Summary: Psilocybin — the active principle behind “magic mushrooms” — is emerging as a promising treatment for depression, anxiety and other neuropsychiatric disorders. Yet many patients and clinicians are concerned about the intense hallucinatory experiences these drugs can produce. Researchers have now developed modified psilocin derivatives that aim to preserve therapeutic benefits while minimizing hallucinogenic effects.
By designing and testing a lead compound called 4e, the team achieved a slower, sustained conversion to psilocin in the brain. In preclinical studies in mice, 4e crossed the blood–brain barrier effectively, engaged key serotonin receptors, and produced far fewer behavioral signs associated with psychedelic activity than standard psilocybin.
Key Facts
- Separating benefit from the “trip”: The study supports the possibility that antidepressant and neurotherapeutic effects of psychedelics can be achieved without the full hallucinogenic experience.
- Candidate 4e: Of five synthesized fluorinated N-alkyl carbamate derivatives, 4e demonstrated the best balance of chemical stability, oral absorption, and gradual release of psilocin.
- Brain penetration and exposure: 4e effectively entered the brain and produced a lower peak but longer-lasting psilocin exposure compared with psilocybin.
- Reduced psychedelic markers: Mice given 4e displayed significantly fewer head twitches — a validated rodent indicator of psychedelic-like action — while the compound still activated serotonin receptors.
- Potential applications: A sub-hallucinogenic psilocin formulation could broaden clinical use for mood disorders, substance use disorders, and possibly some neurodegenerative conditions where serotonin signaling is relevant.
Source: ACS
Psilocybin, the psychoactive compound in “magic mushrooms,” has attracted attention for its therapeutic potential in depression, anxiety, addiction and some neurodegenerative diseases. However, the characteristic hallucinations limit acceptability and clinical adoption for many patients.
In a study published in ACS’ Journal of Medicinal Chemistry, researchers report the design and preclinical evaluation of fluorinated, reversible N-alkyl carbamate derivatives of psilocin. These derivatives were created to slow and control psilocin release, thereby maintaining receptor activity while reducing acute hallucinogenic-like effects in mice.
“Our data support a growing view in the field that serotonergic activity and psychedelic effects can be uncoupled,” says Andrea Mattarei, a corresponding author. “This opens the door to new therapeutics that keep beneficial neurobiological activity while minimizing mind‑altering experiences, making treatments safer and more practical.”
Serotonin imbalance is implicated in mood disorders and certain neurodegenerative diseases such as Alzheimer’s. For years, scientists have explored how psychedelics like psilocybin modulate serotonin pathways to promote neuroplasticity and mood improvement. Still, rapid peaks of psilocin in the brain often trigger hallucinations, which can deter patients from treatment.
To address this, a team led by Sara De Martin, Andrea Mattarei and Paolo Manfredi synthesized five psilocin derivatives engineered to hydrolyze more slowly and provide sustained, controlled psilocin exposure. Initial screening used human plasma and gastrointestinal-mimicking laboratory assays to assess stability and absorption potential.
Those experiments identified compound 4e as the most promising candidate. 4e showed favorable stability in biological media, oral bioavailability, and a tendency to release psilocin gradually rather than producing a sharp concentration spike. Crucially, 4e retained intrinsic activity at key serotonin receptors (including 5‑HT2A and 5‑HT2C) at levels comparable to psilocin.
The researchers then compared equivalent oral doses of 4e and pharmaceutical-grade psilocybin in mice and measured psilocin levels in blood and brain over 48 hours. Mice treated with 4e displayed a lower peak concentration but a longer-lasting presence of psilocin in the brain than mice given psilocybin.
Behavioral assessment showed that 4e-treated animals exhibited significantly fewer head twitches — a standard behavioral proxy for psychedelic-like effects in rodents — despite robust serotonergic receptor engagement. The team attributes this difference mainly to the timing and magnitude of psilocin exposure in the brain: gradual, sustained levels avoided the threshold that typically triggers acute hallucinatory responses.
These findings demonstrate the feasibility of designing brain-penetrant psilocin derivatives that maintain serotonin receptor activity while reducing acute psychotropic effects. The authors caution that additional studies are needed to define mechanisms, confirm safety, and determine whether these sub-hallucinogenic profiles translate from animals to humans.
Funding: The research received support from MGGM Therapeutics, LLC in collaboration with NeuroArbor Therapeutics Inc. Several authors are named inventors on patents related to psilocin chemistry.
Key Questions Answered:
A: Current evidence suggests yes. While some argue that a mystical or peak experience is required for therapeutic benefit, this study supports the idea that neuroplastic and mood‑regulating effects are mediated at the cellular level via serotonin receptors. Maintaining receptor engagement without a sudden, large brain exposure to psilocin may allow therapeutic actions without hallucinations.
A: Hallucinatory responses are frequently linked to a rapid spike of psilocin in the brain. An extended‑release profile, like that produced by 4e, keeps therapeutic concentrations steady and below the threshold that triggers acute perceptual changes while preserving mood‑modulating activity.
A: These results are preliminary and limited to animal models. Further pharmacology, toxicology and human clinical trials will be required to determine safety, efficacy and regulatory approval timelines.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was provided by staff editors.
About this psychopharmacology research news
Author: Sarah Michaud
Source: ACS
Contact: Sarah Michaud – ACS
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Design, Synthesis, and Pharmacokinetic Profiling of Fluorinated Reversible N-Alkyl Carbamate Derivatives of Psilocin for Sub-Hallucinogenic Brain Exposure” by Marco Banzato, Martina Colognesi, Lorena Lucatello, Stefano Comai, Gianfranco Pasut, Francesca Capolongo, Laura Orian, Lucia Biasutto, Anna Signor, Daniela Gabbia, Paolo L. Manfredi, Sara De Martin, and Andrea Mattarei. Journal of Medicinal Chemistry
DOI: 10.1021/acs.jmedchem.5c01797
Abstract
Design, Synthesis, and Pharmacokinetic Profiling of Fluorinated Reversible N-Alkyl Carbamate Derivatives of Psilocin for Sub-Hallucinogenic Brain Exposure
Psilocybin, the phosphorylated prodrug of psilocin, offers therapeutic promise across a spectrum of neuropsychiatric disorders, but its clinical use is limited by acute psychoactive effects. This work describes the rational design, synthesis, and pharmacokinetic evaluation of a focused library of fluorinated reversible N-alkyl carbamate derivatives of psilocin intended to reduce acute psilocin exposure and thereby mitigate hallucinogenic-like responses.
Carbamate bond stability was tuned systematically by changing the number and position of fluorine atoms on the alkyl promoiety, producing compounds with controlled hydrolysis under physiological conditions. A lead compound, 4e, displayed favorable oral bioavailability, effective brain penetration, and partial bioconversion to psilocin. Importantly, 4e showed intrinsic activity at 5-HT2A and 5-HT2C serotonin receptors while eliciting attenuated psychotropic effects compared with psilocybin.
These results highlight fluorinated carbamate chemistry as a practical approach to modulate psilocin exposure and serotonergic signaling, offering a platform to develop therapeutics that balance biological efficacy with reduced acute mind‑altering effects.