N-(furan-2-ylmethyl)-N-methylprop-2-yn-1-amine (F2MPA): A potential cognitive enhancer with MAO inhibitor properties

Profiling the volatile compounds of Peganum harmala L. Based on multiple sample preparation coupled with gas chromatography-mass spectrometry analysis and explored its antidepressants-like activity

Peganum harmala L., a traditional medicinal plant in China, is renowned for its significant alkaloid content in seeds and roots exhibiting a wide range of pharmacological activities, including antidepressant, antiseptic, and antiviral. However, the volatile composition of the herb remained unclear. Apart from that, the extraction of volatile compounds through essential oil presents challenges due to the low yield and the degradation of volatile active compounds at high temperatures. This study used multiple sample preparation methods including headspace (HS), needle trap device (NTD), and liquid-liquid extraction (LLE) coupled with gas chromatography-mass spectrometry (GC-MS) to analyze the volatile compounds from the areal part of P. harmala L.. A total of 93 compounds were identified with NTD facilitating the first detection of harmine among the volatile organic compounds. Through network pharmacology and protein interaction analysis, the compounds' potential therapeutic targets of the compounds were explored, and 23 key targets were obtained (AKT1, ALB, PTGS2, MAOA, etc). KEGG pathway enrichment analysis indicated significant involvement in neuroactive ligand-receptor interactions and serotonergic synapses. The results enhanced the understanding of P. harmala's pharmacological mechanisms and supported its ethnopharmacological use.

Endocannabinoid-serotonin systems interaction in health and disease

Endocannabinoid (eCB) and serotonin (5-HT) neuromodulatory systems work both independently and together to finely orchestrate neuronal activity throughout the brain to strongly sculpt behavioral functions. Surprising parallelism between the behavioral effects of 5-HT and eCB activity has been widely reported, including the regulation of emotional states, stress homeostasis, cognitive functions, food intake and sleep. The distribution pattern of the 5-HT system and the eCB molecular elements in the brain display a strong overlap and several studies report a functional interplay and even a tight interdependence between eCB/5-HT signaling. In this review, we examine the available evidence of the interaction between the eCB and 5-HT systems. We first introduce the eCB system, then we describe the eCB/5-HT crosstalk at the neuronal and synaptic levels. Finally, we explore the potential eCB/5-HT interaction at the behavioral level with the implication for psychiatric and neurological disorders. The precise elucidation of how this neuromodulatory interaction dynamically regulates biological functions may lead to the development of more targeted therapeutic strategies for the treatment of depressive and anxiety disorders, psychosis and epilepsy.

Novel approaches to the discovery of selective human monoamine oxidase-B inhibitors: is there room for improvement?

Introduction: Selective monoamine oxidase-B (MAO-B) inhibitors are currently used as coadjuvants for the treatment of early motor symptoms in Parkinson's disease. They can, based on their chemical structure and mechanism of inhibition, be categorized into reversible and irreversible agents. Areas covered: This review provides a comprehensive update on the development state of selective MAO-B inhibitors describing the results, structures, structure-activity relationships (SARs) and Medicinal chemistry strategies as well as the related shortcomings over the past five years. Expert opinion: Researchers have explored and implemented new and old chemical scaffolds achieving high inhibitory potencies and isoform selectivity. Most of them were characterized and proposed as multitarget agents able to act at different levels (including AChE inhibition, H3R or A_2AR antagonism, antioxidant and chelating properties, Aβ_1-42 aggregation reduction) in the network of aetiologies of neurodegenerative disorders. These results can also be used to avoid 'cheese-reaction' effects and the occurrence of serotonergic syndrome in patients.

Monoamine oxidase-B inhibitors as potential neurotherapeutic agents: An overview and update

Monoamine oxidase (MAO) inhibitors have made significant contributions and remain an indispensable approach of molecular and mechanistic diversity for the discovery of antineurodegenerative drugs. However, their usage has been hampered by nonselective and/or irreversible action which resulted in drawbacks like liver toxicity, cheese effect, and so forth. Hence, the search for selective MAO inhibitors (MAOIs) has become a substantial focus in current drug discovery. This review summarizes our current understanding on MAO-A/MAO-B including their structure, catalytic mechanism, and biological functions with emphases on the role of MAO-B as a potential therapeutic target for the development of medications treating neurodegenerative disorders. It also highlights the recent developments in the discovery of potential MAO-B inhibitors (MAO-BIs) belonging to diverse chemical scaffolds, arising from intensive chemical-mechanistic and computational studies documented during past 3 years (2015-2018), with emphases on their potency and selectivity. Importantly, readers will gain knowledge of various newly established MAO-BI scaffolds and their development potentials. The comprehensive information provided herein will hopefully accelerate ideas for designing novel selective MAO-BIs with superior activity profiles and critical discussions will inflict more caution in the decision-making process in the MAOIs discovery.

Comparative Analysis of the Neurochemical Profile and MAO Inhibition Properties of N-(Furan-2-ylmethyl)-N-methylprop-2-yn-1-amine

The regulation of brain monoamine levels is paramount for cognitive functions, and the monoamine oxidase (MAO A and B) enzymes play a central role in these processes. The aim of this study was to evaluate whether the procognitive properties exerted by propargylamine N-(furan-2-ylmethyl)-N-methylprop-2-yn-1-amine (F2MPA) are related to changes in monoamine content via MAO inhibition. In vivo microdialysis and ex vivo amine metabolite measurement demonstrated region-specific alterations in monoamine metabolism that differ from both of the classic MAO A and MAO B inhibitors, clorgyline and l-deprenyl, respectively. Although all the inhibitors (1 and 4 mg/kg) increased cortical serotonin tissue content, only F2MPA increased the levels of cortical noradrenaline. In the striatum, clorgyline (1 mg/kg), but not F2MPA (1 mg/kg), reduced extracellular levels of dopamine metabolites at rest or stimulated by the intrastriatal application of the MAO substrate 3-methoxytyramine. In vitro, F2MPA exhibited a low affinity toward MAO B and MAO A. Nonetheless, it modified the B form of MAO, forming a flavin adduct structurally similar to that with deprenyl. F2MPA was rapidly metabolized in the presence of rat but not human microsomes, producing a hydroxylated derivative. In conclusion, the effect of F2MPA on cognition may arise from monoaminergic changes in the cortex, but the role of MAO in this process is likely to be negligible, consistent with the poor affinity of F2MPA for MAO.

Monoaminergic neuropathology in Alzheimer's disease

None of the proposed mechanisms of Alzheimer's disease (AD) fully explains the distribution patterns of the neuropathological changes at the cellular and regional levels, and their clinical correlates. One aspect of this problem lies in the complex genetic, epigenetic, and environmental landscape of AD: early-onset AD is often familial with autosomal dominant inheritance, while the vast majority of AD cases are late-onset, with the ε4 variant of the gene encoding apolipoprotein E (APOE) known to confer a 5-20 fold increased risk with partial penetrance. Mechanisms by which genetic variants and environmental factors influence the development of AD pathological changes, especially neurofibrillary degeneration, are not yet known. Here we review current knowledge of the involvement of the monoaminergic systems in AD. The changes in the serotonergic, noradrenergic, dopaminergic, histaminergic, and melatonergic systems in AD are briefly described. We also summarize the possibilities for monoamine-based treatment in AD. Besides neuropathologic AD criteria that include the noradrenergic locus coeruleus (LC), special emphasis is given to the serotonergic dorsal raphe nucleus (DRN). Both of these brainstem nuclei are among the first to be affected by tau protein abnormalities in the course of sporadic AD, causing behavioral and cognitive symptoms of variable severity. The possibility that most of the tangle-bearing neurons of the LC and DRN may release amyloid β as well as soluble monomeric or oligomeric tau protein trans-synaptically by their diffuse projections to the cerebral cortex emphasizes their selective vulnerability and warrants further investigations of the monoaminergic systems in AD.

Role(s) of the 5-HT2C receptor in the development of maximal dentate activation in the hippocampus of anesthetized rats

AIMS

Substantial evidence indicates that 5-HT2C receptors are involved in the control of neuronal network excitability and in seizure pathophysiology. Here, we have addressed the relatively unexplored relationship between temporal lobe epilepsy (TLE), the most frequent type of intractable epilepsy, and 5-HT2CRs.

METHODS

In this study, we investigated this issue using a model of partial complex (limbic) seizures in urethane-anesthetized rat, based on the phenomenon of maximal dentate activation (MDA) using 5-HT2C compounds, electrophysiology, immunohistochemistry, and western blotting techniques.

RESULTS

The 5-HT2C agonists mCPP (1 mg/kg, i.p) and lorcaserin (3 mg/kg, i.p), but not RO60-0175 (1-3 mg/kg i.p.), were antiepileptogenic reducing the MDA response duration. The selective 5-HT2C antagonist SB242084 (2 mg/kg, i.p) unveiled antiepileptogenic effects of RO60-0175 (3 mg/kg, i.p) but did not alter those induced by mCPP and lorcaserin. Compared with control rats, electrically stimulated rats showed an increase in glutamic acid decarboxylase levels and a heterogeneous decrease in 5-HT2CR immunoreactivity in different hippocampal areas.

CONCLUSIONS

In our animal model of TLE, mCPP and lorcaserin were anticonvulsant; likely acting on receptor subtypes other than 5-HT2C. Epileptogenesis induced early adaptive changes and reorganization in the 5-HT2CR and GABA systems.