Arosine and arosinine,two new quaternary oxoaporphine alkaloids

Structure of (I) and (II) were deduced from spectral data, chemical evidence and synthesis.     

The Pauson-Khand reaction, a powerful synthetic tool for the synthesis of complex molecules

There are still some synthetic chemists who hesitate to use metal-mediated or -catalysed reactions. The Pauson-Khand reaction (PKR) is a powerful transformation that has now been sufficiently well developed to be routinely considered when planning a synthesis, especially of polycyclic complex molecules. This tutorial review aims to encourage the use of this process explaining the best ways of performing a PKR both in the stoichiometric and the catalytic version, showing the scope of the process and its limitations. Additionally, asymmetry can be introduced in the reaction using several strategies, which will be discussed. The most recent examples of the synthetic applications of the PKR in natural product synthesis will give the reader an idea of the great usefulness of this reaction.     

Standard addition method applied to solid-state stripping voltammetry: determination of zirconium in minerals and ceramic materials

An application of the standard addition method to stripping voltammetry of solid materials immobilized in inert electrodes is described. The method allows the determination of the mass fraction of a depositable metal M in a material on addition of known amounts of a standard material containing M to a mixture of that material and a reference compound of a second depositable metal, R. After a reductive deposition step, voltammograms recorded for those modified electrodes immersed in a suitable electrolyte produce stripping peaks for the oxidation of the deposits of M and R. If no intermetallic effects appear the quotients between the peak areas and the peak currents for the stripping oxidation of M and R vary linearly with the mass ratio of the added standard and the reference compound, thus providing an electrochemical method for determining the amount of M in the sample. The method has been applied to the determination of Zr in minerals, ceramic frits, and pigments, using ZnO as reference material and ZrO₂ as the standard.     

Copper fractionation by SEC-HPLC and ETAAS: study of breast milk and infant formulae whey used in lactation of full-term newborn infants

This method will allow the determination of bound copper to low relative molecular mass compounds in milk. The milk whey obtained by ultracentrifugation was submitted to fractionation by size exclusion chromatography (SEC) on a TSK-Gel2000 (Toso Haas) column with a mobile phase of 0.2 M NH4NO3 + NH3, pH 6.7. Fractions of effluent corresponding to the protein peaks were collected and the copper content was determined by ETAAS. The method was sensitive (LOD 0.4 microgram l-1 and LOQ 1.5 micrograms l-1 in the fraction; LOQ 7.5-22.5 micrograms l-1 referred to the milk sample and depended on fraction volume) and precise (RSD +/- 10%). Media sample recoveries from the column were 101.2%. Cu was predominantly present in fractions corresponding to relative molecular mass 76 and 15 kDa of breast milk while copper was mostly found in fractions corresponding to 14 and 38 kDa of cow's milk-based infant formulae; moreover, copper was eluted in the relative molecular mass region < 6 kDa.     

Characteristics of complex voluntary mandibular movements in the monkey before and after destruction of most jaw muscle spindle afferents

To study the role of proprioception in voluntary movement, two monkeys were trained to use their mandible to control the position of a lever that electronically loaded the jaw. They “tracked” stationary and moving targets both with and without visual feedback. Lesions of the tract of the mesencephalic nucleus of the fifth nerve, which destroyed most jaw muscle proprioceptors, did not interfere, even transiently, with the ability to perform the basic requirements of the jaw tracking tasks. There was an increase in low-frequency jaw tremor, and a small increase in the tracking error when the visual feedback signal was present, but these effects may have resulted from damage to other neural pathways. We conclude that muscle spindles are not necessary to perform well-practiced movements.     

Synthesis of the tetracyclic core of anthracycline antibiotics by an intramolecular dehydro Diels-Alder approach

[reaction: see text] A conceptually new approach to the tetracyclic core of the anthracycline antibiotics is reported. With use of this approach, the 7,8,9,10-tetrahydronaphthacene-5,12-dione skeleton has been synthesized in three steps, from commercially available reagents, in yields of up to 85%.     

Toward safer methodologies for the synthesis of polyheterocyclic systems: intramolecular arylation of arenes under Mizoroki-Heck reaction conditions

[reaction: see text] A straightforward synthesis of ibudilast-related pyrazolo[1,5-f]phenanthridines is accomplished by a tandem amine-exchange/heterocyclization of arylenaminones followed by an intramolecular biaryl coupling of the so-formed diarylpyrazoles. The direct, environmentally convenient ring-closure of the latter pyrazole intermediates, which show a close resemblance to the antiinflammatory drug celecoxib, is efficiently performed under Mizoroki-Heck reaction conditions.     

Single spin asymmetry for charm mesons

We study single spin asymmetries of D̄⁰ and D^- mesons in polarized proton–proton collisions. A two component model is used to describe charm meson production. The production of D mesons occurs by recombination of the constituents present in the initial state as well as by fragmentation of quarks in the final state. This model has proved to describe the production of charm. The recombination component involves a mechanism of spin alignment that ends up in a single spin asymmetry. Experimental measurements of single spin asymmetry for pions at RHIC are compared with the model. Predictions for the asymmetry in D mesons are presented.     

A Simple Entropic-Driving Separation Procedure of Low-Size Silver Clusters,Through Interaction with DNA

Synthesis and purification of metal clusters without strong binding agents by wet chemical methods are very attractive for their potential applications in many research areas. However, especially challenging is the separation of uncharged clusters with only a few number of atoms, which renders the usual techniques very difficult to apply. Herein, we report the first efficient separation of Ag₂ and Ag₃ clusters using the different entropic driving forces when such clusters interact with DNA, into which Ag₃ selectively intercalates. After sequential dialysis of the samples and denaturalizing the DNA-Ag₃ complex, pure Ag₂ can be found in the dialysate after extensive dialysis. Free Ag₃ is recovered after DNA denaturation.     

Metabolomics reveals significant impairments in the immune system of the APP/PS1 transgenic mice of Alzheimer's disease

Inflammatory processes and other failures related to the immune system are common features associated with Alzheimer's disease (AD), in both brain and the peripheral system. Thus, the study of the main organs of the immune system may have a great potential for the elucidation of pathological mechanisms underlying these abnormalities. This is the first metabolomic investigation performed in spleen and thymus from transgenic mice of AD. Tissues were fingerprinted using a metabolomic platform comprising GC‐MS and ultra‐HPLC‐MS. Multivariate statistics demonstrated significant differences in numerous metabolites between the APP/PS1 mice and wild‐type controls, and it was proven that multiple biochemical pathways are disturbed in these organs including abnormal metabolism of phospholipids, energy deficiencies, altered homeostasis of amino acids, oxidative stress, and others. Therefore, these findings highlight the importance of the proper metabolic functioning of peripheral immune system in the development of neurodegenerative disorders such as AD.