5-HTP (5-Hydroxytryptophan)
A metabolite of the essential amino acid l-tryptophan and intermediate in the production of the neurotransmitter serotonin (5-hydroxytryptamine or 5-HT) as well as the hormone melatonin. 5-HTP is used as an alternative treatment for depression, and included in a number of supplements to improve mood and assist with appetite control/weight loss.
See Andrew Novick’s and David Tolson’s article, “5-HTP” for more information.