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  • Ian Bollinger

Can Psilocybe mushrooms make MAOIs?

Scientists (Felix Blei, Sebastian Dörner et al) investigated whether species of Psilocybe produced β‐carbolines, a tryptamine family known to act as a class of Mono-Amine Oxidase Inhibitors (MAOIs). They were successful in quantifying trace amounts of harmane and harmine in mycelia, mushrooms (carpophores), and truffles (sclerotia) of five different Psilocybe species.

#maois #betacarbolines #harmine #harmane #psilocybe #research #biosynthesis

Hypotheses and Takeaways

The Scientists, during their research on Psilocybe mexicana methanol extracts, noticed signal outside the range of the typical psilocybin-like class of compounds (Fig 1A). They noticed that these signals appeared much later than the psilocybin-like tryptamines, appearing to be of much higher masses. Due to this they "hypothesized that β‐carbolines may account for these signals as the observed masses are in good agreement with that of harmane and harmine.[1]"

This would be quite unique, as in much of the biological world there are rarely cases of simultaneous production in a single species of a natural product and a inhibitor of that product's degradation; much less a psychotropic one!

β -Carboline & Tryptamine Breakdown

Found in flora, fauna, and fungi, β‐carbolines are metabolized from the amino acid tryptophan.[1, 3] Because of their similar origin and shared structure β‐carbolines as compounds are substrates to the enzyme Mono Amine Oxidase (MAOs, explained further below). The enzyme targets the amine 'arm' which in the case of tryptamines like DMT or psilocin are easy targets; however with β‐carbolines the amine 'arm' is bound in a ring structure and the enzyme is not only unable to easily break it down but struggles to remove the substrate as well. This directly relates to why ayahuasca functions as an orally active psychedelic. Since both tryptamines like DMT and β‐carbolines are present in the same extract, ingestion ensures that any present MAO is inhibited by the β‐carbolines, allowing DMT to more readily reach receptor sites. Alternatively this can also be understood from a mushroom product perspective, as the phosphate group present in psilocybin is also active in protecting the compound from MAO breakdown (see last week's post). As an interesting note exposure to UV light causes β‐carbolines fluoresce.[2]

Eating and MAOIs

All enzymes present in our digestive tracts play a role in the absorption and regulation of nutrients our body receives. Lactose sugars in milk are broken down by enzymes called lactases. Mono Amines (like tyramines, tryptamines, and phenylethylamines) are broken down by enzymes called Mono Amine Oxidases (MAOs). Considering this, a person who produces insufficient levels of the enzyme lactase should avoid ingesting milk-based products; so too should people be aware of medications like MAO Inhibitors (MAOIs) and heavy amine Almost all of the substrates for MAOs effect human neurobiology in a significant way; "[s]ubstrates for MAO include...neurotransmitters...trace amines....[and] xenobiotic amines, including drugs".[4] The regulatory role of these enzymes is not to be understated, science has come to show that changes in serotonin and dopamine levels impact mood in significant ways; so much so that Strong Serotonin Re-uptake Inhibitors (SSRIs) and MAOIs are widely used as antidepressants.

MALDI-MS Methodolgy

To create the first image depicted in this article (Fig 3), the Scientists used a method of quantifying and imaging harmane relative to hyphal growth patterns with the high-end analysis instrumentation called Matrix-assisted Laser desorption/ionization (MALDI) tied to a Mass Spectrometer (MS). First, hyphae must be grown on the analysis substrate (matrix), in this case was a mixture of mannitol (sugar), egg yolk (protein), polymyxin B (antibacterial), and agar for structure (MEP agar). Once established, the agar plate is dried, sprayed with a mixture that prepares the sample for analysis. The matrix-layered plate is placed into the MADLI instrument, and fractions of the sample are hit with a laser that causes two things to happen 1) the compounds inside of the matrix are hit by a high-powered laser that causes them to become charged (ionize) and leave the matrix (desorption, opposite of absorption/adsorption) and 2) accelerate in speed based on their molecule mass and charge. Those molecules each 'softly ionized' and moving towards the Mass Spectrometer due to an electric field, can then be quantified based on the time it takes for them to hit the detector, also known as time of flight (TOF). Through multiple micro-samplings at a specific size range, data can be compiled and compared to a common standard, normalized, and prepared for quantification. The Scientists in this case utilized a protein standard since all of these compounds are based on the amino acid tryptophan. The data was then normalized to the heat map you see presented, which was directly overlaid with an image of the analysis sample for investigating hyphal distribution of harmane (Fig 3).

Conclusion and Caveats

In this paper it was quite assuredly concluded that the presence of β‐carbolines was detected in mycelia, sclerotia, and carpophores of numerous Psilocybe species. While only P. mexicana was able to be analyzed for sclerotia, and only mushrooms were analyzed in all species, it is important to note that the sclerotia and hyphae were the location where higher concentrations of β‐carbolines were observed (Fig 1C, 3). Also worth noting are the concentrations being quite low.

Interesting discoveries include a compound that the Scientists presumed to be "consistent with that of cordysinins C and D, i.e., enantiomeric β‐carbolines described from the caterpillar fungus Ophiocordyceps sinensis.[5] Comparison with a synthesized mixture of [cordysinins] confirmed that one of those compounds, or both, is a P. mexicana metabolite as well."

Accept or Reject Proposed Hypotheses?

β‐carbolines may account for [large molecule tryptamine signals in P. mexicana methanol extracts]

Reviewing the data and the conclusions put forth, the hypothesis proposed by the Scientists was supported. The reason for acceptance are quoted below (emphasis and parentheticals mine):

"[We] repeated the analysis...using an acidic aqueous mushroom extract and [a High-Performance Liquid Chromatography] instrument interfaced to a fluorescence detector...[t]he signals were detected again, and authentic [harmane] and [harmine] standards showed identical retention times and masses."

"P. cubensis mycelium was directly grown on indium tin oxide (ITO)‐coated glass slides for Imaging MS." Figure 3 depicts the presence of harmane as a heat map (hot colors: higher concentrations of harmane).


1) J. R. F. Allen, B. R. Holmstedt, Phytochemistry1980, 19, 1573–1582.

2) F. A. O. Rasse-Suriani, F. S. García-Einschlag, M. Rafti, T. Schmidt De León, P. M. David Gara, R. Erra-Balsells, F. M. Cabrerizo, Photochem. Photobiol.2018, 94, 36–51.

3a) W. Steglich, L. Kopanski, M. Wolf, M. Moser, G. Tegtmeyer, Tetrahedron Lett.1984, 25, 2341– 2344.

3b) R. J. Jaeger, M. Lamshöft, S. Gottfried, M. Spiteller, P. Spiteller, J. Nat. Prod.2013, 76, 127– 134.

4) Andrea M. Cesura, in xPharm: The Comprehensive Pharmacology Reference, 2007.

5) M.-L. Yang, P.-C. Kuo, T.-L. Hwang, T.-S. Wu, J. Nat. Prod.2011, 74, 1996– 2000

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