Search Results (6)

The essential amino acid tryptophan yields a plethora of secondary metabolites with key roles in plants and animals. Its fate in different living organisms is crucial for their own health, and metabolic profiling is a valuable tool for investigating it. Among the various metabolites, those retaining the indole structure were examined for qualitative and quantitative profiling. Liquid chromatography coupled with a tandem mass spectrometry detector with an electrospray ionization source (HPLC-ESI-MS/MS), acquiring in multiple reaction monitoring (MRM) mode, was used to develop a selective and sensitive method for the simultaneous analysis of tryptophan and 10 indole structure-retaining metabolites of it. Satisfactory values were obtained for linearity (R² ≥ 0.99 for all compounds except two), sensitivity (LOD, within 6–31 ng/mL, and LOQ, within 17–94 ng/mL, where minimum and maximum values were relative to serotonin and 5-methoxytryptamin, respectively), reproducibility (interday and intraday precision and accuracy), and effect of the matrix (recovery and matrix effect). The method was then successfully applied to the analysis of different types of beverage, such as herbal products, like Eschscholzia californica and a sleep herbal tea marketed with added melatonin (consumed to reduce anxiety and improve sleep quality), and fermented beverages, like beer and kefir. High amounts of tryptophan (from 77 ng/mL in kefir to 26,974 ng/g in the sleep herbal tea) followed by lower contents of serotonin (from 29 ng/mL in kefir to 2207 ng/g in the sleep herbal tea), were found in all samples along with the serotonin pathway-related compounds 5-hydroxytryptophan and tryptamine. Melatonin was detected in the plant matrix Eschscholzia c. for the first time to our knowledge (446 ng/g) and in the fermented beverages (96 ng/mL in beer and 39 ng/mL in kefir), regardless of their vegetable or animal origin, along with the melatonin route metabolites 5-methoxytryptamine and tryptophan ethyl ester. The amount of melatonin in the sleep herbal tea (556,464 ng/g) was in strong agreement with the declared content. Suggested applications include the search for biomarkers in phytochemical characterization, mechanistic studies of tryptophan’s chemistry, valorization of foods, beverages, and tryptophan-rich agro-food by-products and waste for nutraceutical and pharmacological purposes. Full article

Indoles are bioactive components found in wine products and are associated with yeast activity. Cava, a Spanish sparkling wine, is characterized by aging in contact with lees, making it a potential matrix for indoles. Therefore, the aim of this study was to determine the indole content in Cava produced at an industrial scale. Nine indoles were analysed by Ultra High-Performance Liquid Chromatography—Tandem Mass Spectrometry in Cava samples with different ageing times (n = 74). Significant amounts of tryptophan (2.3–1680.4 μg/L), tryptophan ethyl ester (0.1–5.2 μg/L), 5-methoxytryptophol (0.3–29.2 µg/L) and n-acetyl serotonin (0.3–2.3 μg/L) were determined. Tryptophan and tryptophan ethyl ester were positively correlated and decreased with ageing time. In fact, a concentration of less than 0.56 μg of the latter indole can become a marker of the most aged Cavas. The ageing time in contact with lees seems to play a key role affecting the indole content, since base wines show high amount of tryptophan and tryptophan ethyl ester while aged sparkling wines have values around the lower 95% confidence limit. Notably, the identification of tryptophan ethyl ester as a potential marker for aging in Cava suggests a new avenue for further research and quality assessment in its production. Full article

Jerusalem artichoke juice is valued for its nutritional content and health benefits. Spontaneous fermentation enhances its flavor, quality, and functional components through microbial metabolic activities. This study used high-throughput sequencing to analyze microbial community changes, and LC–MS and GC–MS to detect secondary metabolites and flavor compounds during fermentation. During natural fermentation, beneficial bacteria like Lactobacillus and Pediococcus increased, promoting lactic acid production and inhibiting harmful bacteria, while environmental bacteria decreased. Similarly, fungi shifted from environmental types like Geosmithia and Alternaria to fermentation-associated Pichia and Penicillium. A total of 1666 secondary metabolites were identified, with 595 upregulated and 497 downregulated. Key metabolic pathways included phenylpropanoid biosynthesis, with significant increases in phenylalanine, tryptophan, and related metabolites. Lipid and nucleotide metabolism also showed significant changes. Flavor compounds, including 134 identified alcohols, esters, acids, and ketones, mostly increased in content after fermentation. Notable increases were seen in Phenylethyl Alcohol, Ethyl Benzenepropanoate, 3-Methylbutyl Butanoate, Ethyl 4-Methylpentanoate, 5-Ethyl-3-Hydroxy-4-Methyl-2(5H)-Furanone, Ethyl Decanoate, Hexanoic Acid, and 1-Octanol. γ-aminobutyric acid (GABA) and other functional components enhanced the health value of the juice. This study provides insights into microbial and metabolic changes during fermentation, aiding in optimizing processes and improving the quality of fermented Jerusalem artichoke juice for functional food development. Full article

This study aimed to provide novel information on the impact of indigenous non-Saccharomyces yeasts, including Metschnikowia chrysoperlae, Metschnikowia sinensis/shanxiensis, Metschnikowia pulcherrima, Lachancea thermotolerans, Hanseniaspora uvarum, Hanseniaspora guilliermondii, and Pichia kluyveri, on metabolites related to the metabolism of tryptophan, phenylalanine, and tyrosine. The experiment included two fermentation practices: monoculture and sequential fermentation with commercial Saccharomyces cerevisiae, using sterile Maraština grape juice. A targeted approach through ultrahigh-resolution liquid chromatography associated with mass spectrometry was used to quantify 38 metabolites. All the indigenous yeasts demonstrated better consumption of tryptophan in monoculture than in interaction with S. cerevisiae. M. sinensis/shanxiensis was the only producer of indole-3-carboxylic acid, while its ethyl ester was detected in monoculture fermentation with H. guilliermondii. H. guilliermondii consumed the most phenylalanine among the other isolates. 5-hydroxy-L-tryptophan was detected in fermentations with M. pulcherrima and M. sinensis/shanxiensis. M. pulcherrima significantly increased tryptophol content and utilised tyrosine in monoculture fermentations. Sequential fermentation with M. sinensis/shanxiensis and S. cerevisiae produced higher amounts of N-acetyl derivatives of tryptophan and phenylalanine, while H. guilliermondii-S. cerevisiae fermentation resulted in wines with the highest concentrations of L-kynurenine and 3-hydroxyanthranilic acid. P. kluyveri produced the highest concentration of N-acetyl-L-tyrosine in monoculture fermentations. These findings highlight the different yeast metabolic pathways. Full article

The physicochemical characteristics and flavor-related compounds of thigh meat derived from diverse Korean native chickens (KNC), namely Hanhyup No. 3 (HH3), Woorimatdag No 1 (WRMD 1), and Woorimatdag No 2 (WRMD 2), under fresh and frozen-thawed conditions were studied and compared with those of commercial broilers (CB). Regardless of the breed, KNC showed a higher (p < 0.05) percentage of linoleic and arachidonic acid. The highest proportion of docosahexaenoic acid was observed in WRMD 2. Despite having a higher collagen content, thigh meat derived from KNC maintained a similar texture profile in comparison to that of CB. The concentrations of most free amino acids (FAA), except for taurine, tryptophan, and carnosine, were higher in frozen-thawed meat than in fresh meat. Regarding volatile organic compounds (VOC), following freezing, the concentration of favorable VOCs increased in CB, but decreased in WRMD 1, suggesting a loss of pleasant flavor in frozen-thawed meat. This study indicated that changes in VOCs, including hydrocarbons (d-limonene, heptadecane, hexadecane, naphthalene, pentadecane, 3-methyl-, tridecane), esters (arsenous acid, tris(trimethylsilyl) ester, decanoic acid, ethyl ester, hexadecanoic acid, ethyl ester), alcohol (1-hexanol, 2-ethyl-), ketones (5,9-undecadien-2-one, 6,10-dimethyl-), and aldehydes (pentadecanal-, tetradecanal, tridecanal), may be a promising marker for distinguishing between fresh and frozen-thawed chicken thigh meat. These findings are of critical importance as preliminary data for developing high-quality chicken meat products. Full article

Breast cancer (BC) is one of the leading causes of cancer mortality in women worldwide, and therefore, novel biomarkers for early disease detection are critically needed. We performed herein an untargeted plasma metabolomic profiling of 55 BC patients and 55 healthy controls (HC) using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS). Pre-processed data revealed 2494 ions in total. Data matrices’ paired t-tests revealed 792 ions (both positive and negative) which presented statistically significant changes (FDR < 0.05) in intensity levels between cases versus controls. Metabolites identified with putative names via MetaboQuest using MS/MS and mass-based approaches included amino acid esters (i.e., N-stearoyl tryptophan, L-arginine ethyl ester), dipeptides (ile-ser, met-his), nitrogenous bases (i.e., uracil derivatives), lipid metabolism-derived molecules (caproleic acid), and exogenous compounds from plants, drugs, or dietary supplements. LASSO regression selected 16 metabolites after several variables (TNM Stage, Grade, smoking status, menopausal status, and race) were adjusted. A predictive conditional logistic regression model on the 16 LASSO selected ions provided a high diagnostic performance with an area-under-the-curve (AUC) value of 0.9729 (95% CI 0.96–0.98) on all 55 samples. This study proves that BC possesses a specific metabolic signature that could be exploited as a novel metabolomics-based approach for BC detection and characterization. Future studies of large-scale cohorts are needed to validate these findings. Full article