:Trimethylamine N-oxide
{{Short description|TMAO Chemical compound}}
{{DISPLAYTITLE:Trimethylamine N-oxide}}{{Cs1 config|name-list-style=vanc|display-authors=6}}
{{Chembox
|Watchedfields = changed
|Name =Trimethylamine N-oxide
|verifiedrevid = 476993809
|ImageFile_Ref = {{chemboximage|correct|??}}
|ImageFile = Trimethylaminoxid.svg
|ImageClass = skin-invert-image
|ImageSize = 150
|ImageAlt = Structural formula
|ImageFile1 = Trimethylamine-N-oxide-3D-balls.png
|ImageSize1 = 150
|ImageAlt1 = Ball-and-stick model
|PIN = N,N-Dimethylmethanamine N-oxide
|OtherNames = Trimethylamine oxide, TMAO, TMANO
|Section1={{Chembox Identifiers
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 1113
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = FLD0K1SJ1A
|UNII1_Ref = {{fdacite|correct|FDA}}
|UNII1 = C73WZ0186W
|UNII1_Comment = (dihydrate)
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C01104
|InChI = 1/C3H9NO/c1-4(2,3)5/h1-3H3
|InChIKey = UYPYRKYUKCHHIB-UHFFFAOYAU
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C3H9NO/c1-4(2,3)5/h1-3H3
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = UYPYRKYUKCHHIB-UHFFFAOYSA-N
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 1184-78-7
|CASNo1 = 62637-93-8
|CASNo1_Comment = (dihydrate)
|PubChem = 1145
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 15724
|SMILES = C[N+](C)(C)[O-]
}}
|Section2={{Chembox Properties
|Formula = {{chem2|(CH3)3NO}}
|C=3 | H=9 | N=1 | O=1
|Appearance = colorless solid
|MeltingPtC = 220 to 222
|MeltingPt_notes = (dihydrate: 96 °C)
|Solubility = good
|Dipole = 5.4 D
}}
| Section9 = {{Chembox Related
| OtherCompounds = {{ubl|Trifluoramine oxide}}
}}
}}
Trimethylamine N-oxide (TMAO) is an organic compound with the formula {{chem2|(CH3)3NO|auto=1}}. It is in the class of amine oxides. Although the anhydrous compound is known, trimethylamine N-oxide is usually encountered as the dihydrate. Both the anhydrous and hydrated materials are white, water-soluble solids.
TMAO is found in the tissues of marine crustaceans and marine fish, where it prevents water pressure from distorting proteins and thus killing the animal. The concentration of TMAO increases with the depth at which the animal lives; TMAO is found in high concentrations in the deepest-living described fish species, Pseudoliparis swirei, which was found in the Mariana Trench, at a recorded depth of {{convert|8076|m|ft|abbr=on}}.{{cite journal|author1=Linley, T.D.|author2=M.E. Gerringer|author3=P.H. Yancey|author4=J.C. Drazen|author5=C.L. Weinstock|author6=A.J. Jamieson|year=2016|title=Fishes of the hadal zone including new species, in situ observations and depth records of Liparidae|journal=Deep Sea Research Part I: Oceanographic Research Papers|volume=114|pages=99–110|doi=10.1016/j.dsr.2016.05.003|bibcode=2016DSRI..114...99L|doi-access=free}}{{cite journal|author1=Gerringer, M.E.|author2=T.D. Linley|author3=P.H. Yancey|author4=A.J. Jamieson|author5=E. Goetze|author6=J.C. Drazen|year=2016|title=Pseudoliparis swirei sp. nov.: A newly-discovered hadal snailfish (Scorpaeniformes: Liparidae) from the Mariana Trench|journal=Zootaxa|volume=4358|issue=1|pages=161–177|doi=10.11646/zootaxa.4358.1.7|pmid=29245485|doi-access=free}}
In animals, TMAO is a product of the oxidation of trimethylamine, a common metabolite of trimethyl quaternary ammonium compounds, like choline, trimethylglycine, and L-carnitine.{{cite journal |author1=Baker, J.R. |author2=Chaykin, S. |title= The biosynthesis of trimethylamine-N-oxide |journal= J. Biol. Chem. |date=1 April 1962 |volume= 237 |pages= 1309–13 |pmid= 13864146 |issue= 4|doi=10.1016/S0021-9258(18)60325-4 |doi-access= free}} High TMAO concentrations are associated with an increased risk of all-cause mortality and cardiovascular disease.{{cite journal|year=2017|author=Schiattarella GG, Sannino A, Toscano E, Giugliano G, Gargiulo G, Franzone A, Trimarco B, Esposito G, Perrino C.|title=Gut microbe-generated metabolite trimethylamine-N-oxide as cardiovascular risk biomarker: a systematic review and dose-response meta-analysis|journal=European Heart Journal|url=|volume=38|issue=39|pages=2948–2956|doi=10.1093/eurheartj/ehx342|pmid=29020409|doi-access=free}}{{cite journal|author=Li D, Lu Y, Yuan S, Cai X, He Y, Chen J, Wu Q, He D, Fang A, Bo Y, Song P, Bogaert D, Tsilidis K, Larsson SC, Yu H, Zhu H, Theodoratou E, Zhu Y, Li X. |year=2022|title=Gut microbiota-derived metabolite trimethylamine-N-oxide and multiple health outcomes: an umbrella review and updated meta-analysis|journal=Am J Clin Nutr|volume=116|issue=1|pages=230–243|doi=10.1093/ajcn/nqac074|pmid=35348578|pmc=9257469}}{{cite journal|author=Dean YE, Rouzan SS, Loayza Pintado JJ, Talat NE, Mohamed ARH, Verma S, Anwar Kamdi Z, Gir D, Helmy A, Helmy Z, Afzal A, Mady T, Hazimeh Y, Aiash H.|year=2023|title=Serum trimethylamine N-oxide levels among coronary artery disease and acute coronary syndrome patients: a systematic review and meta-analysis|journal=Annals of Medicine and Surgery|volume=85|issue=12|pages=6123–6133|doi=10.1097/MS9.0000000000001426|pmid=38098555|pmc=10718322}}
Marine animals
Trimethylamine N-oxide is an osmolyte found in molluscs, crustaceans, and all marine fishes and bony fishes. It is a protein stabilizer that serves to counteract the protein-destabilizing effects of pressure. In general, the bodies of animals living at great depths are adapted to high pressure environments by having pressure-resistant biomolecules and small organic molecules present in their cells, known as piezolytes, of which TMAO is the most abundant. These piezolytes give the proteins the flexibility they need to function properly under great pressure.{{cite journal |author=Yancey, P. |title=Organic osmolytes as compatible, metabolic, and counteracting cytoprotectants in high osmolarity and other stresses |journal=J. Exp. Biol. |year=2005 |volume=208 |pages= 2819–2830 |doi=10.1242/jeb.01730 |pmid= 16043587 |issue=15|doi-access=free |bibcode=2005JExpB.208.2819Y}}{{cite journal|first1=M.T.|last1=Velasquez|first2=A.|last2=Ramezani|first3=A.|last3=Manal| first4=D.S.|last4=Raj|title=Trimethylamine N-Oxide: The good, the bad and the unknown|date=8 November 2016|journal=Toxins|volume=8|issue=11|pages = 326|doi=10.3390/toxins8110326|pmid=27834801|pmc=5127123|doi-access=free}}{{cite web |url=https://www.bbc.co.uk/earth/story/20150129-life-at-the-bottom-of-the-ocean |title=What does it take to live at the bottom of the ocean? |year=2016 |publisher=BBC Earth |access-date=19 May 2016 |archive-date=13 May 2016 |archive-url=https://web.archive.org/web/20160513205236/http://www.bbc.co.uk/earth/story/20150129-life-at-the-bottom-of-the-ocean |url-status=live}}
TMAO decomposes to trimethylamine (TMA), which is the main odorant that is characteristic of degrading seafood.{{cn|date=November 2024}}
TMAO in diet
TMAO levels increase with consumption of animal protein such as eggs, red meat, shellfish and total fish consumption.{{cite journal|author=Yang JJ, Shu XO, Herrington DM, Moore SC, Meyer KA, Ose J, Menni C, Palmer ND, Eliassen H, Harada S, Tzoulaki I, Zhu H, Albanes D, Wang TJ, Zheng W, Cai H, Ulrich CM, Guasch-Ferré M, Karaman I, Fornage M, Cai Q, Matthews CE, Wagenknecht LE, Elliott P, Gerszten RE, Yu D.|year=2021|title=Circulating trimethylamine N-oxide in association with diet and cardiometabolic biomarkers: an international pooled analysis|journal=The American Journal of Clinical Nutrition|volume=113|issue=5|pages=1145–1156|doi=10.1093/ajcn/nqaa430|pmid=33826706|pmc=8106754 |hdl=10044/1/86226|hdl-access=free}}{{cite journal|author=Lombardo M, Aulisa G, Marcon D, Rizzo G.|year=2022|title=The Influence of Animal- or Plant-Based Diets on Blood and Urine Trimethylamine-N-Oxide (TMAO) Levels in Humans|journal=Curr Nutr Rep|url=|volume=11|issue=1|pages=56–68|doi=10.1007/s13668-021-00387-9|pmid=34990005}} Plant-based diets such as vegan, vegetarian and the Mediterranean diet lower TMAO levels.{{cite journal|author=Evans M, Dai L, Avesani CM, Kublickiene K, Stenvinkel P.|year=2023|title=The dietary source of trimethylamine N-oxide and clinical outcomes: an unexpected liaison|journal=Clin Kidney J|url=https://academic.oup.com/ckj/article/16/11/1804/7136173|volume=16|issue=11|pages=1804–1812|doi=10.1093/ckj/sfad095|pmid=37915930|pmc=10616480}}
Chemistry
TMAO can be synthesized from trimethylamine by treatment with hydrogen peroxide:{{cite book | doi = 10.1002/047084289X.rt268 | chapter = Trimethylamine N -Oxide | title = Encyclopedia of Reagents for Organic Synthesis | date = 2001 | isbn = 0-471-93623-5 | vauthors = Pearson AJ}}
:{{chem2|(CH3)3N + H2O2 → H2O + (CH3)3NO}}
The dihydrate is dehydrated by azeotropic distillation from dimethylformamide.{{cite journal|author1=Soderquist, J. A. |author2=Anderson, C. L. |title=Crystalline anhydrous trimethylamine N-oxide|journal=Tetrahedron Lett.|year=1986|volume=27|issue=34|pages=3961–3962|doi=10.1016/S0040-4039(00)84884-4}}
=Laboratory applications=
Trimethylamine oxide is used in protein folding experiments to counteract the unfolding effects of urea.{{cite journal |author=Zou, Q. |title=The Molecular Mechanism of Stabilization of Proteins by TMAO and Its Ability to Counteract the Effects of Urea |journal=J. Am. Chem. Soc. |year=2002 |volume=124 |issue=7 |pages= 1192–1202 |doi=10.1021/ja004206b |pmid=11841287 |last2=Bennion |first2=Brian J. |last3=Daggett |first3=Valerie |last4=Murphy |first4=Kenneth P.|bibcode=2002JAChS.124.1192Z}}
In the organometallic chemistry reaction of nucleophilic abstraction, {{chem2|(CH3)3NO}} is employed as a decarbonylation agent according to the following stoichiometry:
:{{chem2|M(CO)_{n} + (CH3)3NO + L → M(CO)_{n−1}L + (CH3)3N + CO2}}
where M is a metal. This reaction is used to decomplex organic ligands from metals, e.g. from {{chem2|(diene)Fe(CO)3}}.
It is used in certain oxidation reactions, e.g. the conversion of alkyl iodides to the corresponding aldehyde.{{OrgSynth |author= Volker Franzen |title= Octanal |collvol= 5 |collvolpages= 872 |prep= cv5p0872 |year= 1973}}
==Effects on protein stability==
The effects of TMAO on the backbone and charged residues of peptides are found to stabilize compact conformations,{{cite journal|date=2015-03-03|title=Regulation and aggregation of intrinsically disordered peptides|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=112|issue=9|pages=2758–2763|doi=10.1073/pnas.1418155112|pmid=25691742|pmc=4352815|last1=Shea|first1=Joan-Emma|last2=Feinstein|first2=Stuart C.|last3=Lapointe|first3=Nichole E.|last4=Larini|first4=Luca|last5=Levine|first5=Zachary A.|bibcode=2015PNAS..112.2758L|doi-access=free}} whereas effects of TMAO on nonpolar residues lead to peptide swelling. This suggests competing mechanisms of TMAO on proteins, which accounts for hydrophobic swelling, backbone collapse, and stabilization of charge-charge interactions. These mechanisms are observed in Trp cage.{{cite journal|title=Effects of Trimethylamine-N-oxide on the Conformation of Peptides and its Implications for Proteins|journal=Physical Review Letters|volume=119|issue=10|pages=108102|doi=10.1103/physrevlett.119.108102|pmid=28949191|year=2017|last1=Su|first1=Zhaoqian|last2=Mahmoudinobar|first2=Farbod|last3=Dias|first3=Cristiano L.|bibcode=2017PhRvL.119j8102S}}
Disorders
=Trimethylaminuria=
{{Main|Trimethylaminuria}}
Trimethylaminuria is a rare defect in the production of the enzyme flavin-containing monooxygenase 3 (FMO3).{{cite journal |author=Treacy, E.P. |title=Mutations of the flavin-containing monooxygenase gene (FMO3) cause trimethylaminuria, a defect in detoxication |journal=Human Molecular Genetics |year=1998 |pages=839–45 |volume=7 |issue=5 |doi=10.1093/hmg/7.5.839 |pmid=9536088 |last2=Akerman |first2=BR |last3=Chow |first3=LM |last4=Youil |first4=R |last5=Bibeau |first5=C |last6=Lin |first6=J |last7=Bruce |first7=AG |last8=Knight |first8=M |last9=Danks |first9=DM|doi-access=free}}{{cite journal |vauthors=Zschocke J, Kohlmueller D, Quak E, Meissner T, Hoffmann GF, Mayatepek E |title=Mild trimethylaminuria caused by common variants in FMO3 gene |journal=Lancet |year=1999 |pages=834–5 |volume=354 |issue=9181 |pmid=10485731 |doi=10.1016/S0140-6736(99)80019-1|s2cid=9555588}} Those suffering from trimethylaminuria are unable to convert choline-derived trimethylamine into trimethylamine oxide. Trimethylamine then accumulates and is released in the person's sweat, urine, and breath, giving off a strong fishy odor.{{cn|date=November 2024}}
Health effects
= Mortality =
High circulating TMAO concentrations are associated with an increased risk of all-cause mortality.{{cite journal |author=Guasti L, Galliazzo S, Molaro M, Visconti E, Pennella B, Gaudio GV, Lupi A, Grandi AM, Squizzato A. |year=2021 |title=TMAO as a biomarker of cardiovascular events: a systematic review and meta-analysis |url= |journal=Intern Emerg Med |volume=16 |issue=1 |pages=201–207 |doi=10.1007/s11739-020-02470-5 |pmid=32779113 |s2cid=221099557}}
=Cardiovascular disease=
High circulating TMAO concentrations are associated with an increased risk of cardiovascular events and strokes in particular.{{cite journal |author=Zhang H, Yao G. |year=2023 |title=Significant correlation between the gut microbiota-derived metabolite trimethylamine-N-oxide and the risk of stroke: evidence based on 23 observational studies |journal=European Journal of Clinical Nutrition |volume=77 |issue=7 |pages=731–740 |doi=10.1038/s41430-022-01104-7 |pmid=35468932 |s2cid=248368447}}
=Hypertension=
High circulating TMAO concentrations are associated with an increased risk of hypertension.{{cite journal|year=2020|author=Ge X, Zheng L, Zhuang R, Yu P, Xu Z, Liu G, Xi X, Zhou X, Fan H.|title=The Gut Microbial Metabolite Trimethylamine N-Oxide and Hypertension Risk: A Systematic Review and Dose-Response Meta-analysis|journal=Adv Nutr|volume=11|issue=1|pages=66–76|doi=10.1093/advances/nmz064|pmid=31269204|pmc=7442397}}{{cite journal|year=2024|author=Han JM, Guo L, Chen XH, Xie Q, Song XY, Ma YL.|title=Relationship between trimethylamine N-oxide and the risk of hypertension in patients with cardiovascular disease: A meta-analysis and dose-response relationship analysis|journal=Medicine (Baltimore)|volume=103|issue=1|pages=e36784|doi=10.1097/MD.0000000000036784|pmid=38181288|pmc=10766215}}
=Potential toxicity=
Exposure limit guidelines with a detailed description of toxicity are available such as "Recommendation from the Scientific Committee on Occupational Exposure Limits" by the European Union Commission.{{Cite book |last1=Directorate-General for Employment |first1=Social Affairs and Inclusion (European Commission) |last2=Scientific Committee on Occupational Exposure Limits |last3=Nielsen |first3=G. D. |last4=Pospischil |first4=E. |last5=Johanson |first5=G. |last6=Klein |first6=C. L. |last7=Papameletiou |first7=D. |date=2017 |title=SCOEL/REC/179 trimethylamine: recommendation from the Scientific Committee on Occupational Exposure Limits |url=https://data.europa.eu/doi/10.2767/440659 |access-date=2023-12-17 |publisher=Publications Office of the European Union|doi=10.2767/440659 |isbn=978-92-79-66627-8}}