L-Pyroglutamic acid

L-Pyroglutamic acid (also known as PCA, 5-oxoproline, pidolic acid) [98-79-3] is a five-membered lactam of glutamic acid. It is a pale yellow crystalline solid with the melting point of 155-157 °C.^[1] It is a ubiquitous, but little studied natural amino acid derivative. It occurs naturally in fruits, some plant foods, dairy, and fermented products such as soy sauce. It is a metabolite in the glutathione cycle that is converted to glutamate by 5-oxoprolinase.^[2]

Preparation of L-pyroglutamic acid:

PCA can be easily obtained by direct thermal dehydration of L-glutamic acid in water under reflux.^[3]

Application of L-pyroglutamic acid:

In neurology, the brain-boosting effects of PCA were discovered in 1984. It plays an important role in the preservation and activity of the key neurotransmitters acetylcholine, gamma-aminobutyric acid (GABA) and glutamic acid.^[4] It readily passes the blood-brain barrier to stimulate cognitive-enhancing function in rats^[5] and reduce age-associated memory decline in humans.^[6] In drug delivery, PCA esters can be used as dermal penetration enhancers for therapeutic agents having poor skin permeation or hair growth agents.^[7] In chemical synthesis, it has been used as a versatile chiral building block in asymmetric synthesis of alkaloids, pharmaceuticals, and many other natural products.^[8],^[9] PCA is also known as a novel organic nonlinear optical (NLO) material for tunable UV harmonic generation down to 266 nm at room temperature.^[10]

Product categorization (Chemical groups):

Main category:

• Carboxamides / Thioamides / Imidates
• Carboxylic acids / salts

Second level:

• Aliphatic compounds

Third level:

• Heterocyclic compounds

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