Tryptamine acts as a natural pesticide in plants.
The most well-known tryptamines are serotonin, an important neurotransmitter, and melatonin, a hormone involved in regulating the sleep-wake cycle. Tryptamine alkaloids found in fungi, plants and animals are commonly used by humans for their psychotropic effects. Prominent examples include psilocybin (from "magic mushrooms") and DMT (from numerous plant sources, e.g. chacruna, often used in ayahuasca brews). Many synthetic tryptamines have also been made, including the migraine drug sumatriptan and its relatives. The tables below list some commonly encountered substituted tryptamines.
The tryptamine backbone can also be identified as part of the structure of some
more complex compounds, for example: LSD, ibogaine and yohimbine.
A thorough investigation of dozens of tryptamine compounds was published by Ann and Alexander Shulgin under the title TiHKAL.
The Abramovitch-Shapiro tryptamine synthesis is an organic reaction for the synthesis of tryptamines starting from a beta-Carboline 
^ Jones R.S. (1982). "Tryptamine: a neuromodulator or neurotransmitter in mammalian brain?". Progress in neurobiology19: 117–139.
^ Effects of tryptamine mediated through 2 states of the 5-HT ...
^ Takahashi, Dean Nobutaka, Chemistry of Plant Hormones, CRC Press
^ Dr. Duke's Phytochemical and Ethnobotanical Databases -- Biological Activities of TRYPTAMINE
^880. Tryptamines, carbolines, and related compounds. Part II. A convenient synthesis of tryptamines and -carbolines R. A. Abramovitch and D. Shapiro J. Chem. Soc., 1956, 4589 - 4592, doi:10.1039/JR9560004589