions, which involve all of the hydroxy groups and propagate in sheets that coincide with the (002) family of planes. The water mol­ecule acts as a double hydrogen‐bond donor and single acceptor and thus plays a critical role in the pattern of intermolecular interactions.     

Hölder continuity of local minimizers of vectorial integral functionals

We study the regularity of vector-valued local minimizers in $ W^{1,p}, p > 1 $, of the integral functional where is an open set in $ \mathbb{R}^N $ and f is a continuous function, convex with respect to the last variable, such that $ 0 \leq f(x,u,t)\leq C(1+t^p) $.We prove that if f = f(x, t), or f = f(x, u, t) and $ p \leq N $, then local minimizers are locally Hölder continuous for any exponent less than 1. If f = f(x, u, t) and p < N then local minimizers are Höolder continuous for every exponent less than 1 in an open set $ \Omega_0 $ such that the Hausdorff dimension of $ \Omega \backslash \Omega_0 $ is less than N–p.AMS Subject Classification: 49N60.     

Intramolecular N-acyliminium ion versus Friedel-Crafts cyclization onto 3-indoles: synthesis of the novel rings pyrrolizino[2,1-b]indole and homologues

Acid treatment of indole-2-carboxylic acid β- and γ-oxoamides causes Friedel-Crafts intramolecular cyclization to β-carbolinones and dihydro-2H-azepino[3,4-b]indol-1-ones, in contrast to secondary δ-,?-, and ζ-oxoamides, which cyclize to the novel heterocyclic rings pyrrolizino[2,1-b]indole, indolizino[2,1-b]indole, and 9a,11-diaza-indeno[1,2-a]azulene, via an intermediate N-acyliminium ion. Tertiary amides lead only the Friedel-Crafts ring closure, thus allowing the synthesis of larger fused rings.