Hippuric acid is partly derived via gut microbial metabolism of polyphenols. Higher amounts can indicate increased bacterial degradation of aromatic compounds.
Clarke G, Quilty E, Kennedy PJ, Stanton C, Ross RP, Hill C, et al.. Hippurate as a metabolomic marker of gut microbiome diversity - NCBI. Nature Communications (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651863/
Khafipour E, Kittelmann S, Zebeli Q, McAllister TA. Effects of a blend of Saccharomyces cerevisiae-based direct-fed microbials on rumen fermentation, methane emissions, and bacterial community in steers. Journal of Animal Science and Biotechnology (2020). https://jasbsci.biomedcentral.com/articles/10.1186/s40104-019-0419-5
Berry D, Gautam D, Huttenhower C. Amino acid auxotrophies in human gut bacteria are linked to higher diversity and altered metabolism. Nature Microbiology (2023). https://www.nature.com/articles/s41396-023-01537-3
Wikoff WR, Anfora AT, Liu J, Schultz PG, Lesley SA, Peters EC, et al.. Metabolomics analysis reveals large effects of gut microflora on mammalian physiology. Proceedings of the National Academy of Sciences (2009). https://www.pnas.org/doi/10.1073/pnas.0812874106
Collino S, Binda S, Ciccacci M, Di Cagno R, Ercolini D, Gobbetti M. Disentangling the Complexity of Nutrition, Frailty and Gut Microbial Dysbiosis in the Elderly. Nutrients (2023). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10005077/
Indole is produced by bacterial metabolism of tryptophan in the gut. High levels of indole may indicate increased bacterial activity or gut dysbiosis.
Tomberlin, V., Lee, H. H., Molla, M. N., Cantor, C. R., & Collins, J. J.. Diverse roles of microbial indole compounds in eukaryotic systems. Journal of Molecular Microbiology and Biotechnology (2021). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9290978/
Indoleacetic acid is a metabolite produced from bacterial breakdown of tryptophan. Elevated levels can reflect increased bacterial load or imbalanced gut microbiome.
Pieter C. Dorrestein, J. Christopher Hamilton, and Eric W. Triplett. Indole-3-acetic acid in microbial and microorganism-plant signaling literature. FEMS Microbiology Reviews (2007). https://academic.oup.com/femsre/article/31/4/425/2399113
Sasitorn Bunsangiam, Nattawut Thongpae, Sasitorn Limtong, and Wiyong Sirisansaneeyakul. Large scale production of indole-3-acetic acid and evaluation of the inhibitory effect of indole-3-acetic acid on weed growth. Scientific Reports (2021). https://doi.org/10.1038/s41598-021-92305-w
Indolepropionic acid is formed by bacterial action on tryptophan in the intestines. High amounts suggest greater bacterial metabolism and potential gut flora imbalances.
Ratika Sehgal, Vanessa D. de Mello, Ville Männistö, Jaana Lindström, Jaakko Tuomilehto, Jussi Pihlajamäki. Indolepropionic Acid, a Gut Bacteria-Produced Tryptophan Metabolite and the Risk of Type 2 Diabetes and Non-Alcoholic Fatty Liver Disease. Nutrients (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9653718/
Indoxyl sulfate is derived from bacterial fermentation of tryptophan and is a uremic toxin. Increased levels are associated with an altered gut microbiome composition.
Correspondence: ude.drofnats@hcirist; Tel.: +1-650-493-5000 (ext. 68321);. Indoxyl Sulfate—Review of Toxicity and Therapeutic Strategies. Clinical Journal of the American Society of Nephrology (2016). https://cjasn.asnjournals.org/content/11/11/1965
J. J. Cochain, A. Delanghe, J. Depauw, et al.. Indoxyl sulfate, a gut microbiome-derived uremic toxin, is associated with cardiovascular disease in patients with chronic kidney disease. Scientific Reports (2021). https://doi.org/10.1038/s41598-021-99845-1
Y. Wang, Y. Zhang, J. Zhang, et al.. Targeting the gut microbial metabolic pathway with small molecules: A promising strategy to control host uremic toxin production. Biochemical and Biophysical Research Communications (2020). https://doi.org/10.1016/j.bbrc.2020.09.121
p-Cresol sulfate is generated by intestinal bacteria from tyrosine. Elevated concentrations are linked to dysbiosis and overgrowth of certain bacterial species.
