Baeocystin, norbaeocystin and aeruginascin: the other compounds in magic mushrooms, explained

Psilocybin gets the attention, but psilocybin mushrooms also make several near-identical molecules. The best known are baeocystin, norbaeocystin and aeruginascin, which differ from psilocybin mainly in how many methyl groups sit on one nitrogen atom (Glatfelter et al., 2022). This guide covers where they were found, how they fit into the mushroom’s chemistry, what animal studies show, and how much evidence stands behind the claim that they change the experience.

What is baeocystin?

Baeocystin is a tryptamine, the same chemical family as psilocybin and the brain messenger serotonin. Its chemical name is 4-phosphoryloxy-N-methyltryptamine. Psilocybin is 4-phosphoryloxy-N,N-dimethyltryptamine, so the difference is one methyl group: baeocystin carries one, psilocybin two. Chemists describe baeocystin as a secondary amine, psilocybin as a tertiary amine, and aeruginascin, which carries three methyl groups, as a quaternary ammonium compound (Glatfelter et al., 2022).

Norbaeocystin goes one step further down: it has no methyl groups on that nitrogen at all. It is the phosphate ester of 4-hydroxytryptamine, made when a mushroom enzyme attaches a phosphate to that molecule (Adams et al., 2022). Like psilocybin, these compounds carry a phosphate group. Psilocybin itself works as a prodrug: the body removes the phosphate to give psilocin, the form that acts on serotonin 2A (5-HT2A) receptors. Our guide to psilocin vs psilocybin explains that step. Baeocystin’s dephosphorylated counterpart is called norpsilocin (Sherwood et al., 2020).

That small structural ladder matters. In the 2022 mouse study discussed below, the number of methyl groups tracked closely with whether a compound produced psychedelic-like behaviour (Glatfelter et al., 2022).

Where was baeocystin first found?

Both names come from a mushroom, Psilocybe baeocystis. In 1967 A. Y. Leung and A. G. Paul published a short note in the Journal of Pharmaceutical Sciences describing baeocystin as a “mono-methyl analog of psilocybin” found in saprophytic culture of that species, meaning the fungus grown in the laboratory rather than wild mushrooms (Leung and Paul, 1967). A year later, in the same journal, they reported baeocystin and norbaeocystin together as “new analogs of psilocybin” from the same species (Leung and Paul, 1968).

We could read only the bibliographic records of those two papers, not their text, so we do not describe their methods or amounts. What the record does show is that 1968 is the paper that named norbaeocystin, while baeocystin itself appeared in print the year before. Later papers reported baeocystin in other species and genera, as their titles state (Europe PMC title search).

The largest recent survey measured psilocybin, psilocin, baeocystin, norbaeocystin and aeruginascin in 226 fruiting bodies from 82 collections across seven genera. For many species it reported baeocystin, norbaeocystin and aeruginascin levels for the first time, and it described tryptamine concentrations as extremely variable (Gotvaldová et al., 2022). Why a single measured sample says little about another is the subject of our guide to what lab studies establish about mushroom potency claims.

Where do baeocystin and norbaeocystin sit in the psilocybin pathway?

For decades the chemical route to psilocybin was only partly known. In 2017 a team at the Hans Knöll Institute in Jena characterized four enzymes: PsiD, a new class of fungal tryptophan decarboxylase; PsiK, which adds the phosphate; PsiM, a methyltransferase that adds methyl groups one after another as the last step; and PsiH, a monooxygenase. Combining PsiD, PsiK and PsiM in a test tube produced psilocybin (Fricke et al., 2017).

A 2024 structural study of PsiM sets out the order (Hudspeth et al., 2024); the steps below follow it, with the first enzyme roles taken from the 2017 paper and a 2022 bacterial production study (Adams et al., 2022):

1. The amino acid L-tryptophan loses its carboxyl group (PsiD) and gains a hydroxyl group at the 4-position (PsiH), giving 4-hydroxytryptamine.
2. PsiK attaches a phosphate to that hydroxyl group. The result is norbaeocystin.
3. PsiM adds one methyl group to norbaeocystin’s nitrogen. The result is baeocystin.
4. PsiM adds a second methyl group. The result is psilocybin.
5. A third methyl transfer by PsiM, giving aeruginascin, has been proposed, but the 2024 authors say it lacks experimental evidence.

So in Psilocybe, norbaeocystin and baeocystin are best understood as intermediates: way stations on the road to psilocybin (Hudspeth et al., 2024). A 2025 study found a twist in a different genus. In the fiber cap Inocybe corydalina, the enzymes are unrelated to the Psilocybe set, and the pathway branches, with baeocystin as a second end product rather than only a step on the way. The authors conclude that mushrooms evolved the ability to make psilocybin twice, independently (Schäfer et al., 2025).

Are baeocystin and norbaeocystin psychoactive? What animal studies found

No human study has tested either compound, so the evidence comes from cells and rodents. The main behavioural yardstick is the head-twitch response: a quick head movement that mice and rats make after psychedelics that act on 5-HT2A receptors. It is used as a sign of psychedelic-like activity, not as a measure of what a person would experience (Glatfelter et al., 2022).

The 2020 result is the one most often cited. Researchers at the Usona Institute and the University of California San Diego made the compounds in the lab and found that baeocystin alone did not produce head twitches in mice, even though norpsilocin, its likely breakdown product, strongly activated 5-HT2A receptors in cell assays (Sherwood et al., 2020). A 2025 rat study from the Czech National Institute of Mental Health offers a reason: baeocystin and norpsilocin had a very limited ability to cross the blood-brain barrier, and baeocystin had no significant effect on movement, exploration, anxiety-like behaviour or sensorimotor gating (Danda et al., 2025).

The 2022 study, from the US National Institute on Drug Abuse with partners in Belgium and the United States, compared the whole set side by side. The secondary and tertiary compounds bound many human serotonin receptors in cell tests, but only the tertiary amines, psilocin, psilocybin and psilacetin, produced head twitches. Secondary amines such as baeocystin’s relatives did lower body temperature and movement at higher doses, effects the authors linked to the 5-HT1A receptor (Glatfelter et al., 2022). So “not psychedelic-like in mice” is not the same as “inert”.

Norbaeocystin points the same way. Rats given norbaeocystin made by engineered bacteria showed no head-twitch response (Adams et al., 2022). Yet a study published in October 2026 found that norbaeocystin, like psilocybin, briefly increased anxiety-like behaviour in male rats in one experiment, while a second experiment saw that effect with psilocybin only (Savini et al., 2026). Evidence: consistent on head twitches, preliminary on everything else, and absent in humans.

What is aeruginascin?

Aeruginascin is the three-methyl member of the family. Its structure was worked out in 2006 from the fiber cap mushroom Inocybe aeruginascens, and the authors noted it is closely related to bufotenidine, a frog-skin compound. At the time it had been found only in that one species (Jensen et al., 2006). The 2022 survey later reported aeruginascin concentrations for many species for the first time (Gotvaldová et al., 2022).

Because it is a quaternary ammonium compound, it carries a permanent positive charge. A 2022 conference review by psychiatrists at the University of Alberta and the University of Ottawa concluded that aeruginascin is less likely to cross the blood-brain barrier, that its activity at serotonin receptors is lower than psilocybin’s, that data on it are very limited, and that its direct contribution to any entourage effect is likely limited (Chue et al., 2022). In mice, aeruginascin did not produce head twitches (Glatfelter et al., 2022).

What is the “entourage effect” claim, and how good is the evidence?

The entourage effect is the idea that the minor compounds in a natural material add to, or change, the effect of its main active ingredient. The term was coined in 1998 for cannabis, and a 2025 feature in ACS Central Science notes that a 2020 review found entourage claims in cannabis largely unsubstantiated (Johnson-Groh, 2025). Applied to mushrooms, the claim is that baeocystin, norbaeocystin, aeruginascin and other compounds make a whole mushroom act differently from pure psilocybin (Chue et al., 2022).

Here is what supports it. One research group compared synthetic psilocybin with a psilocybin-containing mushroom extract in mice. Head twitches were similar, but the authors reported larger and more widespread increases in some synaptic proteins and a different brain metabolite profile with the extract, and they called for further studies to confirm the findings and identify which molecules were responsible (Shahar et al., 2024). In a randomized, blind-rated study of 50 mice bred to groom excessively, both treatments reduced grooming equally, and the authors reported a better effect of the extract on head-body twitches and anxiety (Brownstien et al., 2025). That paper drew a published letter of comment from another research group (Gattuso et al., 2025).

Here is what weighs against it. The ACS Central Science feature reports that no human trial has directly compared synthetic and mushroom-derived psilocybin; that the lead author of the extract study described one synaptic-protein difference between the two as not statistically significant; and that researchers who have studied these compounds, including a Usona Institute chemist and the chemist who first identified norpsilocin in mushrooms, are skeptical that baeocystin and its relatives contribute much (Johnson-Groh, 2025). The animal results above point the same way: on their own, baeocystin, norbaeocystin and aeruginascin did not produce psychedelic-like behaviour, and baeocystin barely reached the brain (Danda et al., 2025).

Two further cautions. First, an extract contains many compounds, so even a real difference between extract and pure psilocybin would not show that baeocystin is the cause. Second, the evidence for a human difference is anecdotal. A 2026 commentary from the University of Guelph cites older anecdotal reports linking mushrooms high in aeruginascin with euphoric experiences and mushrooms high in baeocystin with dysphoric ones, and stresses that compounds can also blunt one another’s effects (Perreault et al., 2026). The authors argue for more whole-mushroom research, which is a call for evidence rather than evidence. Evidence: unresolved.

Where does Canada fit in this research?

Canadian researchers are part of the debate rather than its main laboratory. The 2022 aeruginascin review came from psychiatrists at the University of Alberta in Edmonton and the University of Ottawa (Chue et al., 2022). The 2026 call for whole-mushroom research came from three University of Guelph departments: biomedical sciences, integrative biology and plant agriculture (Perreault et al., 2026). And the ACS Central Science feature on the entourage question opens in a facility in a Vancouver suburb that grows psilocybin mushrooms for research and clinical trials (Johnson-Groh, 2025).

On the law, the Controlled Drugs and Substances Act names psilocin and psilocybin, with their salts, as items 11 and 12 of Schedule III. Its section 2(2)(a) says a reference to a controlled substance includes any substance that contains one (CDSA, Justice Laws). Health Canada states that the production, sale and possession of magic mushrooms are illegal in Canada unless authorized (Health Canada). The words baeocystin, norbaeocystin and aeruginascin do not appear in the Act’s text, and we make no claim about how they would be treated on their own. This is general information, not legal advice.

What we still don’t know

• Whether baeocystin, norbaeocystin or aeruginascin has any effect in people. No human study of any of them was found.
• Whether the mouse extract findings hold up in independent labs, and which compound, if any, explains them.
• Whether aeruginascin is really made by PsiM in Psilocybe, or by another route.
• How much of a mushroom’s baeocystin the body turns into norpsilocin, and whether any reaches the brain when the compounds are swallowed with psilocybin rather than injected alone.
• What the 1967 and 1968 papers measured and how. We read their records, not their text.

For the wider picture of how psilocybin itself works, see what psilocybin is. For the blue colour that psilocin produces when tissue is damaged, see why magic mushrooms turn blue.

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