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].

DL-Glutamine (2-amino-4-carbamoylbutanoic acid), a non-essential amino acid, exists abundantly throughout the body and is participated in many metabolic processes. It is synthesized from glutamic acid and ammonia, and is the main carrier of nitrogen in the body and is an important energy source for many cells.

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

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

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