ReviewAmino acids2022
Emerging effects of tryptophan pathway metabolites and intestinal microbiota on metabolism and intestinal function.
Review in Amino acids, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 53 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
53 citing papers in PubMed, 83 citations in OpenAlex.
- Chicken IDO2 and TDO2: Biochemical Characteristics and Regulatory Roles in Avian Tryptophan Metabolism and Inflammatory Response.Animals : an open access journal from MDPI · 2026Article
- Postbiotics as a therapeutic frontier in Parkinson's disease: Insights into molecular pathways and neuroprotective effects.Metabolic brain disease · 2026Review
- Mechanism-First Psychobiotics: Fermented Vegetables, Dairy, and Soy for Depression and Anxiety.International journal of molecular sciences · 2026Review
- Targeting gut-liver-kidney axis: microbiota-derived metabolites and therapeutic implications.Cell communication and signaling : CCS · 2026Review
- Proteases in intestinal health and disease.Nature reviews. Gastroenterology & hepatology · 2026Review
- Gut microbiota-derived tryptophan metabolites: molecular mechanisms, nutritional strategies and implications for swine health.Frontiers in veterinary science · 2026Review
- Gut microbiome-derived indoles differentially suppress type III secretion system-associated virulence inFrontiers in microbiology · 2026Article
- High-fructose diet-induced gut dysbiosis as a mechanistic driver of chronic inflammation and accelerated biological aging: a comprehensive review.Frontiers in microbiology · 2026Review
- Intestinal-related substances in obesity regulation: A comprehensive review.World journal of gastrointestinal pharmacology and therapeutics · 2025Review
- Microbiota-derived IPA alleviates intestinal mucosal inflammation through upregulating Th1/Th17 cell apoptosis in inflammatory bowel disease.Gut microbes · 2025Article
- Indole derivatives ameliorated the methamphetamine-induced depression and anxiety via aryl hydrocarbon receptor along "microbiota-brain" axis.Gut microbes · 2025Article
- Metabolomics and metagenomics in mice reveal the role of the gut microbiota in tryptophan metabolism.iScience · 2025Article
- Dietary Proline Supplementation Promotes Growth and Development in Weaned Foals by Modulating Gut Microbial Amino Acid Metabolism.Microorganisms · 2025Article
- Amino acids and their metabolites as potential biochemical markers in postmortem vitreous humour.International journal of legal medicine · 2025Article
- The Dose-Dependent Influence of Type 2 Resistant Starch on Gut Microbial Communities and Metabolic Outputs: An In Vitro Simulation.Foods (Basel, Switzerland) · 2025Article
- From Microbial Switches to Metabolic Sensors: Rewiring the Gut-Brain Kynurenine Circuit.Biomedicines · 2025Review
- Amino Acid Metabolite Profiling for Predicting and Understanding the Metabolic Effects of Metabolic and Bariatric Surgery.Journal of metabolic and bariatric surgery · 2025Review
- Cannabinoid-2 receptor depletion promotes non-alcoholic fatty liver disease in mice via disturbing gut microbiota and tryptophan metabolism.Acta pharmacologica Sinica · 2025Article
- Metabolomic Analysis of Different Parts of Black Wax Gourd (Foods (Basel, Switzerland) · 2025Article
- The Kynurenine Pathway and Indole Pathway in Tryptophan Metabolism Influence Tumor Progression.Cancer medicine · 2025Review
Corrections and comments
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Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
Abstract
The metabolism of dietary tryptophan occurs locally in the gut primarily via host enzymes, with ~ 5% metabolized by gut microbes. Three major tryptophan metabolic pathways are serotonin (beyond the scope of this review), indole, kynurenine and related derivatives. We introduce the gut microbiome, dietary tryptophan and the potential interplay of host and bacterial enzymes in tryptophan metabolism. Examples of bacterial transformation to indole and its derivative indole-3 propionic acid demonstrate associations with human metabolic disease and gut permeability, although causality remains to be determined. This review will focus on less well-known data, suggestive of local generation and functional significance in the gut, where kynurenine is converted to kynurenic acid and xanthurenic acid via enzymatic action present in both host and bacteria. Our functional data demonstrate a limited effect on intestinal epithelial cell monolayer permeability and on healthy mouse ileum. Other data suggest a modulatory effect on the microbiome, potentially in pathophysiology. Supportive of this, we found that the expression of mRNA for three kynurenine pathway enzymes were increased in colon from high-fat-fed mice, suggesting that this host pathway is perturbed in metabolic disease. These data, along with that from bacterial genomic analysis and germ-free mice, confirms expression and functional machinery of enzymes in this pathway. Therefore, the host and microbiota may play a significant dual role in either the production or regulation of these kynurenine metabolites which, in turn, can influence both host and microbiome, especially in the context of obesity and intestinal permeability.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.