white to light yellow crystal powde
L-Pyroglutamic acid is an amino acid that is used in the synthesis of peptides. It has also been observed to convert when placed at the N-terminus in vivo to create IgG2 antibodies.
There are semi-synthetic methods, enzymatic conversion method and total synthesis method. Currently the major approach of industrial production is the semi-synthetic method with glutamic acid being the raw material. Have the 42% of glutamic acid solution heated at 140 °C for 3h to obtain the reaction solution with L-pyroglutamic acid being the major component. The reaction solution further undergoes concentration under reduced pressure, crystallization, washing, and drying to obtain the L-pyroglutamic acid with the conversion rate being 94%.
In the resolution of racemic amines.
L-pyroglutamic acid is formed by removing one intramolecular water molecule in the L-glutamic acid; the preparation process is simple with the key step being the control of the temperature and dehydration time.
(1) Add100 g of L-glutamic acid into a 500-ml beaker; heat the beaker in an oil bath until the temperature was raised to 145~150 °C, incubate for 45 minutes to perform dehydration reaction. The dehydrated solution was brown.
(2) After the end of dehydration reaction, pour the solution into a volume of about 350 ml of boiling water with a solution of all further being dissolved in water. Cool to 40~50 °C, add appropriate amount of activated carbon for decolorization (repeated twice) to obtain a colorless transparent solution.
(3) directly heat and evaporate the colorless and transparent solution of the step (2) is a colorless and transparent solution for concentration to a half of the previous volume and then continue for concentration in a water bath to a volume of about 1/3 of the previous solution, and then stop heating; have it slightly cooled in the hot water bath for crystallization; the colorless prisms can be obtained after 10 to 20 hours.
The applied amount of L-pyroglutamic acid in cosmetics should depend on the formula. This product can also be applied to cosmetic in the form of 50% concentrated solution.
Pyroglutamic acid is a kind of based 5-oxo-proline. It is produced by the dehydration and formation of intramolecular amide bond between the α-NH2 group and γ-hydroxy of glutamic acid; the molecule can also be produced from glutamine by losing its intramolecular amine group. The condition of glutathione synthetase deficiency can cause the anemia of pyroglutamic acid with a series of clinical symptoms. Pyroglutamic acid anemia is a kind of organic acid metabolic disorder disease caused by glutathione synthetase hyperlipidemia. Clinical manifestations: disease onset occurs within 12 to 24 hours of born with progressive hemolysis, jaundice, chronic metabolic acidosis, mental retardation; urine containing pyroglutamic acid, lactic acid, α-deoxy-4-hydroxyphenyl acetyl acid lactone. For treatment, based on the actual symptoms, pay attention to adjust the diet after yearling.
The above information is edited by the Chemicalbook of Dai Xiongfeng.
1. It can be used as a kind of intermediates of organic synthesis as well as food additives.
2. It is used in food, medicine, cosmetics and other industries
Characteristics and Application
Human skin contains a kind of moisturizing functional water-soluble substances-the natural moisturizing factor, roughly consisting of amino acids (40%), pyroglutamic acid (12%), inorganic salts (Na, K, Ca, containing 18.5% Mg, etc.), and other organic matter (including 29.5%). So, pyroglutamic acid is one of the major components of natural moisturizing factor of the skin, its moisturizing ability is far stronger than glycerin and propylene glycol. Moreover, it is non-toxic, non-irritating, and is an excellent raw material for modern skin care, and hair care cosmetics. Pyroglutamic acid also has inhibitory effect on the tyrosine oxidase activity, and thus preventing "melanoidins" substance from being deposited in the skin, and having a whitening effect on the skin. It has a keratin softening effect which can be used in nail cosmetics. In addition to be applied in cosmetics, L-pyroglutamic acid derivatives can also have reaction with a number of other organic compounds for synthesis of derivatives. It also has some special effect on the surface activity and brilliant effect. Moreover, it can also be used as surfactants for detergents; as a chemical reagent, it can be used for the resolution of racemic amines; it can also be used as a kind of organic intermediates.
L-pyroglutamic acid has its scientific name being L-2-pyrrolidone-5-carboxylic acid. Precipitation from ethanol and petroleum ether mixture were colorless orthorhombic bipyramid crystals with the melting temperature being 162~163 °C. It is soluble in water, alcohol, acetone and acetic acid, slightly soluble in ethyl acetate, and insoluble in ether. Specific rotation-11.9 ° (c = 2, H2O). It is produced from 42% aqueous solution of glutamic acid which subjects to heating dehydration, concentration, crystallization, washing and drying to obtain L-pyroglutamic acid.
A building block for pharmaceuticals and asymmetric synthesis
Glutamic acid is an amino acid which constituting proteins. It has ionized acidic side chains and exhibits a property of water-addiction. Glutamate is prone to be cyclized and converted into pyrrolidone carboxylic acid, that’s pyroglutamic acid.
Glutamic acid has a particularly high content in all kinds of cereal protein. It can provide α-ketoglutarate via the citric acid cycle. α-ketoglutarate, can have reaction with ammonia to directly generate in the catalysis of glutamate dehydrogenase and NADPH (coenzyme II); it can also be synthesized directly from the transamination action of aspartate and alanine in the catalysis of aspartate aminotransferase or glutamate-alanine aminotransferase; glutamate may be additionally synthesize from the mutual reversible inter-conversion between proline and ornithine (from arginine). In this case, glutamate is nutritionally non-essential amino acids for human beings. Upon the catalysis of glutamate dehydrogenase and NAD (coenzyme I), glutamic acid is either deaminated or undergone amino group transfer in the catalysis of aspartate aminotransferase or alanine aminotransferase to generate α-ketoglutarate which further enter into the TCA cycle and produce sugar via gluconeogenesis pathway. From this perspective, the glutamic acid is an important glycogenic amino acid.
In different tissues (such as muscle, liver, brain, etc.), glutamic acid can have reaction with NH3 to generate glutamine in the catalysis of glutamine synthetase. Glutamine is not only a kind of amino acid constituting the proteins but also the detoxification product of ammonia in the brain, as well as the storage and utilization form of the ammonia inside the body. (see "glutamine and metabolic" article for detailed information).
Glutamic acid, together with acetyl CoA, can generate acetyl glutamate under the catalysis of acetyl glutamate synthetase. It is the cofactor of the acetyl glutamate carbamoyl phosphate synthetase in mitochondrial (involved in the synthesis of urea).
γ-amino butyric acid (GABA) is the decarboxylation products of glutamic acid. It has a particularly high concentration in the brain and is also presented in the blood. Its physiological function is considered to be the inhibitory neurotransmitter. The anticonvulsant effects and hypnotic effects of clinically administration of epiphysin may be achieved by GABA. The catabolism of GABA is via GABA transaminase and succinate dehydrogenase for generating succinate and further entering into the citric acid cycle for the formation of GABA shunt.
Crystallise S-pyroglutamic acid by dissolving it in boiling EtOH (20g in 100mL), cooling and after a few minutes additing pet ether (b 40-60o, 120mL), then after 5 minutes adding a further 120mL, and coThis has m 155.5-157.5o and  D -11.4o (c 4.4, H2O) [Hardy Synthesis 290 1978, Pellegata et al. Synthesis 614 1978]. The NH4 salt has m 184-186o (from EtOH). [Beilstein 22/6 V 7.]
It is colorless crystals with the melting point being 162-163 °C; it is soluble in water, alcohol, acetone and acetic acid, slightly soluble in ethyl acetate, but insoluble in ether.
ChEBI: An optically active form of 5-oxoproline having L-configuration.