4417 L-Histidine Histidine is an alpha-amino acid with an imidazole functional group. It is one of the 22 proteinogenic amino acids. Histidine was first isolated by German physician Albrecht Kossel in 1896. Histidine is an essential amino acid in humans and other mammals. It was initially thought that it was only essential for infants, but longer-term studies established that it is also essential for adults. Infants four to six months old require 33 mg/kg of histidine. It is not clear how adults make small amounts of histidine, and dietary sources probably account for most of the histidine in the body. Histidine is a precursor for histamine and carnosine biosynthesis. Inborn errors of histidine metabolism exist and are marked by increased histidine levels in the blood. Elevated blood histidine is accompanied by a wide range of symptoms, from mental and physical retardation to poor intellectual functioning, emotional instability, tremor, ataxia and psychosis. Histidine and other imidazole compounds have anti-oxidant, anti-inflammatory and anti-secretory properties The efficacy of L-histidine in protecting inflamed tissue is attributed to the capacity of the imidazole ring to scavenge reactive oxygen species (ROS) generated by cells during acute inflammatory response Histidine, when administered in therapeutic quantities is able to inhibit cytokines and growth factors involved in cell and tissue damage (US patent 6150392). Histidine in medical therapies has its most promising trials in rheumatoid arthritis where up to 4.5 g daily have been used effectively in severely affected patients. Arthritis patients have been found to have low serum histidine levels, apparently because of very rapid removal of histidine from their blood Other patients besides arthritis patients that have been found to be low in serum histidine are those with chronic renal failure. Urinary levels of histidine are reduced in pediatric patients with pneumonia. Asthma patients exhibit increased serum levels of histidine over normal controls Serum histidine levels are lower and are negatively associated with inflammation and oxidative stress in obese women Histidine supplementation has been shown to reduce insulin resistance, reduce BMI and fat mass and suppress inflammation and oxidative stress in obese women with metabolic syndrome. Histidine appears to suppress pro-inflammatory cytokine expression, possibly via the NF-kappaB pathway, in adipocytes Low plasma concentrations of histidine are associated with protein-energy wasting, inflammation, oxidative stress, and greater mortality in chronic kidney disease patients Histidine may have many other possible functions because it is the precursor of the ubiquitous neurohormone-neurotransmitter histamine. Histidine increases histamine in the blood and probably in the brain. Low blood histamine with low serum histidine occurs in rheumatoid arthritis patients. Low blood histamine also occurs in some manic, schizophrenic, high copper and hyperactive groups of psychiatric patients. Histidine is a useful therapy in all patients with low histamine levels. 71-00-1 6274 C6H9N3O2 155.15 White powder. 287 dec°C 4.56E+004 mg/L (at 25°C) Absorbed from the small intestine via an active transport mechanism requiring the presence of sodium. Since the actions of supplemental L-histidine are unclear, any postulated mechanism is entirely speculative. However, some facts are known about L-histidine and some of its metabolites, such as histamine and trans-urocanic acid, which suggest that supplemental L-histidine may one day be shown to have immunomodulatory and/or antioxidant activities. Low free histidine has been found in the serum of some rheumatoid arthritis patients. Serum concentrations of other amino acids have been found to be normal in these patients. L-histidine is an excellent chelating agent for such metals as copper, iron and zinc. Copper and iron participate in a reaction (Fenton reaction) that generates potent reactive oxygen species that could be destructive to tissues, including joints. <br/>L-histidine is the obligate precursor of histamine, which is produced via the decarboxylation of the amino acid. In experimental animals, tissue histamine levels increase as the amount of dietary L-histidine increases. It is likely that this would be the case in humans as well. Histamine is known to possess immunomodulatory and antioxidant activity. Suppressor T cells have H2 receptors, and histamine activates them. Promotion of suppressor T cell activity could be beneficial in rheumatoid arthritis. Further, histamine has been shown to down-regulate the production of reactive oxygen species in phagocytic cells, such as monocytes, by binding to the H2 receptors on these cells. Decreased reactive oxygen species production by phagocytes could play antioxidant, anti-inflammatory and immunomodulatory roles in such diseases as rheumatoid arthritis. <br/>This latter mechanism is the rationale for the use of histamine itself in several clinical trials studying histamine for the treatment of certain types of cancer and viral diseases. In these trials, down-regulation by histamine of reactive oxygen species formation appears to inhibit the suppression of natural killer (NK) cells and cytotoxic T lymphocytes, allowing these cells to be more effective in attacking cancer cells and virally infected cells. ORL-RAT LD₅₀ > 15000 mg/kg, IPR-RAT LD₅₀ > 8000 mg/kg, ORL-MUS LD₅₀ > 15000 mg/kg, IVN-MUS LD₅₀ > 2000 mg/kg No indication of carcinogenicity to humans (not listed by IARC). The actions of supplemental L-histidine are entirely unclear. It may have some immunomodulatory as well as antioxidant activity. L-histidine may be indicated for use in some with rheumatoid arthritis. It is not indicated for treatment of anemia or uremia or for lowering serum cholesterol. 2014-08-29T06:34:56Z 2026-05-14T16:30:00Z L-Histidine C00135 15971 HIS DB00117 HIS true N[C@@H](CC1=CN=CN1)C(O)=O C6H9N3O2 InChI=1S/C6H9N3O2/c7-5(6(10)11)1-4-2-8-3-9-4/h2-3,5H,1,7H2,(H,8,9)(H,10,11)/t5-/m0/s1 HNDVDQJCIGZPNO-YFKPBYRVSA-N 155.1546 155.069476547 Endogenous Solid -3.32 HMDB00177 CHEMBL17962 6038 <p>Kazumi Araki, Tetsuro Kuga, &#8220;Process for producing L-histidine by fermentation.&#8221; U.S. Patent US4495283, issued April, 1975.</p> CHEM003323 NS00074195 (2S)-2-amino-3-(1H-imidazol-5-yl)propanoic acid 92.0 38.059 14.670259477862192 3 4 3 1.8499726767043656 9.437137464922305 0 1 -2.67 -0.34 7.13e+01 g/l