Structural diversity of nucleophilic adducts from flavanols and oak wood aldehydes

The reactions between (+)-catechin and a representative oak wood aldehyde (furfuraldehyde, 5-(hydroxymethyl)furfuraldehyde, 5-methylfurfuraldehyde, vanillin, or syringaldehyde) in a wine-like model solution were studied and the formed condensation products were characterized by LC/MS and LC/MS/MS.     

Benzophenone vs. Copper/Benzophenone in Light‐Promoted Atom Transfer Radical Additions (ATRAs): Highly Effective Iodoperfluoroalkylation of Alkenes/Alkynes and Mechanistic Studies

Iodoperfluooralkylation of terminal alkenes and alkynes is effectively photo‐promoted by benzophenone 2 (BP) or the photoreducible copper(II) complex 1 . In particular, BP at 1 mol% in methanol upon 365 nm irradiation with a low‐pressure mercury lamp (type TLC=thin layer chromatography, 6 W) results in a fast reaction with excellent reaction yields. Complex 1 and BP 2 exhibited very similar reactivity, suggesting that the reactions involving 1 are likely to be governed by the benzophenone photoactivation processes, rather than copper(I)/(II) redox processes. Mechanistic investigations using transient absorption spectroscopy revealed that a deactivation pathway of the benzophenone triplet (³BP*) is via its reaction with the methanol solvent. We propose that the generated radicals, in particular ^.CH₂OH, play a key role in the initiation step forming R_f^. by reacting with R_fI, R_f^. then entering a radical chain cycle. ¹H NMR studies provided evidence that a substantial amount (∼7% NMR yield) of the hemiacetal CH₃OCH₂OH is formed, i.e., the possible by‐product of the reaction between ^.CH₂OH and R_fI. Finally, DFT calculations indicate that a triplet‐triplet energy transfer (TTET) process from ³BP* to perfluorooctyl iodide (C₈F₁₇I) is unlikely or should be rather slow under the reaction conditions, consistent with the transient absorption studies.

     

Conversion of fern (Pteris vittata L.) biomass from a phytoremediation trial in sub- and supercritical water conditions

Uncontaminated and As-contaminated fronds of Pteris vittata L., an As-hyperaccumulator fern used to phytoextract As from contaminated soils and water, were converted by sub-critical water (300 °C, 25 Pa) and supercritical water (400 °C, 25 Pa) treatments. Frond biomass was reduced between 70 and 77%. Compared to sub-critical conditions, supercritical conditions decreased C and inorganic contents in both the solid and liquid phases for uncontaminated and contaminated fronds and promoted CH₄ formation. Higher As, Fe and Zn contents in contaminated fronds promoted decreasing C contents and the formations of cyclopentenones and benzenediols in the liquid phase. Al, Fe, P, Zn and Ca mainly remained in the solid phase whereas As and S were transferred to the liquid phase for both phytomasses. As the temperature increased from 300 °C to 400 °C, the concentrations of cyclopentenones and phenols in the liquid phase rose while those of guaiacols and other compounds decreased for both phytomasses. Arsenic in the liquid phase was removed by sorption on hydrous iron oxide.     

Impact of ethanol content on the scavenging activities of oak wood C‐glycosidic ellagitannins. Application to the evaluation of the nutritional status of spirits

As a consequence of their structure, ellagitannins have a high level of activity in terms of their oxidative properties. In particular, their scavenging activity is often presented as a noteworthy parameter, since polyphenols have a beneficial impact on human health. A large variety of spirits, brandies and whiskeys are aged in barrels or receive a wood extract rich in polyphenols. Although spirits (alcoholic beverages) represent a very dynamic market with significant growth, very few scientific papers have been published on this topic, or have justified specific research in this field. Firstly, the scavenging properties of ellagitannins when measured in a solution are presented. An oak wood extract was fractionated by gel chromatography to obtain different fractions with different polymeric levels. It is particularly clear that the oligomer forms are the most efficient by comparison with low‐weight and high‐weight fractions. A mixture of ellagitannins has a higher scavenging intensity than the pure molecule; this illustrates the synergic effect of polyphenols. The scavenging activity of different commercial spirits depends on the presence and quantities of ellagitannins. As an example, the percentage of scavenged superoxide anion radicals represents 70 and 18%, respectively, for spirits aged in a barrel (12 years) and white spirits. In a second step, details of the influence of ethanol on the antioxidant properties of ellagitannins are provided. In particular, alcohol increases the scavenging activity of ellagitannins from 0 to 25% vol., and higher concentrations present a certain degree of pro‐oxidant activity. The chemical study of ellagitannin scavenging properties in solution is confirmed by means of a specific in vitro investigation on the DNA extracted from cells, and directly on the cells. Copyright © 2013 The Institute of Brewing & Distilling     

Study and quantification of monomeric flavan‐3‐ol and dimeric procyanidin quinonic forms by HPLC/ESI‐MS. Application to red wine oxidation

Monomeric flavan‐3‐ols and dimeric procyanidins of red wine were oxidised by two processes, chemical and enzymatic. Unstable quinonic forms were stabilised by sulphonation, and the resulting sulphones were quantified by coupled HPLC/ESI‐MS. The effects of temperature and UV light on the oxidation of phenolic compounds were also investigated. The concentration of quinones increased with increasing temperature, but the kinetics of the reaction was independent of temperature. Likewise, more quinones were formed in the presence of UV light than in its absence, but UV light also did not affect the kinetics of the reaction. Thus temperature and UV light affect the quantity of quinones formed but not the rate at which they appear. © 2001 Society of Chemical Industry     

Comparative analysis of triacylglycerols from Olea europaea L. fruits using HPLC and MALDI‐TOFMS

MALDI‐TOFMS and HPLC are two analytical methods that were used to characterize triacylglycerols (TAG) of the Meski, Sayali, and Picholine Tunisian olive varieties. The HPLC chromatograms of the oils showed the presence of 15 TAG species, among which triolein (OOO) was the most abundant (21–48%). In the Sayali cultivar, OOO was the predominant TAG species followed by POO and LOO. However, the minor TAG molecules were represented by LnLO and LnLP. MALDI mass spectra produced sodiated ([M + Na]⁺) and potassiated ([M + K]⁺) TAG molecules; only the major TAG were potassiated [OOO + K] ([OOO + K]⁺, [POO + K]⁺, and [LOO + K]⁺). In contrast to the HPLC chromatograms, the MALDI mass spectra showed 13 peaks of TAG. The major peak was detected at m/z 907, which corresponds to OOO with an Na⁺ adduct. The results from both HPLC and MALDI techniques predict the fatty acid composition and their percentages for each olive variety. Practical applications: TAG are the main components in vegetable oils. These biomolecules determine the physical, chemical, and nutritional properties of the oils. The nutritional benefits of TAG are related to DAG (moderate plasma lipid level) and esterified FA, which are intermediate biosynthetic molecules of TAG. TAG analysis is necessary to discriminate between oils of different origin, since some oils have similar FA profiles. Olive products, oils, and table olives, are the main diet sources of TAG in the Mediterranean countries. In this work, chromatographic and spectrometric methods were used for TAG analysis and characterization of Tunisian olive varieties.     

Study by LC/ESI/MS and ESI/HR/MS of SO2 interactions in flavanols–aldehydes nucleophilic reactions

The study concerns the interactions between (+)-catechin and a representative oak wood aldehyde (5-(hydroxymethyl)furfuraldehyde for furanic aldehydes and vanillin for phenolic aldehydes) in a wine-like model solution in presence or not of SO₂. The formed condensation products were characterised by LC/MS, LC/ESI/MSⁿ, and ESI/HR/MS and we studied the effect of SO₂ on these condensation reactions.     

α-Tocopherol and fatty acids contents of some Tunisian table olives (Olea europea L.): Changes in their composition during ripening and processing

An experimental investigation was carried out on Tunisian olive-fruits of Meski, Sayali and Picholine cultivars. α-Tocopherol and fatty acids (FA) contents were analyzed, during both ripening and processing, according to the Spanish style. The relationship between oil, unsaponifiable and α-tocopherol contents was determined only during ripening. A genetic effect on FA composition was observed throughout the sampling periods. The highest oleic acid content was found in Sayali cultivar at green stage (78.5% of total FA). α-Tocopherol was positively correlated with unsaturated FA content (R = 0.71, p < 0.05), and oil amount (R = 0.984; R = 0.976; R = 0.952, p < 0.05 for Picholine, Sayali and Meski, respectively), but it was not correlated with unsaponifiable matter. In processed olive-fruits, the results showed primarily, that processing according to the Spanish style is not restricted to green olive-fruits but can be successfully used in cherry olives with guaranteed quality and nutritional value of processed product (Meski and Picholine) related to FA content. Secondly, both α-tocopherol and FA amounts decreased during processing for all cultivars. This decrease was cultivar dependent. It was more pronounced in the black fruit than in the green one for the same cultivar. During fermentation, pH variation showed the same profile in all cultivars. Final pH values at the end of fermentation depend on the concentration of free FA (acidity) in the brine.     

The effects of changes in cadmium and lead air pollution on cancer incidence in children

This article presents the results of research on the effects of air pollution on cancer incidence in children in the region of Silesia (Poland), which has undergone one of the most profound anthropogenic transformations in Europe. The main objective of the research was to specify the impact of changes in cadmium and lead pollution in the years 1990-2005 on the incidence of cancers reported in children. Lead concentration ranged from 0 to 1490 · 10^-9 G m⁻²/year, and cadmium concentration ranged from 0 to 33.7 · 10^-9 G  m⁻²/year. There was no strong significant correlation (max 0.3) between air pollution and incidence rate (IR) in the general population of children in any particular year. Alongside the cartographic presentation of dependences, correlation coefficients between the variables in question were calculated. This made it possible to determine the relationship between the pollution levels and incidence rates in the area. There was a significant reduction in the level of pollution during the investigated period. The study of the relationship between the number of cancers reported and the condition of the natural environment revealed increased sensitivity to toxins in boys (correlation coefficient 0.3). In addition, the spatial distribution of the number of cases reported in boys suggests a correlation with the spatial distribution of the coefficients for the entire group of children included in the study. The yearly average IR of childhood cancer in specific districts ranged from 0 to 61.48/100,000 children under 18 years of age during the 1995-2004 period.     

Importance of pore size in high-pressure hydrogen storage by porous carbons

Development of high-capacity hydrogen-storage systems utilizing physisorption at high pressure and low temperature is hindered by poor understanding of the pore size/shape requirements for achieving the maximum hydrogen uptake. Tuning the carbon structure and pore size of carbide-derived carbons (CDCs) with high accuracy by using different starting carbides, chlorination temperatures and activation temperatures allows rational design of carbon materials with increased hydrogen-storage capacity. Systematic experimental investigation of a large number of CDCs with controlled pore size distributions and specific surface area (SSA) shows that pores larger than ∼1.5 nm contribute little to hydrogen storage. It has been experimentally demonstrated that, just as at ambient pressure, pores of 0.6–0.7 nm in diameter provide the largest H₂ uptake per unit SSA at elevated pressures and liquid nitrogen temperatures. The effect of pore size was stronger than the effect of surface chemistry on the hydrogen uptake.