Allantoin is a chemical compound with formula C₄H₆N₄O₃. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of

glyoxylic acid Glyoxylic acid or oxoacetic acid is an organic compound. Together with acetic acid, glycolic acid, and oxalic acid, glyoxylic acid is one of the C2 carboxylic acids. It is a colourless solid that occurs naturally and is useful industrially. Str ...

. Allantoin is a major metabolic intermediate in most organisms including animals, plants and bacteria, though not humans. It is produced from uric acid, which itself is a degradation product of

nucleic acids Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic a ...

, by action of urate oxidase (uricase). Allantoin also occurs as a natural mineral compound ( IMA

symbol A symbol is a mark, Sign (semiotics), sign, or word that indicates, signifies, or is understood as representing an idea, physical object, object, or wikt:relationship, relationship. Symbols allow people to go beyond what is known or seen by cr ...

Aan).

History

Allantoin was first isolated in 1800 by the Italian physician Michele Francesco Buniva (1761–1834) and the French chemist Louis Nicolas Vauquelin, who mistakenly believed it to be present in the amniotic fluid. In 1821, the French chemist Jean Louis Lassaigne found it in the fluid of the allantois; he called it ''"l'acide allantoique"''. In 1837, the German chemists Friedrich Wöhler and Justus Liebig synthesized it from uric acid and renamed it "allantoïn".

Animals

Named after the allantois (an

amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tet ...

embryonic excretory organ in which it concentrates during development in most

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s except humans and other hominids), it is a product of oxidation of uric acid by purine catabolism. After birth, it is the predominant means by which nitrogenous waste is excreted in the

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

of these animals. In humans and other higher apes, the metabolic pathway for conversion of uric acid to allantoin is not present, so the former is excreted. Recombinant rasburicase is sometimes used as a drug to catalyze this metabolic conversion in patients. In fish, allantoin is broken down further (into ammonia) before excretion. Allantoin has been shown to improve insulin resistance when administered to rats and to increase lifespan when administered to the nematode worm '' Caenorhabditis elegans''.

Bacteria

In bacteria, purines and their derivatives (such as allantoin) are used as secondary sources of nitrogen under nutrient-limiting conditions. Their degradation yields ammonia, which can then be utilized. For instance, ''

Bacillus subtilis ''Bacillus subtilis'' (), known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacill ...

'' is able to utilize allantoin as its sole nitrogen source. Mutants in the ''B. subtilis'' ''pucI'' gene were unable to grow on allantoin, indicating that it encodes an allantoin transporter. In '' Streptomyces coelicolor'', allantoinase ( EC 3.5.2.5) and allantoicase (EC 3.5.3.4) are essential for allantoin metabolism. In this species the catabolism of allantoin, and the subsequent release of ammonium, inhibits antibiotic production (''Streptomyces'' species synthesize about half of all known antibiotics of microbial origin).

Applications

Allantoin is present in botanical extracts of the comfrey plant and in the

of most mammals. Chemically synthesized bulk allantoin, which is chemically equivalent to natural allantoin, is safe, non-toxic, compatible with cosmetic raw materials and meets CTFA and JSCI requirements. Over 10,000

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

s reference allantoin.

Cosmetics

Manufacturers may use allantoin as an ingredient in over-the-counter cosmetics.

Pharmaceuticals

It is frequently present in toothpaste, mouthwash, and other oral hygiene products, in shampoos,

lipstick Lipstick is a cosmetics, cosmetic product used to apply coloration and texture to lips, often made of wax and oil. Different pigments are used to produce color, and minerals such as silica may be used to provide texture. The use of lipstick ...

s, anti-acne products, sun care products, and clarifying lotions, various cosmetic lotions and creams, and other cosmetic and pharmaceutical products.

Biomarker of oxidative stress

Since uric acid is the end product of the purine metabolism in humans, only non-enzymatic processes with reactive oxygen species will give rise to allantoin, which is thus a suitable biomarker to measure oxidative stress in chronic illnesses and senescence.

References

{{reflist

External links

* '' E. coli'
Allantoinase
(AllB) in Uniprot
P77671

GMD MS Spectrum
Cosmetics chemicals Ureas Excipients Hydantoins