Evoluzione della fingerprint metabolica di urine di topo soggetto a una dieta arricchita in fruttosio: approcci di fingerprinting dei dati gas cromatografici di tipo targeted e untargeted

Fructose is a monosaccharide that is present in several dietary components; it is the main monosaccharide of fruits and vegetables; honey for example contains a high percentage of fructose that, combined with glucose, forms also saccharose (a disaccharide) and mixtures as high-fructose corn syrups (HFCS-55). The latter is a caloric sweetener extensively used by industries for the preparation of sweet food and beverages, ice-creams, etc... Several studies have associated the overconsumption of fructose (native, from saccharose and from HFCS) with alterations of the healthy status, including gain in body weight, increase in the production of serum triglycerides, total cholesterol and uric acid. A chronic exposure to a diet enriched with fructose produces several metabolic disorders, cardiovascular diseases and insulin resistance. Metabolomics is an emerging discipline aiming at chemically characterizing the metabolome, that is the set of small molecules or metabolites present in an organism, tissue or cell. The final purpose of metabolomics is to explain the role of single metabolites according to the response to external stimuli of diverse nature (abiotic and biotic). This discipline, thanks to powerful analytical tools, studies the distribution of small metabolites (sugars, aminoacids, organic acids, etc...) and their variation due to even small stress or interventions in their environment. Diet, for example, can induce modifications in the metabolome as a consequence of the perturbation of the physiological metabolic pathways (deficiency of essential nutrients intake or overconsumption of certain food). In this thesis project mice urinary metabolome, and its quali-quantitative variations, was studied to reveal the effect of a dietary intervention. Urine samples were gathered from a population of mice exposed to different diets enriched with fructose in liquid or solid form. As reference population, a group of mice was fed by a standard diet whose main carbohydrate component was starch. The urinary metabolome was profiled by gas chromatography combined with single quadrupole mass spectrometry (GC-qMS) and multidimensional gas chromatography (GC×GC-qMS). A set of about seventy metabolites was monitored; analytes belong to different metabolic pathways and for most of them the physiological role is connected to sugars metabolism. Metabolites that showed statistically meaningful variations among diets (liquid and solid fructose diets, or fructose and standard diets) are: fructose, 2-ketoglutaric acid, citric acid, hippuric acid, cis-aconitic acid, D-gluconic acid, succinic acid, glycine e derivative, α-glycerophosphate, glycerol, N-acetyl-D-glucosamine, malic acid, β-hydroxybutyric acid, tartaric acid. Plasma and tissues (liver) metabolic profiling, as well as the evaluation of other biochemical parameters, in some ways connected to the fructose overconsumption, were also considered to delineate a more complete picture of metabolic alterations induced by the dietary intervention and to facilitate the interpretation of the molecular basis of the observed physio-pathological alterations.