Psilocin (also known as 4-HO-DMT, 4-hydroxy DMT, psilocine, psilocyn, or psilotsin) is a substituted tryptamine alkaloid and a serotonergic psychedelic substance. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocybin. Psilocin is a Schedule I drug under the Convention on Psychotropic Substances. Acting on the 5-HT2A receptors, psilocin modulates the production and reuptake of serotonin. The mind-altering effects of psilocin are highly variable and subjective and resemble those of LSD and DMT. Chemistry Psilocin and its phosphorylated cousin, psilocybin, were first isolated and named in 1958 by Swiss chemist Albert Hofmann. Hofmann obtained the chemicals from laboratory-grown specimens of the entheogenic mushroom Psilocybe mexicana. Hofmann also succeeded in finding synthetic routes to these chemicals. Psilocin can be obtained by dephosphorylation of natural psilocybin under strongly acidic or under alkaline conditions (hydrolysis). Another synthetic route uses the Speeter–Anthony tryptamine synthesis procedure. 4-hydroxyindole is acylated with oxalyl chloride. The compound is further reacted with an amine, yielding indole-3-yl-glyoxalyamide. Finally, the product amide is reduced using lithium aluminum hydride yielding psilocin. Psilocin is relatively unstable in solution due to its phenolic hydroxy (-OH) group. In the presence of oxygen, it readily forms bluish and dark black degradation products. Similar products are also formed under acidic conditions in the presence of oxygen and Fe3+ ions (Keller's reagent). Structural analogs Sulfur analogs are known with a benzothienyl replacement as well as 4-SH-DMT. 1-Methylpsilocin is a functionally 5-HT2C receptor preferring agonist. 4-Fluoro-N,N-dimethyltryptamine is known. O-Acetylpsilocin (4-AcO-DMT) is an acetylated analog of psilocin. Additionally, replacement of a methyl group at the dimethylated nitrogen with an isopropyl or ethyl group yields 4-HO-MIPT (4-hydroxy-N-methyl-N-isopropyltryptamine) and 4-HO-MET (4-hydroxy-N-methyl-N-ethyltryptamine), respectively. 4-Acetoxy-MET (4-Acetoxy-N-methyl-N-ethyltryptamine), also known as 4-AcO-MET, is the acetate ester of 4-HO-MET, and a homologue of 4-AcO-DMT. Pharmacology Psilocin is the pharmacologically active agent in the body after ingestion of psilocybin or some species of psychedelic mushrooms. Psilocybin is rapidly dephosphorylated in the body to psilocin which acts as a 5-HT2A, 5-HT2C and 5-HT1A agonist or partial agonist. Psilocin exhibits functional selectivity in that it activates phospholipase A2 instead of activating phospholipase C as the endogenous ligand serotonin does. Psilocin is structurally similar to serotonin (5-HT), differing only by the hydroxyl group being on the 4-position rather than the 5 and the dimethyl groups on the nitrogen. Its effects are thought to come from its agonist activity at 5-HT2A serotonin receptors in the prefrontal cortex. Psilocin has