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Ureidoisobutyric acid, also known as 3-ureidoisobutyrate or beta-UBA, belongs to the class of organic compounds known as ureas. Ureas are compounds containing two amine groups joined by a carbonyl (C=O) functional group. Ureidoisobutyric acid is an extremely weak basic (essentially neutral) compound (based on its pKa). Ureidoisobutyric acid exists in all living organisms, ranging from bacteria to humans. Within humans, ureidoisobutyric acid participates in a number of enzymatic reactions. In particular, ureidoisobutyric acid can be biosynthesized from dihydrothymine through its interaction with the enzyme dihydropyrimidinase. Outside of the human body, ureidoisobutyric acid has been detected, but not quantified in, several different foods, such as bread, squashberries, black elderberries, black crowberries, and climbing beans. This could make ureidoisobutyric acid a potential biomarker for the consumption of these foods. Ureidoisobutyric acid is increased in the urine of patients with beta-ureidopropionase (EC 3.5.1.6) deficiency (PMID: 12271438), a genetic disorder. Ureidoisobutyric acid can be used to predict a patient's individual phenotypes of enzyme deficiencies in pyrimidine metabolism when associated with a risk for severe toxicity against the antineoplastic agent 5-fluorouracil (PMID: 12798197).

D-Glutamine, also known as DGN or D glutamine, belongs to the class of organic compounds known as d-alpha-amino acids. These are alpha amino acids which have the D-configuration of the alpha-carbon atom. Supplementation does not appear to be useful in adults or children with Crohn's disease or inflammatory bowel disease, but clinical studies as of 2016 were underpowered. D-Glutamine is a drug. D-Glutamine exists in all living species, ranging from bacteria to humans. D-Glutamine is a potentially toxic compound. Adverse effects of glutamine have been described for people receiving home parenteral nutrition and those with liver-function abnormalities. Glutamine is the most abundant naturally occurring, nonessential amino acid in the human body, and one of the few amino acids that can directly cross the blood-brain barrier. Glutamine can exist in either of two enantiomeric forms, L-glutamine and D-glutamine.

An alpha-amino acid that consists of butyric acid bearing an amino substituent at position 2 and a carbamoyl substituent at position 4." []

A amino acid amide that is glutamic acid in which the carboxy group is replaced by an aminocarbonyl group." []

Glutamine (Gln), also known as L-glutamine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. Structurally, glutamine is similar to the amino acid glutamic acid. However, instead of having a terminal carboxylic acid, it has an amide. Glutamine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Glutamine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, polar amino acid. In humans glutamine is considered a non-essential amino acid. Enzymatically, glutamine is formed by replacing a side-chain hydroxyl of glutamic acid with an amine functional group. More specifically, glutamine is synthesized by the enzyme glutamine synthetase from glutamate and ammonia. The most relevant glutamine-producing tissue are skeletal muscles, accounting for about 90% of all glutamine synthesized. Glutamine is also released, in small amounts, by the lungs and brain. In human blood, glutamine is the most abundant free amino acid. Dietary sources of glutamine include protein-rich foods such as beef, chicken, fish, dairy products, eggs, beans, beets, cabbage, spinach, carrots, parsley, vegetable juices, wheat, papaya, Brussels sprouts, celery and kale. Glutamine is one of the few amino acids that can directly cross the blood–brain barrier. Glutamine is often used as a supplement in weightlifting, bodybuilding, endurance and other sports, as well as by those who suffer from muscular cramps or pain, particularly elderly people. In 2017, the U.S. Food and Drug Administration (FDA) approved L-glutamine oral powder, marketed as Endari, to reduce severe complications of sickle cell disease in people aged five years and older with the disorder. Subjects who were treated with L-glutamine oral powder experienced fewer hospital visits for pain treated with a parenterally administered narcotic or ketorolac. The main use of glutamine within the diet of either group is as a means of replenishing the body's stores of amino acids that have been used during exercise or everyday activities. Studies which have looked into problems with excessive consumption of glutamine thus far have proved inconclusive. However, normal supplementation is healthy mainly because glutamine is supposed to be supplemented after prolonged periods of exercise (for example, a workout or exercise in which amino acids are required for use) and replenishes amino acid stores. This is one of the main reasons glutamine is recommended during fasting or for people who suffer from physical trauma, immune deficiencies, or cancer. There is a significant body of evidence that links glutamine-enriched diets with positive intestinal effects. These include maintenance of gut barrier function, aiding intestinal cell proliferation and differentiation, as well as generally reducing septic morbidity and the symptoms of Irritable Bowel Syndrome (IBS). The reason for such "cleansing" properties is thought to stem from the fact that the intestinal extraction rate of glutamine is higher than that for other amino acids, and is therefore thought to be the most viable option when attempting to alleviate conditions relating to the gastrointestinal tract. These conditions were discovered after comparing plasma concentration within the gut between glutamine-enriched and non glutamine-enriched diets. However, even though glutamine is thought to have "cleansing" properties and effects, it is unknown to what extent glutamine has clinical benefits, due to the varied concentrations of glutamine in varieties of food. It is also known that glutamine has positive effects in reducing healing time after operations. Hospital waiting times after abdominal surgery are reduced by providing parenteral nutrition regimens containing amounts of glutamine to patients. Clinical trials have revealed that patients on supplementation regimes containing glutamine have improved nitrogen balances, generation of cysteinyl-leukotrienes from polymorphonuclear neutrophil granulocytes and improved lymphocyte recovery and intestinal permeability (in postoperative patients) - in comparison to those who had no glutamine within their dietary regime; all without any side-effects.

Alanylglycine is a dipeptide composed of alanine and glycine that is found in human urine. It is a breakdown product from endogenous and exogenous proteins. This peptide is generated by dipeptidyl-dipeptidase (or tetrapeptide dipeptidase) which leads to the release of dipeptides from a tetrapeptide (more specifically: Ala-GlyAla-Gly). The enzyme acts more slowly on Ala-AlaAla-Ala and Gly-GlyGly-Gly.

A dipeptide obtained by formal condensation of the carboxy group of glycine with the amino group of sarcosine." []

An organic chloride salt in which the cationic component is 1-ethyl-3-methylimidazolium." []

An organic chloride salt in which the cationic component is 1-ethyl-3-methylimidazolium." []