DL-Phenylalanine

Description:DL-Phenylalanine (DLPA) is marketed as a nutritional supplement for its supposed analgesic and antidepressant activities. The reputed analgesic activity of DL-phenylalanine may be explained by the possible blockage by D-phenylalanine of enkephalin degradation by the enzyme carboxypeptidase A.[5] The mechanism of DL-phenylalanine's supposed antidepressant activity may be accounted for by the precursor role of L-phenylalanine in the synthesis of the neurotransmitters norepinephrine and dopamine. Elevated brain levels of norepinephrine and dopamine are thought to have an antidepressant effect. Following ingestion, D-Phenylalanine is absorbed from the small intestine and transported to the liver via the portal circulation. A small amount of D-phenylalanine appears to be converted to L-phenylalanine. D-Phenylalanine is distributed to the various tissues of the body via the systemic circulation. It appears to cross the blood-brain barrier less efficiently than L-phenylalanine, and so a small amount of an ingested dose of D-phenylalanine is not absorbed but excreted in the urine.