What is 5-HTP (5-hydroxytryptophan)? 5-HTP (5-hydroxytryptophan) is a naturally occurring substance derived from the seed pods of Griffonia simplicifolia, a West African medicinal plant. In humans, 5-HTP is the immediate nutrient precursor to the neurotransmitter serotonin (5-HT). This means that 5-HTP converts directly into serotonin in the brain . Serotonin has many profoundly important functions, including a role in sleep, appetite, memory, learning, temperature regulation, mood, sexual …