Two novel steroids from Euphorbia officinarum latex

Two novel steroids, 3beta,7alpha-dihydroxy-4alpha,14alpha-dimethyl-5alpha-cholest-8-en-11-one (2) and 3beta,7beta-dihydroxy-4alpha,14alpha-dimethyl-5alpha-cholest-8-en-11-one (3) were isolated from the latex of Euphorbia officinarum. Their structures were established on the basis of NMR and MS studies.     

Modelling the Influence of Nanoparticles in the Phase Behaviour of an Epoxy/Polystyrene Mixture, 2

The influences of nanoparticle size and concentration on the thermodynamic behaviour of epoxy/polystyrene blends are evaluated in the framework of Ginzburg's simple analytical theory. Two approaches have been employed: NPEPO (for particles coated with epoxy groups) and NPFEN (for particles coated with phenyl groups). Using NPEPO, the particles are found to prefer the phase richer in epoxy, whereas the opposite occurs for NPFEN. The particles size significantly influences blend compatibility. When the particle radius R_p is about the same size as the radius of gyration R_g of PS, the compatibility of blends increases with particle concentration, whereas for R_p > R_g, higher particle concentrations do not clearly stabilize the polymeric blends.

     

Large-scale analysis of posttranslational modifications in the hippocampus of patients with Alzheimer’s disease using pI shift and label-free quantification without enrichment

Posttranslational modifications modulate protein function in cells. Global analysis of multiple posttranslational modifications can provide insight into physiology and disease, but presents formidable challenges. In the present study, we used a technique that does not require target enrichment to analyze alterations in the phosphorylation and ubiquitination of proteins from patients with Alzheimer’s disease (AD). Guided by our previous findings, we applied three strategies to further our understanding of the dysregulation of posttranslationally modified proteins. We first identified phosphorylation sites by determining peptide pI shifts using OFFGEL. Second, using tandem mass spectrometry, we determined the ubiquitination status of the proteins using an assay for a trypsin digestion remnant of ubiquitination (Gly-Gly). Third, for large-scale discovery, we quantified the global differences in protein expression. Of the proteins expressed in AD tissue at levels of 2.0 or greater compared with controls, 60 were phosphorylated and 56 were ubiquitinated. Of the proteins expressed at levels of 0.5 or lower compared with controls, 81 were phosphorylated and 56 were ubiquitinated. Approximately 98 % of the phosphopeptides exhibited a pI shift. We identified 112 new phosphorylation sites (51.38 %), and 92 new ubiquitination sites (96.84 %). Taken together, our findings suggest that analysis of the alterations in posttranslationally modified proteins may contribute to understanding the pathogenesis of AD and other diseases.     

Multivariate curve resolution modeling of liquid chromatography-mass spectrometry data in a comparative study of the different endogenous metabolites behavior in two tomato cultivars treated with carbofuran pesticide

A metabonomic study based on the application of multivariate curve resolution and alternating least squares (MCR-ALS) to three-way data sets obtained by liquid chromatography coupled to mass spectrometry detection (LC-MS) was carried out for Rambo and Raf tomato cultivars treated with carbofuran pesticide. Samples were picked up during a 21 days period after treatment and analyzed by LC-MS in scan mode, along with the corresponding blank samples. Then, MCR-ALS was applied to the three-way data sets using column wise augmented matrices, and the evolutionary profiles as a function of the time after treatment were estimated for the metabolites present in both cultivars, as well as their corresponding pure spectra estimations. A comparative study using those estimations showed that some of these metabolites followed different behavior for the different cultivars after treatment. Since all treated and untreated Rambo and Raf samples were picked up according to the same sampling protocol and in a similar state of maturation, any difference in the behavior between profiles can be interpreted as an effect due to the presence of pesticide and to the kind of cultivar. Based on this hypothesis, several PLS-DA approaches were tested to check if it would be possible to classify samples by using the metabolites MCR estimations. Results showed that PLS-DA models for classification of treated or non-treated (blank) samples were the best ones obtained (98.44% of correct classifications for the validation set), which supports the stress effects related to carbofuran treatment. In addition, excellent discrimination among the four groups could be attained (89.06% of correct classifications for the validation set).     

Stereocontrolled synthesis of cyclopropanol amino acids from allylic sulfones: conformationally restricted building blocks

[reaction: see text] A new amino acid methyl ester with a cyclopropanol has been synthesized starting from the allyl sulfone 10. The starting material, 10, could be obtained in both enantiomeric forms. The stereoselectivity of the cyclopropane formation has been studied by molecular modeling.     

Modelling the influence of nanoparticles in the phase behaviour of an epoxy/polystyrene mixture

The cloud point temperatures of four series of epoxy/polystyrene blends have been experimentally determined as a function of polymer mass and system composition. The phase diagrams show an UCST behaviour, increasing incompatibility as the molar mass increases. The Flory-Huggins theory with a concentration-dependent interaction parameter has been developed to study the compatibility of two polymers in presence of spherical nanoparticles. This theory has been first compared with the experimental cloud point curve in absence of nanoparticles, and secondly it has been used to predict the thermodynamic behaviour in presence of different volume fraction of nanoparticles. Nanoparticles coated with two types of functional groups have been tested. It can be concluded that the inclusion of nanoparticles increases compatibility. Moreover concentration-dependent interaction parameters have been obtained in these systems for the first time.     

2-(aminomethyl)-oxazolines: highly modular scaffolds for the preparation of novel asymmetric ligands

Highly modular chiral 2-(aminoalkyl)oxazolines have been prepared from alpha-amino acids and 1,2-amino alcohols. The amine-functionalized oxazolines were employed as scaffolds in the preparation of a number of different ligands with potential denticities varying from 2 to 5. The obtained ligands were employed and evaluated in the ruthenium-catalyzed asymmetric transfer-hydrogenation of acetophenone and in the titanium-catalyzed addition of diethylzinc to aldehydes. In the latter process, enantioselectivity up to 97% was obtained.