Dephosphorylation means taking a phosphate group off a molecule. Psilocybin carries a phosphate at position 4 of its indole ring; take it off and a hydroxyl is left, which gives psilocin. Canada’s Controlled Drugs and Substances Act names the two by exactly this difference, 4-phosphoryloxy for psilocybin and 4-hydroxy for psilocin (CDSA).
In people, the enzyme alkaline phosphatase does the job, which is why a 2017 review calls psilocybin “primarily a pro-drug” (Dinis-Oliveira, 2017). Inside a damaged Psilocybe cubensis, an enzyme named PsiP performs the same step, and the psilocin it releases is then oxidized into blue products (Lenz et al., 2020).
The same idea explains why some related compounds are studied as pairs. Baeocystin’s dephosphorylated counterpart is called norpsilocin (Sherwood et al., 2020). Why mushrooms store the phosphorylated form at all is unresolved; the 2020 authors suggest the phosphate acts as a reversible protective group, which is a proposal rather than a demonstrated function.
Sources
- Dinis-Oliveira, 2017, Drug Metabolism Reviews
- Lenz et al., 2020, Angewandte Chemie: PsiP and PsiL
- Controlled Drugs and Substances Act, Schedule III (Justice Laws)
- Sherwood et al., 2020, Journal of Natural Products
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