DrugBank
Descriptions
ChEBI
L-tryptophan is the L-enantiomer of tryptophan. It has a role as an antidepressant, a nutraceutical, a micronutrient, a plant metabolite, a human metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite. It is an erythrose 4-phosphate/phosphoenolpyruvate family amino acid, a proteinogenic amino acid, a tryptophan and a L-alpha-amino acid. It is a conjugate base of a L-tryptophanium. It is a conjugate acid of a L-tryptophanate. It is an enantiomer of a D-tryptophan. It is a tautomer of a L-tryptophan zwitterion.
MeSH
1: Tryptophan An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
T3DB
Tryptophan is an essential amino acid that is the precursor of both serotonin and melatonin. Melatonin is a hormone that is produced by the pineal gland in animals, which regulates sleep and wakefulness. Serotonin is a brain neurotransmitter, platelet clotting factor, and neurohormone found in organs throughout the body. Metabolism of tryptophan into serotonin requires nutrients such as vitamin B6, niacin, and glutathione. Niacin (also known as vitamin B3) is an important metabolite of tryptophan. It is synthesized via kynurenine and quinolinic acids, which are products of tryptophan degradation. There are a number of conditions or diseases that are characterized tryptophan deficiencies. For instance, fructose malabsorption causes improper absorption of tryptophan in the intestine, which reduces levels of tryptophan in the blood and leads to depression. High corn or other tryptophan-deficient diets can cause pellagra, which is a niacin-tryptophan deficiency disease with symptoms of dermatitis, diarrhea, and dementia. Hartnup's disease is a disorder in which tryptophan and other amino acids are not absorbed properly. Symptoms of Hartnup's disease include skin rashes, difficulty coordinating movements (cerebellar ataxia), and psychiatric symptoms such as depression or psychosis. Tryptophan supplements may be useful for treating Hartnup's. Assessment of tryptophan deficiency is done through studying excretion of tryptophan metabolites in the urine or blood. Blood may be the most sensitive test because the amino acid tryptophan is transported in a unique way. Increased urination of tryptophan breakdown products (such as kynurenine) correlates with increased tryptophan degradation, which occurs with oral contraception, depression, mental retardation, hypertension, and anxiety states. The requirement for tryptophan and protein decreases with age. The minimum daily requirement for adults is 3 mg/kg/day or about 200 mg a day. There is 400 mg of tryptophan in a cup of wheat germ. A cup of low fat cottage cheese contains 300 mg of tryptophan and chicken and turkey contain up to 600 mg of tryptophan per pound (http://www.dcnutrition.com). Tryptophan plays a role in "feast-induced" drowsiness. Ingestion of a meal rich in carbohydrates triggers the release of insulin. Insulin, in turn, stimulates the uptake of large neutral branched-chain amino acids (BCAAs) into muscle, increasing the ratio of tryptophan to BCAA in the bloodstream. The increased tryptophan ratio reduces competition at the large neutral amino acid transporter (which transports both BCAAs and tryptophan), resulting in greater uptake of tryptophan across the blood-brain barrier into the cerebrospinal fluid (CSF). Once in the CSF, tryptophan is converted into serotonin and the resulting serotonin is further metabolized into melatonin by the pineal gland, which promotes sleep. Under certain situations, tryptophan can be a neurotoxin and a metabotoxin. A neurotoxin is a compound that causes damage to the brain and nerve tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of tryptophan can be found in glutaric aciduria type I (glutaric acidemia type I or GA1). GA1 is an inherited disorder in which the body is unable to completely break down the amino acids lysine, hydroxylysine, and tryptophan. Babies with glutaric acidemia type I are often born with unusually large heads (macrocephaly). Affected individuals may also have difficulty moving and may experience spasms, jerking, rigidity or decreased muscle tone, and muscle weakness. High levels of tryptophan have also been implicated in eosinophilia-myalgia syndrome (EMS), an incurable and sometimes fatal flu-like neurological condition linked to the ingestion of large amounts of L-tryptophan. The risk of developing EMS increases with larger doses of tryptophan and increasing age. Some research suggests that certain genetic polymorphisms may be related to the development of EMS. The presence of eosinophilia is a core feature of EMS, along with unusually severe myalgia (muscle pain). It is thought that both tryptophan and certain unidentified tryptophan contaminants may contribute to EMS (PMID: 1763543). It has also been suggested that excessive tryptophan or elevation of its metabolites could play a role in amplifying some of the pathological features of EMS (PMID: 10721094). This pathological damage is further augmented by metabolites of the kynurenine pathway (a tryptophan degradation pathway).
Wikipedia
HMDB
Tryptophan (Trp) or L-tryptophan 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. L-tryptophan is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Tryptophan is found in all organisms ranging from bacteria to plants to animals. It is classified as a non-polar, uncharged (at physiological pH) aromatic amino acid. Tryptophan is an essential amino acid, meaning the body cannot synthesize it, and it must be obtained from the diet. The requirement for tryptophan and protein decreases with age. The minimum daily requirement for adults is 3 mg/kg/day or about 200 mg a day. There is 400 mg of tryptophan in a cup of wheat germ. A cup of low-fat cottage cheese contains 300 mg of tryptophan and chicken and turkey contain up to 600 mg of tryptophan per pound (http://www.dcnutrition.com). Tryptophan is particularly plentiful in chocolate, oats, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas, almonds, sunflower seeds, pumpkin seeds, buckwheat, spirulina, and peanuts. Tryptophan is the precursor of both serotonin and melatonin. Melatonin is a hormone that is produced by the pineal gland in animals, which regulates sleep and wakefulness. Serotonin is a brain neurotransmitter, platelet clotting factor, and neurohormone found in organs throughout the body. Metabolism of tryptophan into serotonin requires nutrients such as vitamin B6, niacin, and glutathione. Niacin (also known as vitamin B3) is an important metabolite of tryptophan. It is synthesized via kynurenine and quinolinic acids, which are products of tryptophan degradation. There are a number of conditions or diseases that are characterized by tryptophan deficiencies. For instance, fructose malabsorption causes improper absorption of tryptophan in the intestine, which reduces levels of tryptophan in the blood and leads to depression. High corn diets or other tryptophan-deficient diets can cause pellagra, which is a niacin-tryptophan deficiency disease with symptoms of dermatitis, diarrhea, and dementia. Hartnup's disease is a disorder in which tryptophan and other amino acids are not absorbed properly. Symptoms of Hartnup's disease include skin rashes, difficulty coordinating movements (cerebellar ataxia), and psychiatric symptoms such as depression or psychosis. Tryptophan supplements may be useful for treating Hartnup's disease. Assessment of tryptophan deficiency is done through studying excretion of tryptophan metabolites in the urine or blood. Blood may be the most sensitive test because the amino acid tryptophan is transported in a unique way. Increased urination of tryptophan breakdown products (such as kynurenine) correlates with increased tryptophan degradation, which occurs with oral contraception, depression, mental retardation, hypertension, and anxiety states. Tryptophan plays a role in "feast-induced" drowsiness. Ingestion of a meal rich in carbohydrates triggers the release of insulin. Insulin, in turn, stimulates the uptake of large neutral branched-chain amino acids (BCAAs) into muscle, increasing the ratio of tryptophan to BCAA in the bloodstream. The increased tryptophan ratio reduces competition at the large neutral amino acid transporter (which transports both BCAAs and tryptophan), resulting in greater uptake of tryptophan across the blood-brain barrier into the cerebrospinal fluid (CSF). Once in the CSF, tryptophan is converted into serotonin and the resulting serotonin is further metabolized into melatonin by the pineal gland, which promotes sleep. Because tryptophan is converted into 5-hydroxytryptophan (5-HTP) which is then converted into the neurotransmitter serotonin, it has been proposed that consumption of tryptophan or 5-HTP may improve depression symptoms by increasing the level of serotonin in the brain. Tryptophan is sold over the counter in the United States (after being banned to varying extents between 1989 and 2005) and the United Kingdom as a dietary supplement for use as an antidepressant, anxiolytic, and sleep aid. It is also marketed as a prescription drug in some European countries for the treatment of major depression. There is evidence that blood tryptophan levels are unlikely to be altered by changing the diet, but consuming purified tryptophan increases the serotonin level in the brain, whereas eating foods containing tryptophan does not. This is because the transport system that brings tryptophan across the blood-brain barrier also transports other amino acids which are contained in protein food sources. Under certain situations, tryptophan can be a neurotoxin and a metabotoxin. A neurotoxin is a compound that causes damage to the brain and nerve tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of tryptophan can be found in glutaric aciduria type I (glutaric acidemia type I or GA1). GA1 is an inherited disorder in which the body is unable to completely break down the amino acids lysine, hydroxylysine, and tryptophan due to a deficiency of mitochondrial glutaryl-CoA dehydrogenase (EC 1.3.99.7, GCDH). Excessive levels of their intermediate breakdown products (e.g. glutaric acid, glutaryl-CoA, 3-hydroxyglutaric acid, glutaconic acid) can accumulate and cause damage to the brain (and also other organs), but particularly the basal ganglia. Babies with glutaric acidemia type I are often born with unusually large heads (macrocephaly). Other symptoms include spasticity (increased muscle tone/stiffness) and dystonia (involuntary muscle contractions resulting in abnormal movement or posture), but many affected individuals are asymptomatic. High levels of tryptophan have also been implicated in eosinophilia-myalgia syndrome (EMS), an incurable and sometimes fatal flu-like neurological condition linked to the ingestion of large amounts of L-tryptophan. The risk of developing EMS increases with larger doses of tryptophan and increasing age. Some research suggests that certain genetic polymorphisms may be related to the development of EMS. The presence of eosinophilia is a core feature of EMS, along with unusually severe myalgia (muscle pain). It is thought that both tryptophan and certain unidentified tryptophan contaminants may contribute to EMS (PMID: 1763543 ). It has also been suggested that excessive tryptophan or elevation of its metabolites could play a role in amplifying some of the pathological features of EMS (PMID: 10721094 ). This pathological damage is further augmented by metabolites of the kynurenine pathway (a tryptophan degradation pathway). Reduced levels of tryptophan in the blood are typically seen when individuals are fighting chronic infections, suffering from traumatic injuries (burns or wounds) or experiencing sepsis (PMID: 26309411). Tryptophan is mainly catabolized through the enzymatic activity of two enzymes: indoleamine-2,3-dioxygenase (IDO) 1 and IDO2, both of which are expressed widely in human tissues, and both of which are induced by interferon gamma (IFN-gamma or IFNG). IDO1 and IDO2 generate tryptophan catabolites such as kynurenine and kynurenic acid. These tryptophan catabolites activate the aryl hydrocarbon receptor (AhR), which plays a key role immune regulation. The role of IDO1 and IDO2 is to effectively deplete tryptophan levels to starve infectious organisms (bacteria and parasites), thereby killing them or slowing their growth. On the other hand, the AhR activation leads to a state of immunosuppression and is intended to serve as a brake on the immune (overexpression of IFNG and IL-1B) response to the infectious organisms. Unfortunately, tryptophan starvation is often not effective against viruses or even all infectious microbes. As a result, this AhR activation by tryptophan catabolites can lead to a situation where viruses (or certain pathogens) continue to survive and multiply even while the immune system is effectively turning off. As a result, high levels of kynurenine and low levels of tryptophan (a high kynurenine to tryptophan ratio) can lead to or even be symptomatic of chronic viral or pathogenic infections or, at worse, sepsis and septic shock (PMID: 33338598; PMID: 21731667).