Metabolites, discrimination

Tulipani S, Urpi-Sarda M, Garcia-Villalba R, et al. Urolithins are the main urinary microbial-derived phenolic metabolites discriminating a moderate consumption of nuts in free-living subjects with diagnosed metabolic syndrome. / Agric Food Chem. 2012 60 8930-8940. 

A second kind of model is briefly treated, based on isotopic mass balance arguments, and it is shown that large isotopic discrimination during methano-genesis in ruminants may account for data trends when comparing herbivores and carnivores. A third class of model is sketched at the level of biochemical flows, where some fundamental points are made concerning points where the isotopic composition of metabolites may be altered. The relevance of this to nitrogen isotopic enrichment is considered. 

Agarwal et al. 1978), the quantification of these specific enzymes may indicate that exposure to endosulfan has occurred. Blood tests, such as decay curves for aminopyrine in plasma, which are semiquantitative indices of liver enzyme induction, have been used successfully in the past to demonstrate enzyme induction in pesticide-exposed workers. Because numerous chemicals found at hazardous waste sites also induce these hepatic enzymes, these measurements are not specific for endosulfan exposure. However, measurements of enzyme activity, together with the detection of the parent compound or its metabolites in tissue or excreta, can be useful indicators of exposure. All of these potential biomarkers require further verification in epidemiological studies. Further studies with focus on the development of methods to separate and measure the estrogenicity of endosulfan in in vitro assays would be valuable since these assays are more sensitive and discriminative than other conventional biomarkers. Preliminary results have been presented by Sonnenschein et al. (1995). 

The high water-solubility of surfactants and their, often more polar, metabolites prevents direct application of gas chromatographic separation (GC) with appropriate detection. The necessary volatilisation without thermal decomposition can be achieved by derivatisation of the analytes, but these manipulations are time- and manpower-consuming and can be susceptible to discrimination. Additionally, each derivatisation step in environmental analysis is normally target-directed to produce volatile derivatives of the compounds to be determined. Unknown surfactants that are simultaneously present, but differ in structure and therefore cannot react with the derivatisation reagent, are discriminated under these conditions. 

Nencini P, Fraioli S, Pascucci T, Nucerito CV. (1998). (-)-Norpseudoephedrine, a metabolite of cathinone with amphetamine-like stimulus properties, enhances the analgesic and rate decreasing effects of morphine, but inhibits its discriminative properties. Behav Brain Res. 92(1) 11-20. 

EtG and EtS are minor phase II metabolites of alcohol and their presence in a biological sample unequivocally attests exposure to this substance. They can be measured in serum [7] and urine [9,11-13] even after ethanol has been eliminated. Recently, the determination of EtG in hair has been proposed as a sensitive and specific marker of chronic ethanol abuse [8,10], The determination of EtG in postmortem blood enables the discrimination between ethanol postmortem formation and alcohol intake before death [17],... 

Fludeprenyl (7) also has methamphetamine-like discriminative-stimulus properties in squirrel monkeys that appear at twofold higher doses than the L-deprenyl-induced response [35]. These behavioral activities were ascribed to formation of the metabolites, p-fluoroamphetamine and p-fluorometamphetamine. 

A membrane is a semipermeable barrier whose function is to compartmentalize metabolic processes, maintain pH differences on either side, control osmotic pressure and ionic gradients, provide a surface or environment for the stabilization of active biomolecules, provide tissue discrimination, and allow selective access as well as egress to specific metabolites. 

From all these papers, it appears that the geographical characterization of wine is possible when metabolite profiling is used and moreover, it seems that glycerol, alcoholic derivates, and in few cases organic acids could contribute to discrimination between samples when the considered areas are near each other. Conversely, when very different geographical locations are concerned, sugars play the dominant role. 

A high-throughput analytical technique such as NMR has promise of adoption to investigate the metabolite content of vegetables. This information combined with multivariate statistical analysis is expected to offer a conclusive and exhaustive idea of quality discrimination and prediction with high reliability for new samples. In the field of fresh cut fruits and vegetables, demands for quality determination are increasing over the past decade. 

The high-resolution power of capillary electrophoresis-mass spectrometry (CE-MS) makes it a powerful technique for the separation and analysis of charged metabolites however, only a few metabolomics applications have been published to date. Polypeptide fraction isolated from urine or plasma was analyzed by CE-MS and used to discriminate between coronary artery... 

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