4218 Trimethylamine N-oxide TMAO is a uremic toxin, an osmolyte and an atherotoxin (causing atherosclerotic plaques). Uremic toxins can be subdivided into three major groups based upon their chemical and physical characteristics: 1) small, water-soluble, non-protein-bound compounds, such as urea; 2) small, lipid-soluble and/or protein-bound compounds, such as the phenols and 3) larger so-called middle-molecules, such as beta2-microglobulin. Chronic exposure of uremic toxins can lead to a number of conditions including renal damage, chronic kidney disease and cardiovascular disease. Trimethylamine N-oxide (TMAO) is an oxidation product of trimethylamine and a common metabolite in animals and humans. In particular, trimethylamine-N-oxide is biosynthesized endogenously from trimethylamine, which is derived from choline, which can be derived from dietary lecithin (phosphatidylcholines) or dietary carnitine. TMAO decomposes to trimethylamine (TMA), which is the main odorant that is characteristic of degrading seafood. TMAO is an osmolyte that the body will use to counteract the effects of increased concentrations of urea (due to kidney failure) and high levels can be used as a biomarker for kidney problems. Fish odor syndrome or trimethylaminuria is a defect in the production of the enzyme flavin containing monooxygenase 3 (FMO3) causing incomplete breakdown of trimethylamine from choline-containing food into trimethylamine oxide. Trimethylamine then builds up and is released in the person's sweat, urine, and breath, giving off a strong fishy odor. The concentration of TMAO in the blood increases after consuming foods containing carnitine or lecithin (phosphatidylcholines), if the bacteria that convert those substances to TMAO are present in the gut. High concentrations of carnitine are found in red meat, some energy drinks, and certain dietary supplements; lecithin is found in eggs and is commonly used as an ingredient in processed food. High levels of TMAO are found in many seafoods. Some types of normal gut bacteria (e.g. species of Acinetobacter) in the human gut convert dietary carnitine and dietary lecithin to TMAO. TMAO alters cholesterol metabolism in the intestines, in the liver and in arterial wall. When TMAO is present, cholesterol metabolism is altered and there is an increased deposition of cholesterol within, and decreased removal of cholesterol from, peripheral cells such as those in the artery wall (1, 2, 3). 1184-78-7 1145 C3H9NO Colorless solid 95 - 99°C 454 mg/mL Endogenous, Ingestion Uremic toxins such as TMAO are actively transported into the kidneys via organic ion transporters (especially OAT3). Increased levels of uremic toxins can stimulate the production of reactive oxygen species. This seems to be mediated by the direct binding or inhibition by uremic toxins of the enzyme NADPH oxidase (especially NOX4 which is abundant in the kidneys and heart) (5). Reactive oxygen species can induce several different DNA methyltransferases (DNMTs) which are involved in the silencing of a protein known as KLOTHO. KLOTHO has been identified as having important roles in anti-aging, mineral metabolism, and vitamin D metabolism. A number of studies have indicated that KLOTHO mRNA and protein levels are reduced during acute or chronic kidney diseases in response to high local levels of reactive oxygen species (6). TMAO appears to contribute to the development of atherosclerosis in part by promoting cholesterol accumulation within macrophages, perhaps by inducing scavenger receptors such as CD36 and SRA1, both of which are involved in the uptake of modified lipoproteins (A15344). Trimethylamine-N-oxide is biosynthesized in the liver from trimethylamine (TMA), which is derived from choline. Flavin monooxygenase 3 (FMO3) has been implicated in the oxidation of TMA since individuals with mutations in FMO3 present with accumulation of TMA levels, causing fish malodor syndrome. TMAO is secreted in the urine and is not metabolized any further. >100 uM in blood is usually indicative of uremia No indication of carcinogenicity to humans (not listed by IARC). TMAO is produced endogenously in the body. High levels are found in fish. It is a uremic toxic and an atherotoxin or atherogenic. It is also an osmolyte. >75 uM in blood High endogenous levels of TMAO in the blood (>100 uM) can lead to uremia which can lead to a number of conditions including renal damage, chronic kidney disease and cardiovascular disease. Chronically high levels of TMAO in the blood can also lead to the development of atherosclerosis and atherosclerotic plaques. As a uremic toxin, TMAO can cause uremic syndrome. Uremic syndrome may affect any part of the body and can cause nausea, vomiting, loss of appetite, and weight loss. It can also cause changes in mental status, such as confusion, reduced awareness, agitation, psychosis, seizures, and coma. Abnormal bleeding, such as bleeding spontaneously or profusely from a very minor injury can also occur. Heart problems, such as an irregular heartbeat, inflammation in the sac that surrounds the heart (pericarditis), and increased pressure on the heart can be seen in patients with uremic syndrome. Shortness of breath from fluid buildup in the space between the lungs and the chest wall (pleural effusion) can also be present. Symptoms of atherosclerosis include angina, chest pain, breathlessness, nausea, dizziness, leg pains, weakness or numbness in the legs, erectile dysfunction, hairloss on legs or feet and leg sores that never heal. Kidney dialysis is usually needed to relieve the symptoms of uremic syndrome until normal kidney function can be restored. Treatments for atherosclerosis may include lifestyle changes (exercise, eating fruits and vegetables), medicines (statins), and medical procedures or surgery (angioplasty). 2014-08-29T05:48:25Z 2014-12-24T20:26:40Z Trimethylamine oxide C01104 15724 TRIMENTHLAMINE-N-O TMO true CN(C)(C)=O C3H9NO InChI=1S/C3H9NO/c1-4(2,3)5/h1-3H3 InChIKey=UYPYRKYUKCHHIB-UHFFFAOYSA-N 75.1097 75.068413915 Endogenous Solid HMDB00925 1113 Hazard, Rene; Cheymol, Jean; Chabrier, Pierre. Trimethylamine oxide. (1962), 1 p.