In the CNS, Kainic acid is an effective agonist at excitatory amino acid receptor subtypes.

L-Lactic acid ((S)-2-Hydroxypropanoic acid) is a natural product produced by the anaerobic glycolysis of pyruvic acid. L-Lactic acid is a sensitive indicator of tissue hypoxia and can be used as a hemodynamic indicator in critically ill patients.

Dihydroxyfumaric acid is a known generator of superoxide anions and by hydroxyl free radicals. Dihydroxyfumarate exposure can cause insulin inhibitory effects. It can spontaneously convert to hydroxypyruvate or to oxaloglycolate.

3-Hydroxybutyric acid (Butanoic acid) (or beta-hydroxybutyrate) is a ketone body. Like the other ketone bodies (acetoacetate and acetone), levels of 3-hydroxybutyrate in blood and urine are raised in ketosis. In humans, 3-hydroxybutyrate is synthesized in the liver from acetyl-CoA and can be used as an energy source by the brain when blood glucose is low. Blood levels of 3-hydroxybutyric acid levels may be monitored in diabetic patients to look for diabetic ketoacidosis. Persistent mild hyperketonemia is a common finding in newborns. Ketone bodies serve as an indispensable source of energy for extrahepatic tissues, especially the brain and lung of developing mammals. Another important function of ketone bodies is to provide acetoacetyl-CoA and acetyl-CoA for the synthesis of cholesterol, fatty acids, and complex lipids. During the early postnatal period, acetoacetate (AcAc) and beta-hydroxybutyrate are preferred over glucose as substrates for synthesis of phospholipids and sphingolipids in accord with requirements for brain growth and myelination. Thus, during the first 2 weeks of postnatal development, when the accumulation of cholesterol and phospholipids accelerates, the proportion of ketone bodies incorporated into these lipids increases. On the other hand, an increased proportion of ketone bodies is utilized for cerebroside synthesis during the period of active myelination. In the lung, AcAc serves better than glucose as a precursor for the synthesis of lung phospholipids. The synthesized lipids, particularly dipalmitoylphosphatidylcholine, are incorporated into surfactant, and thus have a potential role in supplying adequate surfactant lipids to maintain lung function during the early days of life (PMID: 3884391 ). 3-Hydroxybutyric acid is found to be associated with fumarase deficiency and medium-chain acyl-CoA dehydrogenase deficiency, which are inborn errors of metabolism.

Oxoadipic acid (2-Oxoadipic acid) is a key metabolite of the essential amino acids tryptophan and lysine.Important metabolite between the TCA cycle and lysine biosynthesis. Of interest for research on mitochondrial metabolite transporters.

DSPS (Dioctadecanoylphosphatidylserine) is a glycerophospholipid, an important phospholipid membrane component that plays a key role in cell cycle signaling. DSPS can regulate cellular activity and mediate apoptosis. DSPS is widely used as a nutritional supplement.

NADH disodium salt (Disodium NADH) hydrate is the reduced form of nicotinamide adenine dinucleotide (NAD) that can donate electrons in a reducing reaction, becoming oxidized to produce NAD+. Various enzymes utilize NADH disodium salt hydrate plus H+ to reduce substrates, generating NAD+ and the reduced product.

5-Aminolevulinic acid hydrochloride (5-ALA) is an intermediate in heme biosynthesis and a universal precursor of tetrapyrroles.

N-Methyl-D-aspartic acid is an amino acid that, as the D-isomer, is the defining agonist for the NMDA (N-Methyl-D-aspartic acid) receptor subtype of glutamate receptors.

Cynarin (1,5-Dicaffeoylquinic acid) has neuroprotective, and antioxidant effects, it can inhibition of GSK3β as well as the modulation of Bcl-2 Bax.

Ac-Ala-OH (N-Acetyl-L-alanine) is a substrate for Guanine nucleotide-binding protein G(I) G(S) G(O) gamma-2 subunit, Myelin basic protein, GTP-binding nuclear protein Ran, Tropomyosin alpha 4 chain, HIV-1 Rev binding protein 2, Xaa-Pro dipeptidase, Thymosin beta-10, Actin-like protein 3, Alanine aminotransferase, Serine threonine protein Phosphatase PP1-beta catalytic subunit,10 kDa heat shock protein (mitochondrial), Calmodulin and Beta-1-syntrophin.

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-mal

3-Indoleacetic acid (indolylacetic acid) (IAA) is the most common plant hormone of the auxin class and it regulates various aspects of plant growth and development.

Glutathione oxidized (L(-)-Glutathione) is a GLUTATHIONE dimer formed by a disulfide bond between the cysteine sulfhydryl side chains during the course of being oxidized.

trans-Vaccenic acid is a precursor substance that synthesizes saturated fatty acids in the rumen and conjugated linoleic acid at the tissue level. trans-Vaccenic acid inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells through the mitochondria-mediated apoptotic pathway.

β-N-Methylamino-L-alanine hydrochloride (L-BMAA hydrochloride) is a neurotoxin produced by cyanobacteria that may contribute to the development of amyotrophic lateral sclerosis (ALS) and possibly other neurodegenerative diseases.

Phosphocreatine disodium hydrate ishigh-energy phosphate reservoir in vertebrate and some invertebrate muscle; provides phosphate for ADP-ATP conversion

Spaglumic acid (N-Acetylaspartylglutamic acid) is a neuropeptide found in millimolar concentrations in the brain.

L-SelenoMethionine (L-(+)-Selenomethionine) is a naturally occurring amino acid. It promotes cell cycle progression and elevates the expression of the antioxidant enzymes thioredoxin reductase, glutathione reductase.

L-Methionine (L-Methionin) is the L-isomer of Methionine. Methionine is an essential amino acid for human development and acts as a hepatoprotectant.

D-(-)-Lactic acid sodium (Sodium D-lactate) is an organic acid. It is a chiral molecule, consisting of two optical isomers, L-lactic acid and D-lactic acid, with the L-isomer being the most common in living organisms. D-(-)-Lactic acid sodium also is a microbial metabolite.

L-Citrulline, an amino acid, is derived from ornithine during the catabolism of proline, glutamate, or glutamine, and also from L-arginine via the arginine-citrulline pathway.

DL-Homocysteine (2-Amino-4-mercaptobutyric acid) is a potential marker for tumor cell growth. increased plasma homocysteine is a risk factor for coronary heart disease and carcinogenesis.

N-Acetylleucine belongs to the class of organic compounds known as leucine and derivatives. Leucine and derivatives are compounds containing leucine or a derivative thereof resulting from reaction of leucine at the amino group or the carboxy group, or fro

Pyruvic acid (Acetylformic acid) is an intermediate compound in the metabolism of carbohydrates, proteins, and fats. In thiamine deficiency, its oxidation is retarded and it accumulates in the tissues, especially in nervous structures.

1-Methyl-L-histidine (3-(1-Methylimidazol-4-yl)-L-alanine) is a natural but non-proteinogenic amino acid; employed as index of muscle protein breakdown.

DL-Selenomethionine (Seleno-DL-methionine) is a selenium (Se) analogue of methionine in which sulfur is replaced with the trace element selenium. Selenomethionine (SeMet) can incorporate into proteins in place of methionine with no effects on protein structure and function, providing a mechanism for reversible Se storage in organs and tissues.

β-Alanine (3-Aminopropanoic acid) is a naturally occurring beta amino acid formed in vivo by the degradation of dihydrouracil and carnosine. It acts as a neurotransmitter by activating glycine and GABA receptors.

L-Pipecolic acid (L-Homoproline) is a breakdown product of lysine, accumulates in body fluids of infants with generalized genetic peroxisomal disorders, such as Zellweger syndrome, neonatal adrenoleukodystrophy.

Malonic acid (propanedioic acid) is the archetypal example of a competitive inhibitor: it acts against succinate dehydrogenase (complex II) in the respiratory electron transport chain. Malonic acid is found to be associated with malonyl-CoA decarboxylase deficiency, which is an inborn error of metabolism.

Nystose (1,1-Kestotetraose) is a tetrasaccharide composed of two fructose molecules linked via beta (1→2) bonds to the fructosyl moiety of sucrose.

Creatine (Methylguanidoacetic acid) is an amino acid that occurs in vertebrate tissues and in urine. In muscle tissue, creatine generally occurs as phosphocreatine. Creatine is excreted as creatinine in the urine. Creatine functions as part of the cell's energy shuttle. The high energy phosphate group of ATP is transferred to creatine to form phosphocreatine in the following reaction: Cr + ATP <-> PCr + ADP. This reaction is reversibly catalyzed by creatine kinase. In the human body, creatine is synthesized mainly in the liver by the use of parts from three different amino acids: arginine, glycine, and methionine. 95% of it is later stored in the skeletal muscles and the rest is stored in the brain, heart, and testes.

Sarcosine (Methylglycine) is a competitive inhibitor of the type I glycine transporter (GlyT1) and an N-methyl-D-aspartate receptor (NMDAR) co-agonist.

(S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a tart-tasting organic dicarboxylic acid found in many sour foods, such as apples, and contributes to the sourness of green apples and tartness of wine, although its concentration decreases with fruit ripeness (wikipedia). In its ionized form, it is called malate, an intermediate in the TCA cycle alongside fumarate, and can be formed from pyruvate through anaplerotic reactions. In humans, malic acid is derived from food sources and synthesized in the body via the citric acid cycle in mitochondria, playing a crucial role in energy production under both aerobic and anaerobic conditions. Under aerobic conditions, malate is oxidized to oxaloacetate, providing reducing equivalents via the malate-aspartate redox shuttle, while during anaerobic conditions, its simultaneous reduction to succinate and oxidation to oxaloacetate removes excess reducing equivalents, reversing hypoxia’s inhibition of glycolysis and energy production. Studies on rats have shown that tissue malate depletes following exhaustive physical activity, suggesting that malic acid deficiency may cause physical exhaustion. Administering malic acid to rats has been shown to elevate mitochondrial malate, increasing mitochondrial respiration and energy production.

Tylosin tartrate, a macrolide antibiotic, is approved for the control of mycoplasmosis in poultry.

(-)-Hydroxycitric acid (Garcinia acid) is the principal acid found in the fruit rinds of Garcinia cambogia. It acts as a potent and competitive inhibitor of ATP citrate lyase, suppressing fatty acid synthesis, food intake, lipogenesis, and inducing weight loss.

Rosmarinate acid(Rosemary acid) inhibits MAO-A, MAO-B and COMT enzymes with IC50s of 50.1, 184.6 and 26.7 μM, respectively

D-Glutamic acid ((R)-Glutamic acid), the enantiomer of L-glutamic acid, is widely used in medicine and food.

Myristic acid (Crodacid) , a 14 carbon saturated fatty acid, is a rare molecule in cells and is a substrate of some fatty acid desaturases. This compound has the ability to acylate proteins by covalently binding to the N-terminal glycine residues, in a process called N-terminal myristoylation. Myristoylation of substrate proteins by this fatty acid has the potential to activate and mediate many physiological pathways. Furthermore, saturated fatty acids have been reported to be essential for biological activities of lipopolysaccharides and have demonstrated the ability to induce expression of COX-2 and NFκB (nuclear factor κB) activation.

3,5-Diiodo-L-thyronine (Diiodothyronine) is an iodinated thyronine hormone that regulates gene activity affecting processes such as homeostasis, lipid metabolism and insulin resistance.

Oxalic acid is a strong dicarboxylic acid occurring in many plants. Oxalic acid is produced in the body by metabolism of glyoxylic acid or ascorbic acid.

1-Aminocyclopropane-1-carboxylic acid (ACC) is an intermediate in the synthesis of ethylene, the plant hormone responsible for biological processes ranging from seed germination to organ senescence. It is a small molecule agonist at the glycine modulatory site of the NMDA receptor (EC50 = 0.7-0.9 μM) in the presence of low levels (1 μM) of glutamate and as a competitive antagonist at the glutamate-binding site on NMDA receptors (EC50 = 81.6 nM) with high levels (10 μM) of glutamate.2 This compound has been reported to protect against neuron cell death in vivo models of ischemia by enabling moderate levels of NMDA receptor activation and attenuating any excess NMDA receptor signaling that may lead to neurotoxicity.

5-aminovalerate (or 5-aminopentanoic acid) is a lysine degradation product. It can be produced both endogenously or through bacterial catabolism of lysine. 5-aminovalerate is formed via the following multi-step reaction: L-lysine leads to cadverine leads

L-Homoserine ((S)-(-)-2-AMINO-4-HYDROXYBUTYRIC ACID) is a more reactive variant of the amino acid serine. In this variant, the hydroxyl side chain contains an additional CH2 group which brings the hydroxyl group closer to its own carboxyl group, allowing it to chemically react to form a five-membered ring. This occurs at the point that amino acids normally join to their neighbours in a peptide bond. L-Homoserine is therefore unsuitable for forming proteins and has been eliminated from the repertoire of amino acids used by living things. L-Homoserine is the final product on the C-terminal end of the N-terminal fragment following a cyanogen bromide cleavage.

O-PHOSPHO-L-SERINE is an ester of serine and phosphate, which are normal metabolites in human biofluids.O-phospho-L-serine is a phagocytosis inhibitor that inhibits glial cell proliferation and cone cell regeneration after photodamage.

Methylmalonic acid is an indicator of vitamin B-12 deficiency in cancer patients.Methylmalonic acid is a competitive succinate dehydrogenase inhibitor.

4-Guanidinobutanoic acid (4-GBA) is an L-arginine metabolite that has been used in the intestinal transport tranport studies. It has been specifically use to human proton coupled amino acid transporters hPAT1.

N-(3-Phenylpropionyl)glycine (Phenylpropionylglycine) is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. Acyl glycines are produced through the action of glycine N-acyltransferase which is an enzyme that catalyzes the chemical reaction:acyl-CoA + glycine < - > CoA + N-acylglycineThe detection of phenylpropionylglycine in urine after an oral load of phenylpropionic acid can be used to diagnose deficiency of medium-chain acyl-CoA dehydrogenase, a frequent and treatable metabolic defect.