psilocin
n. an indolealkylamine hallucinogen that is the principal psychoactive compound in “magic mushrooms” of the genus Psilocybe, which were used by the Aztecs for religious and ceremonial purposes. Psilocybin, first isolated in 1958, differs from psilocin only in having an additional phosphate group; it is rapidly metabolized in the body and converted to psilocin. Like other indolealkylamine hallucinogens (e.g., LSD, DMT), psilocin is active at various serotonin receptors: Agonism at 5-HT1A and 5-HT2A receptors in the cerebral cortex of the brain appears to be responsible for the psychoactive effects of these drugs.