Imidazoleacetic acid

Metabolism. MetaboHsm of histamine occurs via two principal enzymatic pathways (Fig. 1). Most (50 to 70%) histamine is metabolized to /V-methylhistamine by A/-methyltransferase, and some is metabolized further by monoamine oxidase to /V-methy1imidazo1eacetic acid and excreted in the urine. The remaining 30 to 40% of histamine is metabolized to imidazoleacetic acid by diamine oxidase, also called histaminase. Only 2 to 3% of histamine is excreted unchanged in the urine. 

Granerus, G. (1968). Effects of oral histamine, histidine, and diet on urinary excretion of histamine, methylhistamine, and l-methyl-4-imidazoleacetic acid in man, Scand. J. Clin. Lab. Invest., 10, suppl., 49. 

An alternative pathway of histamine metabolism involves oxidative deamination by the enzyme diamine oxidase (histaminase) to form 5-imidazoleacetic acid. Diamine oxidase is present in both tissues and blood and plays a particular role in metabolizing the large concentrations of histamine that may be present in food. An additional metabolite, A-acetyl histamine (a conjugate of acetic acid and histamine), can be produced if histamine is ingested orally. This product may result from metabolism of histamine by gastrointestinal tract bacteria. Because of its rapid breakdown after oral administration, histamine produces few systemic effects when given by this route. 

Imidazoleacetic acid riboside Figure 4.11 Histamine metabolism. 

Histamine is formed by decarboxylation of the amino acid l -histidine, a reaction catalyzed in mammalian tissues by the enzyme histidine decarboxylase. Once formed, histamine is either stored or rapidly inactivated. Very little histamine is excreted unchanged. The major metabolic pathways involve conversion to /V-methylhistamine, methylimidazoleacetic acid, and imidazoleacetic acid (IAA). Certain neoplasms (systemic mastocytosis, urticaria pigmentosa, gastric carcinoid, and occasionally myelogenous leukemia) are associated with increased numbers of mast cells or basophils and with increased excretion of histamine and its metabolites. 

A minor route for histamine catabolism involves histamine conversion to imidazoleacetic acid [via diamine oxidase (histaminase)]. In the major route histamine is converted to methylhistamine [via histamine jV-methyl transferase] which is then converted to methylimi-dazoleacetic acid [via MAO]. A large number of MAO inhibitors have been isolated from plants (Table 6.5). 

Raman spectroscopy showed the presence of Co2C and Co3C units in Co/C60 nano-composite materials.327 The IR and Raman spectra of Co(II), Ni(II) and Cu(II) complexes of 4-imidazoleacetic acid (HIA) have been reported, M(IA)2(L)2, where L = HzO, MeOH. There is evidence for extensive mixing of Cu-N and Cu-O modes.328... 

A / iV-imidazoleacetic acid (I A A, 99), a metabolite of histidine 100, and histamine S found in brain and cerebrospinal fluid , has been synthesized by oxidizing A, Af-DL-histidine with sodium hypochlorite, subsequent acid hydrolysis of the formed A, A -imidazoleacetonitrile 101 and separation of the product 99 on an anion exchange column with 0.1 N acetic acid (equation 42). The A, A -IAA obtained served as an internal standard for GC-MS analysis of physiological fluids. 

Histamine is formed from the amino acid histidine and is stored in high concentrations in vesicles in mast cells. Histamine is metabolized by the enzymes monoamine oxidase and diamine oxidase. Excess production of histamine in the body (by. for example, systemic mastocytosis) can be detected by measurement of imidazoleacetic acid (its major metabolite) in tbe urine. Because it is released from mast cells in response to IgE-mediated (immediate) allergic reactions, this autacoid plays an important pathophysiologic role in seasonal rhinitis (hay fever), urticaria, and angioneurotic e ma. Histamine also plays an important physiologic role in the control of acid secretion in the stomach and as a neurotransmitter. 

Imidazoleacetic acid 3-Aminopropanesulfonic acid ( )-fmn5-3-Aminocyclopentane-1 -carboxylic acid ( )-cis-3-Aminocyclopentane-1 -carboxylic acid Bicuculline... 

Histamine is degraded to imidazoleacetic acid, which either yields aspartic acid derivatives (Fig. 242) or is transformed to the riboside. 

Histamine possesses hormone activity in animals (E 3.1) and acts as a neurotransmitter (E 3.2). It is a plant feeding deterrent present, for instance, in nettle toxin (E 5.5.3). Also the alkaloid pilocarpine has strong physiological activity in vertebrates and deters potential predators (E 5.5.3). It is used as a cholinergic drug in medicine (F 2). Urocanic acid, hydantoin propionic acid, imidazoleacetic acid riboside, 1-methylhistidine, 1-methylimidazoleacetic acid and other imidazole derivatives are involved in the removal of L-histidine and histamine residues from the organism of animals. They are found in the urine. Urocanic acid is also a constituent of sweat (E 1). It is involved in the protection of skin to UV radiation (E 2.2). 

Determination of Urinary 1,4-Methyl-imidazoleacetic Acid J. Chromatogr. 82(2) 394-397 (1973) ... 

Gas Chromatography of Ring-Methylated Imidazoleacetic Acids in Urine... 

Gas Chromatographic Analysis of Histamine Metabolites in Human Urine Ring Methylated Imidazoleacetic Acids... 

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