2-(2-Methyl-2-nitrovinyl)furan but Not Furvina Interfere with Staphylococcus aureus Agr Quorum-Sensing System and Potentiate the Action of Fusidic Acid against Biofilms

Quorum sensing (QS) plays an essential role in the production of virulence factors, in biofilm formation and antimicrobial resistance. Consequently, inhibiting QS is being considered a promising target for antipathogenic/anti-virulence therapies. This study aims to screen 2-nitrovinylfuran derivatives structurally related to Furvina (a broad-spectrum antibiotic already used for therapeutic purposes) for their effects on QS and in biofilm prevention/control. Furvina and four 2-nitrovinylfuran derivatives (compounds 1–4) were tested to assess the ability to interfere with QS of Staphylococcus aureus using bioreporter strains (S. aureus ALC1742 and ALC1743). The activity of Furvina and the most promising quorum-sensing inhibitor (QSI) was evaluated in biofilm prevention and in biofilm control (combined with fusidic acid). The biofilms were further characterized in terms of biofilm mass, viability and membrane integrity. Compound 2 caused the most significant QS inhibition with reductions between 60% and 80%. Molecular docking simulations indicate that this compound interacts preferentially with the protein hydrophobic cleft in the LytTR domain of AgrA pocket. Metabolic inactivations of 40% for S. aureus ALC1742 and 20% for S. aureus ALC1743 were reached. A 24 h-old biofilm formed in the presence of the QSI increased the metabolic inactivation by fusidic acid to 80%, for both strains. The overall results highlight the effects of compound 2 as well as the potential of combining QSI with in-use antibiotics for the management of skin and soft tissues infections.     

Ethylene polymerisation by Ni–diphosphine azine complexes

The properties of [NiX(PR₂CH₂C(Bu^t)?NN?C(Bu^t)CH₂PR₂)]⁺ complexes (where X = Br, and R = cyclohexyl (Cy), isopropyl (Prⁱ), tert‐butyl (Bu^t), phenyl (Ph); X = Cl or I, and R = cyclohexyl) as catalysts for the polymerisation of ethylene were evaluated with or without the co‐catalysts methylaluminoxane (MAO), diethylaluminium chloride, trimethylaluminium or tri(isobutyl)aluminium. Their efficiency depends on the characteristics of the halogen (X) and the R group of the diphosphine azine ligand. Bromide (X) strongly enhances the catalytic properties of the complexes within the R order Cy > Prⁱ > Ph > Bu^t. Temperature, co‐catalyst ratio (Al/Ni) and complex concentration also influence the catalytic activity. The best results were obtained with [NiBr{PCy₂CH₂C(Bu^t)?NN?C(Bu^t)CH₂PCy₂}]Br activated by MAO (A = 25.8 kg (mol Ni)^?1 bar^?1 h^?1). The polymers were characterised using NMR and differential scanning calorimetry as branched polyethylenes, the number of branches increasing with the temperature of polymerisation. The molecular weights of the polymers were estimated using NMR. A proposal for the catalyst active precursor is made on the basis of experimental data and molecular orbital calculations. Copyright © 2007 Society of Chemical Industry     

Characterization of a chiral menthyldimethyltin molybdate and its use as an olefin epoxidation catalyst

Vibrational spectroscopy and EXAFS studies of an organotin molybdate with the formula [((Me)₂(menthyl)Sn)₂MoO₄(H₂O)_3.5] reveal that the compound is polymeric and contains [MoO₄]²⁻ tetrahedra coordinated to [R₃Sn]⁺ cationic spacers. The compound can be used as a recyclable solid catalyst for the selective epoxidation of cyclooctene by tert-butylhydroperoxide. In the epoxidation of prochiral olefins such as trans-β-methylstyrene, the corresponding epoxide isomers are obtained with fairly good to excellent selectivity, albeit with low enantiomeric or diastereomeric excesses.     

Photodegradation of 1-nitropyrene in solution and in the adsorbed state

The photodegradation of the 1-nitropyrene (NPy) has been studied using conventional (Xe and medium pressure Hg lamps) and laser sources (XeCl excimer and Nd-YAG UV). Low energy monochromatic light sources were used to study the early stages of degradation (up to 50% conversion). The medium pressure Hg lamp was used for longer periods of irradiation (up to 6h) and for greater degradation of NPy. The results of our work confirm that degradation occurs by radical mechanism. Aromatic hydroxymethyl, methoxy, hydroxy and nitroso derivatives of pyrene (Py) are created by low energy UV irradiation. After a massive UV irradiation, the Py aromatic system is destroyed and more polar low-molecular compounds are generated. The photochemical method described in this paper, based on irradiation by UV lamp, is therefore, suitable for degradation of fused benzene ring(s) and thus should also be effective for degradation of other nitrated polycyclic aromatic compounds.     

Nutritional composition of low protein and phenylalanine-restricted dishes prepared for phenylketonuric patients

Nutritional management is essential for Phenylketonuria (PKU) treatment, consisting in a semi-synthetic and low phenylalanine (Phe) diet, which includes strictly controlled amounts of low protein natural foods (essentially fruits and vegetables) supplemented with Phe-free protein substitutes and dietetic low-protein products. PKU diet has to be carefully planned, providing the best ingredient combinations, so that patients can achieve good metabolic control and an adequate nutritional status. Hereupon, it is mandatory to know the detailed composition of natural and/or cooked foodstuffs prepared specifically for these patients.     

Incorporation of Chlorella vulgaris and Spirulina maxima biomass in pasta products. Part 1: Preparation and evaluation

BACKGROUND: Microalgae are able to enhance the nutritional content of conventional foods and hence to positively affect human health, due to their original chemical composition. The aim of the present study was to prepare fresh spaghetti enriched with different amounts of microalgae biomass (Chlorella vulgaris and Spirulina maxima) and to compare the quality parameters (optimal cooking time, cooking losses, swelling index and water absorption), chemical composition, instrumental texture and colour of the raw and cooked pasta enriched with microalgae biomass with standard semolina spaghetti. RESULTS: The incorporation of microalgae results in an increase of quality parameters when compared to the control sample. The colour of microalgae pastas remained relatively stable after cooking. The addition of microalgae resulted in an increase in the raw pasta firmness when compared to the control sample. Of all the microalgae studied, an increase in the biomass concentration (0.5–2.0%) resulted in a general tendency of an increase in the pasta firmness. Sensory analysis revealed that microalgae pastas had higher acceptance scores by the panellists than the control pasta. CONCLUSION: Microalgae pastas presented very appellative colours, such as orange and green, similar to pastas produced with vegetables, with nutritional advantages, showing energetic values similar to commercial pastas. The use of microalgae biomass can enhance the nutritional and sensorial quality of pasta, without affecting its cooking and textural properties. Copyright © 2010 Society of Chemical Industry