Browsing Compounds

Methylmalonic acid is a malonic acid derivative, which is a vital intermediate in the metabolism of fat and protein. In particular, the coenzyme A-linked form of methylmalonic acid, methylmalonyl-CoA, is converted into succinyl-CoA by methylmalonyl-CoA mutase in a reaction that requires vitamin B12 as a cofactor. In this way, methylmalonic acid enters the Krebs cycle and is thus part of one of the anaplerotic reactions. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This inborn error of metabolism is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA. Methylmalonic acid is also found to be associated with other inborn errors of metabolism, including cobalamin deficiency, cobalamin malabsorption, malonyl-CoA decarboxylase deficiency, and transcobalamin II deficiency. When present in sufficiently high levels, methylmalonic acid can act as an acidogen and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of methylmalonic acid are associated with at least 5 inborn errors of metabolism, including Malonyl CoA decarboxylase deficiency, Malonic Aciduria, Methylmalonate Semialdehyde Dehydrogenase Deficiency, Methylmalonic Aciduria and Methylmalonic Aciduria Due to Cobalamin-Related Disorders. Methylmalonic acid is an organic acid and abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart abnormalities, kidney abnormalities, liver damage, seizures, coma, and possibly death. These are also the characteristic symptoms of the untreated IEMs mentioned above. Many affected children with organic acidemias experience intellectual disability or delayed development. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures.

Phenylpyruvic acid is a keto-acid that is an intermediate or catabolic byproduct of phenylalanine metabolism. It has a slight honey-like odor. Levels of phenylpyruvate are normally very low in blood or urine. High levels of phenylpyruvic acid can be found in the urine of individuals with phenylketonuria (PKU). PKU is due to lack of the enzyme phenylalanine hydroxylase (PAH), so that phenylalanine is converted not to tyrosine but to phenylpyruvic acid. In particular, excessive phenylalanine can be metabolized into phenylketones through, a transaminase pathway route involving glutamate. Metabolites of this transamination reaction include phenylacetate, phenylpyruvate and phenethylamine. In persons with PKU, dietary phenylalanine either accumulates in the body or some of it is converted to phenylpyruvic acid. Individuals with PKU tend to excrete large quantities of phenylpyruvate, phenylacetate and phenyllactate, along with phenylalanine, in their urine. If untreated, mental retardation effects and microcephaly are evident by the first year along with other symptoms which include: unusual irritability, epileptic seizures and skin lesions. Hyperactivity, EEG abnormalities and seizures, and severe learning disabilities are major clinical problems later in life. A "musty or mousy" odor of skin, hair, sweat and urine (due to phenylacetate accumulation); and a tendency to hypopigmentation and eczema are also observed. The neural-development effects of PKU are primarily due to the disruption of neurotransmitter synthesis. In particular, phenylalanine is a large, neutral amino acid which moves across the blood-brain barrier (BBB) via the large neutral amino acid transporter (LNAAT). Excessive phenylalanine in the blood saturates the transporter. Thus, excessive levels of phenylalanine significantly decrease the levels of other LNAAs in the brain. But since these amino acids are required for protein and neurotransmitter synthesis, phenylalanine accumulation disrupts brain development, leading to mental retardation.

Oxoglutaric acid, also known as alpha-ketoglutarate, alpha-ketoglutaric acid, AKG, or 2-oxoglutaric acid, is classified as a gamma-keto acid or a gamma-keto acid derivative. gamma-Keto acids are organic compounds containing an aldehyde substituted with a keto group on the C4 carbon atom. alpha-Ketoglutarate is considered to be soluble (in water) and acidic. alpha-Ketoglutarate is a key molecule in the TCA cycle, playing a fundamental role in determining the overall rate of this important metabolic process (PMID: 26759695). In the TCA cycle, AKG is decarboxylated to succinyl-CoA and carbon dioxide by AKG dehydrogenase, which functions as a key control point of the TCA cycle. Additionally, AKG can be generated from isocitrate by oxidative decarboxylation catalyzed by the enzyme known as isocitrate dehydrogenase (IDH). In addition to these routes of production, AKG can be produced from glutamate by oxidative deamination via glutamate dehydrogenase, and as a product of pyridoxal phosphate-dependent transamination reactions (mediated by branched-chain amino acid transaminases) in which glutamate is a common amino donor. AKG is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. In particular, AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in skeletal muscles (PMID: 26759695). Interestingly, enteric feeding of AKG supplements can significantly increase circulating plasma levels of hormones such as insulin, growth hormone, and insulin-like growth factor-1 (PMID: 26759695). It has recently been shown that AKG can extend the lifespan of adult C. elegans by inhibiting ATP synthase and TOR (PMID: 24828042). In combination with molecular oxygen, alpha-ketoglutarate is required for the hydroxylation of proline to hydroxyproline in the production of type I collagen. A recent study has shown that alpha-ketoglutarate promotes TH1 differentiation along with the depletion of glutamine thereby favouring Treg (regulatory T-cell) differentiation (PMID: 26420908). alpha-Ketoglutarate has been found to be associated with fumarase deficiency, 2-ketoglutarate dehydrogenase complex deficiency, and D-2-hydroxyglutaric aciduria, which are all inborn errors of metabolism (PMID: 8338207).

Phenyl acetate (or phenylacetate) is a carboxylic acid ester that has been found in the biofluids of patients with nephritis and/or hepatitis as well as patients with phenylketonuria (PKU). Excess phenylalanine in the body can be disposed of through a transamination process leading to the production of phenylpyruvate. The phenylpyruvate can be further metabolized into a number of products. Decarboxylation of phenylpyruvate gives phenylacetate, while a reduction reaction gives phenyllactate. The phenylacetate can be further conjugated with glutamine to give phenylacetyl glutamine. All of these metabolites can be detected in serum and urine of PKU patients. Phenyl acetate is also produced endogenously as the metabolite of 2-Phenylethylamine, which is mainly metabolized by monoamine oxidase to form phenyl acetate. 2-phenylethylamine is an "endogenous amphetamine" which may modulate central adrenergic functions, and the urinary phenyl acetate levels have been postulated as a marker for depression. (PMID: 17978765, 476920, 6857245). Phenylacetate is also found in essential oils, e.g. neroli, rose oil, free and as esters' and in many fruits. As a result it is used as a perfumery and flavoring ingredient.

Pantothenic acid, also called vitamin B5, is a water-soluble vitamin required to sustain life. Pantothenic acid is needed to form coenzyme-A (CoA), and is thus critical in the metabolism and synthesis of carbohydrates, proteins, and fats. Its name is derived from the Greek pantothen meaning "from everywhere" and small quantities of pantothenic acid are found in nearly every food, with high amounts in whole grain cereals, legumes, eggs, meat, and royal jelly.

myo-Inositol is an inositol isoform. Inositol is a derivative of cyclohexane with six hydroxyl groups, making it a polyol. It also is known as a sugar alcohol, having exactly the same molecular formula as glucose or other hexoses. Inositol exists in nine possible stereoisomers, of which cis-1,2,3,5-trans-4,6-cyclohexanehexol, or myo-inositol is the most widely occurring form in nature. The other known inositols include scyllo-inositol, muco-inositol, D-chiro-inositol, L-chiro-inositol, neo-inositol, allo-inositol, epi-inositol and cis-inositol. myo-Inositol is found naturally in many foods (particularly in cereals with high bran content) and can be used as a sweetner as it has half the sweetness of sucrose (table sugar). myo-Inositol was once considered a member of the vitamin B complex and given the name: vitamin B8. However, because it is produced by the human body from glucose, it is not an essential nutrient, and therefore cannot be called a vitamin. myo-Inositol is a precursor molecule for a number of secondary messengers including various inositol phosphates. In addition, inositol/myo-inositol is an important component of the lipids known as phosphatidylinositol (PI) phosphatidylinositol phosphate (PIP). myo-Inositol is synthesized from glucose, via glucose-6-phosphate (G-6-P) in two steps. First, G-6-P is isomerised by an inositol-3-phosphate synthase enzyme to myo-inositol 1-phosphate, which is then dephosphorylated by an inositol monophosphatase enzyme to give free myo-inositol. In humans, myo-inositol is primarily synthesized in the kidneys at a rate of a few grams per day. myo-Inositol can be used in the management of preterm babies who have or are at a risk of infant respiratory distress syndrome. It is also used as a treatment for polycystic ovary syndrome (PCOS). It works by increasing insulin sensitivity, which helps to improve ovarian function and reduce hyperandrogenism. Reduced levels of myo-inositol have been found in the spinal fluid of depressed patients and levels are significantly reduced in brain samples of suicide victims.

Myo-inositol 1-phosphate is a metabolite of the Inositol phosphate metabolism and the Phosphatidylinositol signaling system. Inositol phosphatases [EC:3.1.3.25] play a crucial role in the phosphatidylinositol signaling pathway; in brain, the expression is substantially higher in the subcortical regions, most prominently in the caudate. The phosphatidylinositol pathway is thought to be modified by lithium, a commonly prescribed medication in treating bipolar disorder. (OMIM 605922).

Ornithine is an amino acid produced in the urea cycle by the splitting off of urea from arginine. It is a central part of the urea cycle, which allows for the disposal of excess nitrogen. L-Ornithine is also a precursor of citrulline and arginine. In order for ornithine produced in the cytosol to be converted to citrulline, it must first cross the inner mitochondrial membrane into the mitochondrial matrix where it is carbamylated by ornithine transcarbamylase. This transfer is mediated by the mitochondrial ornithine transporter (SLC25A15; AF112968; ORNT1). Mutations in the mitochondrial ornithine transporter result in hyperammonemia, hyperornithinemia, homocitrullinuria (HHH) syndrome, a disorder of the urea cycle. (PMID 16256388) The pathophysiology of the disease may involve diminished ornithine transport into mitochondria, resulting in ornithine accumulation in the cytoplasm and reduced ability to clear carbamoyl phosphate and ammonia loads. (OMIM 838970).

N-Acetyl-D-Glucosamine (N-acetlyglucosamine) is a monosaccharide derivative of glucose. Chemically it is an amide between glucosamine and acetic acid. A single N-acetlyglucosamine moiety linked to serine or threonine residues on nuclear and cytoplasmic proteins -O-GlcNAc, is an ubiquitous post-translational protein modification. O-GlcNAc modified proteins are involved in sensing the nutrient status of the surrounding cellular environment and adjusting the activity of cellular proteins accordingly. O-GlcNAc regulates cellular responses to hormones such as insulin, initiates a protective response to stress, modulates a cell's capacity to grow and divide, and regulates gene transcription. In humans, it exists in skin, cartilage and blood vessel as a component of hyaluronic acid, and bone tissue, cornea and aorta as a component of keratan sulfate. (PMID 16237703).

Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.

Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5-phosphate (NMN) coupled by pyrophosphate linkage to the 5-phosphate adenosine 2,5-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed.) Hydrogen carrier in biochemical redox systems. In the hexose monophosphoric acid system it is reduced to Dihydrocoenzyme II and reoxidation in the presence of flavoproteins (Dictionary of Organic Compounds).

Orotidylic acid (OMP), is a pyrimidine nucleotide which is the last intermediate in the biosynthesis of uridine monophosphate. Decarboxylation by Orotidylate decarboxylase affords Uridine 5'-phosphate which is the route to Uridine and its derivatives de novo and consequently one of the most important processes in nucleic acid synthesis (Dictionary of Organic Compounds). In humans, the enzyme UMP synthase converts OMP into uridine 5'- monophosphate. If UMP synthase is defective, orotic aciduria can result. (Wikipedia).

Palmitic acid, or hexadecanoic acid, is one of the most common saturated fatty acids found in animals, plants, and microorganisms. As its name indicates, it is a major component of the oil from the fruit of oil palms (palm oil). Excess carbohydrates in the body are converted to palmitic acid. Palmitic acid is the first fatty acid produced during fatty acid synthesis and is the precursor to longer fatty acids. As a consequence, palmitic acid is a major body component of animals. In humans, one analysis found it to make up 21–30% (molar) of human depot fat (PMID: 13756126), and it is a major, but highly variable, lipid component of human breast milk (PMID: 352132). Palmitic acid is used to produce soaps, cosmetics, and industrial mould release agents. These applications use sodium palmitate, which is commonly obtained by saponification of palm oil. To this end, palm oil, rendered from palm tree (species Elaeis guineensis), is treated with sodium hydroxide (in the form of caustic soda or lye), which causes hydrolysis of the ester groups, yielding glycerol and sodium palmitate. Aluminium salts of palmitic acid and naphthenic acid were combined during World War II to produce napalm. The word "napalm" is derived from the words naphthenic acid and palmitic acid (Wikipedia). Palmitic acid is also used in the determination of water hardness and is a surfactant of Levovist, an intravenous ultrasonic contrast agent.

Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed.).

L-Palmitoylcarnitine is a long-chain acyl fatty acid derivative ester of carnitine which facilitates the transfer of long-chain fatty acids from cytoplasm into mitochondria during the oxidation of fatty acids. L-palmitoylcarnitine, due to its amphipatic character is, like detergents, a surface-active molecule and by changing the membrane fluidity and surface charge can change activity of several enzymes and transporters localized in the membrane. L-palmitoylcarnitine has been also reported to change the activity of certain proteins. On the contrary to carnitine, palmitoylcarnitine was shown to stimulate the activity of caspases 3, 7 and 8 and the level of this long-chain acylcarnitine increased during apoptosis. Palmitoylcarnitine was also reported to diminish completely binding of phorbol esters, the protein kinase C activators and to decrease the autophosphorylation of the enzyme. Apart from these isoform nonspecific phenomena, palmitoylcarnitine was also shown to be responsible for retardation in cytoplasm of protein kinase C isoforms β and δ and, in the case of the latter one, to decrease its interaction with GAP-43. Some of the physico-chemical properties of palmitoylcarnitine may help to explain the need for coenzyme A-carnitine-coenzyme A acyl exchange during mitochondrial fatty acid import. The amphiphilic character of palmitoylcarnitine may also explain its proposed involvement in the pathogenesis of myocardial ischemia. L-Palmitoylcarnitine accumulates in ischemic myocardium and potentially contribute to myocardial damage through alterations in membrane molecular dynamics , one mechanism through which could play an important role in ischemic injury. Palmitoylcarnitine is characteristically elevated in carnitine palmitoyltransferase II deficiency, late-onset (OMIM 255110). (PMID 2540838, 15363641, 8706815).

Oxaloacetic acid, also known as oxosuccinic acid or oxalacetic acid, is a four-carbon dicarboxylic acid appearing as an intermediate of the citric acid cycle. In vivo, oxaloacetate (the ionized form of oxaloacetic acid) is formed by the oxidation of L-malate, catalyzed by malate dehydrogenase, and reacts with Acetyl-CoA to form citrate, catalyzed by citrate synthase.(wikipedia) A class of ketodicarboxylic acids derived from oxalic acid. Oxaloacetic acid is an intermediate in the citric acid cycle and is converted to aspartic acidD by a transamination reaction.

Phosphoethanolamine (PE) is a phosphomonoester metabolite of the phospholipid metabolism. PE is a precursor of phospholipid synthesis and a product of phospholipid breakdown. Phosphomonoesters are present at much higher levels in brain than in other organs. In developing brain, phosphomonoesters are normally elevated during the period of neuritic proliferation. This also coincides with the occurrence of normal programmed cell death and synaptic pruning in developing brain. These findings are consistent with the role of phosphomonoesters in membrane biosynthesis. PE shows a strong structural similarity to the inhibitory neurotransmitter, GABA, and the GABAB receptor partial agonist, 3-amino-propylphosphonic acid. PE is a phosphomonoester which is decreased in post-mortem Alzheimer's disease (AD) brain. (PMID: 7791524, 8588821, 11566853).

2-Oxoadipic acid is produced from lysine in the cytosol of cells via the saccharopine and the pipecolic acid pathways. Catabolites of hydroxylysine and tryptophan enter these pathways as 2-aminoadipic-semialdehyde and 2-oxoadipate, respectively. In the mitochondrial matrix, 2-oxoadipate is decarboxylated to glutaryl-CoA by the 2-oxoadipate dehydrogenase complex and then converted into acetyl-CoA. Chronically high levels of oxoadipic acid are associated with at least two inborn errors of metabolism, including 2-aminoadipic aciduria and 2-oxoadipic aciduria. 2-Oxoadipic aciduria is an inborn error of metabolism involving lysine, tryptophan, and hydroxylysine, in which abnormal quantities of 2-aminoadipic acid are found in body fluids along with 2-oxoadipic acid. Patients with 2-oxoadipic acidemias are mentally retarded with hypotonia or seizures. 2-Oxoadipic aciduria can occur in patients with Kearns-Sayre syndrome, a progressive disorder with onset prior to 20 years of age in which multiple organ systems are affected. Affected individuals have progressive external ophthalmoplegia (PEO) and retinopathy, both of which are classically associated with abnormalities in cardiac conduction, cerebellar signs, and elevated cerebrospinal fluid protein (PMID: 10655159, 16183823, 11083877). When present in sufficiently high levels, oxoadipic acid can act as an acidogen and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Oxoadipic acid is an organic acid. Abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart abnormalities, kidney abnormalities, liver damage, seizures, coma, and possibly death. These are also the characteristic symptoms of the untreated IEMs mentioned above. Many affected children with organic acidemias experience intellectual disability or delayed development. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures.

Orotic acid is a minor dietary constituent. Indeed, until it was realized that it could be synthesized by humans, orotic acid was known as vitamin B-13. The richest dietary sources of orotic acid are cow's milk and other dairy products as well as root vegetables such as carrots and beets. Dietary intake probably contributes to a basal rate of orotic acid excretion in urine because fasting decreases excretion by ~50%. However, it is now apparent that most urinary orotic acid is synthesized in the body, where it arises as an intermediate in the pathway for the synthesis of pyrimidine nucleotides. Orotic acid is converted to UMP by UMP synthase, a multifunctional protein with both orotate phosphoribosyltransferase and orotidylate decarboxylase activity. The most frequently observed inborn error of pyrimidine nucleotide synthesis is a mutation of the multifunctional protein UMP synthase (UMP synthase deficiency or orotic aciduria). This disorder prevents the conversion of orotic acid to UMP, and thus to other pyrimidines. As a result, plasma orotic acid accumulates to high concentrations, and increased quantities appear in the urine. Indeed, urinary orotic acid is so markedly increased in individuals harboring a mutation in UMP synthase that orotic acid crystals can form in the urine. The urinary concentration of orotic acid in individuals suffering from orotic aciduria can be of the order of millimoles per millimole creatinine. By comparison, the urinary level in unaffected individuals is ~ 1 µmol/mmol creatinine (PMID: 17513443). Orotic aciduria is characterized by megaloblastic anemia and orotic acid crystalluria that is frequently associated with some degree of physical and mental retardation. These features respond to appropriate pyrimidine replacement therapy and most cases appear to have a good prognosis. When present in sufficiently high levels, orotic acid can act as an acidogen and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of orotic acid are associated with at least seven inborn errors of metabolism, including argininemia, LPI syndrome (lysinuric protein intolerance), hyperornithinemia-hyperammonemia-homocitrullinuria (HHH), OTC deficiency, citrullinemia type I, purine nucleoside phosphorylase deficiency, and orotic aciduria. Orotic acid is an organic acid. Abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart abnormalities, seizures, coma, and possibly death. These are also the characteristic symptoms of the untreated IEMs mentioned above. Many affected children with organic acidemias experience intellectual disability or delayed development. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures.

Mevalonic acid is a key organic compound in biochemistry. It is a precursor in the biosynthetic pathway, known as the HMG-CoA reductase pathway, that produces terpenes and steroids. Mevalonate is produced by NADPH from 3-hydroxy-3-methylglutaryl CoA via reduction. This reaction occurs in the cytosol. It is the committed step in cholesterol synthesis, -- Wikipedia The production of mevalonic acid (MVA) by the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, is the rate-limiting step in the biosynthesis of cholesterol. (Jemal et. al, Rapid Communications in Mass Spectrometry, 2003, 17:1715) Plasma concentrations and urinary excretion of MVA are decreased by HMG-CoA reductase inhibitor drugs such as pravastatin, simvastatin and atorvastatin. Naoumova RP, Marais AD, Mountney J, Firth JC, Rendell NB, Taylor GW, Thompson GR. Atherosclerosis 1996; 119: 203.