Study of the intestinal tyrosine metabolism using stable isotopes and gas chromatography-mass spectrometry

Curtius, Hans−Christoph; Mettler, M.; Ettlinger, L.

doi:10.1016/s0021-9673(01)84102-9

Cited by 94 publications

(42 citation statements)

References 5 publications

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“…Intestinal microflora can exert a large effect on mammalian blood and urinary metabolites, especially those from amino acids (Williams et al, 2002;Wikoff et al, 2009). Acetophenone may be derived from phenylalanine, whereas 4-methylphenol (p-cresol), and 4-ethylphenol may result from tyrosine catabolism (Curtius et al, 1976;Martin, 1982;Schulz and Dickschat, 2007).…”

Section: Discussionmentioning

confidence: 99%

Chemical Signals of Elephant Musth: Temporal Aspects of Microbially-Mediated Modifications

et al. 2012

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Mature male African (Loxodonta africana) and Asian (Elephas maximus) elephants exhibit periodic episodes of musth, a state in which serum androgens are elevated, food intake typically decreases, aggressiveness often increases, and breeding success is enhanced. Urine is a common source of chemical signals in a variety of mammals. Elephants in musth dribble urine almost continuously for lengthy periods, suggesting that the chemicals in their urine may reveal their physiological condition to conspecifics. We investigated the volatile urinary chemicals in captive male elephants using automated solid phase dynamic extraction (SPDE) and gas chromatography-mass spectrometry (GC-MS). We found higher levels of alkan-2-ones, alkan-2-ols, and some aromatic compounds in urine from males in musth than in urine from non-musth males or from females. Levels of ketones and alcohols increased as the urine aged, likely due to microbial metabolism of fatty acids. Protein-derived aromatic metabolites also increased in abundance after urination, likely due to microbial hydrolysis of hydrophilic conjugates. We suggest that microbes may play an important role in timed release of urinary semiochemicals during elephant musth.

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Section: Discussionmentioning

confidence: 99%

Chemical Signals of Elephant Musth: Temporal Aspects of Microbially-Mediated Modifications

et al. 2012

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“…The possible formation of 3,4-dihydroxyphenylacetic acid via aoxidation of 3,4-dihydroxyphenylpropionic acid (as described for tyrosine 49,62 ) in the microbial catabolism pathway of monomeric flavan-3-ols, has been widely debated. Firstly, it was thought that 3,4-dihydroxyphenylacetic acid was only characteristic of the catabolism of dimeric procyanidins; 63 however, other authors have recently proposed a-oxidation as a possible pathway for the formation of this compound in the case of both monomers and dimers, 61 without discarding other possible pathways, as proposed by Appeldoorn et al 54 in the case of dimers.…”

Section: Iii2 Metabolites Arising From the Catabolism Of Dimeric Promentioning

confidence: 99%

Insights into the metabolism and microbial biotransformation of dietary flavan-3-ols and the bioactivity of their metabolites

et al. 2010

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Flavan-3-ols, occurring in monomeric, as well as in oligomeric and polymeric forms (also known as condensed tannins or proanthocyanidins), are among the most abundant and bioactive dietary polyphenols, but their in vivo health effects in humans may be limited because of their recognition as xenobiotics. Bioavailability of flavan-3-ols is largely influenced by their degree of polymerization; while monomers are readily absorbed in the small intestine, oligomers and polymers need to be biotransformed by the colonic microbiota before absorption. Therefore, phenolic metabolites, rather than the original high molecular weight compounds found in foods, may be responsible for the health effects derived from flavan-3-ol consumption. Flavan-3-ol phenolic metabolites differ in structure, amount and excretion site. Phase II or tissular metabolites derived from the small intestine and hepatic metabolism are presented as conjugated derivatives (glucuronic acid or sulfate esters, methyl ether, or their combined forms) of monomeric flavan-3-ols and are preferentially eliminated in the bile, whereas microbial metabolites are rather simple conjugated lactones and phenolic acids that are largely excreted in urine. Although the colon is seen as an important organ for the metabolism of flavan-3-ols, the microbial catabolic pathways of these compounds are still under consideration, partly due to the lack of identification of bacteria with such capacity. Studies performed with synthesized or isolated phase II conjugated metabolites have revealed that they could have an effect beyond their antioxidant properties, by interacting with signalling pathways implicated in important processes involved in the development of diseases, among other bioactivities. However, the biological properties of microbederived metabolites in their actual conjugated forms remain largely unknown. Currently, there is an increasing interest in their effects on intestinal infections, inflammatory intestinal diseases and overall gut health. The present review will give an insight into the metabolism and microbial biotransformation of flavan-3-ols, including tentative catabolic pathways and aspects related to the identification of bacteria with the ability to catabolize these kinds of polyphenols. Also, the in vitro bioactivities of phase II and microbial phenolic metabolites will be covered in detail.

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“…Indoxyl sulfate and p -cresyl sulfate are the sulfate conjugates of indole and p -cresol, which are end-products of bacterial protein fermentation of respectively tryptophan and tyrosine in the colon [6], [7]. Targeted and untargeted metabolomics-based investigations in mice and humans identified indoxyl sulfate and p -cresyl sulfate as unique microbial co-metabolites [8], [9] and emphasized the major impact of diet on their generation [10], [11].…”

Section: Introductionmentioning

confidence: 99%

Heritability and Clinical Determinants of Serum Indoxyl Sulfate and p-Cresyl Sulfate, Candidate Biomarkers of the Human Microbiome Enterotype

et al. 2014

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BackgroundIndoxyl sulfate and p-cresyl sulfate are unique microbial co-metabolites. Both co-metabolites have been involved in the pathogenesis of accelerated cardiovascular disease and renal disease progression. Available evidence suggests that indoxyl sulfate and p-cresyl sulfate may be considered candidate biomarkers of the human enterotype and may help to explain the link between diet and cardiovascular disease burden.Objective and DesignInformation on clinical determinants and heritability of indoxyl sulfate and p-cresyl sulfate serum is non-existing. To clarify this issue, the authors determined serum levels of indoxyl sulfate and p-cresyl sulfate in 773 individuals, recruited in the frame of the Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO study).ResultsSerum levels of indoxyl sulfate and p-cresyl sulfate amounted to 3.1 (2.4–4.3) and 13.0 (7.4–21.5) μM, respectively. Regression analysis identified renal function, age and sex as independent determinants of both co-metabolites. Both serum indoxyl sulfate (h2 = 0.17) and p-cresyl sulfate (h2 = 0.18) concentrations showed moderate but significant heritability after adjustment for covariables, with significant genetic and environmental correlations for both co-metabolites.LimitationsFamily studies cannot provide conclusive evidence for a genetic contribution, as confounding by shared environmental effects can never be excluded.ConclusionsThe heritability of indoxyl sulfate and p-cresyl sulfate is moderate. Besides genetic host factors and environmental factors, also renal function, sex and age influence the serum levels of these co-metabolites.

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Study of the intestinal tyrosine metabolism using stable isotopes and gas chromatography-mass spectrometry

Cited by 94 publications

References 5 publications

Chemical Signals of Elephant Musth: Temporal Aspects of Microbially-Mediated Modifications

Chemical Signals of Elephant Musth: Temporal Aspects of Microbially-Mediated Modifications

Insights into the metabolism and microbial biotransformation of dietary flavan-3-ols and the bioactivity of their metabolites

Heritability and Clinical Determinants of Serum Indoxyl Sulfate and p-Cresyl Sulfate, Candidate Biomarkers of the Human Microbiome Enterotype

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