“The quantitative determination of indolic microbial tryptophan metabolites in human and rodent samples: A systematic review”

Anderson, George M.

doi:10.1016/j.jchromb.2021.123008

Cited by 11 publications

(6 citation statements)

References 106 publications

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“…Total Plasma IND: The observed mean concentration for plasma IND of 3.05 ± 3.07 ng/mL was consistent with the summary mean of four previous reports (4.51 + 3.5 ng/mL) [ 14 ]. It can be pointed out that IND is volatile and can be lost during sample preparation, and this may have contributed to the large variance observed within and across studies.…”

Section: Discussionsupporting

confidence: 90%

“…The microbial metabolites of tryptophan have become of greater interest due to an increasing recognition of their importance in human health and disease [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. It appears that the most predominant indolic microbial metabolites in humans and rodents are indolepropionic acid (IPA), indolelactic acid (ILA), indoleacetic acid (IAA), and indole [ 14 ]. The latter compound is rapidly converted to 3-hydroxyindole (indoxyl) and subsequently to indoxylsulfate (ISO4).…”

Section: Introductionmentioning

confidence: 99%

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Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva

Anderson

2023

Metabolites

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The microbial metabolite indolepropionic acid (IPA) and related indolic metabolites, including indolecarboxylic acid (ICA), indolelactic acid (ILA), indoleacetic acid (IAA), indolebutyric acid (IBA), indoxylsulfate (ISO4), and indole, were determined in human plasma, plasma ultrafiltrate (UF), and saliva. The compounds were separated on a 150 × 3 mm column of 3 μm Hypersil C18 eluted with a mobile phase of 80% pH 5 0.01 M sodium acetate containing 1.0 g/L of tert-butylammonium chloride/20% acetonitrile and then detected fluorometrically. Levels of IPA in human plasma UF and of ILA in saliva are reported for the first time. The determination of IPA in plasma UF enables the first report of free plasma IPA, the presumed physiologically active pool of this important microbial metabolite of tryptophan. Plasma and salivary ICA and IBA were not detected, consistent with the absence of any prior reported values. Observed levels or limits of detection for other indolic metabolites usefully supplement limited prior reports.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva

Anderson

2023

Metabolites

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“…The conversion of indole to indoxyl sulfate, however, occurs in the liver and is mediated by cytochrome P450 and sulfotransferase [52,53]. The measurement and concentrations of these metabolites differ significantly depending on the sample in which is it measured (e.g., in brain tissue, cerebrospinal fluid, saliva, plasma and feces) [54]. The kinetics of indole absorption and distribution are not fully understood.…”

Section: Indole Pathwaymentioning

confidence: 99%

Interactions between Tryptophan Metabolism, the Gut Microbiome and the Immune System as Potential Drivers of Non-Alcoholic Fatty Liver Disease (NAFLD) and Metabolic Diseases

2022

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The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing and therefore is its burden of disease as NALFD is a risk factor for cirrhosis and is associated with other metabolic conditions such as type II diabetes, obesity, dyslipidaemia and atherosclerosis. Linking these cardiometabolic diseases is a state of low-grade inflammation, with higher cytokines and c-reactive protein levels found in individuals with NAFLD, obesity and type II diabetes. A possible therapeutic target to decrease this state of low-grade inflammation is the metabolism of the essential amino-acid tryptophan. Its three main metabolic pathways (kynurenine pathway, indole pathway and serotonin/melatonin pathway) result in metabolites such as kynurenic acid, xanturenic acid, indole-3-propionic acid and serotonin/melatonin. The kynurenine pathway is regulated by indoleamine 2,3-dioxygenase (IDO), an enzyme that is upregulated by pro-inflammatory molecules such as INF, IL-6 and LPS. Higher activity of IDO is associated with increased inflammation and fibrosis in NAFLD, as well with increased glucose levels, obesity and atherosclerosis. On the other hand, increased concentrations of the indole pathway metabolites, regulated by the gut microbiome, seem to result in more favorable outcomes. This narrative review summarizes the interactions between tryptophan metabolism, the gut microbiome and the immune system as potential drivers of cardiometabolic diseases in NAFLD.

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“…[9,10,47] Moreover, the most abundant microbial tryptophan metabolites that could be present in the colon were indole, IAA, I3M, IPA, tryptamine, and ICA, considering previous literature. [48,49] Among these metabolites, IAA, IAcrA, IPA, and ICA were reported to exert protective and anti-inflammatory effects in the gut through activating AhR signaling. [50,51] In addition, SCFAs, and butyrate in particular, enhanced the basal and tryptophan metabolites-induced AhR activation through inhibition of histone deacetylase.…”

Section: Discussionmentioning

confidence: 99%

Effect of Protein Fermentation Products on Gut Health Assessed in an In Vitro Model of Human Colon (TIM‐2)

Wang

Geffen

Venema

et al. 2023

Molecular Nutrition Food Res

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Scope: Western type of diets are characterized by high animal protein intake and are associated with various chronic inflammatory diseases. With a higher protein consumption, excess undigested protein will reach the colon and be subsequently metabolized by gut microbiota. Depending on the type of protein, fermentation in the colon generates different metabolites with varying biological effects. This study aims to compare the impact of protein fermentation products from different sources on gut health. Methods and results: Three high protein diets (vital wheat gluten [VWG], lentil, or casein) are submitted to the in vitro model of colon. Fermentation of excess lentil protein for 72 h results in highest production of short-chain fatty acids and lowest production of branched-chain fatty acids. Exposure of Caco-2 monolayers or Caco-2 monolayers co-cultured with THP-1 macrophages to luminal extracts of fermented lentil protein results in less cytotoxicity of Caco-2 monolayers and less damage to barrier integrity, when compared to VWG and casein. Lowest induction of interleukin-6 is observed in THP-1 macrophages after treatment with lentil luminal extracts, which is identified to be regulated by aryl hydrocarbon receptor signaling. Conclusion: The findings indicate that protein sources affect the health effects of high protein diet in the gut.

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“The quantitative determination of indolic microbial tryptophan metabolites in human and rodent samples: A systematic review”

Cited by 11 publications

References 106 publications

Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva

Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva

Interactions between Tryptophan Metabolism, the Gut Microbiome and the Immune System as Potential Drivers of Non-Alcoholic Fatty Liver Disease (NAFLD) and Metabolic Diseases

Effect of Protein Fermentation Products on Gut Health Assessed in an In Vitro Model of Human Colon (TIM‐2)

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