5 hydroxytryptophan is an intermediate in the synthesis of the essential amino acid, tryptophan to serotonin. The enzyme tryptophan hydroxylase adds a hydroxyl group to tryptophan, formin the 5-HTP intermediate. In the body, it converts to serotonin with the removal of a carboxyl group (COOH) by a second enzyme. Serotonin is an important neurotransmitter involved in teh regulation of endocrine and brain activity responsible for emotion, appetite and sleep/wake cycles. It is usually derived from the Griffonia simplicifolia plant.