Isolation of C-glycosyl xanthones from Coffea pseudozanguebariae and their location

The biochemical composition of leaves from Coffea pseudozanguebariae, a wild caffeine-free coffee species, was determined. Two phenolic compounds were extracted from leaves, separated and characterized. Their structures were elucidated by mass spectrometry, and 1D and 2D NMR spectroscopy and were shown to be mangiferin (1) and isomangiferin (2), which were the main polyphenol products. Multiphoton fluorescence imaging was performed to visualize polyphenol distribution in leaf cross sections. Consistent biochemical analysis cell imaging techniques on leaves revealed yellow fluorescence in the epidermis and parenchyma cells corresponding to xanthone compounds.     

Study of the acidity of H3PW12O40 supported on activated carbon by microcalorimetry and methanol dehydration reaction

H₃PW₁₂O₄₀/activated carbon catalysts have been studied by microcalorimetry and by the dehydration of methanol to dimethyl ether. It has been shown that the acidity of the polyacid is greatly reduced upon grafting on activated carbon. The decrease is so high that, at low polyanion loadings, the catalysts are relatively inactive in the dehydration of methanol to dimethyl ether.     

Role of reactive species in processing materials at laboratory temperature by spray plasma devices

Processing the aerosol of metal salts in non-equilibrium plasma represents a promising technique that combines the advantages of spray pyrolysis with the high reactivity of plasmas at nearlaboratory temperature in order to produce mixed-oxides and perovskite materials. The aim of this paper is to describe the principles of this new technique and to present the various applications and latest developments. This technique’s capacity to deposit various mixed metal oxides with precise stoichiometry is demonstrated. It is shown that oxidant plasma species play a key role in the chemical transformation of starting materials into oxides at laboratory temperature, while the configuration of the reactor determines the morphology and texture of the deposited layers. Two different reactor configurations are presented. The porous layers of La _x Sr_1−x MnO₃ as the cathode for fuel cells were synthesised in a wave shock reactor configuration, while nanostructured ZnO-Al layers to form a transparent conductive cathode for photovoltaic cells were deposited in the spray plasma reactor of the latest generation for this technique. The experimental results emphasise the role of plasma species in the rate of chemical reactions and in the chemical composition of the deposited layers.     

Introduction of Primary Amino Groups on Poly(ethylene terephthalate) Surfaces by Ammonia and a Mix of Nitrogen and Hydrogen Plasma

With the aim of introducing primary amino groups on the surface of poly(ethylene terephthalate) (PET), two methods were compared—the use of ammonia or a combination of nitrogen and hydrogen low-pressure microwave plasma. Several plasma parameters were optimized on the reactor to increase the –NH₂ surface density, which was estimated by colorimetric titration and X-ray photoelectron spectroscopy (XPS). These techniques show that whatever the plasma treatment, almost 2 –NH₂/nm2 are incorporated on PET films. Emission spectroscopy highlighted a correlation between the density of primary amino groups and the ratio between an NH peak intensity and an Ar peak intensity (I_NH/I_Ar). Variation in surface hydrophilicity with aging in air after plasma treatment was monitored with contact angle measurements and showed a hydrophobic recovery. This was confirmed by XPS, which suggests also that surfaces treated by NH₃ plasma are more stable than surfaces treated by N₂/H₂.     

Inclusion complexes of trivalent lutetium cations with an acidic derivative of per(3,6-anhydro)-alpha-cyclodextrin

The cyclodextrin derivative (hexakis (2-O-carboxymethyl-3,6-anhydro)-alpha-cyclodextrin) forms mono- and bimetallic complexes with lutetium(III) in aqueous solution; the X-ray structure of the binuclear complex [Lu2(ACX)(H2O)2] is the first example of a lanthanide-cyclodextrin inclusion complex.     

Interactions between cyclodextrins and fluorescent T-2 and HT-2 toxin derivatives: a physico-chemical study

T-2 and HT-2 toxins are mycotoxins produced by several Fusarium species that are commonly found in various cereal grains, including oats, barley, wheat and maize. Intake estimates indicate that the presence of these mycotoxins in the diet can be of concern for public health. In this work, the inclusion processes occurring between fluorescent anthracene-derivatives of T-2 and HT-2 toxins and different cyclodextrin (CD) molecules were investigated in aqueous solutions by means of UV–Vis absorption, fluorescence emission and dynamic light scattering. Binding constant values and chemico-physical parameters were calculated. It was found that β-CDs give stronger inclusion reactions with both T-2 and HT-2 derivatives, as stated by important emission intensity increments. Such interactions were found to be fundamentally enthalpy-driven. Among β-CDs, the effect of the methylation at hydroxyl groups was tested: as a result, the di-methyl form of β-CD was found to induce the best fluorescence intensity enhancements.     

Mycotoxin profile of Fusarium langsethiae isolated from wheat in Italy: production of type‐A trichothecenes and relevant glucosyl derivatives

Fusarium langsethiae, formally described as a new species over a decade ago, has been identified as the main producer of HT‐2 (HT2) and T‐2 (T2) toxins in Europe in small cereal grains. Mycotoxin contamination caused by this Fusarium species can represent a food safety hazard that deserves further attention. In the present work, the mycotoxin profile in wheat cultures of F. langsethiae is presented with particular reference to the production of major type‐A trichothecenes and their glucosyl derivatives. F. langsethiae isolates, representative of the major Italian wheat cultivation areas, were tested for the production of T2, HT2, diacetoxyscirpenol (DAS) and neosolaniol (NEO), and relevant glucosyl derivatives. Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) was used for the identification and chemical characterization of these metabolites. F. langsethiae isolates under investigation resulted to be potent producers of T2, HT2 and NEO. Furthermore, a well‐defined set of isolates, all originating from Central Italy, produced also DAS. All isolates were found to be able to produce HT2 glucosyl derivatives, whereas only traces of T2 glucoside were detected in one sample. Furthermore, two mono‐glucosyl derivatives of NEO and one mono‐glucoside derivative of DAS were identified and characterized. The screening for the presence/absence of glucosylated trichothecenes in analyzed fungal extracts revealed a general co‐occurrence of these derivatives with the parent toxin at levels that could be roughly estimated to account up to 37% of the relevant unconjugated toxin. This is the first report of the production of glucosylated trichothecenes by F. langsethiae cultured on small grains. Copyright © 2013 John Wiley & Sons, Ltd.     

A Convenient Synthesis of Diversely Substituted N,N-Dimethyl-4-oxo-2-(E)-alkenamides

An efficient synthesis of diversely substituted N,N-dimethyl-4-oxo-2-(E)-alkenamides is reported. These derivatives were obtained in three steps from I,4benzodioxin with fair to good yields     

Selective deoxygenation of leurosine: concise access to anhydrovinblastine

Straightforward access to anhydrovinblastine starting from the parent alkaloid leurosine is reported. The key deoxygenation step was first optimized on a model substrate. However, applied to leurosine, only the low-valent Cp2TiCl gave satisfactory results.     

Intramolecular C-glycosylation of 2-O-benzylated pentenyl mannopyranosides: remarkable 1,2-trans stereoselectivity

The IDCP-promoted intramolecular C-glycosylation of pentenyl α-mannopyranosides carrying, at O-2, an activated benzyl group gave, unexpectedly, the 1,2-trans-fused bicyclic product which corresponds to an α-C-aryl mannopyranose derivative. This remarkable, strained C-glycosyl compound was rapidly epimerized to the more stable 1,2-cis product on treatment with BF₃·Et₂O. The IDCP-reaction product could be elaborated into a 2-(α-C-mannopyranosyl)-3,4,5-trimethoxybenzyl alcohol derivative.