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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. Pantothenic acid is classified as a member of the secondary alcohols. Secondary alcohols are compounds containing a secondary alcohol functional group, with the general structure HOC(R)(R') (R,R'=alkyl, aryl). Pantothenic acid is considered to be soluble (in water) and acidic.

Creatinine, or creatine anhydride, is a breakdown product of creatine phosphate in muscle. The loss of a water molecule from creatine results in the formation of creatinine. Creatinine is transferred to the kidneys by blood plasma, whereupon it is eliminated from the body by glomerular filtration and partial tubular excretion. Creatinine is usually produced at a fairly constant rate by the body. Measuring serum creatinine is a simple test and it is the most commonly used indicator of renal function. A rise in blood creatinine levels is observed only with marked damage to functioning nephrons. Therefore, this test is not suitable for detecting early kidney disease. The typical reference range for women is considered about 45-90 µmol/L; for men 60-110 µmol/L. Creatine and creatinine are metabolized in the kidneys, muscle, liver, and pancreas.

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).

Chlorogenic acid is an ester of caffeic acid and quinic acid. Chlorogenic acid is the major polyphenolic compound in coffee, isolated from the leaves and fruits of dicotyledonous plants. This compound, long known as an antioxidant, also slows the release of glucose into the bloodstream after a meal. Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid. The chlorogenic acid content of a 200 ml (7-oz) cup of coffee has been reported to range from 70-350 mg, which would provide about 35-175 mg of caffeic acid. The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 diabetes mellitus, Parkinson's disease and liver disease (cirrhosis and hepatocellular carcinoma). Most prospective cohort studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure and plasma homocysteine. At present, there is little evidence that coffee consumption increases the risk of cancer. (PMID:16507475, 17368041).

Chenodeoxycholic acid is a bile acid. Bile acids are steroid acids found predominantly in the bile of mammals. The distinction between different bile acids is minute, depending only on the presence or absence of hydroxyl groups on positions 3, 7, and 12. Bile acids are physiological detergents that facilitate excretion, absorption, and transport of fats and sterols in the intestine and liver. Bile acids are also steroidal amphipathic molecules derived from the catabolism of cholesterol. They modulate bile flow and lipid secretion, are essential for the absorption of dietary fats and vitamins, and have been implicated in the regulation of all the key enzymes involved in cholesterol homeostasis. Bile acids recirculate through the liver, bile ducts, small intestine and portal vein to form an enterohepatic circuit. They exist as anions at physiological pH and, consequently, require a carrier for transport across the membranes of the enterohepatic tissues. The unique detergent properties of bile acids are essential for the digestion and intestinal absorption of hydrophobic nutrients. Bile acids have potent toxic properties (e.g. membrane disruption) and there are a plethora of mechanisms to limit their accumulation in blood and tissues (PMID: 11316487, 16037564, 12576301, 11907135). Usually conjugated with either glycine or taurine. It acts as a detergent to solubilize fats for intestinal absorption and is reabsorbed by the small intestine. It is used as cholagogue, a choleretic laxative, and to prevent or dissolve gallstones.

Hippuric acid is an acyl glycine formed from the conjugation of benzoic acid with glycine. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine < -- > CoA + N-acylglycine. Hippuric acid is a normal component of urine and is typically increased with increased consumption of phenolic compounds (tea, wine, fruit juices). These phenols are converted into benzoic acid which is then converted into hippuric acid and excreted in the urine. Hippuric acid is the most frequently used biomarker in the biological monitoring of occupational exposure to toluene. This product of solvent biotransformation may be also found in the urine of individuals who have not been exposed to the solvent. A smaller fraction of the absorbed toluene is oxidized into aromatic compounds including ortho-cresol, which is not found in the urine of nonexposed individuals in a significant amount. The concentration of hippuric acid in the urine of individuals exposed to a low toluene concentration does not differ from that of individuals not exposed to the solvent. This has led to the conclusion that hippuric acid should not be utilized in the biological monitoring of occupational exposure to low levels of toluene in the air. Protein-bound organic acids such as hippuric acid are markedly accumulated in uremic plasma and produce defective protein binding of drugs (PMID: 9120876 , 8734460). Hippuric acid has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). Hippuric acid is also found to be associated with phenylketonuria, propionic acidemia, and tyrosinemia I, which are inborn errors of metabolism. Hippuric acid is an endogenous phenolic acid metabolite detected after the consumption of whole grain.

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.

Laurocapram is a member of caprolactams. Laurocapram is a percutaneous enhancer. Upon application to the skin, laurocapram interacts with lipids in the stratum corneum and may enhance the ability of the skin to absorb a hydrophilic chemical.

Erythrosphingosine; erythro-C18-Sphingosine; trans-4-Sphingenine is a natural product found in Homo sapiens with data available.

Murocholic acid is a bile acid. Bile acids are steroid acids found predominantly in the bile of mammals. The distinction between different bile acids is minute, depending only on the presence or absence of hydroxyl groups on positions 3, 7, and 12. Bile acids are physiological detergents that facilitate excretion, absorption, and transport of fats and sterols in the intestine and liver. Bile acids are also steroidal amphipathic molecules derived from the catabolism of cholesterol. They modulate bile flow and lipid secretion, are essential for the absorption of dietary fats and vitamins, and have been implicated in the regulation of all the key enzymes involved in cholesterol homeostasis. Bile acids recirculate through the liver, bile ducts, small intestine and portal vein to form an enterohepatic circuit. They exist as anions at physiological pH and, consequently, require a carrier for transport across the membranes of the enterohepatic tissues. The unique detergent properties of bile acids are essential for the digestion and intestinal absorption of hydrophobic nutrients. Bile acids have potent toxic properties (e.g. membrane disruption) and there are a plethora of mechanisms to limit their accumulation in blood and tissues (PMID: 11316487, 16037564, 12576301, 11907135).

Indoxyl sulfate is a dietary protein metabolite and also a metabolite of the common amino acid tryptophan. It has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). It is a circulating uremic toxin stimulating glomerular sclerosis and interstitial fibrosis. Indoxyl sulfate is one of the well-known substances of a group of protein-bound uremic retention solutes. Indoxyl sulfate increases the rate of progression of renal failure. In plasma, indoxyl sulfate is a protein-bound uremic solute that induces endothelial dysfunction by inhibiting endothelial proliferation and migration in vitro. Some studies suggest that indoxyl sulfate is also involved in oxidative stress. In hemodialyzed patients, serum levels of indoxyl sulfate are associated with levels of pentosidine, a marker of carbonyl and oxidative stress. In vitro, indoxyl sulfate increases reactive oxygen species (ROS) production in tubular cells and increases NAD(P)H oxidase activity in endothelial cells. Indoxyl sulfate impairs osteoblast function and induces abnormalities of bone turnover. Indoxyl sulfate strongly decreases the levels of glutathione, one of the most active antioxidant systems of the cell (PMID: 10681668 , 14681860 , 17471003 , 17403109). Indoxyl sulfate is a microbial metabolite found in Escherichia (PMID: 19946322).

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.

Catechin, also known as cyanidanol or catechuic acid, belongs to the class of organic compounds known as catechins. Catechins are compounds containing a catechin moiety, which is a 3,4-dihydro-2-chromene-3,5.7-tiol. Catechin also belongs to the group of compounds known as flavan-3-ols (or simply flavanols), part of the chemical family of flavonoids. Catechin is one of the 4 catechin known diastereoisomers. Two of the isomers are in trans configuration and are called catechin and the other two are in cis configuration and are called epicatechin. The most common catechin isomer is the (+)-catechin. The other stereoisomer is (-)-catechin or ent-catechin. The most common epicatechin isomer is (-)-epicatechin. Catechin is a very hydrophobic molecule, practically insoluble (in water), and relatively neutral. Catechin is a bitter tasting compound and is associated with the bitterness in tea. Catechin is a plant secondary metabolite. Secondary metabolites are metabolically or physiologically non-essential metabolites that may serve a role as defense or signalling molecules. In some cases they are simply molecules that arise from the incomplete metabolism of other secondary metabolites. Catechin is an antioxidant flavonoid, occurring especially in woody plants as both Catechin and (-)-Catechin (cis) forms. Outside of the human body, Catechin is found, on average, in the highest concentration in foods, such as blackcurrants (Ribes nigrum), evergreen blackberries (Rubus laciniatus), and blackberries (Rubus) and in a lower concentration in dills (Anethum graveolens), hot chocolates, and medlars (Mespilus germanica). Catechin has also been detected, but not quantified in, several different foods, such as rice (Oryza sativa), apple ciders, peanuts (Arachis hypogaea), fruit juices, and red teas. This could make catechin a potential biomarker for the consumption of these foods. Based on a literature review a significant number of articles have been published on Catechin.

Uric acid is a heterocyclic purine derivative that is the final oxidation product of purine metabolism. It is a weak acid distributed throughout the extracellular fluid as sodium urate. Uric acid is produced by the enzyme xanthine oxidase, which oxidizes oxypurines such as xanthine into uric acid. In most mammals, except humans and higher primates, the enzyme uricase further oxidizes uric acid to allantoin. Interestingly, during the Miocene epoch (~15-20 million years ago), two distinct mutations in the primate genome occurred that led to a nonfunctioning uricase gene. Consequently, humans, apes, and certain New World monkeys have much higher uric acid levels (>120 μM) compared with other mammals (<<120 uM). The loss of uricase in higher primates parallels the similar loss of the ability to synthesize ascorbic acid vitamin C. This may be because in higher primates uric acid partially replaces ascorbic acid. Like ascorbic acid, uric acid is an antioxidant. In fact, in primates, uric acid is the major antioxidant in serum and is thought to be a major factor in lengthening life-span and decreasing age-specific cancer rates in humans and other primates (PMID: 6947260). Uric acid is also the end product of nitrogen metabolism in birds and reptiles. In these animal species, it is excreted in feces as a dry mass. In humans and other mammals, the amount of urate in the blood depends on the dietary intake of purines, the level of endogenous urate biosynthesis, and the rate of urate excretion. Several kidney urate transporters are involved in the regulation of plasma urate levels. These include the urate transporter 1 (URAT1), which controls the reabsorption of urate as well as a number of organic ion transporters (OAT), such as OAT1 and OAT3, and the ATP-dependent urate export transporter MRP4. URAT1 is believed to be most critical in the regulation of plasma urate levels. (PMID: 17890445) High levels of plasma uric acid lead to a condition called hyperuricemia while low levels are associated with a condition called hypouricemia. Hyperuricemia has been defined as a uric acid concentration greater than 380 μM, while hypouricemia is generally defined as a urate concentration of less than 120 μM. Hyperuricemia can arise from a number of factors, including both acute and chronic causes. Acute causes of hyperuricemia include the intake of large amounts of alcohol, tumor lysis syndrome and a diet that is rich in purines or proteins. Chronic hyperuricemia can arise from a reduction in the kidney’s glomerular filtration rate, a decrease in the excretion of urate or an increase in overall tubular absorption in the kidneys. Hyperuricemia has been linked to a number of diseases and conditions, including gout, hypertension, cardiovascular disease, myocardial infarction, stroke, and renal disease. Uric acid has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). Many of the causes of hyperuricemia are correctable either with lifestyle changes or drugs. Lifestyle changes include reducing weight and reducing the consumption of protein, purines, and alcohol. There are two kinds of drugs that can be used to treat chronic hyperuricemia. Xanthine oxidase inhibitors, such as allopurinol, inhibit the production of urate by blocking urate synthesis. Alternately, uricosuric drugs, such as probenecid, sulfinpyrazone, and benzpromarone, are used to reduce the serum urate concentration through the inhibition of the URAT1 transporter. (PMID: 17890445). Uric acid (especially crystalline uric acid) is also thought to be an essential initiator and amplifier of allergic inflammation for asthma and peanut allergies (PMID: 21474346). 

Uracil, also known as U, belongs to the class of organic compounds known as pyrimidones. Pyrimidones are compounds that contain a pyrimidine ring, which bears a ketone. Pyrimidine is a 6-membered ring consisting of four carbon atoms and two nitrogen centers at the 1- and 3- ring positions. Uracil is a common naturally occurring pyrimidine found in RNA. It base pairs with adenine and is replaced by thymine in DNA. Uracil is one of the four nucleobases in RNA that are represented by the letters A, G, C and U. Methylation of uracil produces thymine. The name "uracil" was coined in 1885 by the German chemist Robert Behrend, who was attempting to synthesize derivatives of uric acid. Originally discovered in 1900, uracil was isolated by hydrolysis of yeast nuclein that was found in bovine thymus and spleen, herring sperm, and wheat germ. Uracil exists in all living species, ranging from bacteria to plants to humans. Uracil's use in the body is to help carry out the synthesis of many enzymes necessary for cell function through bonding with riboses and phosphates. Uracil serves as an allosteric regulator and a coenzyme for many important biochemical reactions. Uracil (via the nucleoside uridine) can be phosphorylated by various kinases to produce UMP, UDP and UTP. UDP and UTP regulate carbamoyl phosphate synthetase II (CPSase II) activity in animals. Uracil is also involved in the biosynthesis of polysaccharides and in the transport of sugars containing aldehydes. Within humans, uracil participates in a number of enzymatic reactions. In particular, uracil and ribose 1-phosphate can be biosynthesized from uridine; which is mediated by the enzyme uridine phosphorylase 2. In addition, uracil can be converted into dihydrouracil through the action of the enzyme dihydropyrimidine dehydrogenase [NADP(+)]. Uracil is rarely found in DNA, and this may have been an evolutionary change to increase genetic stability. This is because cytosine can deaminate spontaneously to produce uracil through hydrolytic deamination. Therefore, if there were an organism that used uracil in its DNA, the deamination of cytosine (which undergoes base pairing with guanine) would lead to formation of uracil (which would base pair with adenine) during DNA synthesis. Uracil can be used for drug delivery and as a pharmaceutical. When elemental fluorine reacts with uracil, it produces 5-fluorouracil. 5-Fluorouracil is an anticancer drug (antimetabolite) that mimics uracil during the nucleic acid (i.e. RNA) synthesis and transcription process. Because 5-fluorouracil is similar in shape to, but does not undergo the same chemistry as, uracil, the drug inhibits RNA replication enzymes, thereby blocking RNA synthesis and stopping the growth of cancerous cells.

p-Cresol sulfate is a microbial metabolite that is found in urine and likely derives from secondary metabolism of p-cresol. It appears to be elevated in the urine of individuals with progressive multiple sclerosis (PMID:10775436). p-Cresol sulfate is the major component of urinary MBPLM (myelin basic protein-like material). p-Cresol sulfate is a small protein-bound molecule that is poorly cleared with dialysis. It has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID:22626821). Uremic toxins include other low-molecular-weight compounds such as indoxyl sulfate, 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, and asymmetric dimethylarginine (PMID:18941347). It has also been linked to cardiovascular disease and oxidative injury. Higher levels are associated with overgrowth of intestinal bacteria from Clostridia species, including C. difficile. p-Cresol is generated by the partial breakdown of tyrosine and phenylalanine by a wide range of intestinal obligate or facultative anaerobes, including the genera Bacteroides, Lactobacillus, Enterobacter, Bifidobacterium, and especially Clostridium (PMID:2394806).

Phenylacetylglutamine is a product formed from the conjugation of phenylacetate and glutamine. Technically, it is the amino acid acetylation product of phenylacetate (or phenylbutyrate after beta-oxidation). Phenylacetylglutamine is a normal constituent of human urine, but other mammals such as the dog, cat, rat, monkey, sheep, and horse do not excrete this compound. Phenylacetyl-CoA and L-glutamine react to form phenylacetylglutamine and coenzyme A. The enzyme (glutamine N-acetyl transferase) that catalyzes this reaction has been purified from human liver mitochondria and shown to be a polypeptide species distinct from glycine-N-acyltransferase. Phenylacetylglutamine is a major nitrogenous metabolite that accumulates in uremia (PMID: 2791363, 8972626). It has been shown that over 50% of urine phenylacetylglutamine may be derived from kidney conjugation of free plasma phenylacetic acid and/or from the kidney's preferential filtration of conjugated phenylacetic acid (PMID: 6420430). Phenylacetylglutamine is a microbial metabolite found in Christensenellaceae, Lachnospiraceae and Ruminococcaceae (PMID: 26241311).

A member of the class of morpholines that is 2,6-dimethylmorpholine in which the hydrogen attached to the nitrogen is replaced by a cyclododecyl group. It is a fungicide used for the control of powdery mildew, particularly in rose culture." []

Sucrose is a nonreducing disaccharide composed of glucose and fructose linked via their anomeric carbons. It is obtained commercially from sugarcane (Saccharum officinarum), sugar beet (Beta vulgaris), and other plants and used extensively as a food and a sweetener. Sucrose is derived by crushing and extracting sugarcane with water or by extracting sugar beet with water, evaporating, and purifying with lime, carbon, and various liquids. Sucrose is also obtainable from sorghum. Sucrose occurs in low percentages in honey and maple syrup. Sucrose is used as a sweetener in foods and soft drinks, in the manufacture of syrups, in invert sugar, confectionery, preserves and jams, demulcent, pharmaceutical products, and caramel. Sucrose is also a chemical intermediate for detergents, emulsifying agents, and other sucrose derivatives. Sucrose is widespread in the seeds, leaves, fruits, flowers, and roots of plants, where it functions as an energy store for metabolism and as a carbon source for biosynthesis. The annual world production of sucrose is in excess of 90 million tons mainly from the juice of sugar cane (20%) and sugar beet (17%). In addition to its use as a sweetener, sucrose is used in food products as a preservative, antioxidant, moisture control agent, stabilizer, and thickening agent. BioTransformer predicts that sucrose is a product of 6-O-sinapoyl sucrose metabolism via a hydrolysis-of-carboxylic-acid-ester-pattern1 reaction occurring in human gut microbiota and catalyzed by the liver carboxylesterase 1 (P23141) enzyme (PMID: 30612223).

Norvaline is a non-proteinogenic branched-chain amino acid with the chemical formula C5H11NO2, isomeric with valine. It has previously been reported to be a natural component of an antifungal peptide of Bacillus subtilis. Norvaline and other modified branched chain amino acids have received attention in recent studies, as they appear to be incorporated in some recombinant proteins found in E. coli. This amino acid is often made synthetically.

O-BENZYL-l-SERINE is a L-alpha-amino acid.

Deoxyinosine is a nucleoside that is formed when hypoxanthine is attached to a deoxyribose ring (also known as a ribofuranose) via a beta-N9-glycosidic bond. Deoxyinosine is found in DNA while inosine is found in RNA. Inosine is a nucleic acid important for RNA editing. Adenosine deaminase (ADA) catalyzes the conversion of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. ADA-deficient individuals suffer from severe combined immunodeficiency (SCID) and are unable to produce significant numbers of mature T or B lymphocytes. This occurs as a consequence of the accumulation of ADA substrates or their metabolites. Inosine is also an intermediate in a chain of purine nucleotides reactions required for muscle movements. Moreover, deoxyinosine is found to be associated with purine nucleoside phosphorylase (PNP) deficiency, which is an inborn error of metabolism.

Ketoleucine is an abnormal metabolite that arises from the incomplete breakdown of branched-chain amino acids. Ketoleucine is both a neurotoxin and a metabotoxin. 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 ketoleucine are associated with maple syrup urine disease (MSUD). MSUD is a metabolic disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKDC), leading to a buildup of the branched-chain amino acids (leucine, isoleucine, and valine) and their toxic by-products (ketoacids) in the blood and urine. The symptoms of MSUD often show in infancy and lead to severe brain damage if untreated. MSUD may also present later depending on the severity of the disease. If left untreated in older individuals, during times of metabolic crisis, symptoms of the condition include uncharacteristically inappropriate, extreme, or erratic behaviour and moods, hallucinations, anorexia, weight loss, anemia, diarrhea, vomiting, dehydration, lethargy, oscillating hypertonia and hypotonia, ataxia, seizures, hypoglycemia, ketoacidosis, opisthotonus, pancreatitis, rapid neurological decline, and coma. In maple syrup urine disease, the brain concentration of branched-chain ketoacids can increase 10- to 20-fold. This leads to a depletion of glutamate and a consequent reduction in the concentration of brain glutamine, aspartate, alanine, and other amino acids. The result is a compromise of energy metabolism because of a failure of the malate-aspartate shuttle and a diminished rate of protein synthesis (PMID: 15930465).

3-Hydroxypropionic acid is a carboxylic acid. It is an intermediate in the breakdown of branched-chain amino acids and propionic acid from the gut. Typically it originates from propionyl-CoA and a defect in the enzyme propionyl carboxylase. This leads to a buildup in propionyl-CoA in the mitochondria.  Such a buildup can lead to a disruption of the esterified CoA:free CoA ratio and ultimately to mitochondrial toxicity. Detoxification of these metabolic end products occurs via the transfer of the propionyl moiety to carnitine-forming propionyl-carnitine, which is then transferred across the inner mitochondrial membrane. 3-Hydroxypropionic acid is then released as the free acid. As an industrial chemical, it is used in the production of various chemicals such as acrylates in industry. When present in sufficiently high levels, 3-hydroxypropionic 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 hydroxypropionic acid are associated with many inborn errors of metabolism including biotinidase deficiency, malonic aciduria, methylmalonate semialdehyde dehydrogenase deficiency, methylmalonic aciduria, methylmalonic aciduria due to cobalamin-related disorders, and propionic acidemia. Hydroxypropionic 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. Infants with acidosis have symptoms that 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 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. 3-Hydroxypropionic acid is also a microbial metabolite found in Escherichia, Klebsiella and Saccharomyces (PMID: 26360870).

D-proline is an isomer of the naturally occurring amino acid, L-Proline. D-amino acids have been found in relatively high abundance in human plasma and saliva (PMID: 16480744). These amino acids may be of bacterial origin, but there is also evidence that they are endogenously produced through amino acid racemase activity (PMID: 1426150).

Sulforaphane (SFN) is the most characterized isothiocyanate. SFN has received a great deal of attention because of its ability to simultaneously modulate multiple cellular targets involved in cancer development, including: (i) DNA protection by modulating carcinogen-metabolizing enzymes and blocking the action of mutagens; (ii) inhibition of cell proliferation and induction of apoptosis, thereby retarding or eliminating clonal expansion of initiated, transformed, and/or neoplastic cells; (iii) inhibition of neoangiogenesis, progression of benign tumors to malignant tumors, and metastasis formation. SFN is therefore able to prevent, delay, or reverse preneoplastic lesions, as well as to act on cancer cells as a therapeutic agent. Taking into account this evidence and its favorable toxicological profile, SFN can be viewed as a conceptually promising agent in cancer prevention and/or therapy. SFN is the hydrolysis product of glucoraphanin, particularly high in the young sprouts of broccoli and cauliflower. SFN can also be obtained by eating cruciferous vegetables such as brussel sprouts, broccoli, cauliflower, bok choy, kale, collards, arugula, broccoli sprouts, chinese broccoli, broccoli raab, kohlrabi, mustard, turnip, radish, watercress and cabbage (PMID:17134937).

There are two forms of glutamic acid found in nature: L-glutamic acid and D-glutamic acid. D-glutamic acid, is not endogenously produced in higher mammals. It is found naturally primarily in the cell walls of certain bacteria. D-glutamate is also present in certain foods e.g., soybeans and also arises from the turnover of the intestinal tract microflora, whose cell walls contain significant D-glutamate. Unlike other D-amino acids, D-glutamate is not oxidized by the D-amino acid oxidases, and therefore this detoxification pathway is not available for handling D-glutamate. Likewise, D-glutamic acid, when ingested, largely escapes most deamination reactions (unlike the L-counterpart). Free D-glutamate is found in mammalian tissue at surprisingly high levels, with D-glutamate accounting for 9% of the total glutamate present in liver. D-glutamate is the most potent natural inhibitor of glutathione synthesis identified to date and this may account for its localization to the liver, since circulating D-glutamate may alter redox stabiity (PMID 11158923). Certain eels are known to use D-glutamic acid as a phermone for chemical communication. D-Glutamic acid has been found to be a metabolite of Lactobacillus (PMID: 22754309).