Characterization of Pentaclethra macroloba oil

The Pracaxi oil—(Pentaclethra macroloba) contains high concentrations of fatty acids with emollient action that contribute to skin hydration. The use of this oil is supported by the utilization of natural resources thus enabling regional development and social contribution. The objective of this study was to characterize the P. macroloba oil by thermogravimetry (TG, DTG, and DTA), gas chromatography, Fourier transform infrared spectroscopy (FT-IR), and oxidation stability—Rancimat, aiming at the quality control of plant raw material. Three samples of crude oil sold by Amazon Oil Industry (Ananindeua, Pará, Brazil) were studied. The analysis of these oil samples showed different fatty acids, especially the behenic, oleic, linoleic, and lignoceric acids totalizing approximately 96 % of the grease composition and in smaller percentage arachidic, lauric, myristic, palmitic, and linolenic acids were found. The major acids have wide medicinal use. According to the TG/DTG curve, thermal stability was observed up to 220 °C, indicating a greater mass loss related to the dehydration and elimination of volatile substances. The thermal decomposition process occurred in the range of 430–450° C according to the DTG curve. The absorption spectrum in the infrared region (FT-IR) showed well-defined bands confirming the presence of functional groups present in the oil. Tests in a Rancimat have shown an induction period between 8 and 10 h demonstrating that the samples are in agreement with the standards required by ANP No. 14/2012 which requires at least 6 h of testing.     

Application of Acid and Cold Stresses to Enhance the Production of Clavulanic Acid by Streptomyces clavuligerus

Clavulanic acid (CA) is frequently prescribed for treatment of bacterial infections. Despite the large number of studies concerning CA production, there is still a need to search for more effective and productive processes because it is mainly produced by biochemical route and is chemically unstable. This paper evaluates the influence of acid and cold stresses on CA production by Streptomyces clavuligerus in bench scale stirred tank bioreactor. Four batch cultures were conducted at constant pH (6.8 or 6.3) and temperature (30, 25, or 20 °C) and five batch cultures were performed with application of acid stress (pH reduction from 6.8 to 6.3), cold stress (reduction from 30 to 20 °C), or both. The highest maximum CA concentration (684.4 mg L⁻¹) was obtained in the culture conducted at constant temperature of 20 °C. However, the culture under acid stress, in which the pH was reduced from 6.8 to 6.3 at a rate of 0.1 pH unit every 6 h, provided the most promising result, exhibiting a global yield coefficient of CA relative to cell formation (Y_CA/X) of 851.1 mg_CA g_X⁻¹. High Y_CA/X values indicate that a small number of cells are able to produce a large amount of antibiotic with formation of smaller amounts of side byproducts. This could be especially attractive for decreasing the complexity and cost of the downstream processing, enhancing CA production.

     

Preparative mass‐spectrometry profiling of minor concentrated metabolites in Salicornia gaudichaudiana Moq by high‐speed countercurrent chromatography and off‐line electrospray mass‐spectrometry injection

Salicornia species have just been introduced to the European market as a vegetable named ‘samphire’, ‘green asparagus’, or ‘sea asparagus’. Due to its increasing attention, and associated value, minor compounds of Salicornia gaudichaudiana Moq were investigated. The use of countercurrent chromatography and mass spectrometry enabled the search for known, as well as potentially novel natural products. Their identification was achieved based on molecular weights and mass‐spectrometric fragmentation data. Low detection limits enabled the visualization of all compounds with their identification in almost real time close to the preparative countercurrent chromatography experiment. A list of known natural products from Salicornia genus guided the identification process of compounds occurring in Salicornia gaudichaudiana Moq by tandem mass spectrometry fragment comparison. The natural product classes were divided into four groups: chlorogenic acid derivatives; flavonoid derivatives; pentacyclic triterpenoid saponins; and other compounds.     

A close analysis of metal-enhanced fluorescence of tryptophan induced by silver nanoparticles: wavelength emission dependence

In the last few years, silver nanoparticles have been proposed as a promising alternative for the label-free detection of proteins via metal-enhanced fluorescence. Generally, the aromatic amino acid tryptophan is most frequently used in this type of studies, because the intrinsic fluorescence of proteins is usually dominated by tryptophan emissions. In the present study, we evaluated the fluorescence behavior of tryptophan in the presence of a silver colloid with nanoparticles of 100 nm in diameter. The results showed that a nanoparticles concentration of 32 mg L^?1 induced maximum fluorescence enhancement. However, the metal-enhanced fluorescence was dependent on the emission wavelength of tryptophan, and this phenomenon was closely related to the metal surface reabsorption process (inner filter effect), suggesting that the plasmon resonance reabsorption effect should be taken into account in analyses involving protein studies by metal-enhanced fluorescence.     

Influence of pH and Matrix Components in the Chromatographic Response of Pesticides

The pH effect of potato, apple, and soil matrices on the chromatographic response of nine pesticides was evaluated. All chromatographic analyses were performed in duplicate on a gas chromatograph with electron capture detection. The matrix effect observed in the chromatographic response of the pesticides was evaluated by comparison. We compared the chromatographic response of each pesticide in pure solvent and in organic extract obtained for the matrices. The organic extracts were obtained by solid–liquid extraction with partition at low temperature. Depending on the matrix pH, a greater or lesser amount of co-extractives can be extracted into the organic phase, which affects the matrix effect. The pH of the samples before the extraction process was modified in order to check their influence on pesticide responses. Statistical analyses involving principal component analysis and marginal means revealed that, in the potato and apple matrices, the co-extractives exerted positive effects on the chromatographic response of the analytes. At lower pH, the extraction of co-extractives from potato and apple was favored, thus increasing the matrix effect for these samples.     

Determination of seven selected antipsychotic drugs in human plasma using microextraction in packed sorbent and gas chromatography–tandem mass spectrometry

A method using microextraction by packed sorbent (MEPS) and gas chromatography–tandem mass spectrometry (GC-MS/MS) is described for the determination of seven antipsychotic drugs in human plasma. The studied compounds were chlorpromazine (CPZ), haloperidol (HAL), cyamemazine, quetiapine, clozapine, olanzapine (OLZ), and levomepromazine; promazine, protriptyline, and deuterated CPZ were used as internal standards. The validation parameters included selectivity, linearity and limits of detection and quantitation, intra- and interday precision and trueness, recovery, and stability and were studied according to internationally accepted guidelines. The method was found to be linear between the lower limit of quantitation and 1000 ng/mL, except for OLZ and HAL (200 ng/mL), with determination coefficients higher than 0.99 for all analytes, and extraction efficiencies ranged from 62 to 92 %. Intra- and interday precision ranged from 0.24 to 10.67 %, while trueness was within a ±15 % interval from the nominal concentration for all analytes at all studied levels. MEPS has shown to be a rapid procedure for the determination of the selected antipsychotic drugs in human plasma, allowing reducing the handling time and the costs of analysis. Furthermore, GC-MS/MS has demonstrated to be a powerful tool for the simultaneous quantitation of the studied compounds, enabling obtaining adequate selectivity and sensitivity using a sample volume of as low as 0.25 mL.     

Evaluation of gamma irradiation effect on physico-chemical properties of a mixed beverage based in soy milk and grape juice

The effects of the main operation variables on the electrochemical oxidation of simulated tributyl phosphate (TBP) waste by a boron-doped diamond anode are individually studied. The optimum operating conditions are obtained as follows: 4 g L^?1 initial TBP concentration, 180 min degradation time, 40 mA cm^?2 current density, 0.5 mol L^?1 Na₂SO₄ as the supporting electrolyte, and unadjusted pH of the aqueous phase. Under such conditions, a chemical oxygen demand (COD) removal ratio of 82.3% is achieved, and the energy consumption is 26.16 kWh m^?3. A degradation mechanism of TBP is tentatively proposed.     

Study of structural transformations of equiatomic compounds of rare earth metals with copper

Electrical resistivity, magnetic susceptibility, X-ray diffraction and differential thermal analysis have been performed over a wide temperature range on binary compounds RCu. Melting points or decomposition temperatures for RCu (R=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy) phases and a number of FeB-CsCl structural transitions are reported, and heats and entropies of transformation are evaluated. Large hysteresis effects are observed for the structural transformations at different temperatures.In LaCu and CeCu no structural transformation was detected, while TbCu and DyCu failed to reveal any high-temperature thermal effect of transformation. In EuCu a nonreproducible thermal effect was evidenced after thermal cycling.

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Zusammenfassung Messungen der elektrischen Leitfähigkeit und der magnetischen Susceptibilität sowie röntgendiffraktometrische und differentialthermoanalytische Untersuchungen von binären Verbindungen des Typs RCu wurden in einem weiten Temperaturbereich ausgeführt. Schmelzpunkte bzw. Zersetzungstemperaturen von RCu-Phasen (R=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb und Dy) und eine anzahl von Phasenübergängen im System FeB-CsCl sind zusammen mit den bestimmten Entropiewerten der Phasenübergänge angegeben. Die Temperaturabhängigkeit der Phasenübergänge weist eine ausgeprägte Hysterese auf. In den Systemen LaCu und CeCu konnten keine Phasenübergänge festgestellt werden, während sich bei TbCu und DyCu kein auf einen Phsenübergang hinweisender thermischer Effekt im Hochtemperaturbereich zeigt. Bei EuCu wurde ein nicht-reproduzierbarer thermischer Effekt nach einem thermischen Kreisprozeß nachgewiesen.

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, , RCu. RCu (=La, , Pr, Nd,Sm, Eu, Gd, Tb Dy) , FeB-CsCl, . . LaCu , TbCu DyCu - . EuCu .

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The authors are grateful to Prof. A. Iandelli for his interest and for helpful discussion.

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This work was supported by the Italian Consiglio Nazionale delle Ricerche.     

Transition metal-catalysed organic reactions promoted by chelating or metallacycle-forming substrates

Chelating or metallacycle-forming substrates are very useful for directing organometallic reactions. This review covers the more recent research that has been carried out in the authors' laboratory. Rhodium(I)- and (III)-catalysed reactions of C---C coupling of butadiene with N-allylamides or N-alkylbutenamides are described. These reactions are controlled by the size and strength of the chelate ring formed by double-bond insertion into the crotyl-rhodium bond (formed from butadiene) and their regioselectivity can change with the oxidation state of the metal. Rhodium(I)-catalysed reactions of butadiene with enamides are also chelation controlled and lead to different products, depending on the substituents at nitrogen. Cobalt(II) metallacycles have been utilized for promoting some organic reactions. It has been shown that alkenes can be catalytically incorporated into cobaltacyclopentadiene rings, that spirocycles can be obtained from diynes, carbon monoxide and acrylic esters and that a Pauson-Khand-type reaction can be combined with a Michael-type reaction to prepare catalytically new cyclopentenones. The use of palladacycles, derived from norbornene insertion into aryl-palladium bonds, followed by cyclization, has allowed the selective functionalization of either end of the metallacycle and the formation of condensed rings. Conversion of a palladium(II) into a palladium(IV) metallacycle, and catalytic processes involving these intermediates, have been achieved. The formation of alkylaromatic palladacycles has also been exploited for the selective meta functionalization of the aromatic moiety by means of alkyl groups, accompanied by expulsion of the norbornene molecule.