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(R)-beta-Aminoisobutyric acid is the product of the catabolism of the pyrimidine bases uracil and thymine by the enzyme dihydropyrimidine dehydrogenase (DPD), in what constitutes the first step of the pyrimidine degradation pathway. The other product of the reaction is beta-alanine (PMID: 14705962).

L-alpha-Aminobutyric acid, also known as (S)-2-aminobutanoic acid, homoalanine, 2-AABA, or alpha-Aminobutyric acid, is a member of the class of compounds known as L-alpha-amino acids. L-alpha-Amino acids are alpha amino acids which have the L-configuration of the alpha-carbon atom. 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. L-alpha-Aminobutyric acid is a non-proteogenic amino acid that can be found in the human kidney, in liver tissues, and in most biofluids or excreta (e.g. feces, breast milk, urine, and blood). Within the cell, L-alpha-aminobutyric acid is primarily located in the cytoplasm. alpha-Aminobutyric acid is biosynthesized by transamination of oxobutyrate, a metabolite in isoleucine biosynthesis. As a non-proteogenic amino acid, alpha-aminobutyric acid can be used by nonribosomal peptide synthases. One example of a nonribosomal peptide containing alpha-aminobutyric acid is ophthalmic acid, which was first isolated from calf lens. alpha-Aminobutyric acid is a non-essential amino acid that is primarily derived from the catabolism of methionine, threonine, and serine. High protein diets can result in significantly higher alpha-aminobutyrate levels in plasma (PMID: 26227325). alpha-Aminobutyric acid is elevated in the plasma of children with Reye's syndrome, tyrosinemia, homocystinuria, nonketotic hyperglycinemia, and ornithine transcarbamylase deficiency (PMID: 420125). alpha-Aminobutyric acid is one of the three isomers of aminobutyric acid. The two others are the neurotransmitter gamma-aminobutyric acid (GABA) and beta-aminobutyric acid (BABA) which is known for inducing plant disease resistance.

2-Aminoisobutyric acid, also known as alpha-methylalanine or a-aminoisobutanoate, belongs to the class of organic compounds known as alpha amino acids. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). 2-Aminoisobutyric acid is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. 2-Aminoisobutyric acid exists in all living organisms, ranging from bacteria to humans. Outside of the human body, 2-Aminoisobutyric acid has been detected, but not quantified in cow milk. Aminoisobutyric acid is a nonprotein amino acid (is an end product of pyrimidine metabolism) excreted in the urine of about 5% of healthy individuals (PMID 14806475), and high excretion is an autosomal recessive phenotype (PMID 13058271).

3-Aminoisobutanoic acid, also known as b-aminoisobutyrate or 2-methyl-beta-alanine, belongs to the class of organic compounds known as beta amino acids and derivatives. These are amino acids having a (-NH2) group attached to the beta carbon atom. 3-Aminoisobutanoic acid is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. 3-Aminoisobutanoic acid exists in all eukaryotes, ranging from yeast to humans. 3-aminoisobutanoic acid can be biosynthesized from ureidoisobutyric acid; which is mediated by the enzyme Beta-ureidopropionase. In humans, 3-aminoisobutanoic acid is involved in the metabolic disorder called the beta-ureidopropionase deficiency pathway. Beta-ureidopropionase deficiency is an inborn error of pyrimidine degradation associated with neurological abnormalities (OMIM 606673). 3-Aminoisobutanoic acid is a potentially toxic compound.

gamma-Aminobutyric acid (GABA) is an inhibitory neurotransmitter found in the nervous systems of widely divergent species, including humans. It is the chief inhibitory neurotransmitter in the vertebrate central nervous system. In vertebrates, GABA acts at inhibitory synapses in the brain. It acts by binding to specific transmembrane receptors in the plasma membrane of both pre- and postsynaptic neurons. This binding causes the opening of ion channels to allow either the flow of negatively-charged chloride ions into the cell or positively-charged potassium ions out of the cell. This will typically result in a negative change in the transmembrane potential, usually causing hyperpolarization. Three general classes of GABA receptor are known (PMID: 10561820). These include GABA-A and GABA-C ionotropic receptors, which are ion channels themselves, and GABA-B metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries known as G proteins (PMID: 10561820). Activation of the GABA-B receptor by GABA causes neuronal membrane hyperpolarization and a resultant inhibition of neurotransmitter release. In addition to binding sites for GABA, the GABA-A receptor has binding sites for benzodiazepines, barbiturates, and neurosteroids. GABA-A receptors are coupled to chloride ion channels. Therefore, activation of the GABA-A receptor induces increased inward chloride ion flux, resulting in membrane hyperpolarization and neuronal inhibition (PMID: 10561820). After release into the synapse, free GABA that does not bind to either the GABA-A or GABA-B receptor complexes can be taken up by neurons and glial cells. Four different GABA membrane transporter proteins (GAT-1, GAT-2, GAT-3, and BGT-1), which differ in their distribution in the CNS, are believed to mediate the uptake of synaptic GABA into neurons and glial cells. The GABA-A receptor subtype regulates neuronal excitability and rapid changes in fear arousal, such as anxiety, panic, and the acute stress response (PMID: 10561820). Drugs that stimulate GABA-A receptors, such as the benzodiazepines and barbiturates, have anxiolytic and anti-seizure effects via GABA-A-mediated reduction of neuronal excitability, which effectively raises the seizure threshold. GABA-A antagonists produce convulsions in animals and there is decreased GABA-A receptor binding in a positron emission tomography (PET) study of patients with panic disorder. Neurons that produce GABA as their output are called GABAergic neurons and have chiefly inhibitory action at receptors in the vertebrate. Medium spiny neurons (MSNs) are a typical example of inhibitory CNS GABAergic cells. GABA has been shown to have excitatory roles in the vertebrate, most notably in the developing cortex. Organisms synthesize GABA from glutamate using the enzyme L-glutamic acid decarboxylase and pyridoxal phosphate as a cofactor (PMID: 12467378). It is worth noting that this involves converting the principal excitatory neurotransmitter (glutamate) into the principal inhibitory one (GABA). Drugs that act as agonists of GABA receptors (known as GABA analogs or GABAergic drugs), or increase the available amount of GABA typically have relaxing, anti-anxiety, and anti-convulsive effects. GABA is found to be deficient in cerebrospinal fluid and the brain in many studies of experimental and human epilepsy. Benzodiazepines (such as Valium) are useful in status epilepticus because they act on GABA receptors. GABA increases in the brain after administration of many seizure medications. Hence, GABA is clearly an antiepileptic nutrient. Inhibitors of GAM metabolism can also produce convulsions. Spasticity and involuntary movement syndromes, such as Parkinson's, Friedreich's ataxia, tardive dyskinesia, and Huntington's chorea, are all marked by low GABA when amino acid levels are studied. Trials of 2 to 3 g of GABA given orally have been effective in various epilepsy and spasticity syndromes. Agents that elevate GABA are also useful in lowering hypertension. Three grams orally have been effective in controlling blood pressure. GABA is decreased in various encephalopathies. GABA can reduce appetite and is decreased in hypoglycemics. GABA reduces blood sugar in diabetics. Chronic brain syndromes can also be marked by deficiencies of GABA. Vitamin B6, manganese, taurine, and lysine can increase both GABA synthesis and effects, while aspartic acid and glutamic acid probably inhibit GABA effects. Low plasma GABA has been reported in some depressed patients and may be a useful trait marker for mood disorders. GABA has an important role in embryonic development, especially facial development, as substantiated by the association of a cleft palate in transgenic mice deficient in GAD67 (glutamate decarboxylase). A recent Japanese population study reported linkage in patients with a nonsyndromic cleft lip with or without a cleft palate and specific GAD67 haplotypes (PMID: 23842532). Unusually high levels of GABA (especially in the brain) can be toxic and GABA can function as both a neurotoxin and a metabotoxin. A neurotoxin is a compound that damages the brain and/or nerve tissue. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of GABA are associated with at least five inborn errors of metabolism, including D-2-hydroxyglutaric aciduria, 4-hydroxybutyric aciduria/succinic semialdehyde dehydrogenase deficiency, GABA-transaminase deficiency, homocarnosinosis, and hyper beta-alaninemia. Nearly all of these conditions are associated with seizures, hypotonia, intellectual deficits, macrocephaly, encephalopathy, and other serious neurological or neuromuscular problems. Increased levels of GABA seem to alter the function of the GABA-B receptor, which may play a role in the tonic-clonic seizures that are often seen in patients with the above disorders. GABA is also a microbial metabolite, urinary GABA is produced by Lactobacillus and Bifidobacterium (PMID: 24621061).

D-alpha-Aminobutyric acid (AABA), also known as alpha-aminobutyrate, (R)-2-aminobutanoic acid or D-homoalanine, 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. D-alpha-aminobutyric acid is an optically active form of alpha-aminobutyric acid having D-configuration. It is an enantiomer of a L-alpha-aminobutyric acid and a non-proteinogenic amino acid. Alpha-aminobutyric acid is one of the three isomers of aminobutyric acid. The two others are the neurotransmitter Gamma-Aminobutyric acid (GABA) and Beta-Aminobutyric acid (BABA) which is known for inducing plant disease resistance. Optically active organic compounds found in meteorites typically exist in racemic form, yet life on Earth has almost exclusively selected for L- over D-enantiomers of amino acids. D-enantiomers of non-proteinogenic amino acids are known to inhibit aerobic microorganisms. D-alpha-aminobutyric acid has been shown to inhibit microbial iron reduction by a number of Geobacter strains including Geobacter bemidjiensis, Geobacter metallireducens and Geopsychrobacter electrodiphilus (PMID: 25695622). D-alpha-Aminobutyric acid is a known substrate of D-amino acid oxidase (PMID: 6127341).

beta-Aminoisobutyric acid is a non-protein amino acid originating from the catabolism of thymine and valine. The concentration of beta-aminoisobutyric acid is normally low in urine as beta-aminoisobutyric acid is further catabolized by beta-aminoisobutyrate aminotransferases to methylmalonic acid semialdehyde and propionyl-CoA. beta-Aminoisobutyric acid occurs in two isomeric forms and both enantiomers of beta-aminoisobutyric acid can be detected in human urine and plasma. In plasma, the S-enantiomer is the predominant type due to active renal reabsorption. In contrast, urine almost exclusively contains the R-enantiomer of beta-aminoisobutyric acid, which is eliminated both by filtration and tubular secretion. Persistently increased levels of beta-aminoisobutyric acid have been observed in individuals with a deficiency of R (-)-beta-aminoisobutyrate-pyruvate aminotransferase. In addition, transient high levels of beta-aminoisobutyric acid have been observed under a variety of pathological conditions such as lead poisoning, starvation, in total body irradiation, and in a number of malignancies. The S-enantiomer of beta-aminoisobutyric acid is predominantly derived from the catabolism of valine. It has been suggested that altered homeostasis of beta-alanine underlies some of the clinical abnormalities encountered in patients with a dihydropyrimidine dehydrogenase (DPD) deficiency. DPD constitutes the first step of the pyrimidine degradation pathway, in which the pyrimidine bases uracil and thymine are catabolized to beta-alanine and the R-enantiomer of beta-aminoisobutyric acid respectively. In normal individuals with an intact pyrimidine degradation pathway, R-methylmalonic acid semialdehyde can be synthesized directly from the catabolism of thymine. Hence, there might be less cross-over between the valine and thymine pathway, allowing the conversion of S-methylmalonic acid semialdehyde into S-beta-aminoisobutyric acid and the subsequent accumulation of S-beta-aminoisobutyric acid in plasma (PMID: 14705962, 14292857, 14453202).

N-Ethylglycine, also known as EG, belongs to the family of compounds known as alpha amino acids and derivatives. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). N-ethylglyicne is a known metabolite of the anesthesia drug lidocaine (PMID: 25932687). N-ethylglyicne is also an endogenously produced metabolite and appears in normal subjects’ urine in small amounts, but its presence is significantly higher in patients with metastatic bone disease (PMID: 16962088). Research has shown that it is lidocaine’s metabolites, n-ethylglycine and monoethylglycinexylidide inhibit GlyT1-mediated uptake of glycine. N-ethylglycine acts as a substrate for the glycine transporter GlyT1 (PMID: 22133759, 25932687).

N-Methylalanine, also known as (S)-2-methylaminopropanoate or N-methyl-L-alanine, is classified as an alanine or an alanine derivative. Alanines are compounds containing alanine or a derivative thereof resulting from reaction of alanine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom. N-Methylalanine is considered to be soluble (in water) and acidic. (ChemoSummarizer)

Dimethylglycine (DMG) is an amino acid derivative found in the cells of all plants and animals and can be obtained in the diet in small amounts from grains and meat. The human body produces DMG when metabolizing choline into glycine. Dimethylglycine that is not metabolized in the liver is transported by the circulatory system to body tissue. Dimethylglycine was popular with Russian athletes and cosmonauts owing to its reputed ability to increase endurance and reduce fatigue. DMG is also a byproduct of homocysteine metabolism. Homocysteine and betaine are converted to methionine and N,N-dimethylglycine by betaine-homocysteine methyltransferase. DMG in the urine is a biomarker for the consumption of legumes. It is also a microbial metabolite (PMID: 25901889).

Butyl nitrite is found in animal foods. Butyl nitrite is a preservative for meats. Claimed not to generate nitrosamines as byproducts Amyl nitrite is employed medically to treat heart diseases such as angina and to treat cyanide poisoning. It is also used as an inhalant drug that induces a brief euphoria; whilst already intoxicated with stimulant drugs such as cocaine or ecstasy (see MDMA) the euphoric state intensifies and lasts for several minutes longer. Once some stimulative drugs wear off, a common side effect is a period of depression or anxiety, colloquially called a "come down"; amyl nitrite is sometimes used to "come up" again in order to stop the user from feeling lousy. Butyl nitrite is an alkyl nitrite made from butyl alcohol. It can be used as an antianginal. Butyl nitrite is also used recreationally as poppers

3-Aminobutanoic acid, also known as beta-aminobutyric acid (BABA) or 3-aminobutyrate, belongs to the class of compounds known as beta amino acids and derivatives. Beta amino acids are amino acids having an (-NH2) group attached to the beta carbon atom. 3-Aminobutanoic acid is found in cereals and cereal products. It is produced by Oryza sativa (rice). 3-Aminobutanoic acid can be found in feces.

O-Acetylethanolamine is found in pulses. O-Acetylethanolamine is isolated from seeds of Lens culinaris (lentil), also present in other Leguminosae.

Alpha-Aminobutyric Acid is an alpha-amino acid that is a derivative of alanine with a side chain that is one carbon longer than the alanine side chain. It is synthesized through the transamination of oxobutyrate and is utilized in the biosynthesis of nonribosomal peptides.

Isobutyl nitrite is a clear colorless to pale yellow liquid. Boiling point 154.4 °F (68 °C). Isobutyl nitrite is a member of nitrite esters. It is functionally related to an isobutanol. Isobutyl Nitrite can cause cancer according to The National Toxicology Program.