L-Glutamic acid monosodium salt (MSG) (Monosodium glutamate) is an activator of mGlu1 receptor.

L-Glutamine (L-Glutamic acid 5-amide) , a non-essential amino acid, is synthesized from glutamic acid and ammonia.

L-Glutamic acid (Glutaminol) acts as an excitatory transmitter, shows a direct activating effect on the release of DA from dopaminergic terminals.

N-Acetyl-L-glutamic acid (Ac-L-Glu-OH) (NAcGlu) is an acetylated amino acid. NAcGlu is biosynthesized from glutamic acid and acetyl-CoA by the enzyme N-acetyl glutamate synthase (NAGS). NAcGlu activates carbamoyl phosphate synthetase in the urea cycle. A deficiency in N-acetyl glutamate synthase or a genetic mutation in the gene coding for the enzyme will lead to urea cycle failure in which ammonia is not converted to urea, but rather accumulated in the blood leading to the condition called Type I hyperammonemia.

5'-Guanylic acid disodium salt (GMP-5) belongs to the class of organic compounds known as purine ribonucleoside monophosphates. In particular, L-Glutamic acid and guanosine monophosphate can be biosynthesized from xanthylic acid and L-glutamine; which is catalyzed by the enzyme GMP synthase [glutamine-hydrolyzing]. In addition, Guanosine triphosphate and guanosine monophosphate can be biosynthesized from diguanosine tetraphosphate; which is catalyzed by the enzyme bis(5'-nucleosyl)-tetraphosphatase [asymmetrical]. In humans, guanosine monophosphate is involved in the kanamycin action pathway, the telithromycin action pathway, the tobramycin action pathway, and the erythromycin action pathway. Guanosine monophosphate is also involved in several metabolic disorders, some of which include the AICA-ribosiduria pathway, adenosine deaminase deficiency, adenine phosphoribosyltransferase deficiency (aprt), and the 2-hydroxyglutric aciduria (D and L form) pathway. Outside of the human body, guanosine monophosphate can be found in a number of food items such as onion-family vegetables, millet, chinese water chestnut, and red rice. This makes guanosine monophosphate a potential biomarker for the consumption of these food products.

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

L-Pyroglutamic acid (pidolic acid), a cyclized derivative of the L-GLUTAMIC ACID, can elevate blood levels. This function may be associated with problems of GLUTATHIONE or GLUTAMINE metabolism.

DL-Glutamic acid, the conjugate acid of Glutamic acid, serves as a crucial metabolite. In comparison to the α and β polymorphs of L-Glutamic acid's second phase, DL-Glutamic acid exhibits enhanced stability[1].