A metabolomic study has been performed to identify sensitive and robust biomarkers of malnutrition in farmed fish, using gilthead sea bream (Sparus aurata) as a model. The metabolomic fingerprinting of serum from fasted fish was assessed by means of ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. More than 15,000 different m/z ions were detected and Partial Least Squares–Discriminant analysis allowed a clear differentiation between the two experimental groups (fed and 10-day fasted fish) with more than 90% of total variance explained by the two first components. The most significant metabolites (up to 45) were elucidated on the basis of their tandem mass spectra with a broad representation of amino acids, oligopeptides, urea cycle metabolites, L-carnitine-related metabolites, glutathione-related metabolites, fatty acids, lysophosphatidic acids, phosphatidylcholines as well as biotin- and noradrenaline-related metabolites. This untargeted approach highlighted important adaptive responses in energy and oxidative metabolism, contributing to identify robust and nutritionally-regulated biomarkers of health and metabolic condition that will serve to assess the welfare status of farmed fish.

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The aim of this study was to evaluate the impact of fish meal (FM) and fish oil (FO) replacement by plant proteins and oils in the serum metabolome of two-year old gilthead sea bream (Sparus aurata) fed from early life stages with control and experimental diets. Randomly selected fish were overnight sampled and clotted serum was used for metabolomics fingerprinting by means of ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. More than 12,500 different m/z ions were detected, and Partial Least Squares-Discriminant analysis separated fish fed control and plant-based diets, with a 71% of variance explained and 44% of variance predicted by the two first components. After variable importance in projection (VIP) and Benjamini-Hochberg test correction filtering, 50 endogenous compounds were elucidated as highly discriminant features of dietary treatment. Most of them were lipid-related compounds and reflected the different fatty acid composition of dietary oils, whereas changes in N-acyl taurines, cytidine and nucleoside related compounds would indicate changes in tissue repair and DNA degradation processes. Untargeted analysis also identified some exogenous compounds as markers of marine and vegetable raw materials. In the case of hercynine (antioxidant fungi and mycobacteria product), this was exemplified by a close lineal association between circulating and feed levels. Targeted approaches were focused on vitamins and a clear reduction of B 12 , indirectly assessed via methylmalonic acid levels, was found in fish fed vegetable diets. Conversely, serum riboflavin (B 2) and pantothenic acid (B 5) levels were consistently increased, which highlighted the close link between nutrition and gut microbiota.

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Synthetic cannabinoids (SCs) are consumed as legal alternative to cannabis and often allow passing drug-screening tests. Their rapid transience on the drug scene, combined with their mostly unknown metabolic profiles, creates a scenario with constantly moving analytical targets, making their monitoring and identification challenging. The development of fast screening strategies for SCs, not directly focused on their chemical structure, as an alternative to the commonly applied target acquisition methods, would be highly appreciated in forensic and public health laboratories. An innovative untargeted metabolomics approach, focused on herbal components commonly used for 'spice' products, was applied. Saliva samples of healthy volunteers were collected at pre-dose and after smoking herbal components and analysed by high-resolution mass spectrometry. The data obtained, combined with appropriate statistical analysis, allowed to highlight and elucidate two markers (scopoletin and N,N-bis(2-hydroxyethyl)dodecylamine), which ratio permitted to differentiate herbal smokers from non-smokers. The proposed strategy will allow discriminating potential positives, on the basis of the analysis of two markers identified in the herbal blends. This work is presented as a step forward in SC drug testing, promoting a smart first-line screening approach, which will allow reducing the number of samples to be further investigated by more sophisticated HRMS methods. Graphical abstract The development of an alternative, generic screening methods of synthetic cannabinoids, not directly based on the chemical structure, in order to provide fast response on its potential consumption.