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Zgarbová E, Vrzal R. Skatole: A thin red line between its benefits and toxicity. Biochimie 2022; 208:1-12. [PMID: 36586563 DOI: 10.1016/j.biochi.2022.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 12/30/2022]
Abstract
Skatole (3-methylindole) is a heterocyclic compound naturally found in the feces of vertebrates and is produced by certain flowers. Skatole has been used in specific products of the perfume industry or as a flavor additive in ice cream. Additionally, skatole is formed by tryptophan pyrolysis of tobacco and has been demonstrated to be a mutagen. Skatole-induced pulmonotoxicity was reliably described in ruminants and rodents, but no studies have been conducted in humans. Initially, we provide basic knowledge and a historical overview of skatole. Then, skatole bacterial formation in the intestine is described, and the importance of the microbiome during this process is evaluated. Increased skatole concentrations could serve as a marker for intestinal disease development. Therefore, the human molecular targets of skatole that may have significant effects on various processes in the human body are described. Ultimately, we suggest a link between skatole intestinal formation in humans and skatole-induced pulmonotoxicity, which should be explored further in the future.
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Affiliation(s)
- Eliška Zgarbová
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Slechtitelu 27, 783 71, Olomouc, Czech Republic
| | - Radim Vrzal
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Slechtitelu 27, 783 71, Olomouc, Czech Republic.
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Application of CYP1A2-Template System to Understand Metabolic Processes in the Safety Assessment. FOOD SAFETY (TOKYO, JAPAN) 2022; 10:129-139. [PMID: 36619007 PMCID: PMC9789917 DOI: 10.14252/foodsafetyfscj.d-22-00008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/04/2022] [Indexed: 12/24/2022]
Abstract
Cytochrome P450 (CYP)-mediated metabolisms of four chemicals have been investigated to understand their unresolved phenomena of their metabolisms using human CYP-Template systems developed in our previous studies (Drug Metab Pharmacokinet 2019, 2021, 2022). Simulation experiments of a topoisomerase-targeting agent, amonafide, offered a possible new inhibitory-mechanism as Trigger-residue inactivation on human CYP1A2 Template. N-Acetylamonafide as well as amonafide would inactivate CYP1A2 through the interference of Trigger-residue movement with their dimethylaminoethyl parts. The mechanism was also supported on the inhibition/inactivation of two other drugs, DSP-1053 and binimetinib. Both the drugs, after other CYP-mediated slight structural alterations, were expected to interact with Trigger-residue for the intense inhibition on CYP1A2 Template. Possible formation of reactive intermediates of amonafide and 3-methylindole was also examined on CYP1A2 Template. Placements of amonafide suggested the scare N-oxidation of the arylamine part due to the Trigger-residue interaction. Placements of 3-methylindole suggested the formation of a reactive intermediate, 3-methyleneindolenine, rather selectively on rodent CYP1A2 than on human CYP1A2, in consistent with the experimental data. These results suggest that CYP Template systems developed are effective tools to warn an appearance of unstable reactive intermediates. Our CYP-Template systems would support confident judgements in safety assessments through offering the mechanistic understandings of the metabolism.
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Fu B, Nazemi A, Levin BJ, Yang Z, Kulik HJ, Balskus EP. Mechanistic Studies of a Skatole-Forming Glycyl Radical Enzyme Suggest Reaction Initiation via Hydrogen Atom Transfer. J Am Chem Soc 2022; 144:11110-11119. [PMID: 35704859 PMCID: PMC9248008 DOI: 10.1021/jacs.1c13580] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Gut microbial decarboxylation
of amino acid-derived arylacetates
is a chemically challenging enzymatic transformation which generates
small molecules that impact host physiology. The glycyl radical enzyme
(GRE) indoleacetate decarboxylase from Olsenella uli (Ou IAD) performs the non-oxidative radical decarboxylation
of indole-3-acetate (I3A) to yield skatole, a disease-associated metabolite
produced in the guts of swine and ruminants. Despite the importance
of IAD, our understanding of its mechanism is limited. Here, we characterize
the mechanism of Ou IAD, evaluating previously proposed
hypotheses of: (1) a Kolbe-type decarboxylation reaction involving
an initial 1-e– oxidation of the carboxylate of
I3A or (2) a hydrogen atom abstraction from the α-carbon of
I3A to generate an initial carbon-centered radical. Site-directed
mutagenesis, kinetic isotope effect experiments, analysis of reactions
performed in D2O, and computational modeling are consistent
with a mechanism involving initial hydrogen atom transfer. This finding
expands the types of radical mechanisms employed by GRE decarboxylases
and non-oxidative decarboxylases, more broadly. Elucidating the mechanism
of IAD decarboxylation enhances our understanding of radical enzymes
and may inform downstream efforts to modulate this disease-associated
metabolism.
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Affiliation(s)
- Beverly Fu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Azadeh Nazemi
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Benjamin J Levin
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Zhongyue Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, United States
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Acute interstitial pneumonia and the biology of 3-methylindole in feedlot cattle. Anim Health Res Rev 2022; 23:72-81. [PMID: 35833480 DOI: 10.1017/s1466252322000020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Acute interstitial pneumonia (AIP) of cattle has been recognized for many decades. While the pathogenesis and risk factors for this condition in pastured cattle are relatively well characterized, there remains a poor understanding of the disease as it occurs in intensively fed cattle such as in beef feedlots. Specifically, in pastured cattle, AIP results from excessive ruminal production of the pneumotoxicant 3-methylindole (3-MI). In feedlot cattle, the evidence to substantiate the role of 3-MI is comparatively deficient and further investigations into the cause, pathogenesis, and control are sorely needed. This review highlights our current understanding of AIP with a focus on the disease as it occurs in feedlot cattle. Additionally, it illustrates the need for further work in understanding the specific animal factors (e.g. the ruminal microbiome, and the role of concurrent diseases), management factors (e.g. animal stocking and vaccination protocols), and dietary factors (e.g. dietary supplements) that may impact the development of AIP and which are relatively unique to the feedlot setting. All stakeholders in the beef industry stand to benefit from a greater understanding of what remains a pressing yet poorly understood issue in beef production.
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Comparison of oxidation status and antioxidant capacity of meat from surgically castrated and immunocastrated pigs, entire males and sows. ACTA VET BRNO 2019. [DOI: 10.2754/avb201988010113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of the present study was to evaluate the influence of castration (surgical and immunological) and sex on lipid hydrolysis, oxidation and antioxidant capacity in selected muscles/cuts of pigs. Nine muscles/cuts from four groups of pigs (surgically castrated, entire males, immunocastrated and sow) were analysed. Free fatty acids (FFA) were analysed using standard methods according to CSN EN ISO 660. Thiobarbituric reactive substances (TBARS) were determined as malondialdehyde (MDA) equivalents and antioxidant capacity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method . The highest content of FFA was observed in sows, detected to be significantly (P < 0.001) higher than in entire males. The highest content of TBARS was found in entire males; the content was significantly (P < 0.05) higher than in sows. Generally, the highest values of DPPH inhibition were detected in samples of surgically castrated pigs whereas the lowest values were observed in samples of entire males. Antioxidant capacity in musculus longissimus dorsi and backfat of surgically castrated pigs was significantly (P < 0.05) higher than in other evaluated groups of pigs. The study confirmed the differences in FFA and TBARS formation between analysed groups of pigs, probably due to differences in the fatty acid composition. The results of our study indicate that methods of castration have an effect on the antioxidant capacity of pork. These findings are of value to the meat industry.
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Indoleacetate decarboxylase is a glycyl radical enzyme catalysing the formation of malodorant skatole. Nat Commun 2018; 9:4224. [PMID: 30310076 PMCID: PMC6181972 DOI: 10.1038/s41467-018-06627-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/07/2018] [Indexed: 12/30/2022] Open
Abstract
Skatole is a malodorous compound that contributes to the characteristic smell of animal faeces. Although skatole has long been known to originate from bacterial tryptophan fermentation, the enzyme catalysing its formation has so far remained elusive. Here we report the use of comparative genomics for the discovery of indoleacetate decarboxylase, an O2-sensitive glycyl radical enzyme catalysing the decarboxylation of indoleacetate to form skatole as the terminal step of tryptophan fermentation in certain anaerobic bacteria. We describe its biochemical characterization and compare it to other glycyl radical decarboxylases. Indoleacetate decarboxylase may serve as a genetic marker for the identification of skatole-producing environmental and human-associated bacteria, with impacts on human health and the livestock industry. Skatole is a bacterial metabolite responsible for boar taint and the objectionable smell of manure. Here, the authors elucidate the final step of skatole biosynthesis, describing the discovery and biochemical characterization of the enzyme catalysing the conversion of indoleacetate into skatole.
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Abstract
Abstract
Cytochrome P450s belong to a superfamily of enzymes that catalyse a wide variety of oxidative transformations. Hydroxylation is one the most thoroughly investigated of all identified P450-catalysed reactions whilst dehydrogenation has been relatively much less explored to date. P450-catalysed dehydrogenation is often found to occur with hydroxylation and thus, it was initially suspected to be a stepwise process consisting of hydroxylation and subsequent dehydration to yield the final olefin product. This theory has been proven to be invalid and the olefin was shown to be the direct product of a P450-catalysed reaction. This interesting reaction plays a vital role in the metabolism of xenobiotics and the biosynthesis of endogenous compounds, including a number of steroids. A number of well-known examples of P450 mediated dehydrogenation, including those in the metabolism of valproic acid, capsaicin and 3-methylindole and those in the biosynthesis of plant and fungal sterols are discussed in this review.
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Rasmussen MK, Balaguer P, Ekstrand B, Daujat-Chavanieu M, Gerbal-Chaloin S. Skatole (3-Methylindole) Is a Partial Aryl Hydrocarbon Receptor Agonist and Induces CYP1A1/2 and CYP1B1 Expression in Primary Human Hepatocytes. PLoS One 2016; 11:e0154629. [PMID: 27138278 PMCID: PMC4854444 DOI: 10.1371/journal.pone.0154629] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/16/2016] [Indexed: 12/18/2022] Open
Abstract
Skatole (3-methylindole) is a product of bacterial fermentation of tryptophan in the intestine. A significant amount of skatole can also be inhaled during cigarette smoking. Skatole is a pulmonary toxin that induces the expression of aryl hydrocarbon receptor (AhR) regulated genes, such as cytochrome P450 1A1 (CYP1A1), in human bronchial cells. The liver has a high metabolic capacity for skatole and is the first organ encountered by the absorbed skatole; however, the effect of skatole in the liver is unknown. Therefore, we investigated the impact of skatole on hepatic AhR activity and AhR-regulated gene expression. Using reporter gene assays, we showed that skatole activates AhR and that this is accompanied by an increase of CYP1A1, CYP1A2 and CYP1B1 expression in HepG2-C3 and primary human hepatocytes. Specific AhR antagonists and siRNA-mediated AhR silencing demonstrated that skatole-induced CYP1A1 expression is dependent on AhR activation. The effect of skatole was reduced by blocking intrinsic cytochrome P450 activity and indole-3-carbinole, a known skatole metabolite, was a more potent inducer than skatole. Finally, skatole could reduce TCDD-induced CYP1A1 expression, suggesting that skatole is a partial AhR agonist. In conclusion, our findings suggest that skatole and its metabolites affect liver homeostasis by modulating the AhR pathway.
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Affiliation(s)
- Martin Krøyer Rasmussen
- INSERM, U1183, Institute of Regenerative Medicine and Biotherapy, Montpellier, F-34290, France
- Montpellier University, UMR 1183, Montpellier, F-34203, France
- Department of Food Science, Aarhus University, Foulum, Denmark
- * E-mail:
| | - Patrick Balaguer
- Institut de Recherche en Cancérologie de Montpellier, Montpellier, F-34298, France
| | - Bo Ekstrand
- Department of Food Science, Aarhus University, Foulum, Denmark
| | - Martine Daujat-Chavanieu
- INSERM, U1183, Institute of Regenerative Medicine and Biotherapy, Montpellier, F-34290, France
- CHU Montpellier, Institute of Regenerative Medicine and Biotherapy, Montpellier, F-34290, France
| | - Sabine Gerbal-Chaloin
- INSERM, U1183, Institute of Regenerative Medicine and Biotherapy, Montpellier, F-34290, France
- Montpellier University, UMR 1183, Montpellier, F-34203, France
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Fatty acid composition of subcutaneous adipose tissue from entire male pigs with extremely divergent levels of boar taint compounds--an exploratory study. Meat Sci 2014; 99:1-7. [PMID: 25280356 DOI: 10.1016/j.meatsci.2014.08.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/25/2014] [Accepted: 08/09/2014] [Indexed: 01/28/2023]
Abstract
This exploratory study investigated the variability of fatty acid composition in entire male pigs with extremely divergent levels of boar taint compounds. Fatty acids were quantified in back fat samples from 20 selected carcasses of Pietrain*F1 sired boars (average carcass weight 84 kg) with extremely low (LL) or extremely high (HH) levels of androstenone, skatole, and indole. Concentrations of polyunsaturated fatty acids (PUFA) were significantly (p<0.05) increased in LL boars (23.4%) compared to HH boars (19.7%). This was mainly due to increased levels of linoleic acid (C18:2 n-6) and α-linolenic acid (C18:3 n-3). Correspondingly, unsaturated fatty acids (SFA) were significantly lower (p<0.05) in LL boars (35.2%) compared to HH boars (37.7%). The findings are discussed with respect to potential effects on flavor formation in boar fat and meat. Further research is needed to study the gender specificity and the interplay of the synthesis and the metabolism of steroids, lipids, and the clearance of skatole in pigs.
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Beumer JH, Hillebrand MJX, Pluim D, Rosing H, Foley K, Yule SM, Schellens JHM, Beijnen JH. Human metabolism of [(14)C]indisulam following i.v. infusion in cancer patients. Invest New Drugs 2006; 23:317-30. [PMID: 16012791 DOI: 10.1007/s10637-005-1440-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Indisulam is a new anticancer drug with a unique mechanism of action, arresting the cell cycle at the G1/S transition. The major excretory pathway of indisulam is via the urine, accounting for 63% of the radioactive dose ([(14)C]indisulam) administered in a human mass balance study. Radiochromatographic profiling of urine samples resulted in the detection of several radioactive peaks. The purpose of the present investigation was to elucidate the chemical structures of these observed indisulam metabolites. We collected fractions after chromatographic separation of the urine samples. These fractions were analysed using tandem mass spectrometry. We propose the chemical structure of 15 indisulam metabolites in urine. The metabolism of indisulam is very complex, consisting of oxidative dechlorination, hydroxylation, hydrolysis, acetylation, sulphation and glucuronidation. The clinical relevance of the observed indisulam metabolites needs further investigation.
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Affiliation(s)
- Jan-Hendrik Beumer
- Department of Pharmacy and Pharmacology, Slotervaart Hospital/The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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Loneragan GH, Morley PS, Wagner JJ, Mason GL, Yost GS, Thoren MA, Triantis J. Time-dependent changes in plasma concentrations of 3-methylindole and blood concentrations of 3-methyleneindolenine-adduct in feedlot cattle. Am J Vet Res 2002; 63:591-7. [PMID: 11939325 DOI: 10.2460/ajvr.2002.63.591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To describe time-dependent changes in plasma concentrations of 3-methylindole (3MI) and blood concentrations of 3-methyleneindolenine (3MEIN)-adduct in feedlot cattle. ANIMALS 64 yearling steers. PROCEDURES Steers were assigned to 2 groups (32 steers/group). During the first 8 weeks, blood samples were collected from group 1 before the morning ration was fed, whereas samples from group 2 were collected 2 to 3 hours after the ration was fed. Blood samples were collected from all steers approximately 4 times/wk for 3 weeks and 3 times/wk for the subsequent 5 weeks. Samples were collected at the same time for all steers for an additional 10 weeks. Plasma samples were analyzed for 3MI concentrations. Blood samples collected from cattle in group 2 during the first 8 weeks were analyzed for 3MEIN-adduct concentrations. RESULTS Mean blood concentration of 3MEIN-adduct increased to a maximum value on day 33 (0.80 U/microg of protein) and then decreased to a minimum on day 54 0.40 U/microg of protein). Plasma 3MI concentrations initially decreased and remained low until after day 54. Group-1 cattle had lower plasma 3MI concentrations, compared with concentrations for group-2 cattle. Blood 3MEIN-adduct concentrations and plasma 3MI concentrations were not associated with deleterious effects on weight gains. CONCLUSIONS AND CLINICAL RELEVANCE Blood 3MEIN-adduct concentrations peaked during the period of greatest risk for development of bovine respiratory disease complex. Conversely, plasma 3MI concentrations decreased during the same period. Animal-to-animal variation in metabolic capacity to convert 3MI to 3MEIN may be of more importance than differences in plasma 3MI concentration.
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Affiliation(s)
- Guy H Loneragan
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA
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Price RJ, Renwick AB, Wield PT, Beamand JA, Lake BG. Toxicity of 3-methylindole, 1-nitronaphthalene and paraquat in precision-cut rat lung slices. Arch Toxicol 1995; 69:405-9. [PMID: 7495379 DOI: 10.1007/s002040050191] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The toxicity of 3-methylindole, 1-nitronaphthalene and paraquat has been studied in precision-cut rat lung slice cultures. Lung slices were prepared from male Sprague-Dawley rats using an agarose gel instilling technique with a Krumdieck tissue slicer and cultured for 24 h in a dynamic organ culture system. Treatment of rat lung slices with 3-methylindole, 1-nitronaphthalene or paraquat produced concentration dependent decreases in lung slice protein synthesis and potassium content. EC50 values (concentration to produce a 50% inhibition) for protein synthesis were 0.024, 0.27 and 0.57 mM for paraquat, 1-nitronaphthalene and 3-methylindole, respectively. These results demonstrate that precision-cut lung slices are a useful in vitro model system for studying the pulmonary toxicity of xenobiotics. Lung slices offer the potential as a rapid in vitro screen for identifying pulmonary toxicants and to evaluate species differences in response.
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Affiliation(s)
- R J Price
- BIBRA Toxicology International, Carshalton, Surrey, UK
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