Search Results (7)

Background/Objectives: This study explores the roles of kynurenine and 5-hydroxytryptophan (5-HTP) in modulating gut microbiota and their potential implications for exudative age-related macular degeneration (AMD). By examining the interplay between these metabolites and the microbiome, we aim to uncover novel pathways that may influence the pathogenesis of AMD. Understanding these associations could lead to innovative therapeutic approaches for managing this leading cause of vision loss in the elderly. To investigate the roles of kynurenine and 5-HTP, alongside the composition of the nasopharyngeal microbiota, in patients with exudative AMD. Methods: Blood metabolite profiling was performed using LC–MS–based metabolomics. Metabolites were extracted with cold methanol/water containing internal standards, filtered through a 10 kDa cutoff filter, separated on a ZIC-HILIC HPLC column, and detected using an Orbitrap mass spectrometer. Metabolites were identified using MZmine 2 software. Results: Patients with exudative AMD exhibited a profound systemic shift in tryptophan metabolism, characterized by significantly lower plasma levels of 5-HTP and higher levels of kynurenine compared to control subjects (p < 0.001 for both). Logistic regression analysis confirmed that both metabolites were independent predictors of AMD status; higher kynurenine levels were associated with increased disease probability, while higher 5-HTP levels demonstrated a protective effect. The kynurenine/5-HTP ratio emerged as a robust biomarker, achieving an area under the curve (AUC) of 0.85 with an optimal threshold of 3.43 (74.1% sensitivity, 84.4% specificity). When integrated with age and gender, the diagnostic performance of the model reached an excellent AUC of 0.92. After adjusting for demographic factors, the kynurenine/5-HTP ratio remained a potent independent risk factor, with each unit increase associated with a 6.30-fold increase in the odds of exudative AMD. Conclusions: Exudative AMD is characterized by a shift in tryptophan metabolism toward the kynurenine pathway, with decreased 5-HTP, increased kynurenine, and an elevated kynurenine/5-HTP ratio. This ratio showed a strong independent association with AMD and excellent diagnostic performance, highlighting its potential as a biomarker and its role in disease pathogenesis. Full article

Introduction: Currently, there are few tools for monitoring recovery in substance use disorder. As substance use has increased in prevalence, tools for measuring recovery are needed to improve therapeutic outcomes. Measuring the kynurenine pathway for imbalances in metabolites could be a possible solution to monitor recovery. Methods: We developed a liquid chromatography–tandem mass spectrometry (LC-MS/MS) method to quantify tryptophan, kynurenine, kynurenic acid, and quinolinic acid in urine. Metabolites were separated using a stepwise gradient and detected with an Agilent 6460 triple quadrupole mass analyzer. The samples were extracted using a simple protein precipitation protocol. Method validation was performed using routine toxicology urine samples and laboratory contrived samples. The performance characteristics assessed included precision, linearity, stability, interference, and matrix effects. Additionally, urine samples from two cohorts (illicit drug-negative and drug-positive; n = 120 per cohort) were analyzed for significant concentration differences in the four metabolites using Mann–Whitney, PCA, and Area Under the Receiver Operating Characteristic Curve statistical analysis. Results: The LC-MS/MS assay was linear from 195 to 100,000 ng/mL for tryptophan, 6 to 3000 ng/mL for kynurenine, 14 to 7200 ng/mL for kynurenic acid, and 125 to 64,000 ng/mL for quinolinic acid using an 8-point calibration curve. Imprecision ranged from 1.17% to 12.46% CV using two controls that spanned the analytical measurement range. Matrix effects were observed; however, the use of labeled internal standards matching the metabolites of interest minimized the impact on quantification. The extraction recovery efficiency was acceptable for the analytical validation. Ambient stability extended to 10 days, resulting in individual sample biases of up to 22%. A statistically significant increase in TRP, KYN, and QA was observed in drug-positive urine compared to illicit drug-negative urine (p < 0.01). Conclusion: We developed a rapid and sensitive LC-MS/MS method for quantifying tryptophan, kynurenine, kynurenic acid, and quinolinic acid in urine that can aid in future research elucidating the relationship between substance use disorders and tryptophan metabolism. Full article

Yeast metabolism significantly contributes to functional beverage production by generating bioactive compounds such as tryptophan derivatives (dTRPs). While Saccharomyces cerevisiae is traditionally used, non-Saccharomyces yeasts like Torulaspora delbrueckii and Zygosaccharomyces bailii are gaining interest for their ability to enhance aroma profiles and influence metabolite synthesis. This study evaluated the dTRP production of T. delbrueckii CBS1146^T and Z. bailii ATCC36947^T in synthetic medium and Cabernet Sauvignon must supplemented with 100 mg/L tryptophan. LC-MS/MS analysis revealed strain-dependent differences in metabolite profiles, with a predominance of kynurenine pathway compounds and the first identification of two tryptophan-ethylester (TEE) isomers. T. delbrueckii exhibited significant TEE production, correlating with the consumption of dTRPs; conversely, Z. bailii synthesized diverse metabolites, including 5OH-tryptophan and kynurenic acid. Notably, melatonin was not detected. The fermentation matrix strongly influenced dTRP biosynthesis, with must conditions enhancing TEE and kynurenic acid accumulation. These findings highlight the role of growth medium composition in modulating yeast metabolism and support the potential of non-Saccharomyces yeasts for functional beverage development. Full article

Background/Objectives: Asymptomatic carotid artery stenosis is usually detected by physicians in patients, coincidentally, during an ultrasound examination of the neck. Therefore, measurable biomarkers in blood are needed to define the presence and severity of atherosclerotic plaque in patients to identify and manage it. We hypothesized that biomarkers that indicate pathways related to the pathogenesis of atherosclerosis could be used to identify the presence and severity of atherosclerotic plaque. For this purpose, the levels of participants’ inflammatory and oxidative stress biomarkers were determined. Kynurenine/tryptophan and neopterin levels were measured as relatively new biomarkers of inflammation in this study. Methods: Our study included 57 patients diagnosed with asymptomatic carotid artery stenosis and 28 healthy volunteers. Blood kynurenine and tryptophan levels were measured with LCMS/MS. Blood catalase, total superoxide dismutase (t-SOD), glutathione peroxidase (GPx), malondialdehyde, and neopterin levels were measured using the ELISA assay method. Result: The kynurenine/tryptophan ratio reflecting IDO activity was higher in patients than in healthy volunteers. Decreased tryptophan levels and increased kynurenine and neopterin levels were observed in patients who underwent carotid endarterectomy. In patients, catalase, t-SOD, and malondialdehyde levels were higher, while GPx activity was lower. These differences were found to be more significant in patients who underwent carotid endarterectomy. Conclusions: Increased kynurenine/tryptophan ratio and neopterin levels in patients with asymptomatic carotid artery stenosis were associated with the inflammatory status of the patients. Oxidative stress and inflammatory biomarkers can be considered effective diagnostic and severity indicators for asymptomatic carotid artery stenosis. Full article

Chronic inflammatory enteropathy (CIE) and low-grade intestinal T-cell lymphoma (LGITL) are common chronic enteropathies (CE) in cats. Enteric microbiota dysbiosis is implicated in the pathogenesis of CE; however, the mechanisms of host–microbiome interactions are poorly understood in cats. Microbial indole catabolites of tryptophan (MICT) are gut bacterial catabolites of tryptophan that are hypothesized to regulate intestinal inflammation and mucosal barrier function. MICTs are decreased in the sera of humans with inflammatory bowel disease and previous studies identified altered tryptophan metabolism in cats with CE. We sought to determine whether MICTs were decreased in cats with CE using archived serum samples from cats with CIE (n = 44) or LGITL (n = 31) and healthy controls (n = 26). Quantitative LC-MS/MS was used to measure serum concentrations of tryptophan, its endogenous catabolites (kynurenine, kynurenate, serotonin) and MICTs (indolepyruvate, indolealdehyde, indoleacrylate, indoleacetamide, indoleacetate, indolelactate, indolepropionate, tryptamine). Serum concentrations of tryptophan, indolepropionate, indoleacrylate, indolealdehyde, indolepyruvate, indolelactate were significantly decreased in the CIE and LGITL groups compared to those in healthy controls. Indolelactate concentrations were significantly lower in cats with LGITL compared to CIE (p = 0.006). Significant correlations were detected among serum MICTs and cobalamin, folate, fPLI, and fTLI. Our findings suggest that MICTs are promising biomarkers to investigate the role of gut bacteria in the pathobiology of chronic enteropathies in cats. Full article

Amaranthus crops are important for their use as food and nutritional sources, as well as for their medicinal properties. They are mostly harvested from the wild, and cultivation of Amaranthus species is still rare, and therefore, attempts are being made to commercialize and market this important crop. This research investigated the effect of cultivation and environment on the chemical profile of both cultivated and wild A. cruentus and A. hybridus by multivariate statistical analysis of spectral data deduced by Nuclear Magnetic Resonance (NMR). Furthermore, wild samples of A. cruentus and A. hybridus were subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) for further analysis. Through NMR analysis, it was found that maltose and sucrose increased in both cultivated A. cruentus and A. hybridus. Moreover, the amino acid, proline was present in cultivated A. cruentus in high quantity whereas, proline and leucine were prominent in A. hybridus. Other compounds that were found in both wild and cultivated A. cruentus and A. hybridus are trehalose, trigonelline, lactulose, betaine, valine, alanine, fumarate, formate and kynurenine. LC-MS analysis revealed the presence of rutin, 2-phenylethenamine and amaranthussaponin I in both wild A. cruentus and A. hybridus, while chlorogenic acid was identified only in cultivated A. hybridus. On the contrary, L-tryptophan, kaempferol, phenylalanine and quercetin were detected only in wild A. cruentus. Amaranth is not only rich in macro and micronutrients, but the leaves also contain phytochemicals that vary between species and cultivated plants, and might, therefore, affect the medicinal properties of the material. Full article

Given the pharmacological properti es and the potential role of kynurenic acid (KYNA) in human physiology and the pleiotropic activity of the neurohormone melatonin (MEL) involved in physiological and immunological functions and as regulator of antioxidant enzymes, this study aimed at evaluating the capability of Saccharomyces cerevisiae EC1118 to release tryptophan derivatives (dTRPs) from the kynurenine (KYN) and melatonin pathways. The setting up of the spectroscopic and chromatographic conditions for the quantification of the dTRPs in LC-MS/MS system, the optimization of dTRPs’ production in fermentative and whole-cell biotransformation approaches and the production of dTRPs in a soybean-based cultural medium naturally enriched in tryptophan, as a case of study, were included in the experimental plan. Variable amounts of dTRPs, with a prevalence of metabolites of the KYN pathway, were detected. The LC-MS/MS analysis showed that the compound synthesized at highest concentration is KYNA that reached 9.146 ± 0.585 mg/L in fermentation trials in a chemically defined medium at 400 mg/L TRP. Further experiments in a soybean-based medium confirm KYNA as the main dTRPs, whereas the other dTRPs reached very lower concentrations. While detectable quantities of melatonin were never observed, two MEL isomers were successfully measured in laboratory media. Full article