Psilocin

Psilocin, also known as 4-hydroxy-N,N-dimethyltryptamine (4-HO-DMT), is a psychedelic drug and fungal alkaloid of the tryptamine and 4-hydroxytryptamine families. Along with its phosphate ester psilocybin, it is found in most species of psilocybin-containing mushrooms, such as Psilocybe cubensis and Psilocybe mexicana, and is the compound responsible for their hallucinogenic effects, although concentrations of psilocin are variably lower than those of psilocybin. The drug is taken orally and its effects include perceptual changes and visual effects, emotional changes, ego dissolution, time dilation, and mystical experiences, among others. Synthetic acyl esters such as 4-AcO-DMT (psilacetin; O-acetylpsilocin) and 4-PrO-DMT (O-propionylpsilocin), are prodrugs of psilocin and have similar properties and effects. More recently, MSP-1014 has emerged as a novel prodrug of psilocin under development for the treatment of major depressive disorder.

Psilocin acts as a non-selective serotonin receptor agonist, including of the serotonin 5-HT_2A receptor among others. The drug produces its hallucinogenic effects specifically via activation of the serotonin 5-HT_2A receptor. However, other serotonin receptors, such as the serotonin 5-HT_1A and 5-HT_2C receptors, may also contribute to its effects. Notable analogues of psilocin include dimethyltryptamine (DMT), its positional isomer bufotenin (5-HO-DMT), its higher homologue 4-HO-MET (metocin), and others.

Psilocin and psilocybin were discovered via isolation from psilocybin-containing mushrooms by Albert Hofmann in 1958. This followed the Western re-discovery of psilocybin-containing mushrooms by Robert Gordon Wasson and Valentina Pavlovna Wasson in Mexico in 1955. Psilocin, in the form of psilocybin, psilocybin-containing mushrooms, and other prodrugs such as 4-AcO-DMT, is a widely used entheogen as well as recreational psychedelic drug. Psilocybin and psilocin became controlled substances in the United States and internationally under the United Nations in 1971. Since then, psilocin, as the active form of psilocybin, has become of interest for potential use in medicine to treat psychiatric disorders such as depression. Psilocybin was approved for such purposes in Australia in 2023 and is in late-stage clinical trials in the United States and other countries.