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Hypoxanthine, also known as purine-6-ol or Hyp, belongs to the class of organic compounds known as purines. Purines are a bicyclic aromatic compound made up of a pyrimidine ring fused to an imidazole ring. Hypoxanthine is also classified as an oxopurine, Hypoxanthine is a naturally occurring purine derivative and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the nucleotide salvage pathway. Hypoxanthine exists in all living species, ranging from bacteria to plants to humans. Hypoxanthine has been detected, but not quantified in, several different foods, such as radish (var.), mountain yams, welsh onions, greenthread tea, and common beets. Hypoxanthine is occasionally found as a constituent of nucleic acids, where it is present in the anticodon of tRNA in the form of its nucleoside inosine. Biologically, hypoxanthine can be formed a number of ways. For instance, it is one of the products of the action of xanthine oxidase on xanthine. However, more frequently xanthine is formed from oxidation of hypoxanthine by xanthine oxidoreductase. The enzyme hypoxanthine-guanine phosphoribosyltransferase converts hypoxanthine into IMP in the nucleotide salvage pathway. Hypoxanthine is also a spontaneous deamination product of adenine. Under normal circumstances hypoxanthine is readily converted to uric acid. In this process, hypoxanthine is first oxidized to xanthine, which is further oxidized to uric acid by xanthine oxidase. Molecular oxygen, the oxidant in both reactions, is reduced to H2O2 and other reactive oxygen species. In humans, uric acid is the final product of purine degradation and is excreted in the urine. Within humans, hypoxanthine participates in a number of other enzymatic reactions. In particular, hypoxanthine and ribose 1-phosphate can be biosynthesized from inosine through its interaction with the enzyme purine nucleoside phosphorylase. Hypoxanthine is also involved in the metabolic disorder called the purine nucleoside phosphorylase deficiency. Purine nucleoside phosphorylase (PNP) deficiency is a disorder of the immune system (primary immunodeficiency) characterized by recurrent infections, neurologic symptoms, and autoimmune disorders. PNP deficiency causes a shortage of white blood cells, called T-cells, that help fight infection. Affected individuals develop neurologic symptoms, such as stiff or rigid muscles (spasticity), uncoordinated movements (ataxia), developmental delay, and intellectual disability. PNP deficiency is associated with an increased risk to develop autoimmune disorders, such as autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura (ITP), autoimmune neutropenia, thyroiditis, and lupus.

Citric acid (citrate) is a tricarboxylic acid, an organic acid with three carboxylate groups. Citrate is an intermediate in the TCA cycle (also known as the Tricarboxylic Acid cycle, the Citric Acid cycle or Krebs cycle). The TCA cycle is a central metabolic pathway for all animals, plants, and bacteria. As a result, citrate is found in all living organisms, from bacteria to plants to animals. In the TCA cycle, the enzyme citrate synthase catalyzes the condensation of oxaloacetate with acetyl CoA to form citrate. Citrate then acts as the substrate for the enzyme known as aconitase and is then converted into aconitic acid. The TCA cycle ends with regeneration of oxaloacetate. This series of chemical reactions in the TCA cycle is the source of two-thirds of the food-derived energy in higher organisms. Citrate can be transported out of the mitochondria and into the cytoplasm, then broken down into acetyl-CoA for fatty acid synthesis, and into oxaloacetate. Citrate is a positive modulator of this conversion, and allosterically regulates the enzyme acetyl-CoA carboxylase, which is the regulating enzyme in the conversion of acetyl-CoA into malonyl-CoA (the commitment step in fatty acid synthesis). In short, citrate is transported into the cytoplasm, converted into acetyl CoA, which is then converted into malonyl CoA by acetyl CoA carboxylase, which is allosterically modulated by citrate. In mammals and other vertebrates, Citrate is a vital component of bone, helping to regulate the size of apatite crystals (PMID: 21127269). Citric acid is found in citrus fruits, most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit. Citric acid is a natural preservative and is also used to add an acidic (sour) taste to foods and carbonated drinks. Because it is one of the stronger edible acids, the dominant use of citric acid is as a flavoring and preservative in food and beverages, especially soft drinks and candies. Citric acid is an excellent chelating agent, binding metals by making them soluble. It is used to remove and discourage the buildup of limescale from boilers and evaporators. It can be used to treat water, which makes it useful in improving the effectiveness of soaps and laundry detergents. The salts of citric acid (citrates) can be used as anticoagulants due to their calcium chelating ability. Intolerance to citric acid in the diet is known to exist. Little information is available as the condition appears to be rare, but like other types of food intolerance it is often described as a "pseudo-allergic" reaction.

Citraconic acid, also known as 2-methylmaleate or methylmaleic acid, belongs to the class of organic compounds known as methyl-branched fatty acids. These are fatty acids with an acyl chain that has a methyl branch. Usually, they are saturated and contain only one or more methyl group. However, branches other than methyl may be present. Citraconic acid is a dicarboxylic acid consisting of maleic acid having a methyl substituent at the 2-position. Citraconic acid exists as a white solid. It is the cis-isomer of mesaconic acid and is one of the pyrocitric acids formed upon the heating of citric acid. Citraconic acid has been detected in the urine of both normal and fasting individuals (PMID: 6778884). Citraconic acid is also elevated in the urine of individuals with methylmalonic acidaemia who have suffered ketotic attacks (PMID: 116077). Altered serum levels of citraconic acid have been detected in patients with primary biliary cholangitis (PMID: 28400566).

Itaconic acid is a dicarboxylic acid that is methacrylic acid in which one of the methyl hydrogens is substituted by a carboxylic acid group. It has a role as a fungal metabolite and a human metabolite. It is a dicarboxylic acid and an olefinic compound. It derives from a succinic acid. It is a conjugate acid of an itaconate(2-). This dicarboxylic acid is a white solid that is soluble in water, ethanol, and acetone. Historically, itaconic acid was obtained by the distillation of citric acid, but currently it is produced by fermentation. The name itaconic acid was devised as an anagram of aconitic acid, another derivative of citric acid. Itaconic acid, also known as itaconate, belongs to the class of organic compounds known as branched fatty acids. These are fatty acids containing a branched chain. Itaconic acid is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. Since the 1960s, it is produced industrially by the fermentation of carbohydrates such as glucose or molasses using fungi such as Aspergillus itaconicus or Aspergillus terreus. For A. terreus the itaconate pathway is mostly elucidated. The generally accepted route for itaconate is via glycolysis, tricarboxylic acid cycle, and a decarboxylation of cis-aconitate to itaconate via cis-aconitate-decarboxylase. The smut fungus Ustilago maydis uses an alternative route. Cis-aconitate is converted to the thermodynamically favoured trans-aconitate via aconitate-Δ-isomerase (Adi1). trans-Aconitate is further decarboxylated to itaconate by trans-aconitate-decarboxylase (Tad1). Itaconic acid is also produced in cells of macrophage lineage. It was shown that itaconate is a covalent inhibitor of the enzyme isocitrate lyase in vitro. As such, itaconate may possess antibacterial activities against bacteria expressing isocitrate lyase (such as Salmonella enterica and Mycobacterium tuberculosis). It is also sythesized in the laboratory, where dry distillation of citric acid affords itaconic anhydride, which undergoes hydrolysis to itaconic acid.

Allopurinol is only found in individuals that have used or taken this drug. It is a xanthine oxidase inhibitor that decreases uric acid production. It also acts as an antimetabolite on some simpler organisms. [PubChem]Allopurinol and its active metabolite, oxypurinol, inhibits the enzyme xanthine oxidase, blocking the conversion of the oxypurines hypoxanthine and xanthine to uric acid. Elevated concentrations of oxypurine and oxypurine inhibition of xanthine oxidase through negative feedback results in a decrease in the concentrations of uric acid in the serum and urine. Allopurinol also facilitates the incorporation of hypoxanthine and xanthine into DNA and RNA, leading to a feedback inhibition of de novo purin synthesis and a decrease in serum uric acid concentrations as a result of an increase in nucleotide concentration.

Mesaconic acid, also known as 2-methylfumarate or citronic acid, belongs to the class of organic compounds known as methyl-branched fatty acids. These are fatty acids with an acyl chain that has a methyl branch. Usually, they are saturated and contain only one or more methyl group. However, branches other than methyl may be present. Mesaconic acid is a dicarboxylic butenoic acid, with a methyl group in position 2 and the double bound between carbons 2 and 3. Mesaconic acid was first studied for its physical properties in 1874 by Jacobus van ‘t Hoff (https://web.archive.org/web/20051117102410/http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Van%27t-Hoff-1874.html). It is now known to be involved in the biosynthesis of vitamin B12 and it is also a competitor inhibitor of the reduction of fumarate.

Aconitic acid is a tricarboxylic acid that is prop-1-ene substituted by carboxy groups at positions 1, 2 and 3. It is a conjugate acid of an aconitate(3-). Aconitic acid is a natural product found in Glycine max, Zea mays, and other organisms with data available. A tricarboxylic acid with the formula (COOH)-CH2-C(COOH)=CH-COOH.

Pyroglutamic acid (5-oxoproline) is a cyclized derivative of L-glutamic acid. It is an uncommon amino acid derivative in which the free amino group of glutamic acid cyclizes to form a lactam. It is formed nonenzymatically from glutamate, glutamine, and gamma-glutamylated peptides, but it can also be produced by the action of gamma-glutamylcyclotransferase on an L-amino acid. Elevated blood levels may be associated with problems of glutamine or glutathione metabolism. This compound is found in substantial amounts in brain tissue and other tissues in bound form, especially skin. It is also present in plant tissues. It is sold, over the counter, as a "smart drug" for improving blood circulation in the brain. Pyroglutamate in the urine is a biomarker for the consumption of cheese. When present in sufficiently high levels, pyroglutamic 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 pyroglutamic acid are associated with at least five inborn errors of metabolism including 5-oxoprolinuria, 5-oxoprolinase deficiency, glutathione synthetase deficiency, hawkinsinuria, and propionic acidemia. Pyroglutamic 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, liver, and kidney 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. It has been shown that pyroglutamic acid releases GABA from the cerebral cortex and displays anti-anxiety effects in a simple approach-avoidance conflict situation in the rat. In clinical pharmacology experiments, pyroglutamic acid significantly shortens the plasma half-life of ethanol during acute intoxication.

trans-Aconitic acid, also known as trans-aconitate or (e)-aconitic acid, belongs to the class of organic compounds known as tricarboxylic acids and derivatives. These are carboxylic acids containing exactly three carboxyl groups. trans-Aconitic acid exists in all living species, ranging from bacteria to humans. trans-Aconitic acid is a dry, musty, and nut tasting compound. Outside of the human body, trans-aconitic acid has been detected, but not quantified in several different foods, such as garden tomato fruits, root vegetables, soy beans, and rices. trans-Aconitic acid is normally present in human urine, and it has been suggested that is present in larger amounts with Reye's syndrome and organic aciduria. trans-Aconitic acid in the urine is a biomarker for the consumption of soy products. trans-Aconitic acid is a substrate of enzyme trans-Aconitic acid 2-methyltransferase (EC2.1.1.144).

N-Acetyl-L-glutamic acid or N-Acetylglutamate, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetyl-L-glutamate can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetyl-L-glutamate is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-glutamic acid. N-Acetyl-L-glutamic acid is found in all organisms ranging from bacteria to plants to animals. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85% of all human proteins and 68% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylglutamate can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free glutamic acid can also occur. In particular, N-Acetyl-L-glutamic acid can be biosynthesized from glutamate and acetylornithine by ornithine acetyltransferase, and from glutamic acid and acetyl-CoA by the enzyme known as N-acetylglutamate synthase. N-Acetyl-L-glutamic acid is the first intermediate involved in the biosynthesis of arginine in prokaryotes and simple eukaryotes and a regulator of the urea cycle in vertebrates. In vertebrates, N-acetylglutamic acid is the allosteric activator molecule to mitochondrial carbamyl phosphate synthetase I (CPSI) which is the first enzyme in the urea cycle. It triggers the production of the first urea cycle intermediate, a compound known as carbamyl phosphate. Notably the CPSI enzyme is inactive when N-acetylglutamic acid is not present. A deficiency in N-acetyl glutamate synthase or a genetic mutation in the gene coding for the enzyme will lead to urea cycle failure in which ammonia is not converted to urea, but rather accumulated in the blood leading to the condition called Type I hyperammonemia. Excessive amounts N-acetyl amino acids can be detected in the urine with individuals with aminoacylase I deficiency, a genetic disorder (PMID: 16465618). These include N-acetylalanine (as well as N-acetylserine, N-acetylglutamine, N-acetylglutamate, N-acetylglycine, N-acetylmethionine and smaller amounts of N-acetylthreonine, N-acetylleucine, N-acetylvaline and N-acetylisoleucine. Aminoacylase I is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. In humans, Aminoacylase I is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that consists of 15 exons (OMIM 609924). Individuals with aminoacylase I deficiency will experience convulsions, hearing loss and difficulty feeding (PMID: 16465618). ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. Many N-acetylamino acids are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557).

Glutaconic acid is related to the fully saturated glutaric acid and belongs to the class of compounds known as dicarboxylic acids and derivatives. These are organic compounds containing exactly two carboxylic acid groups. Glutaconic acid is soluble (in water) and a weakly acidic compound (based on its pKa). Glutaconic acid has been detected in the urine of individuals with inborn errors of metabolism. When present in sufficiently high levels, glutaconic acid can act as an acidogen, a neurotoxin, and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A neurotoxin is a compound that is toxic to neural tissues and cells. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of glutaconic acid are associated with glutaric aciduria type I (glutaric acidemia type I, glutaryl-CoA dehydrogenase deficiency, GA1, or GAT1). 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. GA1 is associated with a risk for intracranial and retinal hemorrhage, and non-specific white matter changes. 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. Seizures and coma (encephalopathy) are rare. GA1 also causes secondary carnitine deficiency because 3-hydroxyglutaric acid, like other organic acids, is detoxified by carnitine. Glutaconic acid's neurotoxicity is thought to be partially caused by an excitotoxic mechanism in which glutaconic acid overactivates N-methyl-D-aspartate (NMDA) receptors. Accumulating trans-glutaconic (TG) acids have been proposed to be involved in the development of the striatal degeneration seen in children with glutaric acidemia type I via an excitotoxic mechanism.

cis-Aconitic acid is an intermediate in the tricarboxylic acid cycle produced by the dehydration of citric acid. The enzyme aconitase (aconitate hydratase; EC 4.2.1.3) catalyses the stereo-specific isomerization of citrate to isocitrate via cis-aconitate in the tricarboxylic acid cycle.

2-Acetamido-4-O-(1-carboxyethyl)-2-deoxyglucose is a natural product found in Proteus penneri with data available.

But-2-enoic acid, also known as (2E)-2-butenoate or alpha-crotonic acid, belongs to the class of organic compounds known as straight chain organic acids. These are organic acids with a straight aliphatic chain. But-2-enoic acid is a very hydrophobic molecule, practically insoluble in water, and relatively neutral.

The D-enantiomer of isoleucine." []

Uridine, also known as beta-uridine or 1-beta-D-ribofuranosylpyrimidine-2,4(1H,3H)-dione, is a member of the class of compounds known as pyrimidine nucleosides. Pyrimidine nucleosides are compounds comprising a pyrimidine base attached to a ribosyl or deoxyribosyl moiety. More specifically, uridine is a nucleoside consisting of uracil and D-ribose and a component of RNA. Uridine is soluble (in water) and a very weakly acidic compound (based on its pKa). Uridine can be synthesized from uracil. It is one of the five standard nucleosides which make up nucleic acids, the others being adenosine, thymidine, cytidine and guanosine. The five nucleosides are commonly abbreviated to their one-letter codes U, A, T, C and G respectively. Uridine is also a parent compound for other transformation products, including but not limited to, nikkomycin Z, 3'-(enolpyruvyl)uridine 5'-monophosphate, and 5-aminomethyl-2-thiouridine. Uridine can be found in most biofluids, including urine, breast milk, cerebrospinal fluid (CSF), and blood. Within the cell, uridine is primarily located in the mitochondria, in the nucleus and the lysosome. It can also be found in the extracellular space. As an essential nucleoside, uridine exists in all living species, ranging from bacteria to humans. In humans, uridine is involved in several metabolic disorders, some of which include dhydropyrimidinase deficiency, MNGIE (mitochondrial neurogastrointestinal encephalopathy), and beta-ureidopropionase deficiency. Moreover, uridine is found to be associated with Lesch-Nyhan syndrome, which is an inborn error of metabolism. Uridine is a nucleoside consisting of uracil and D-ribose and a component of RNA. Uridine plays a role in the glycolysis pathway of galactose. In humans there is no catabolic process to metabolize galactose. Therefore, galactose is converted to glucose and metabolized via the normal glucose metabolism pathways. More specifically, consumed galactose is converted into galactose 1-phosphate (Gal-1-P). This molecule is a substrate for the enzyme galactose-1-phosphate uridyl transferase which transfers a UDP molecule to the galactose molecule. The end result is UDP-galactose and glucose-1-phosphate. This process is continued to allow the proper glycolysis of galactose. Uridine is found in many foods (anything containing RNA) but is destroyed in the liver and gastrointestinal tract, and so no food, when consumed, has ever been reliably shown to elevate blood uridine levels. On the other hand, consumption of RNA-rich foods may lead to high levels of purines (adenine and guanosine) in blood. High levels of purines are known to increase uric acid production and may aggravate or lead to conditions such as gout.

A homodetic cyclic peptide resulting from the formal condensation of both the amino and acid groups of L-histidine with the acid and amino groups of L-proline. It is a metabolite of thyrotropin-releasing hormone (TRH)." []

Cyclo(L-His-L-Pro) is a homodetic cyclic peptide resulting from the formal condensation of both the amino and acid groups of L-histidine with the acid and amino groups of L-proline. It is a metabolite of thyrotropin-releasing hormone (TRH). It has a role as a human blood serum metabolite, a dopamine uptake inhibitor and an anti-inflammatory agent. It is a homodetic cyclic peptide, a dipeptide, a pyrrolopyrazine and a member of imidazoles. It is functionally related to a L-histidine and a L-proline.

Urocanic acid (CAS: 104-98-3) is a breakdown (deamination) product of histidine. In the liver, urocanic acid is an intermediate in the conversion of histidine to glutamic acid, whereas, in the epidermis, it accumulates and may be both a UV protectant and an immunoregulator. Urocanic acid (UA) exists as a trans isomer (t-UA, approximately 30 mg/cm2) in the uppermost layer of the skin (stratum corneum). t-UA is formed as the cells of the second layer of the skin become metabolically inactive. During this process, proteins and membranes degrade, histidine is released, and histidase (histidine ammonia lyase) catalyzes the deamination of histidine to form t-UA. t-UA accumulates in the epidermis until removal by either the monthly skin renewal cycle or sweat. Upon absorption of UV light, the naturally occurring t-UA isomerizes to its cis form, c-UA. Because DNA lesions (e.g., pyrimidine dimers) in the lower epidermis can result from UV-B absorption, initial research proposed that t-UA acted as a natural sunscreen absorbing UV-B in the stratum corneum before the damaging rays could penetrate into lower epidermal zones. Researchers have found that c-UA also suppresses contact hypersensitivity and delayed hypersensitivity, reduces the Langerhans cell count in the epidermis, prolongs skin-graft survival time, and affects natural killer cell activity. (E)-Urocanic acid is found in mushrooms. It has been isolated from Coprinus atramentarius (common ink cap) and Phallus impudicus (common stinkhorn).

This compound belongs to the family of N-acyl-alpha-hexosamines. These are carbohydrate derivatives containing a hexose moeity in which the oxygen atom is replaced by an n-acyl group.

D-Maltose, also known as maltose, maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an alpha (1→4) bond. Its name comes from malt, combined with the suffix '-ose' which is used in names of sugars. Maltose is a key structural motif of starch. When alpha-amylase breaks down starch, it removes two glucose units at a time, producing maltose. Maltose can be further broken down to glucose by the maltase enzyme, which catalyses the hydrolysis of the glycosidic bond. D-maltose exists in all living species, ranging from bacteria to plants to humans. Within humans, D-maltose participates in a number of enzymatic reactions. In particular, maltose can be converted into glucose; which is mediated by the enzyme maltase-glucoamylase. In addition, maltose can be converted into glucose through its interaction with the enzyme glycogen debranching enzyme. Maltose is found in high concentrations in oriental wheats and in a lower concentrations in sweet potato, grape wines, yellow pond-lilies, sunflowers, and spinach. Maltose is a component of malt, a substance which is obtained in the process of allowing grain to soften in water and germinate. It is also present in highly variable quantities in partially hydrolysed starch products like maltodextrin, corn syrup and acid-thinned starch. Maltose has a sweet taste but is only about 30–60% as sweet as sucrose, depending on the concentration.

A glycosylfructose that is D-fructofuranose attached to a alpha-D-glucopyranosyl unit at position 6 via a glycosidic linkage. It is found in honey and sugarcane." []

Diacetyl, also known as 2,3-butadione or dimethylglyoxal, belongs to the class of organic compounds known as alpha-diketones. These are organic compounds containing two ketone groups on two adjacent carbon atoms. Thus, diacetyl is considered to be an oxygenated hydrocarbon lipid molecule. Diacetyl is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. Diacetyl exists in all living species, ranging from bacteria to humans. Diacetyl is a strong, sweet, and butter tasting compound. Outside of the human body, diacetyl is found, on average, in the highest concentration in kohlrabis. diacetyl has also been detected, but not quantified in several different foods, such as nances, tartary buckwheats, tamarinds, pineapples, and celeriacs. This could make diacetyl a potential biomarker for the consumption of these foods. Diacetyl is a potentially toxic compound. Diacetyl has been found to be associated with several diseases such as crohn's disease, ulcerative colitis, and nonalcoholic fatty liver disease; also diacetyl has been linked to the inborn metabolic disorders including celiac disease.

Threonic acid, also known as threonate, belongs to the class of organic compounds known as sugar acids and derivatives. Sugar acids and derivatives are compounds containing a saccharide unit which bears a carboxylic acid group. Threonic acid is a sugar acid derived from threose. The L-isomer is a metabolite of ascorbic acid (vitamin C). One study suggested that because L-threonate inhibits DKK1 expression in vitro, it may have potential in the treatment of androgenic alopecia (PMID:21034532). Threonic acid is probably derived from glycated proteins or from degradation of ascorbic acid. It is a normal component in aqueous humour and blood (PMID:10420182). Threonic acid is a substrate of L-threonate 3-dehydrogenase (EC 1.1.1.129) in the ascorbate and aldarate metabolism pathway (KEGG). It has been found to be a microbial metabolite (PMID:20615997).

A butynediol that is but-2-yne substituted by hydroxy groups at positions 1 and 4." []

Cyclopropanecarboxylic acid is a monocarboxylic acid and a member of cyclopropanes. It is a conjugate acid of a cyclopropanecarboxylate.

Pyrroline hydroxycarboxylic acid is a metabolite identified in the urine of patients with type II hyperprolinemia. (OMIM 239510). The urinary excretion of Pyrroline hydroxycarboxylic acid increased in hyperprolinemic patients but not in healthy controls during oral loading of hydroxyproline and hydroxyproline-ornithine. (PMID: 533224). Hyperprolinemia type II (HP II) is a rare inherited metabolic disease due to the deficiency of pyroline-5-carboxylate dehydrogenase. It is generally believed to be a benign condition although some patients have neurological problems such as refractory convulsions. (PMID: 15214748). The oxidation of pyrroline-carboxylate generates glutamate and pyrroline-hydroxycarboxylate, a reaction catalyzed by hydroxyproline oxidase (PMID: 500817).

Phosphorylcholine is a natural product found in Homo sapiens with data available. Calcium and magnesium salts used therapeutically in hepatobiliary dysfunction.