A limited number of antibiotics can be used against Helicobacter pylori infection, and resistance jeopardizes the success of treatment. Therefore, a search for new agents is warranted. The use of probiotics to enhance gastrointestinal health has been proposed for many years, but the scientific basis of the prophylactic and therapeutic actions of probiotics has not yet been clearly delineated. Probiotic strain Bacillus subtilis 3, whose safety has previously been demonstrated, is known to have antagonistic properties against species of the family Enterobacteriaceae. In the present study, it was also found to inhibit H. pylori. The anti-H. pylori activity present in the cell-free supernatant was not related to pH or organic acid concentration. It was heat stable and protease insensitive. At least two antibiotics, detected by thin-layer chromatography (R f values, 0.47 and 0.85, respectively) and confirmed by high-performance liquid chromatographic analysis, were found to be responsible for this anti-H. pylori activity. All H. pylori strains tested were sensitive to both compounds. One of these compounds was identified as amicoumacin A, an antibiotic with anti-inflammatory properties. MICs for H. pylori determined in solid and liquid media ranged between 1.7 and 6.8 g/ml and 0.75 and 2.5 g/ml, respectively. The underestimation of MICs determined in solid medium may be due to physicochemical instability of the antibiotic under these test conditions. An additive effect between amicoumacin A and the nonamicoumacin antibiotic against H. pylori was demonstrated.

Our study aimed to establish the complete structure of the main dihydroxy conjugated triene issued from the lipoxygenation (soybean enzyme) of docosahexaenoic acid, named PDX, an isomer of protectin/neuroprotectin D1 (PD1/NPD1) described by Bazan and Serhan. NMR approaches and other chemical characterization (e.g. GC-MS, HPLC and LC-MS/MS) indicated that PDX is 10(S),17(S)-dihydroxy-docosahexa-4Z,7Z,11E,13Z,15E,19Z-enoic acid. The use of (18)O(2) and mass spectrometry showed that PDX is a double lipoxygenation product. Its structure differs from PD1, with E,Z,E geometry (PDX) instead of E,E,Z (PD1) and S configuration at carbon 10 instead of R. PDX inhibits human blood platelet aggregation at sub-micromolar concentrations.

The solute-solvent interactions and the site-site distances between toluene and ionic liquids (ILs) 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [BMMIm][NTf2] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIm][NTf2] at various molar ratios were determined by NMR experiments (1D NMR, rotating-frame Overhauser effect spectroscopy (ROESY)) and by molecular simulation using an atomistic force field. The difference in behavior of toluene in these ILs has been related to the presence of H-bonding between the C2-H and the anion in [BMIm][NTf2] generating a stronger association (>20 kJ.mol-1) than in the case of [BMMIm][NTf2]. Consequently, toluene cannot cleave this H-bond in [BMIm][NTf2] which remains in large aggregates of ionic pairs. However, toluene penetrates the less strongly bonded network of [BMMIm][NTf2] and interacts with [BMMIm] cations.

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The stoichiometric reaction of B(C6F5)3 and NEt2Ph I, at room temperature, in an aromatic solvent, has been investigated by 1D and 2D NMR spectroscopy (1H, 11B,13C, 15N and 19F). No Et2PhN·B(C6F5)3 adduct was observed. An equilibrium between free B(C6F5)3, NEt2Ph, [HB(C6F5)3]−(HNEt2Ph)+ and two zwitterionic stereoisomers (E)‐ and (Z)‐[EtPhN+=CH‐CH2‐B−(C6F5)3] (30%) in an E/Z ratio of 3:2 was observed. Whatever the protic reagent Z‐OH [Z = H, SiPh3, (c‐C5H9)7O12Si8, or silanol group of silica], all the equilibria involved in solutions of I are quantitatively displaced towards the ionic form [Z‐O‐B(C6F5)3]−(HNEt2Ph)+. In the case of dimethylaniline, besides free B(C6F5)3 and Me2NPh, the 1:1 adduct (C6F5)3B·NMe2Ph and an iminium salt [PhCH3N=CH2]+[HB(C6F5)3]− have been identified. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Preparing highly active and stable non-noble-metal-based dry reforming catalysts remains a challenge today. In this context, supported nickel nanoparticles with sizes of 1.3 ± 0.2 and 2.1 ± 0.2 nm were synthesized on silica and ceria, respectively, via a two-step colloidal approach. First, 2-nm nickel-silicide colloids were synthesized from Ni(COD)(2) and octylsilane at low temperature; they were subsequently dispersed onto supports prior to reduction under H(2). The resulting catalysts display high activity in dry reforming compared to their analogues prepared using conventional approaches, ceria providing greatly improved catalyst stability.

Imidazoles have numerous applications in pharmacology, chemistry, optics and electronics, making the development of their environmentally-friendly synthetic procedures worthwhile. In this work, the formation of imidazole, imidazole-2-carboxaldehyde, and 2,2-bis-1H-imidazole was investigated in the self-reaction of glyoxal and its cross-reactions with each of these compounds in aqueous solutions of inorganic ammonium salts at pH =7. Such conditions are relevant both as cheap and environmentally-friendly synthetic procedures and for the chemistry of natural environments where NH4(+) is abundant, such as in atmospheric aerosols. These reactions were investigated both by (1)H-NMR and UV-Vis absorption spectroscopy at room temperature with the objective to determine the formation pathways of the three imidazoles and the parameters affecting their yields, to identify the optimal conditions for their synthesis. The results show that only the simplest imidazole is produced by the self-reaction of glyoxal and that imidazole-2-carboxaldehyde and 2,2-bis-1H-imidazole are produced by cross-reactions of glyoxal with imidazole and imidazole-2-carboxaldehyde, respectively. The yields of imidazole-2-carboxaldehyde and 2,2-bis-1H-imidazole formed by the cross-reactions were close to unity, but the yield of imidazole formed by the self-reaction of glyoxal, YIm, was small and varied inversely with the initial glyoxal concentration, [G]0: YIm > 10% only for [G]0 < 0.1 M. The latter result was attributed to the kinetic competition between the imidazole-forming condensation pathway and the acetal/oligomer formation pathway of the glyoxal self-reaction and constitutes a bottleneck for the formation of higher imidazoles. Other parameters such as pH and the NH4(+) concentration did not affect the yields. Thus, by maintaining small glyoxal concentrations, high imidazole yields can be achieved in environmentally-friendly aqueous ammonium solutions at neutral pH. Under the same conditions, higher yields are expected expected from substituted carbonyl compounds, regardless of their concentration, as they produce less acetals.

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