Comparison of solution conformational preferences for the hallucinogens bufotenin and psilocin using 360-MHz proton NMR spectroscopy

Psychedelic-like Activity of Norpsilocin Analogues

Primary metabolites of mushroom tryptamines, psilocybin and baeocystin (i.e., psilocin and norpsilocin), exhibit potent agonist activity at the serotonin 2A receptor (5-HT2A) in vitro but differ in their 5-HT2A-mediated effects in vivo. In particular, psilocin produces centrally mediated psychedelic effects in vivo, whereas norpsilocin, differing only by the loss of an N-methyl group, is devoid of psychedelic-like effects. These observations suggest that the secondary methylamine group in norpsilocin impacts its central nervous system (CNS) bioavailability but not its receptor pharmacodynamics. To test this hypothesis, eight norpsilocin derivatives were synthesized with varied secondary alkyl-, allyl-, and benzylamine groups, primarily aiming to increase their lipophilicity and brain permeability. Structure-activity relationships for the norpsilocin analogues were evaluated using the mouse head-twitch response (HTR) as a proxy for CNS-mediated psychedelic-like effects. HTR studies revealed that extending the N-methyl group of norpsilocin by a single methyl group, to give the corresponding secondary N-ethyl analogue (4-HO-NET), was sufficient to produce psilocin-like activity (median effective dose or ED50 = 1.4 mg/kg). Notably, N-allyl, N-propyl, N-isopropyl, and N-benzyl derivatives also induced psilocin-like HTR activity (ED50 = 1.1-3.2 mg/kg), with variable maximum effects (26-77 total HTR events). By contrast, adding bulkier tert-butyl or cyclohexyl groups in the same position did not elicit psilocin-like HTRs. Pharmacological assessments of the tryptamine series in vitro demonstrated interactions with multiple serotonin receptor subtypes, including 5-HT2A, and other CNS signaling proteins (e.g., sigma receptors). Overall, our data highlight key structural requirements for CNS-mediated psychedelic-like effects of norpsilocin analogues.

The molecular basis of the antidepressant action of the magic mushroom extract, psilocin

Magic mushrooms, and their extract psilocybin, are well-known for their psychedelic properties and recreational use. Psilocin, the bio-active form of psilocybin, can potentially treat various psychiatric diseases. Psilocin putatively exerts its psychedelic effect as an agonist to the serotonin 2A receptor (5-HT2AR), which is also the receptor for the neurological hormone serotonin. The two key chemical differences between the two molecules are first, that the primary amine in serotonin is replaced with a tertiary amine in psilocin, and second, the hydroxyl group is substituted differently on the aromatic ring. Here, we find that psilocin can bind to 5-HT2AR with an affinity higher than serotonin, and provide the molecular logic behind the higher binding affinity of psilocin using extensive molecular dynamics simulations and free energy calculations. The binding free energy of psilocin is dependent upon the protonation states of the ligands, as well as that of the key residue in the binding site: Aspartate 155. We find that the tertiary amine of psilocin, and not the altered substitution of the hydroxyl group in the ring is responsible for the increased affinity of psilocin. We propose design rules for effective antidepressants based on molecular insights from our simulations.

The evolution and ecology of psilocybin in nature

Fungi produce diverse metabolites that can have antimicrobial, antifungal, antifeedant, or psychoactive properties. Among these metabolites are the tryptamine-derived compounds psilocybin, its precursors, and natural derivatives (collectively referred to as psiloids), which have played significant roles in human society and culture. The high allocation of nitrogen to psiloids in mushrooms, along with evidence of convergent evolution and horizontal transfer of psilocybin genes, suggest they provide a selective benefit to some fungi. However, no precise ecological roles of psilocybin have been experimentally determined. The structural and functional similarities of psiloids to serotonin, an essential neurotransmitter in animals, suggest that they may enhance the fitness of fungi through interference with serotonergic processes. However, other ecological mechanisms of psiloids have been proposed. Here, we review the literature pertinent to psilocybin ecology and propose potential adaptive advantages psiloids may confer to fungi.

The neural basis of psychedelic action

Psychedelics are serotonin 2A receptor agonists that can lead to profound changes in perception, cognition and mood. In this review, we focus on the basic neurobiology underlying the action of psychedelic drugs. We first discuss chemistry, highlighting the diversity of psychoactive molecules and the principles that govern their potency and pharmacokinetics. We describe the roles of serotonin receptors and their downstream molecular signaling pathways, emphasizing key elements for drug discovery. We consider the impact of psychedelics on neuronal spiking dynamics in several cortical and subcortical regions, along with transcriptional changes and sustained effects on structural plasticity. Finally, we summarize neuroimaging results that pinpoint effects on association cortices and thalamocortical functional connectivity, which inform current theories of psychedelic action. By synthesizing knowledge across the chemical, molecular, neuronal, and network levels, we hope to provide an integrative perspective on the neural mechanisms responsible for the acute and enduring effects of psychedelics on behavior.

Magic mushroom extracts in lipid membranes

The active hallucinogen of magic mushrooms, psilocin, is being repurposed to treat nicotine addiction and treatment-resistant depression. Psilocin belongs to the tryptamine class of psychedelic compounds which include the hormone serotonin. It is believed that psilocin exerts its effect by binding to the serotonin 5-HT_2A receptor. However, recent in-vivo evidence suggests that psilocin may employ a different mechanism to exert its effects. Membrane-mediated receptor desensitization of neurotransmitter receptors is one such mechanism. We compare the impact of the neutral and charged versions of psilocin and serotonin on the properties of zwitterionic and anionic lipid membranes using molecular dynamics simulations and calorimetry. Both compounds partition to the lipid interface and induce membrane thinning. The tertiary amine in psilocin, as opposed to the primary amine in serotonin, limits psilocin's impact on the membrane although more psilocin partitions into the membrane than serotonin. Calorimetry corroborates that both compounds induce a classical melting point depression like anesthetics do. Our results also lend support to a membrane-mediated receptor-binding mechanism for both psilocin and serotonin and provide physical insights into subtle chemical changes that can alter the membrane-binding of psychedelic compounds.

Assessment of Bioactivity-Modulating Pseudo-Ring Formation in Psilocin and Related Tryptamines

Psilocybin (1) is the major alkaloid found in psychedelic mushrooms and acts as a prodrug to psilocin (2, 4‐hydroxy‐N,N‐dimethyltryptamine), a potent psychedelic that exerts remarkable alteration of human consciousness. In contrast, the positional isomer bufotenin (7, 5‐hydroxy‐N,N‐dimethyltryptamine) differs significantly in its reported pharmacology. A series of experiments was designed to explore chemical differences between 2 and 7 and specifically to test the hypothesis that the C‐4 hydroxy group of 2 significantly influences the observed physical and chemical properties through pseudo‐ring formation via an intramolecular hydrogen bond (IMHB). NMR spectroscopy, accompanied by quantum chemical calculations, was employed to compare hydrogen bond behavior in 4‐ and 5‐hydroxylated tryptamines. The results provide evidence for a pseudo‐ring in 2 and that sidechain/hydroxyl interactions in 4‐hydroxytryptamines influence their oxidation kinetics. We conclude that the propensity to form IMHBs leads to a higher number of uncharged species that easily cross the blood‐brain barrier, compared to 7 and other 5‐hydroxytryptamines, which cannot form IMHBs. Our work helps understand a fundamental aspect of the pharmacology of 2 and should support efforts to introduce it (via the prodrug 1) as an urgently needed therapeutic against major depressive disorder.

1H Nuclear Magnetic Resonance: A Future Approach to the Metabolic Profiling of Psychedelics in Human Biofluids?

While psychedelics may have therapeutic potential for treating mental health disorders such as depression, further research is needed to better understand their biological effects and mechanisms of action when considering the development of future novel therapy approaches. Psychedelic research could potentially benefit from the integration of metabonomics by proton nuclear magnetic resonance (1H NMR) spectroscopy which is an analytical chemistry-based approach that can measure the breakdown of drugs into their metabolites and their metabolic consequences from various biofluids. We have performed a systematic review with the primary aim of exploring published literature where 1H NMR analysed psychedelic substances including psilocin, lysergic acid diethylamide (LSD), LSD derivatives, N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and bufotenin. The second aim was to assess the benefits and limitations of 1H NMR spectroscopy-based metabolomics as a tool in psychedelic research and the final aim was to explore potential future directions. We found that the most current use of 1H NMR in psychedelic research has been for the structural elucidation and analytical characterisation of psychedelic molecules and that no papers used 1H NMR in the metabolic profiling of biofluids, thus exposing a current research gap and the underuse of 1H NMR. The efficacy of 1H NMR spectroscopy was also compared to mass spectrometry, where both metabonomics techniques have previously shown to be appropriate for biofluid analysis in other applications. Additionally, potential future directions for psychedelic research were identified as real-time NMR, in vivo 1H nuclear magnetic resonance spectroscopy (MRS) and 1H NMR studies of the gut microbiome. Further psychedelic studies need to be conducted that incorporate the use of 1H NMR spectroscopy in the analysis of metabolites both in the peripheral biofluids and in vivo to determine whether it will be an effective future approach for clinical and naturalistic research.

Bioactive Azepine-Indole Alkaloids from Psychotria nemorosa

Phytochemical investigation of the alkaloid extract of the aerial parts of Psychotria nemorosa led to the isolation and characterization of 10 azepine-indole alkaloids, i.e., cimitrypazepine (1), fargesine (2), nemorosines A (3), and B (12), nemorosinosides A-F (4-9), as well as two β-carboline derivatives, 10-hydroxyisodolichantoside (10) and 10-hydroxydolichantoside (11), an isoxazole alkaloid, nemorosinoside G (13), serotonin (14), bufotenine (15), and (S)-gentianol (16). Compounds 3-13 have not yet been described. These compounds were isolated by semipreparative HPLC, and their structures were determined by means of HRMS, NMR, and ECD measurements. In addition, the monoamine oxidase-A (MAO-A), MAO-B, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activities were evaluated. Alkaloids 1-3 inhibited the MAO-A activity with IC₅₀ values of 1.4, 1.4, and 0.9 μM, respectively.

Synthesis and Biological Evaluation of Tryptamines Found in Hallucinogenic Mushrooms: Norbaeocystin, Baeocystin, Norpsilocin, and Aeruginascin

A general synthetic method was developed to access known tryptamine natural products present in psilocybin-producing mushrooms. In vitro and in vivo experiments were then conducted to inform speculations on the psychoactive properties, or lack thereof, of the natural products. In animal models, psychedelic activity by baeocystin alone was not evident using the mouse head twitch response assay, despite its putative dephosphorylated metabolite, norpsilocin, possessing potent agonist activity at the 5-HT_2A receptor.

Microdosing psychedelics: More questions than answers? An overview and suggestions for future research

BACKGROUND

In the past few years, the issue of 'microdosing' psychedelics has been openly discussed in the public arena where claims have been made about their positive effect on mood state and cognitive processes such as concentration. However, there are very few scientific studies that have specifically addressed this issue, and there is no agreed scientific consensus on what microdosing is.

AIM

This critique paper is designed to address questions that need to be answered by future scientific studies and to offer guidelines for these studies.

APPROACH

Owing to its proximity for a possible approval in clinical use and short-lasting pharmacokinetics, our focus is predominantly on psilocybin. Psilocybin is allegedly, next to lysergic acid diethylamide (LSD), one of the two most frequently used psychedelics to microdose. Where relevant and available, data for other psychedelic drugs are also mentioned.

CONCLUSION

It is concluded that while most anecdotal reports focus on the positive experiences with microdosing, future research should also focus on potential risks of (multiple) administrations of a psychedelic in low doses. To that end, (pre)clinical studies including biological (e.g. heart rate, receptor turnover and occupancy) as well as cognitive (e.g. memory, attention) parameters have to be conducted and will shed light on the potential negative consequences microdosing could have.

Biological Effects and Biodistribution of Bufotenine on Mice

Bufotenine is an alkaloid derived from serotonin, structurally similar to LSD and psilocin. This molecule is able to inhibit the rabies virus infection in in vitro and in vivo models, increasing the survival rate of infected animals. Being a very promising molecule for an incurable disease and because of the fact that there is no consensus regarding its neurological effects, this study aimed to evaluate chronic treatment of bufotenine on behavior, pathophysiology, and pharmacokinetics of mice. Animals were daily treated for 21 consecutive days with 0.63, 1.05, and 2.1 mg/animal/day bufotenine and evaluated by open field test and physiological parameters during all the experiment. After this period, organs were collected for histopathological and biodistribution analysis. Animals treated with bufotenine had mild behavioral alterations compared to the control group, being dose-response relationship. On the other hand, animals showed normal physiological functions and no histological alterations in the organs. With high doses, an inflammatory reaction was observed in the site of injection, but with no cellular damage. The alkaloid could be found in the heart and kidney with all doses and in the lungs and brain with higher doses. These results show that the effective dose, 0.63 mg/day, is safe to be administered in mice, since it did not cause significant effects on the animals' physiology and on the CNS. Higher doses were well tolerated, causing only mild behavioral effects. Thus, bufotenine might be a drug prototype for rabies treatment, an incurable disease.

Glucuronidation of psilocin and 4-hydroxyindole by the human UDP-glucuronosyltransferases

We have examined the glucuronidation of psilocin, a hallucinogenic indole alkaloid, by the 19 recombinant human UDP-glucuronosyltransferases (UGTs) of subfamilies 1A, 2A, and 2B. The glucuronidation of 4-hydroxyindole, a related indole that lacks the N,N-dimethylaminoethyl side chain, was studied as well. UGT1A10 exhibited the highest psilocin glucuronidation activity, whereas the activities of UGTs 1A9, 1A8, 1A7, and 1A6 were significantly lower. On the other hand, UGT1A6 was by far the most active enzyme mediating 4-hydroxyindole glucuronidation, whereas the activities of UGTs 1A7-1A10 toward 4-hydroxyindole resembled their respective psilocin glucuronidation rates. Psilocin glucuronidation by UGT1A10 followed Michaelis-Menten kinetics in which psilocin is a low-affinity high-turnover substrate (K(m) = 3.8 mM; V(max) = 2.5 nmol/min/mg). The kinetics of psilocin glucuronidation by UGT1A9 was more complex and may be best described by biphasic kinetics with both intermediate (K(m1) = 1.0 mM) and very low affinity components. The glucuronidation of 4-hydroxyindole by UGT1A6 exhibited higher affinity (K(m) = 178 microM) and strong substrate inhibition. Experiments with human liver and intestinal microsomes (HLM and HIM, respectively) revealed similar psilocin glucuronidation activity in both samples, but a much higher 4-hydroxyindole glucuronidation rate was found in HLM versus HIM. The expression levels of UGTs 1A6-1A10 in different tissues were studied by quantitative real-time-PCR, and the results, together with the activity assays findings, suggest that whereas psilocin may be subjected to extensive glucuronidation by UGT1A10 in the small intestine, UGT1A9 is likely the main contributor to its glucuronidation once it has been absorbed into the circulation.

Bufotenine: toward an understanding of possible psychoactive mechanisms

A review of the neuropharmacology of the alleged hallucinogen bufotenine is presented, including recent experimental results showing activity similar to LSD and other known hallucinogens (psilocin and 5-MeO-DMT) at the purported hallucinogenic serotonin (5-HT) receptors, 5-HT2A and 5-HT2C. In addition, current reports of computer modeling of the receptors and ligand binding sites give evidence of bufotenine's ability to bind and activate these receptors. While binding and activation of the purported hallucinogenic receptors are not the full extent of the hallucinogenic signature, this evidence shows support for the rationale that the reported lack of the drug's classic hallucinogenic response in human experiments is due to poor ability to cross the blood brain barrier (BBB), not lack of activation of the appropriate brain receptors. Further evidence is reviewed that in some physiological states, some drugs with characteristics similar to bufotenine which do not normally cross the BBB, cross it and enter the brain. While direct human experimental evidence of bufotenine's hallucinogenic activity seems lacking, the above combined factors are considered, and possible explanations of bufotenine's reported psychoactivity are suggested. Additionally, updated experimental models testing the possible nature of bufotenine's hallucinogenic potential are proposed.

Bufo toads and bufotenine: fact and fiction surrounding an alleged psychedelic

This paper investigates the supposedly psychedelic Bufo toad and the allegedly psychedelic drug bufotenine, which is contained in the skin and glands of this toad. The bufo toad has held a place in human mythologies and medicines worldwide since archaic times. Used by ancient peoples for a variety of purposes, its most spectacular effects, according to lore, involve magical and shamanic or occult uses for casting spells and for divination. In the Middle Ages, the Bufo toad was celebrated as a panacea and persecuted as a powerful poison. More recently, in the 1960s the Bufo toad was resurrected as a countercultural icon, with people purportedly licking or smoking the secretions to get high. Bufotenine has been at the center of a scientific debate since its discovery in 1893. This paper examines the extensive literature surrounding the Bufo toad and bufotenine, and untangles many of the myths and the misinformation that continue to vex both science and popular reporting. Finally, to promote further investigation, a comprehensive bibliography is provided that charts the history of the Bufo toad and bufotenine.

Studies of the relationship between molecular structure and hallucinogenic activity

The nature of the stereochemistry and aromatic ring substituents and their importance to biological activity for phenethylamine-type hallucinogens is presented. The possibility of a hydrophobic site to bind to the 4-substituent and its likely geometry is described. A brief discussion of the structure-activity relationships for tryptamines such as psilocin and DMT is also given, with comments about the stereochemistry of alpha-methyltryptamines. Evaluation of a series of N(6)-alkyl-nor-LSD derivatives indicated that selected members such as N(6)-ethyl, allyl and propyl were as potent as, if not more potent than LSD, both in a two-lever drug discrimination assay in rats, and in man. N(6)-alkyl groups longer than n-propyl, such as n-butyl or 2-phenethyl, gave compounds that were greatly reduced in activity.

Indolealkylamine and phenalkylamine hallucinogens: a brief overview

Various indolealkylamine and phenalkylamine derivatives are hallucinogenic in man and/or are behaviorally active in animals. This overview is divided into two parts. The first part attempts to bring together information concerning the activity of indolealkylamines (i.e., tryptamines, alpha-methyltryptamines, N,N-dimethyltryptamines, N-alkyltryptamines, lysergic acid derivatives and beta-carbolines) and phenalkylamines (i.e., phenethylamines, phenylisopropylamines) along with major key references, and with emphasis on those agents not recently reviewed. The latter portion of this overview describes some of the work being conducted in our laboratories in an effort to elucidate the role of the neurotransmitter serotonin in the mechanism of action of various indolealkylamine and phenalkylamine hallucinogens.