Chemicals & Chemistry

  2010 MAR 12 - (VerticalNews.com) -- "A vegetarian diet has been demonstrated to have a profound influence on human metabolism as well as to aid the prevention of several chronic diseases relative to an omnivorous diet. However, there have been no systematic metabolomic studies on all of the biochemical changes induced in human subjects by long-term vegetarianism," scientists in Xiamen, People's Republic of China report.

  "In this study, H-1 NMR spectroscopy in combination with multivariate statistical analysis was applied to explore the variability in the metabolic urinary profiles of healthy populations from four groups: lactovegetarian male (VEGMALE), lactovegetarian female (VEGFEMALE), omnivorous male (OMNMALE), and omnivorous female (OMNFEMALE). Differences in metabolic profiles were examined in relation to diet and gender by principal component analysis (PCA) and spectral integrals. It was found that the most influential low molecular weight metabolites responsible for the differences between the diet groups were N-acetyl glycoprotein (NAG), succinate, citrate, trimethylamine-N-oxide (TMAO), taurine, glycine, hippurate, phenylalanine, methylhistidine and formate, whereas for the differences in gender groups the most discriminatory metabolites were NAG, succinate, creatinine, arginine, TMAO, taurine, hippurate, mannitol, phenylalanine, and methylhistidine. The results from the PCA of all four groups indicated that diet plays a greater role in influencing metabolite differences than gender," wrote J.J. Xu and colleagues, Xiamen University ...read more

  2010 MAR 12 - (VerticalNews.com) -- According to a study from France, "An important route for the detoxification of tropane alkaloids involves N-demethylation to the nor-compounds followed by further degradation. In order to study the mechanisms of the pertinent reactions, a suitable means to determine the isotope ratios of the substrates and products is required."

  "However, the polarity and functionality of the nortropane compounds makes their analysis as free bases difficult. A method is described which allows both the quantification of nortropane alkaloids and the determination of their natural abundance delta N-15 values. The protocol exploits the derivatisation of the alkaloids by reaction with ethyl chloroformate in aqueous medium and the quantitative extraction of the ensuing ethylcarbamate esters. The improved chromatographic properties of these derivatives gives ample separation of the isomeric nor-tropine and norpseudotropine for measurement of their delta N-15 (parts per thousand) values by isotope ratio mass spectrometry interfaced to gas chromatography. Adequate separation could not be achieved with the underivatised compounds. Repeatability and precision are sufficient to allow differences in the delta N-15 values (Delta delta N-15) >0.8 parts per thousand to be measured, with a standard deviation routinely similar to 0.3 parts per thousand. The methodology has been tested by determining the changes in the delta N-15 values of nor-tropine and norpseudotropine during degradation by cell suspension cultures of a Pseudomonas strain expressing a specific capacity for tropine catabolism," wrote K. Kosieradzka and colleagues ...read more

  2010 MAR 12 - (VerticalNews.com) -- According to a study from Turin, Italy, "Plant gums are present in works of art as binding media for watercolours and adhesives for cellulosic substrates. Thermally assisted hydrolysis and methylation (THM) in combination with analytical pyrolysis coupled to GC/MS has been applied to the characterisation of plant gums typically used in artworks."

  "THM products from standard samples of arabic gum, tragacanth gum and cherry gum were characterised. The main products identified are permethylated and partially methylated aldonic acids, characteristic of specific epimeric sugars. Aldonic acids were formed by alkaline hydrolysis of free reducing sugars and of reducing polysaccharide terminal groups, while methylation occurs during pyrolysis. The presence of these characteristic markers allows gum identification. A systematic analysis of all the parameters that can affect the marker yields was performed. In particular, the influence of pyrolysis temperature, reagent concentration and contact time between tetramethylammonium hydroxide and sample were studied, and different kinds of sample preparation procedures were tested," wrote C. Riedo and colleagues, University of Turin ...read more