Study Identifies Compounds and Mechanism that Causes Psilocybin Mushroom Bluing

These bluing compounds can exist as dimeric, trimeric, and tetrameric forms of psilocin and/or its structural analogs.


A recent study is further unraveling the mystery surrounding the bluing reaction of psilocybin mushrooms (aka psychedelic mushrooms or magic mushrooms) in the genus Psilocybe.

Blue bruising (from bumping, cutting, or another injury) is a signature feature of psilocybin-containing mushrooms. Since the 1960s, scientists have known that enzymes in mushrooms oxidize psilocin to a blue color.1–5 However, these tests were done using mammalian tissues and they may not represent the mechanism by which the blue color forms in mushrooms.

Bluing provides strong evidence that a particular mushroom is an active psilocybin mushroom. According to mushroom expert Paul Stamets, the blue bruising is one of two features often used for determining if a mushroom has a high probability of containing psilocybin: blue bruising and a purple-brown spore print.6

The Enzymes Involved in Magic Mushroom Bluing

Researchers at the Hans-Knöll Institute in Jena, Germany, used spectroscopy technologies to identify two enzymes in Psilocybe cubensis that lead to blue reaction products.7 The study found that PsiP (a phosphatase) and PsiL (a laccase) degrade psilocybin (Figure 1) in a cascade reaction. This degradation prepares the psilocybin molecule for oxidative oligormization that leads to the formation of a blue compound. Specifically, PsiP removes the 4-O-phosphate group form psilocybin to form psilocin (Figure 1). At the same time, PsiL oxidizes the 4-hydroxy group.

Figure 1: The chemical structures of psilocybin and psilocin. Note that psilocin is dephosphorylated psilocybin, a reaction catalyzed by the enzyme PsiP.7

Dimeric, Trimeric, and Tetrameric Chromophores of Psilocin

Using MALDI-MS (matrix-assisted laser desorption/ionization mass spectroscopy) and in situ NMR (nuclear magnetic resonance) spectroscopy, three chemical structures of the chromophores responsible for bluing were identified. The main structure is shown in Figure 2. The study authors summed up their findings with the statement,

“…the blue color is due to a heterogeneous mixture of quinoid psilocyl oligomers, primarily coupled via C-5.

Figure 2: The chemical structure of the primary quinol compound that makes magic mushrooms turn blue.7 This basic structure is two psilocin molecules (called a dimer) connected by a double bond at the 5th position. The quinoid results when the -OH group on carbon 4 is oxidized to =O by the enzyme PsiL. The dotted lines with brackets indicate additional carbons where oxidized psilocin can attach to create a quinoid trimer. A quinol tetramer is formed when oxidized psilocin attaches to all four carbons. The oxidation reactions are reversible.

Dr. Dirk Hoffmeister of the Leibniz Institute for Natural Product Research and Infection Biology at the Hans-Knöll Institute and his research team have been working with magic P. cubensis for years. During that time, they have curiously witnessed the bluing phenomenon and set their sights on solving the mystery. However, their interest in magic mushrooms is not just about their chemistry. In a recent interview, Dr. Hoffmeister told Chemistry World,

Psilocybin is looked at as this illegal, recreational drug, but it has a fantastic potential as a medication for therapy resistant depression.

There’s More to Learn About the Chemistry of Magic Mushroom Bluing

This study data indicates that the blue (or in some cases blue-green) color observed in magic mushrooms may be due to one or more combinations of compounds, collectively “bluing compounds.” These bluing compounds can exist as dimeric, trimeric, and tetrameric forms of psilocin and/or its structural analogs. The multitude of different bluing compounds explains the different shades of blue and blue/green that are observed in different species of magic mushrooms.

There may be several biosynthetic routes by which the mushrooms created bluing compounds. Based on the data from this study, the oxidative power and substrate concentration appear to be limiting factors in how much of each oligomer is present. More research will help clarify these aspects of the bluing mechanism.

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