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In the present study, the effects of polyphenols on the chemical composition of the hepatopancreas of the Astacus leptodactylus, a highly sought farmed crayfish, have been investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The hepatopancreas spectrum was quite complex and contained several peaks arising from the contribution of different functional groups belonging to protein, lipids and carbohydrates. The PCA statistical analysis revealed that there were significant differences between crayfish fed a diet without polyphenols and crayfish fed a diet containing polyphenols. Such differences indicated an increase in lipids and proteins in the hepatopancreas of polyphenol-fed crayfish. In conclusion, the analysis of the infrared spectral profile of the hepatopancreas of Astacus leptodactylus, allowed us to elucidate the changes in different biomolecules in response to polyphenol treatment, and confirms the suitability of ATR-FTIR spectral data to analyze diet-induced metabolic effects. These considerations, coupled with the small amount of sample and no preparation needed, make ATR-FTIR a useful tool for routine analyses where the metabolic impact of substances is investigated, especially with a large number of samples.

1H-NMR analysis of the hepatopancreas, muscle and haemolymph of Astacus leptodactylus after feeding with polyphenol-enriched diet is reported. 1H-NMR spectra of lipophilic extracts showed the presence of cholesterol, fatty acid residues, phospholipids and triglycerides. 1H-NMR spectra of aqueous extracts identified 35 metabolites in the hepatopancreas, 31 in the muscle and 22 in the haemolymph. A total of 20 metabolites (amino acids and their derivatives) were present in the hepatopancreas, the muscle and the haemolymph. A total of 10 metabolites were present in both the hepatopancreas and the muscle (five amino acids, 2-hydroxybutyrate, choline, myo-inositol, glycogen and uracil). 2-Hydroxyisobutyrate and creatine were present in both the hepatopancreas and the haemolymph. Phosphorylethanolamine, phosphocholine and fumarate were present only in the hepatopancreas and isoleucine only in the muscle. Statistical analysis showed that the percentage of weight gain was statistically higher in polyphenol-enriched diet groups compared to the control and that polyphenols had a stimulating effect on the general metabolism. No stress-related metabolites were higher in crayfish fed with polyphenol-enriched diet. Conversely, phosphatidylcholine, cholesterol and DHA, linked to resistance to environmental stress and diseases, were higher compared to the control diet. This study indicates that 1H-NMR is a useful tool to study the metabolomics in relation to diet differences.