Molecular basis of the selective binding of MDMA enantiomers to the alpha4beta2 nicotinic receptor subtype: Synthesis, pharmacological evaluation and mechanistic studies

Applications and Potential of In Silico Approaches for Psychedelic Chemistry

Molecular-level investigations of the Central Nervous System have been revolutionized by the development of computational methods, computing power, and capacity advances. These techniques have enabled researchers to analyze large amounts of data from various sources, including genomics, in vivo, and in vitro drug tests. In this review, we explore how computational methods and informatics have contributed to our understanding of mental health disorders and the development of novel drugs for neurological diseases, with a special focus on the emerging field of psychedelics. In addition, the use of state-of-the-art computational methods to predict the potential of drug compounds and bioinformatic tools to integrate disparate data sources to create predictive models is also discussed. Furthermore, the challenges associated with these methods, such as the need for large datasets and the diversity of in vitro data, are explored. Overall, this review highlights the immense potential of computational methods and informatics in Central Nervous System research and underscores the need for continued development and refinement of these techniques and more inclusion of Quantitative Structure-Activity Relationships (QSARs).

The promise of psychedelic research

The use of psychedelics as medicines and for overall better brain health is potentially one of the most transformative developments given their immediate and long-lasting therapeutic effects across a plethora of neuropsychiatric disorders and, more recently, some neurodegenerative diseases. The US psychedelic drugs market is forecasted to grow by 16.3% by 2027 due to the increasing prevalence of treatment-resistant depression and mental health disorders. Decades-long restrictions, which date back to when psychedelics were declared controlled substances in 1970, have been lifted to allow researchers to publish on the therapeutic benefits of psychedelics. This review will feature the incredible depth of research underway revealing how psychedelics impact brain structure and function to treat mental health and other neurological disorders.

Dark Classics in Chemical Neuroscience: 3,4-Methylenedioxymethamphetamine

Better known as "ecstasy", 3,4-methylenedioxymethamphetamine (MDMA) is a small molecule that has played a prominent role in defining the ethos of today's teenagers and young adults, much like lysergic acid diethylamide (LSD) did in the 1960s. Though MDMA possesses structural similarities to compounds like amphetamine and mescaline, it produces subjective effects that are unlike any of the classical psychostimulants or hallucinogens and is one of the few compounds capable of reliably producing prosocial behavioral states. As a result, MDMA has captured the attention of recreational users, the media, artists, psychiatrists, and neuropharmacologists alike. Here, we detail the synthesis of MDMA as well as its pharmacology, metabolism, adverse effects, and potential use in medicine. Finally, we discuss its history and why it is perhaps the most important compound for the future of psychedelic science-having the potential to either facilitate new psychedelic research initiatives, or to usher in a second Dark Age for the field.

3,4-Methylenedioxymethamphetamine (MDMA) Alters Synaptic Dopamine Release in the Dorsal Striatum Through Nicotinic Receptors and DAT Inhibition

An increase of extracellular dopamine (DA) has been implicated in the psychostimulant properties of 3,4-methylenedioxymethamphetamine (MDMA). Although this drug has been reported to affect the DA uptake transporter (DAT), it might activate other mechanisms to regulate the outflow of DA in the brain. Our aim was to examine the overall effects of MDMA on the release of DA in the striatum. We studied the effect of MDMA on stimulus-evoked synaptic DA release in dorsal striatal slices of mice using in vitro amperometric techniques. We also tested the effects of MDMA on the nicotine-induced responses in substantia nigra pars compacta (SNpc) neurons using intracellular electrophysiological recordings. MDMA (1-30 µM) depressed the amplitude and prolonged the decay-time of synaptic DA release in the striatum. Interestingly, in the presence of the broad nicotinic receptor antagonist mecamylamine, and the more selective α₄β₂ antagonist dihydroβerythroidine (DHβE), MDMA enhanced both peak and duration of DA release. A similar effect was found on cocaine-insensitive (DAT-CI) mice slices. Concentrations of MDMA higher than 100 µM enhanced striatal DA outflow that was in turn, reduced by cocaine. Electrophysiological recordings of dopaminergic neurons in SNpc showed that MDMA depressed the effects of nicotine. Our data are consistent with a prevalent MDMA-induced inhibition of the synaptic release of DA in the dorsal striatum mediated by an interaction with nicotinic receptors. This drug also blocks DAT acting on a different site from cocaine and, at higher concentrations, has amphetamine-like releasing properties.

Nitrile in the Hole: Discovery of a Small Auxiliary Pocket in Neuronal Nitric Oxide Synthase Leading to the Development of Potent and Selective 2-Aminoquinoline Inhibitors

Neuronal nitric oxide synthase (nNOS) inhibition is a promising strategy to treat neurodegenerative disorders, but the development of nNOS inhibitors is often hindered by poor pharmacokinetics. We previously developed a class of membrane-permeable 2-aminoquinoline inhibitors and later rearranged the scaffold to decrease off-target binding. However, the resulting compounds had decreased permeability, low human nNOS activity, and low selectivity versus human eNOS. In this study, 5-substituted phenyl ether-linked aminoquinolines and derivatives were synthesized and assayed against purified NOS isoforms. 5-Cyano compounds are especially potent and selective rat and human nNOS inhibitors. Activity and selectivity are mediated by the binding of the cyano group to a new auxiliary pocket in nNOS. Potency was enhanced by methylation of the quinoline and by introduction of simple chiral moieties, resulting in a combination of hydrophobic and auxiliary pocket effects that yielded high (∼500-fold) n/e selectivity. Importantly, the Caco-2 assay also revealed improved membrane permeability over previous compounds.

Design of novel 3,6-diazabicyclo[3.1.1]heptane derivatives with potent and selective affinities for α4β2 neuronal nicotinic acetylcholine receptors

New analogues (3a-l) of the previously described α4β2 selective ligand 3-(6-halopyridin-3-yl)-3,6-diazabicyclo[3.1.1]heptanes (2a,b) have been synthesized and their binding activity for neuronal acetylcholine receptor subtypes α4β2 and α7 were assayed. Six of these compounds (3a,b,c,j,k and l) showed high affinity and selectivity for α4β2 receptors. The phenylpyridyl-diazabicycloheptane 3c displayed Ki value of 11.17 pM for α4β2, in line with that of the halogenated homologues 3a,b, although it was characterized by an improved selectivity (Ki = 17 μM for α7 receptors). The influence of substitutions on the phenylpyridyl moiety on binding at both α4β2 and α7 receptors has been examined through the Topliss decision tree analysis. Substitution with electron-donating groups (as CH3 and OCH3) resulted in a good affinity for α4β2 receptors and substantially no affinity for α7. Amongst all the tested phenyl-substituted compounds, the p-NO2-phenyl substituted analogue 3j exhibited the highest α4β2 affinity, with Ki value comparable to that of 3c. Intrinsic α4β2 receptor mediated activity in [(3)H]-DA release assay was showed by compound 3a as well as by the reference analogue 2a, whereas phenyl substituted derivative 3c exhibited α4β2 antagonist activity.