Jun 252013

Emerging research indicates that low doses of the active chemical psilocybin can have positive psychiatric effects. Image via Wikimedia Commons/Dohduhdah Read more:  Follow us: @SmithsonianMag on Twitter

Emerging research indicates that low doses of the active chemical psilocybin can have positive psychiatric effects. Image via Wikimedia Commons/Dohduhdah

The latest study, published last week in Experimental Brain Research, showed that dosing mice with a purified form of psilocybin reduced their outward signs of fear. The rodents in the study had been conditioned to associate a particular noise with the feeling of being electrically shocked, and all the mice in the experiment kept freezing in fear when the sound was played even after the shocking apparatus was turned off. Mice who were given low doses of the drug, though, stopped freezing much earlier on, indicating that they were able to disassociate the stimuli and the negative experience of pain more easily.


Psilocybin is a naturally occurring psychedeliccompound produced by more than 200 species of mushrooms, collectively known aspsilocybin mushrooms. The most potent are members of the genus Psilocybe, such asP. azurescensP. semilanceata, and P. cyanescens, but psilocybin has also been isolated from about a dozen other genera. As a prodrug, psilocybin is quickly converted by the body to psilocin, which has mind-altering effects similar to those of LSDmescaline, and DMT. The effects generally include euphoria, visual and mental hallucinations, changes in perception, a distorted sense of time, and spiritual experiences, and can include possible adverse reactions such as nausea and panic attacks.


Psilocybin (O-phosphoryl-4-hydroxy-N,N-dimethyltryptamine or 4-PO-DMT) is a prodrug that is converted into the pharmacologicallyactive compound psilocin in the body by a dephosphorylation reaction. This chemical reaction takes place under strongly acidicconditions, or under physiological conditions in the body, through the action of enzymes called phosphatases.

Psilocybin is a tryptamine compound with a chemical structure containing an indole ring linked to an ethylamine substituent. It is chemically related to the amino acid tryptophan, and is structurally similar to the neurotransmitter serotonin. Psilocybin is a member of the general class of tryptophan-based compounds that originally functioned as antioxidants in earlier life forms before assuming more complex functions in multicellular organisms, including humans. Other related indole-containing psychedelic compounds includedimethyltryptamine, found in many plant species and in trace amounts in some mammals, and bufotenine, found in the skin ofpsychoactive toads. Biosynthetically, the biochemical transformation from tryptophan to psilocybin involves several enzyme reactions: decarboxylation, methylation at the N9 position, 4-hydroxylation, and O-phosphorylation. Isotopic labeling experiments suggest that tryptophan decarboxylation is the initial biosynthetic step and that O-phosphorylation is the final step. The precise sequence of the intermediate enzymatic steps is not known with certainty, and the biosynthetic pathway may differ between species.

A possible biosynthetic route to psilocybin. Although the order of the first (decarboxylation) and last (phosphorylation) steps are known with some certainty, the sequence of the two intermediate steps is speculative.


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