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Showing 141 - 160 of 55724 compounds

Compound ID

Compound

Pathways

PW_C000153

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Phenol

Phenol, is a toxic, colourless crystalline solid with a sweet tarry odor that resembles a hospital smell. It is commonly used as an antiseptic and disinfectant. It is active against a wide range of micro-organisms including some fungi and viruses, but is only slowly effective against spores. It has been used to disinfect skin and to relieve itching. Phenol is also used in the preparation of cosmetics including sunscreens, hair dyes, and skin lightening preparations. It is also used in the production of drugs (it is the starting material in the industrial production of aspirin), weedkillers, and synthetic resins. Phenol can be found in areas with high levels of motor traffic, therefore, people living in crowded urban areas are frequently exposed to traffic-derived phenol vapor. The average (mean +/- SD) phenol concentration in urine among normal individuals living in urban areas is 7.4 +/- 2.2 mg/g of creatinine. Exposure of the skin to concentrated phenol solutions causes chemical burns which may be severe; in laboratories where it is used, it is usually recommended that polyethylene glycol solution is kept available for washing off splashes. Notwithstanding the effects of concentrated solutions, it is also used in cosmetic surgery as an exfoliant, to remove layers of dead skin (Wikipedia). In some bacteria phenol can be directly synthesized from tyrosine via the enzyme tyrosine phenol-lyase [EC:4.1.99.2].

PW_C000154

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Nicotinamide ribotide

Nicotinamide ribotide (NMN) is an important intermediate metabolite in the nicotinate and nicotinamide metabolism pathway. Mammals predominantly use nicotinamide rather than nicotinic acid as a precursor for NAD biosynthesis. Instead of the deamidation to nicotinic acid, nicotinamide is directly converted to NMN by nicotinamide phosphoribosyltransferase (NAMPT, EC 2.4.2.12). The enzyme nicotinamide mononucleotide adenylyltransferase (NMNAT, EC 2.7.7.1), which is a member of the nucleotidyltransferase alpha/beta-phosphodiesterase superfamily, catalyzes the reaction NMN + ATP <=> Nicotinamide adenine dinucleotide (NAD) + PPi, representing the final step in the biosynthesis of NAD. NAD is a molecule that plays a fundamental role as a cofactor in cellular redox reactions. Thus NMN is an important metabolite for the maintenance of normal NAD biosynthesis. Circulating NMN levels may play an important role in regulating cell function in physiological and pathophysiological conditions. (PMID: 15078171, 17983582).

PW_C000155

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N-Acetylneuraminic acid

N-Acetylneuraminic acid (NeuAc) or sialic acid is an acetyl derivative of the amino sugar neuraminic acid. It occurs in many glycoproteins, glycolipids, and polysaccharides in both mammals and bacteria. The most abundant sialic acid, NeuAc, is synthesized in vivo from N-acetylated D-mannosamine (ManNAc) or D-glucosamine (GlcNAc). NeuAc and its activated form, CMP-NeuAc, are biosynthesized in five consecutive reactions: UDP-N-acetylglucosamine (UDP-GlcNAc) N-acetylmannosamine (ManNAc) ManNAc 6-phosphate NeuAc 9-phosphate NeuAc CMP-NeuAc. CMP-NeuAc is transported into the Golgi apparatus and, with the aid of specific sialyltransferases, added onto nonreducing positions on oligosaccharide chains of glycoproteins and glycolipids. NeuAc is widely distributed throughout human tissues and found in several fluids, including serum, cerebrospinal fluid, saliva, urine, amniotic fluid, and breast milk. It is found in high levels in the brain, adrenal glands, and the heart. Serum and urine levels of the free acid are elevated in individuals suffering from renal failure. Serum and saliva Neu5Ac levels are also elevated in alcoholics. A disorder known as Salla disease or infantile NeuAc storage disease is also characterized by high serum and urine levels of this compound. The negative charge of is responsible for the slippery feel of saliva and mucins coating the body's organs. This particular sialic acid is known to act as a "decoy" for invading pathogens. Along with involvement in preventing infections (mucus associated with mucous membranes mouth, nose, GI, respiratory tract), Neu5Ac acts as a receptor for influenza viruses, allowing attachment to mucous cells via hemagglutinin (an early step in acquiring influenzavirus infection). NeuAc is also becoming known as an agent necessary for mediating ganglioside distribution and structures in the brain. Sialic acid (SA) is an N-acetylated derivative of neuraminic acid that is an abundant terminal monosaccharide of glycoconjugates. Normal human serum SA is largely bound to glycoproteins or glycolipids (Total sialic acid, TSA, 1.5-2.5 mmol/L), with small amounts of free SA (1-3 umol/L). Negatively charged SA units stabilize glycoprotein conformation in cell surface receptors to increase cell rigidity. This enables signal recognition and adhesion to ligands, antibodies, enzymes and microbes. SA residues are antigenic determinant residues in carbohydrate chains of glycolipids and glycoproteins, chemical messengers in tissue and body fluids, and may regulate glomeruli basement membrane permeability. Sialic acids are structurally unique nine-carbon keto sugars occupying the interface between the host and commensal or pathogenic microorganisms. An important function of host sialic acid is to regulate innate immunity. Sialic acid is the moiety most actively recycled for metabolic purposes in the salvage pathways in glycosphingolipid metabolism. Sialic acid is indispensable for the neuritogenic activities of gangliosides constituents which are unique in that a sialic acid directly binds to the glucose of the cerebroside, they are mutually connected in tandem, and some are located in the internal parts of the sugar chain. Sialylation (sialic acid linked to galactose, N-acetylgalactosamine, or linked to another sialic acid) represents one of the most frequently occurring terminations of the oligosaccharide chains of glycoproteins and glycolipids. The biosynthesis of the various linkages is mediated by the different members of the sialyltransferase family. (PMID: 11425186 , 11287396 , 12770781 , 16624269 , 12510390 , 15007099 ).

PW_C000156

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Quinolinic acid

Quinolinic acid is a metabolite of tryptophan with a possible role in neurodegenerative disorders. Elevated CSF levels of quinolinic acid are correlated with the severity of neuropsychological deficits in patients who have AIDS. Quinolinic acid (QUIN) is a product of tryptophan metabolism that can act as an endogenous brain excitotoxin when released by activated macrophages. (Valle et. al, Brain 127:1047 (2004)).

PW_C000157

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Testosterone

Testosterone is the most important androgen in potency and quantity. Testosterone is synthesized and released by the Leydig cells that lie between the tubules and comprise less than 5% of the total testicular volume. testosterone diffuses into the seminiferous tubules where it is essential for maintaining spermatogenesis. Some binds to an androgen-binding protein (ABP) that is produced by the Sertoli cells and is homologous to the sex-hormone binding globulin that transports testosterone in the general circulation. The ABP carries testosterone in the testicular fluid where it maintains the activity of the accessory sex glands and may also help to retain testosterone within the tubule and bind excess free hormone. Some testosterone is converted to estradiol by Sertoli cell-derived aromatase enzyme. Leydig cell steroidogenesis is controlled primarily by luteinizing hormone with negative feedback of testosterone on the hypothalamic-pituitary axis. The requirement of spermatogenesis for high local concentrations of testosterone means that loss of androgen production is likely to be accompanied by loss of spermatogenesis. Indeed, if testicular androgen production is inhibited by the administration of exogenous androgens then spermatogenesis ceases. This is the basis of using exogenous testosterone as a male contraceptive. testosterone is converted to dihydrotestosterone by 5a-reductase type 2 (EC 1.3.1.22, SRD5A2), the androgen with the highest affinity for the androgen receptor. SRD5A2 deficiency illustrates the importance of dihydrotestosterone for external virilization, as individuals with this condition have normal male internal structures but their external genitalia are of female appearance. There is now clear evidence that the human fetal testis and also the fetal adrenal gland is capable of testosterone biosynthesis during the first trimester. Regardless of the source of androgen production, the target tissue responds by male sexual differentiation of the external genitalia by the end of the first trimester. It is clear that testicular damage may result in loss of testosterone production or the loss of spermatogenesis or both. Loss of androgen production results in hypogonadism, the symptoms of which reflect the functions of testosterone. Male hypogonadism is defined as failure of the testes to produce normal amounts of testosterone, combined with signs and symptoms of androgen deficiency. Systemic testosterone levels fall by about 1% each year in men. Therefore, with increasing longevity and the aging of the population, the number of older men with testosterone deficiency will increase substantially over the next several decades. Serum testosterone levels decrease progressively in aging men, but the rate and magnitude of decrease vary considerably. Approximately 1% of healthy young men have total serum testosterone levels below normal; in contrast, approximately 20% of healthy men over age 60 years have serum testosterone levels below normal. (PMID: 17904450, 17875487).

PW_C000158

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Thiamine

Thiamine or thiamin, also known as vitamin B1, is a colorless compound with the chemical formula C12H17N4OS. It is soluble in water and insoluble in alcohol. Thiamine decomposes if heated. Thiamine was first discovered by Umetaro Suzuki in Japan when researching how rice bran cured patients of Beriberi. Thiamine plays a key role in intracellular glucose metabolism and it is thought that thiamine inhibits the effect of glucose and insulin on arterial smooth muscle cell proliferation. thiamine plays an important role in helping the body convert carbohydrates and fat into energy. It is essential for normal growth and development and helps to maintain proper functioning of the heart and the nervous and digestive systems. Thiamine cannot be stored in the body; however, once absorbed, the vitamin is concentrated in muscle tissue.

PW_C000159

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Propionic acid

Propionic acid (PA) is widely used as an antifungal agent in food. It is present naturally at low levels in dairy products and occurs ubiquitously, together with other short-chain fatty acids (SCFA), in the gastro-intestinal tract of humans and other mammals as an end-product of the microbial digestion of carbohydrates. It has significant physiological activity in animals. PA is irritant but produces no acute systemic effects and has no demonstrable genotoxic potential. (PMID 1628870) Propionic aciduria is one of the most frequent organic acidurias, a disease that comprise many various disorders. The outcome of patients born with Propionic aciduria is poor intellectual development patterns, with 60% having an IQ less than 75 and requiring special education. Successful liver and/or renal transplantations, in a few patients, have resulted in better quality of life but have not necessarily prevented neurological and various visceral complications. These results emphasize the need for permanent metabolic follow-up whatever the therapeutic strategy. (PMID 15868474) Decreased early mortality, less severe symptoms at diagnosis, and more favorable short-term neurodevelopmental outcome were recorded in patients identified through expanded newborn screening. (PMID 16763906).

PW_C000160

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Sepiapterin

Sepiapterin, also known as lopac-S-154, belongs to the class of organic compounds known as pterins and derivatives. These are polycyclic aromatic compounds containing a pterin moiety, which consist of a pteridine ring bearing a ketone and an amine group to form 2-aminopteridin-4(3H)-one. Sepiapterin is slightly soluble (in water) and a very weakly acidic compound (based on its pKa). Sepiapterin has been primarily detected in cerebrospinal fluid. Within the cell, sepiapterin is primarily located in the cytoplasm and mitochondria. In humans, sepiapterin is involved in pterine biosynthesis pathway. Sepiapterin is also involved in several metabolic disorders, some of which include sepiapterin reductase deficiency, hyperphenylalaninemia due to DHPR-deficiency, hyperphenylalaninemia due to 6-pyruvoyltetrahydropterin synthase deficiency (PTPS), and the dopa-responsive dystonia pathway. Sepiapterin is an intermediate in the salvage pathway of tetrahydrobiopterin (BH(4)). It is a yellow fluorescing pigment. Sepiapterin accumulates in the brain of patients with sepiapterin reductase (SR) deficiency.

PW_C000161

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Pyridoxine

The 4-methanol form of vitamin B6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). Pyridoxine is one of the compounds that can be called vitamin B6. Pyridoxine assists in the balancing of sodium and potassium as well as promoting red blood cell production. It is linked to cancer immunity and helps fight the formation of homocysteine. It has been suggested that Pyridoxine might help children with learning difficulties, and may also prevent dandruff, eczema, and psoriasis. In addition, pyridoxine can help balance hormonal changes in women and aid in immune system. Lack of pyridoxine may cause anemia, nerve damage, seizures, skin problems, and sores in the mouth. -- Wikipedia Deficiency, though rare because of widespread distribution in foods, leads to the development of peripheral neuritis in adults and affects the central nervous system in children (DOSE - 3rd edition).

PW_C000162

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Sulfite

Endogenous sulfite is generated as a consequence of the body's normal processing of sulfur-containing amino acids. Sulfites occur as a consequence of fermentation and also occur naturally in a number of foods and beverages. As food additives, sulfiting agents were first used in 1664 and have been approved in the United States since the 1800s. Sulfite is an allergen, a neurotoxin, and a metabotoxin. An allergen is a compound that causes allergic reactions such as wheezing, rash, or rhinitis. A neurotoxin is a substance that causes damage to nerves or brain tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. As an allergen, sulfite is known to induce asthmatic reactions. Sulfite sensitivity occurs most often in asthmatic adults (predominantly women), but it is also occasionally reported in preschool children. Adverse reactions to sulfites in nonasthmatics are extremely rare. Asthmatics who are steroid-dependent or who have a higher degree of airway hyperreactivity may be at greater risk of experiencing a reaction to sulfite-containing foods. Sulfite sensitivity reactions vary widely, ranging from no reaction to severe. The majority of reactions are mild. These manifestations may include dermatologic, respiratory, or gastrointestinal signs and symptoms. The precise mechanisms of the sensitivity responses have not been completely elucidated: inhalation of sulfur dioxide (SO2) generated in the stomach following ingestion of sulfite-containing foods or beverages, a deficiency in a mitochondrial enzyme, and an IgE-mediated immune response have all been implicated. Exogenously supplied sulfite is detoxified by the enzyme sulfite oxidase. Sulfite oxidase (EC 1.8.3.1) is 1 of 3 enzymes in humans that require molybdenum as a cofactor. Under certain circumstances, chronically high levels of sulfite can lead to serious neurotoxicity. Sulfite oxidase deficiency (also called molybdenum cofactor deficiency) is a rare autosomal inherited disease that is typified by high concentrations of sulfite in the blood and urine. It is characterized by severe neurological symptoms such as untreatable seizures, attenuated growth of the brain, and mental retardation. It results from defects in the enzyme sulfite oxidase, which is responsible for the oxidation of sulfite to sulfate. This sulfite to sulfate reaction is the final step in the degradation of sulfur-containing metabolites (including the amino acids cysteine and methionine). The term "isolated sulfite oxidase deficiency" is used to define the deficiency caused by mutations in the sulfite oxidase gene. This differentiates it from another version of sulfite oxidase deficiency that is due to defects in the molybdenum cofactor biosynthetic pathway (with mutations in the MOCS1 or MOCS2 genes). Isolated sulfite oxidase deficiency is a rare but devastating neurologic disease that usually presents in early infancy with seizures and alterations in muscle tone (PMID: 16234925, 16140720, 8586770). Sulfite oxidase deficiency (as caused by MOCS1 or MOCS2) may be treated with cPMP, a precursor of the molybdenum cofactor (PMID: 20385644). The mechanism behind sulfite neurotoxicity appears to be related to its ability to bind and inhibit glutamate dehydrogenase (GDH). Inhibition of GDH leads to a decrease in alpha-ketoglutarate and a diminished flux through the tricarboxylic acid cycle. This is accompanied by a decrease in NADH through the mitochondrial electron transport chain, which leads to a decrease in mitochondrial membrane potential and in ATP synthesis. Since glutamate is a major metabolite in the brain, inhibition of GDH by sulfite appears to contribute to neural damage characteristic of sulfite oxidase deficiency in human infants (PMID: 15273247).

PW_C000163

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Protoporphyrin IX

Protoporphyrins are tetrapyrroles containing 4 methyl, 2 propionic, and 2 vinyl side chains. Protoporphyrin is produced by oxidation of the methylene bridge of protoporphyrinogen. Protoporphyrin IX is the only naturally occurring isomer; it is an intermediate in heme biosynthesis, combining with ferrous iron to form protoheme IX, the heme prosthetic group of hemoglobin. Protoporphyrin IX is created by the enzyme protoporphyrinogen oxidase. The enzyme ferrochelatase converts it into heme. Protoporphyrin IX naturally occurs in small amounts in feces. Protoporphyrin IX is also responsible for the brown pigment (ooporphyrin) of birds' eggs. Protoporphyrin IX is used as a branch point in the biosynthetic pathway leading to heme (by insertion of iron) and chlorophylls (by insertion of Mg and further side-chain transformation). Protoporphyrin IX can be used to treat liver disorders, mainly as the sodium salt. Under certain conditions, protoporphyrin IX can act as a neurotoxin, a phototoxin, and a metabotoxin. A neurotoxin causes damage to nerve cells and nerve tissues. A phototoxin causes cell damage upon exposure to light. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of porphyrins are associated with porphyrias such as porphyria variegate, acute intermittent porphyria, and hereditary coproporphyria (HCP). In particular, it is accumulated and excreted excessively in the feces in acute intermittent porphyria, protoporphyria, and variegate porphyria. There are several types of porphyrias (most are inherited). Hepatic porphyrias are characterized by acute neurological attacks (seizures, psychosis, extreme back and abdominal pain, and an acute polyneuropathy), while the erythropoietic forms present with skin problems (usually a light-sensitive blistering rash and increased hair growth). The neurotoxicity of porphyrins may be due to their selective interactions with tubulin, which disrupt microtubule formation and cause neural malformations (PMID: 3441503).

PW_C000164

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Pyruvic acid

Pyruvic acid is an intermediate compound in the metabolism of carbohydrates, proteins, and fats. In thiamine deficiency, its oxidation is retarded and it accumulates in the tissues, especially in nervous structures. (From Stedman, 26th ed.) Biological Source: Intermediate in primary metabolism including fermentation processes. Present in muscle in redox equilibrium with Lactic acid. A common constituent, as a chiral cyclic acetal linked to saccharide residues, of bacterial polysaccharides. Isolated from cane sugar fermentation broth and peppermint. Constituent of Bauhinia purpurea, Cicer arietinum (chickpea), Delonix regia, Pisum sativum (pea) and Trigonella caerulea (sweet trefoil) Use/Importance: Reagent for regeneration of carbonyl compdounds from semicarbazones, phenylhydrazones and oximes. Flavoring ingredient (Dictionary of Organic Compounds).

PW_C000165

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Riboflavin

Riboflavin or vitamin B2 is an easily absorbed, water-soluble micronutrient with a key role in maintaining human health. Like the other B vitamins, it supports energy production by aiding in the metabolizing of fats, carbohydrates, and proteins. Vitamin B2 is also required for red blood cell formation and respiration, antibody production, and for regulating human growth and reproduction. It is essential for healthy skin, nails, hair growth and general good health, including regulating thyroid activity. Riboflavin is found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. Riboflavin is yellow or orange-yellow in color and in addition to being used as a food coloring it is also used to fortify some foods. It can be found in baby foods, breakfast cereals, sauces, processed cheese, fruit drinks and vitamin-enriched milk products. The richest natural source is yeast. It occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as flavin mononucleotide and flavin adenine dinucleotide.

PW_C000166

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Porphobilinogen

Porphobilinogen (PBG) is a pyrrole-containing intermediate in the biosynthesis of porphyrins. It is generated from aminolevulinate (ALA) by the enzyme ALA dehydratase. Porphobilinogen is then converted into hydroxymethylbilane by the enzyme porphobilinogen deaminase (also known as hydroxymethylbilane synthase). Under certain conditions, porphobilinogen can act as a phototoxin, a neurotoxin, and a metabotoxin. A phototoxin leads to cell damage upon exposure to light. A neurotoxin causes damage to nerve cells and nerve tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of porphyrins are associated with porphyrias such as porphyria variegate, acute intermittent porphyria, and hereditary coproporphyria (HCP). There are several types of porphyrias (most are inherited). Hepatic porphyrias are characterized by acute neurological attacks (seizures, psychosis, extreme back and abdominal pain, and an acute polyneuropathy), while the erythropoietic forms present with skin problems (usually a light-sensitive blistering rash and increased hair growth). The neurotoxicity of porphyrins may be due to their selective interactions with tubulin, which disrupt microtubule formation and cause neural malformations (PMID: 3441503).

PW_C000168

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Sorbitol

Sorbitol is a polyhydric alcohol with about half the sweetness of sucrose. Sorbitol occurs naturally and is also produced synthetically from glucose. It was formerly used as a diuretic and may still be used as a laxative and in irrigating solutions for some surgical procedures. It is also used in many manufacturing processes, as a pharmaceutical aid, and in several research applications. Ascorbic acid fermentation; in solution form for moisture-conditioning of cosmetic creams and lotions, toothpaste, tobacco, gelatin; bodying agent for paper, textiles, and liquid pharmaceuticals; softener for candy; sugar crystallization inhibitor; surfactants; urethane resins and rigid foams; plasticizer, stabilizer for vinyl resins; food additive (sweetener, humectant, emulsifier, thickener, anticaking agent); dietary supplement. (Hawley's Condensed Chemical Dictionary) Biological Source: Occurs widely in plants ranging from algae to the higher orders. Fruits of the plant family Rosaceae, which include apples, pears, cherries, apricots, contain appreciable amounts. Rich sources are the fruits of the Sorbus and Crataegus species Use/Importance: Used for manufacturing of sorbose, propylene glycol, ascorbic acid, resins, plasticizers and as antifreeze mixtures with glycerol or glycol. Tablet diluent, sweetening agent and humectant, other food uses. Sorbitol is used in photometric determination of Ru(VI) and Ru(VIII); in acid-base titration of borate (Dictionary of Organic Compounds).

PW_C000169

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Thyroxine

The thyronamines function via some unknown mechanism to inhibit neuronal activity; this plays an important role in the hibernation cycles of mammals. One effect of administering the thyronamines is a severe drop in body temperature. Iodide is actively absorbed from the bloodstream and concentrated in the thyroid follicles. (If there is a deficiency of dietary iodine, the thyroid enlarges in an attempt to trap more iodine, resulting in goitre.) Via a reaction with the enzyme thyroperoxidase, iodine is covalently bound to tyrosine residues in the thyroglobulin molecules, forming monoiodotyrosine (MIT) and diiodotyrosine (DIT). Linking two moieties of DIT produces thyroxine. Combining one particle of MIT and one particle of DIT produces triiodothyronine. Both T3 and T4 are used to treat thyroid hormone deficiency (hypothyroidism). They are both absorbed well by the gut, so can be given orally. Levothyroxine, the most commonly used synthetic thyroxine form, is a stereoisomer of physiological thyroxine, which is metabolized more slowly and hence usually only needs once-daily administration. Natural desiccated thyroid hormones, which are derived from pig thyroid glands, are a "natural" hypothyroid treatment containing 20% T3 and traces of T2, T1 and calcitonin. this plays an important role in the hibernation cycles of mammals. One effect of administering the thyronamines is a severe drop in body temperature. The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. The thyronamines function via some unknown mechanism to inhibit neuronal activity.

PW_C000170

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Pyrophosphate

The anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. The pyrophosphate anion is abbreviated PPi and is formed by the hydrolysis of ATP into AMP in cells. This hydrolysis is called pyrophosphorolysis. The pyrophosphate anion has the structure P2O74-, and is an acid anhydride of phosphate. It is unstable in aqueous solution and rapidly hydrolyzes into inorganic phosphate. Pyrophosphate is an osteotoxin (arrests bone development) and an arthritogen (promotes arthritis). It is also a metabotoxin (an endogenously produced metabolite that causes adverse health affects at chronically high levels). Chronically high levels of pyrophosphate are associated with hypophosphatasia. Hypophosphatasia (also called deficiency of alkaline phosphatase or phosphoethanolaminuria) is a rare, and sometimes fatal, metabolic bone disease. Hypophosphatasia is associated with a molecular defect in the gene encoding tissue non-specific alkaline phosphatase (TNSALP). TNSALP is an enzyme that is tethered to the outer surface of osteoblasts and chondrocytes. TNSALP hydrolyzes several substances, including inorganic pyrophosphate (PPi) and pyridoxal 5'-phosphate (PLP), a major form of vitamin B6. When TSNALP is low, inorganic pyrophosphate (PPi) accumulates outside of cells and inhibits the formation of hydroxyapatite, one of the main components of bone, causing rickets in infants and children and osteomalacia (soft bones) in adults. Vitamin B6 must be dephosphorylated by TNSALP before it can cross the cell membrane. Vitamin B6 deficiency in the brain impairs synthesis of neurotransmitters which can cause seizures. In some cases, a build-up of calcium pyrophosphate dihydrate crystals in the joints can cause pseudogout.

PW_C000171

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Taurine

Taurine is a sulfur amino acid like methionine, cystine, cysteine and homocysteine. It is a lesser-known amino acid because it is not incorporated into the structural building blocks of protein. Yet taurine is an essential amino acid in pre-term and newborn infants of humans and many other species. Adults can synthesize their own taurine, yet are probably dependent in part on dietary taurine. Taurine is abundant in the brain, heart, breast, gallbladder and kidney and has important roles in health and disease in these organs. Taurine has many diverse biological functions serving as a neurotransmitter in the brain, a stabilizer of cell membranes and a facilitator in the transport of ions such as sodium, potassium, calcium and magnesium. Taurine is highly concentrated in animal and fish protein, which are good sources of dietary taurine. It can be synthesized by the body from cysteine when vitamin B6 is present. Deficiency of taurine occurs in premature infants and neonates fed formula milk, and in various disease states. Inborn errors of taurine metabolism have been described. OMIM 168605, an unusual neuropsychiatric disorder inherited in an autosomal dominant fashion through 3 generations of a family. Symptoms began late in the fifth decade in 6 affected persons and death occurred after 4 to 6 years. The earliest and most prominent symptom was mental depression not responsive to antidepressant drugs or electroconvulsive therapy. Sleep disturbances, exhaustion and marked weight loss were features. Parkinsonism developed later, and respiratory failure occurred terminally. OMIM 145350 describes congestive cardiomyopathy and markedly elevated urinary taurine levels (about 5 times normal). Other family members had late or holosystolic mitral valve prolapse and elevated urinary taurine values (about 2.5 times normal). In 2 with mitral valve prolapse, congestive cardiomyopathy eventually developed while the amounts of urinary taurine doubled. Taurine, after GABA, is the second most important inhibitory neurotransmitter in the brain. Its inhibitory effect is one source of taurine's anticonvulsant and antianxiety properties. It also lowers glutamic acid in the brain, and preliminary clinical trials suggest taurine may be useful in some forms of epilepsy. Taurine in the brain is usually associated with zinc or manganese. The amino acids alanine and glutamic acid, as well as pantothenic acid, inhibit taurine metabolism while vitamins A and B6, zinc and manganese help build taurine. Cysteine and B6 are the nutrients most directly involved in taurine synthesis. Taurine levels have been found to decrease significantly in many depressed patients. One reason that the findings are not entirely clear is because taurine is often elevated in the blood of epileptics who need it. It is often difficult to distinguish compensatory changes in human biochemistry from true metabolic or deficiency disease. Low levels of taurine are found in retinitis pigmentosa. Taurine deficiency in experimental animals produces degeneration of light-sensitive cells. Therapeutic applications of taurine to eye disease are likely to be forthcoming. Taurine has many important metabolic roles. Supplements can stimulate prolactin and insulin release. The parathyroid gland makes a peptide hormone called glutataurine (glutamic acid-taurine), which further demonstrates taurine's role in endocrinology. Taurine increases bilirubin and cholesterol excretion in bile, critical to normal gallbladder function. It seems to inhibit the effect of morphine and potentiates the effects of opiate antagonists. Low plasma taurine levels have been found in a variety of conditions, i.e., depression, hypertension, hypothyroidism, gout, institutionalized patients, infertility, obesity, kidney failure and others. (http://www.dcnutrition.com/AminoAcids/).

PW_C000172

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Sphingosine

Sphingosine is a 18-carbon amino alcohol with a long unsaturated hydrocarbon chain. Sphingosine and its derivative sphinganine are the major bases of the sphingolipids in mammals. (Dorland, 28th ed.). Sphingosine can be phosphorylated in vivo via two kinases, sphingosine kinase type 1 and sphingosine kinase type 2. This leads to the formation of sphingosine-1-phosphate, a potent signaling lipid.(Wikipedia).

PW_C000173

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Pregnenolone

Pregnenolone is a derivative of cholesterol, the product of cytochrome P450 side-chain cleavage (EC 1.14.15.6, CYP11A1. This reaction consists of three consecutive monooxygenations, a 22-hydroxylation, a 20-hydroxylation, and the cleavage of the C20-C22 bond, yielding pregnenolone. Pregnenolone is the precursor to gonadal steroid hormones and the adrenal corticosteroids. This reaction occurs in steroid hormone-producing tissues such as the adrenal cortex, corpus luteum, and placenta. The most notable difference between the placenta and other steroidogenic tissues is that electron supply to CYP11A1 limits the rate at which cholesterol is converted into pregnenolone in the placenta. The limiting component for electron delivery to CYP11A1 is the concentration of adrenodoxin reductase in the mitochondrial matrix which is insufficient to maintain the adrenodoxin pool in a fully reduced state. Pregnenolone is also a neurosteroid, and is produced in the spinal cord; CYP11A1 is the key enzyme catalyzing the conversion of cholesterol into pregnenolone, the rate-limiting step in the biosynthesis of all classes of steroids, and has been localized in sensory networks of the spinal cord dorsal horn. In the adrenal glomerulosa cell, angiotensin II, one of the major physiological regulators of mineralocorticoid synthesis, appears to affect most of the cholesterol transfer to the mitochondrial outer membrane and many steps in the transport to the inner membrane. Thus, it exerts a powerful control over the use of cholesterol for aldosterone production (PMID: 17222962, 15823613, 16632873, 15134809).
Showing 141 - 160 of 55724 compounds