Theanine

Theanine

Clinical data
Pregnancy category	US: A (No risk in human studies)
Dependence liability	None
Routes of administration	Oral
ATC code	none
Legal status
Legal status	US: OTC UN: Unscheduled
Pharmacokinetic data
Onset of action	about 1 hour
Biological half-life	3 hours
Identifiers
IUPAC name N-ethyl-L-glutamine; (2S)-2-ammonio-5-(ethylamino)-5-oxopentanoate
Synonyms	γ-L-glutamylethylamide
CAS Number	3081-61-6 Y
PubChem CID	439378
ChemSpider	388498 Y
UNII	8021PR16QO
KEGG	C01047
ChEBI	CHEBI:17394 Y
ECHA InfoCard	100.019.436
Chemical and physical data
Formula	C7H14N2O3
Molar mass	174.19766 g/mol
3D model (Jmol)	Interactive image Interactive image
Melting point	174.20 °C (345.56 °F)
Boiling point	215 °C (419 °F)
SMILES CC[nH]:c(:[o])CCC(N)c(:[o]):[oH] CCNC(=O)CCC(N)C(O)=O
InChI InChI=1S/C7H14N2O3/c1-2-9-6(10)4-3-5(8)7(11)12/h5H,2-4,8H2,1H3,(H,9,10)(H,11,12) Y Key:DATAGRPVKZEWHA-UHFFFAOYSA-N Y

Theanine /ˈθiːəniːn/, also known as L-γ-glutamylethylamide and N⁵-ethyl-L-glutamine, is an amino acid analogue of the proteinogenic amino acids L-glutamate and L-glutamine and is found primarily in particular and fungal species. It was discovered as a constituent of green tea in 1949 and in 1950 was isolated from gyokuro leaves, which have high theanine content. Appearance of the name "theanine" without a prefix is understood to imply the L-enantiomer, which is the form found in fresh teas and in some, but not all dietary supplements. The opposite D-enantiomer has far less studied pharmacologic properties, but is present in racemic chemical preparations, and substantially in some studied theanine supplements.

As an analogue of glutamate and glutamine, the theanine in common preparations is absorbed in the small intestine after oral ingestion; its hydrolysis is to L-glutamate and ethylamine occurs in both the intestine and liver. It can also cross the blood–brain barrier intact, and register pharmacological effects directly.

In Japan, L-theanine has been approved for use in all foods, including herb teas, soft drinks, desserts, etc., with some restrictions applying to infant foods. It provides a unique brothy or savory (umami) flavor to green tea infusions. As an ingredient, it is generally recognized as safe (GRAS) by the Food and Drug Administration (FDA), and is sold as a dietary supplement in the US. However, the German Federal Institute for Risk Assessment, an agency of their Federal Ministry of Food and Agriculture, has objected to the addition of isolated theanine to beverages.