Analogous β-Carboline Alkaloids Harmaline and Harmine Ameliorate Scopolamine-Induced Cognition Dysfunction by Attenuating Acetylcholinesterase Activity, Oxidative Stress, and Inflammation in Mice

Unraveling the mechanistic interplay of mediators orchestrating the neuroprotective potential of harmine

Neurodegenerative diseases (NDDs) encompass a range of conditions characterized by the specific dysfunction and continual decline of neurons, glial cells, and neural networks within the brain and spinal cord. The majority of NDDs exhibit similar underlying causes, including oxidative stress, neuroinflammation, and malfunctioning of mitochondria. Elevated levels of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), alongside decreased expression of brain-derived neurotrophic factor (BDNF) and glutamate transporter subtype 1 (GLT-1), constitute significant factors contributing to the pathogenesis of NDDs. Additionally, the dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) gene has emerged as a significant target for the treatment of NDDs at the preclinical level. It significantly contributes to developmental brain defects, early onset neurodegeneration, neuronal loss, and dementia in Down syndrome. Moreover, an impaired ubiquitin-proteosome system (UPS) also plays a pathological role in NDDs. Malfunctioning of UPS leads to abnormal protein buildup or aggregation of α-synuclein. α-Synuclein is a highly soluble unfolded protein that accumulates in Lewy bodies and Lewy neurites in Parkinson's disease and other synucleinopathies. Recent research highlights the promising potential of natural products in combating NDDs relative to conventional therapies. Alkaloids have emerged as promising candidates in the fight against NDDs. Harmine is a tricyclic β-carboline alkaloid (harmala alkaloid) with one indole nucleus and a six-membered pyrrole ring. It is extracted from Banisteria caapi and Peganum harmala L. and exhibits diverse pharmacological properties, encompassing neuroprotective, antioxidant, anti-inflammatory, antidepressant, etc. Harmine has been reported to mediate its neuroprotective via reducing the level of inflammatory mediators, NADPH oxidase, AChE, BChE and reactive oxygen species (ROS). Whereas, it has been observed to increase the levels of BDNF, GLT-1 and anti-oxidant enzymes, along with protein kinase-A (PKA)-mediated UPS activation. This review aims to discuss the mechanistic interplay of various mediators involved in the neuroprotective effect of harmine.

Neuroinflammation Plays a Potential Role in the Medulla Oblongata After Moderate Traumatic Brain Injury in Mice as Revealed by Nontargeted Metabonomics Analysis

Moderate traumatic brain injury (mTBI) involves a series of complex pathophysiological processes in not only the area in direct contact with mechanical violence but also in other brain regions far from the injury site, which may be important factors influencing subsequent neurological dysfunction or death. The medulla oblongata (MO) is a key area for the maintenance of basic respiratory and circulatory functions, whereas the pathophysiological processes after mTBI have rarely drawn the attention of researchers. In this study, we established a closed-head cortical contusion injury model, identified 6 different time points that covered the acute, subacute, and chronic phases, and then used nontargeted metabolomics to identify and analyze the changes in differential metabolites (DMs) and metabolic pathways in the MO region. Our results showed that the metabolic profile of the MO region underwent specific changes over time: harmaline, riboflavin, and dephospho-coenzyme A were identified as the key DMs and play important roles in reducing inflammation, enhancing antioxidation, and maintaining homeostasis. Choline and glycerophospholipid metabolism was identified as the key pathway related to the changes in MO metabolism at different phases. In addition, we confirmed increases in the levels of inflammatory factors and the activation of astrocytes and microglia by Western blot and immunofluorescence staining, and these findings were consistent with the nontargeted metabolomic results. These findings suggest that neuroinflammation plays a central role in MO neuropathology after mTBI and provide new insights into the complex pathophysiologic mechanisms involved after mTBI.

Recent synthetic strategies for N-arylation of pyrrolidines: a potential template for biologically active molecules

The chemistry of nitrogen-containing heterocyclic compounds has been a multifaceted area of research for an extended period due to their varied therapeutic and biological significance. N-Aryl pyrrolidine formed by condensation of aryl group with nitrogen atom of pyrrolidine is present in a wide array of compounds. Various significant activities shown by N-arylated pyrrolidine include anti-Alzheimer, antihypoxic, anticancer, plant activator, analgesic effect, and hepatitis C inhibitor. This review summarizes different synthetic approaches, e.g., transition-metal catalyzed and transition-metal-free synthesis, decarboxylation reaction, reductive amination, nucleophilic cyclization, Ullmann-Goldberg amidation, Buchwald-Hartwig reaction, Chan-Evans-Lam coupling, addition to benzyne, multistep reaction, green synthesis, rearrangement reaction, and multicomponent reaction, to afford the derivatives of N-aryl pyrrolidine. It encompasses synthetic strategies documented from 2015 to 2023.

Unveiling the multifaceted antiproliferative efficacy of Cichorium endivia root extract by dual modulation of apoptotic and inflammatory genes, inducing cell cycle arrest, and targeting COX-2

Chicory (Cichorium endivia L. divaricatum) is a renowned medicinal plant traditionally used for various ailments, yet the pharmacological potential of its roots, particularly in terms of antitumor activity, remains elusive. In the present study, we explore, for the first time, the metabolomic profile of ethanolic extract from Cichorium endivia roots (CIR) and further unveil its antiproliferative potential. The untargeted phytochemical analysis UPLC/T-TOF-MS/MS identified 131 metabolites in the CIR extract, covering acids, amino acids, flavonoids, alkaloids, nucleotides, and carbohydrates. The antiproliferative activity of the CIR extract was tested in 14 cancer cell lines, revealing significant cytotoxicity (IC50: 2.85-29.15 μg mL-1) and a high selectivity index. Among the cells examined, the CIR extract recorded the most potent antiproliferative activity and selectivity toward HepG2 and Panc-1 cells, with an IC50 of 2.85 μg mL-1 and 3.86 μg mL-1, respectively, and SI > 10. Insights into the mode of action of the antiproliferative activity revealed that CIR extract induces cell arrest in the S phase while diminishing cell distribution in the G0/G1 and G2/M phases in HepG-2 and Panc-1 cells. Flow cytometric and RT-PCR analysis revealed that the CIR extract significantly triggers apoptosis and modulates the expression of pro-apoptotic and anti-apoptotic genes. Furthermore, the CIR extract exhibited a pronounced anti-inflammatory activity, as evidenced by down-regulating key cytokines in LPS-induced RAW 264.7 cells and selectively inhibiting the COX-2 enzyme. Finally, the CIR extract showed a robust total antioxidant capacity, together with potent free radicals and metal scavenging properties, highlighting its role in alleviating oxidative stress. Taken together, this study highlights the multifaceted therapeutic potential of CIR extract as a natural-based antitumor supplement.

Revealing the Improved Binding Interaction of Plant Alkaloid Harmaline with Human Hemoglobin in Molecular Crowding Condition

Harmaline and harmine are two structurally similar β-carboline alkaloids with several therapeutic activities, such as anti-inflammatory, antioxidant, neuroprotective, nephroprotective, antidiabetic, and antitumor activities. It has been previously reported that the interaction between harmaline and hemoglobin (Hb) is weak in buffer media compared to harmine. Crowding agents induce a molecular crowding environment in the ex vivo condition, which is almost similar to the intracellular environment. In this present study, we have investigated the nature of the interactions of harmaline and harmine with Hb by increasing the percentage of the crowding agent in buffer solution. The results of the UV-vis and fluorescence spectroscopy analysis have showed that with an increasing proportion of crowding agents, the interaction between harmaline and Hb is steadily improving in comparison to harmine. It has been found that the binding constant of Hb-harmaline reaches 6.82 × 105 M-1 in the 40% polyethylene glycol 200-mediated crowding condition, indicating high affinity compared to very low interaction in buffer media. Steady-state fluorescence anisotropy along with fluorescence lifetime measurements further revealed that the rotational movement of harmaline is maximally restricted by Hb in high crowding environments. Stoichiometry results represent that Hb and harmaline interacts in a 1:1 ratio in different percentages of the crowding agent. The circular dichroism spectroscopic results predict stronger interaction of harmaline with Hb (secondary structure alterations) in a higher crowding environment. From the melting study, it was found that the reactions between Hb and harmaline in crowding environments are endothermic (ΔH > 0) and disordering (ΔS > 0) in nature, indicating that hydrogen bonding and van der Waals interactions are the main interacting forces between Hb and harmaline. Harmaline molecules are more reactive in molecular crowding conditions than in normal buffer condition. This study represents that the interaction between harmaline and Hb is stronger compared to the structurally similar harmine in a molecular crowding environment, which may enlighten the drug discovery process in cell-mimicking conditions.

The roles of autophagy, ferroptosis and pyroptosis in the anti-ovarian cancer mechanism of harmine and their crosstalk

This study aimed to investigate the role of autophagy, ferroptosis, and pyroptosis in the antitumour mechanism of harmine (Har) and its crosstalk in ovarian cancer. By transmission electron microscopy, we found that compared with those in the control group, the cytoplasm of human ovarian cancer cells (SKOV3) treated with Har showed increased numbers of autophagic vesicles, decreased intracellular mitochondrial volume, increased bilayer membrane density, and decreased cristae. Western blot, immunofluorescence, and monodasylcadaverine (MDC) staining all suggested that Har promoted autophagy in SKOV3 cells. LY294002 and siFOXO3 rescued the inhibition of the PI3K/AKT/mTOR/FOXO3 signalling pathway and the promotion of autophagy by Har. Additionally, the levels of ferroptosis- and pyroptosis-related proteins and the levels of Fe2+ , glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD) suggested that Har promoted ferroptosis and pyroptosis in SKOV3 cells. Interestingly, pretreatment with chloroquine (CQ), erastin, rapamycin (Rap), or ferrostatin-1 (Fer-1) increased or reversed the ferroptosis and pyroptosis promoted by Har, respectively. In vivo, the volume of tumours in the Har group was decreased, and immunohistochemistry revealed decreased levels of Ki-67 and GPX4 and increased levels of ATG5 and NARL3. In conclusion, Har exerts its anti-ovarian cancer effect not only by promoting autophagy by regulating the PI3K/AKT/mTOR/FOXO3 signalling pathway but also by promoting ferroptosis and pyroptosis. Additionally, there is complex crosstalk between autophagy, ferroptosis, and pyroptosis in ovarian cancer.

Harmaline to Human Mitochondrial Caseinolytic Serine Protease Activation for Pediatric Diffuse Intrinsic Pontine Glioma Treatment

Diffuse intrinsic pontine glioma (DIPG), affecting children aged 4-7 years, is a rare, aggressive tumor that originates in the pons and then spreads to nearby tissue. DIPG is the leading cause of death for pediatric brain tumors due to its infiltrative nature and inoperability. Radiotherapy has only a palliative effect on stabilizing symptoms. In silico and preclinical studies identified ONC201 as a cytotoxic agent against some human cancer cell lines, including DIPG ones. A single-crystal X-ray analysis of the complex of the human mitochondrial caseinolytic serine protease type C (hClpP) and ONC201 (PDB ID: 6DL7) allowed hClpP to be identified as its main target. The hyperactivation of hClpP causes damage to mitochondrial oxidative phosphorylation and cell death. In some DIPG patients receiving ONC201, an acquired resistance was observed. In this context, a wide program was initiated to discover original scaffolds for new hClpP activators to treat ONC201-non-responding patients. Harmaline, a small molecule belonging to the chemical class of β-carboline, was identified through Fingerprints for Ligands and Proteins (FLAP), a structure-based virtual screening approach. Molecular dynamics simulations and a deep in vitro investigation showed interesting information on the interaction and activation of hClpP by harmaline.

Chemical Compositions, Pharmacological Properties and Medicinal Effects of Genus Passiflora L.: A Review

Practically all aboveground plants parts of Passiflora vines can be included in the compositions of dietary supplements, medicines, and cosmetics. It has a diverse chemical composition and a wide range of biologically active components that determine its diverse pharmacological properties. Studies related to the chemical composition of the plant are summarized here, and attention has been paid to various medical applications-(1) anti-inflammatory, nephroprotective; (2) anti-depressant; (3) antidiabetic; (4) hepatoprotective; (5) antibacterial and antifungal; and (6) antipyretic and other. This review includes studies on the safety, synergistic effects, and toxicity that may occur with the use of various dietary supplements based on it. Attention has been drawn to its application in cosmetics and to patented products containing passionflower.

Ameliorative effect of scopolamine-induced cognitive dysfunction by Fufangmuniziqi formula: The roles of alkaloids, saponins, and flavonoids

ETHNOPHARMACOLOGICAL RELEVANCE

Fufangmuniziqi formula (FFMN), a traditional Uyghur medicine used in China, is derived from an ancient Uyghur medical book and consists of 13 herbs. The herbs of FFMN, such as Peganum harmala L., Glycyrrhiza uralensis Fisch., and Nigella glandulifera, have been demonstrated to have acetylcholinesterase (AChE) inhibitory, anti-neuroinflammatory, or antioxidant effects. Therefore, FFMN may have a good anti-Alzheimer's disease (AD) effect, but its specific action and mechanism need to be further proven.

AIM OF THE STUDY

This study aims to investigate the anti-AD effects of FFMN and the role played by alkaloids, flavonoids, and saponins in anti-AD.

MATERIALS AND METHODS

The alkaloids, flavonoids, and saponins fractions of FFMN were prepared by macroporous resin chromatography. The absorbed ingredients in the drug-containing serum were identified by UPLC⁃Q⁃TOF⁃MS. An AD mouse model was established by intraperitoneal injection of scopolamine (SCO). The role of different fractions of FFMN in the anti-AD process was examined by Morris water maze (MWM), in-vitro cell, and AChE inhibition assay.

RESULTS

A total of 20 ingredients were identified in the serum samples collected after oral administration of FFMN, and seven compounds were selected as candidate active compounds. MWM experiments showed that different fractions of FFMN could significantly improve SCO-induced learning memory impairment in mice. The alkaloids fraction (ALK) regulated cholinergic function by inhibiting AChE activity, activating choline acetyltransferase activity, and protein expression. Flavonoids and saponins were more potent than the ALK in downregulating pro-inflammatory factors or inflammatory mediators, such as TNF-α, MPO, and nitric oxide. Western blot results further confirmed that flavonoids and saponins attenuated neuroinflammation by inhibiting the phosphorylation of IκB and NF-κB p65. This result was also verified by in-vitro cellular assays. FFMN enhanced antioxidant defense by increasing the activity of superoxide dismutase and reducing the production of MDA. Combined with cellular experiments, flavonoids and saponins were proven more protective against oxidative damage.

CONCLUSION

FFMN improved cognitive and memory impairment in the SCO-induced AD mouse model. ALK mainly enhanced the function of the cholinergic system. Flavonoid and saponin fractions mainly attenuated neuroinflammation and oxidative stress by modulating the NF-κB pathway. All these findings strongly suggested that the combination of alkaloid, flavonoid, and saponin fractions derived from FFMN is a promising anti-AD agent that deserves further development.

Paradigms and Success Stories of Natural Products in Drug Discovery Against Neurodegenerative Disorders (NDDs)

Neurodegenerative disorders (NDDs) are multifaceted complex disorders that have put a great health and economic burden around the globe nowadays. The multi-factorial nature of NDDs has presented a great challenge in drug discovery and continuous efforts are in progress in search of suitable therapeutic candidates. Nature has a great wealth of active principles in its lap that has cured the human population since ancient times. Natural products have revealed several benefits over conventional synthetic medications and scientists have shifted their vision towards exploring the therapeutic potentials of natural products in the past few years. The structural mimicking of natural compounds to endogenous ligands has presented them as a potential therapeutic candidate to prevent the development of NDDs. In the presented review, authors have summarized demographical facts about various NDDs including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and various types of sclerosis in the brain. The significant findings of new active principles of natural origin along with their therapeutic potentials on NDDs have been included. Also, a description of clinical trials and patents on natural products has been enlisted in this compilation. Although natural products have shown promising success in drug discovery against NDDs, still their use is associated with several ethical issues which need to be solved in the upcoming time.

Novel harmine derivatives as potent acetylcholinesterase and amyloid beta aggregation dual inhibitors for management of Alzheimer's disease

In this study, a series of potential ligands for the treatment of AD were synthesised and characterised as novel harmine derivatives modified at position 9 with benzyl piperazinyl. In vitro studies revealed that the majority of the derivatives exhibited moderate to potent inhibition against hAChE and Aβ1 - 42 aggregation. Notably, compounds 13 and 17d displayed potent drug - likeness and ADMET properties, demonstrating remarkable inhibitory activities towards AChE (IC50 = 58.76 nM and 89.38 nM, respectively) as well as Aβ aggregation (IC50 = 9.31 μM and 13.82 μM, respectively). More importantly, compounds 13 and 17d showed exceptional neuroprotective effects against Aβ1 - 42-induced SH - SY5Y damage, while maintaining low toxicity in SH - SY5Y cells. Further exploration of the mechanism through kinetic studies and molecular modelling confirmed that compound 13 could interact with both the CAS and the PAS of AChE. These findings suggested that harmine derivatives hold great potential as dual - targeted candidates for treating AD.

Exploring the Structural Importance of the C3=C4 Double Bond in Plant Alkaloids Harmine and Harmaline on Their Binding Interactions with Hemoglobin

Harmine and harmaline are two structurally similar heterocyclic β-carboline plant alkaloids with various therapeutic properties, having a slight structural difference in the C3=C4 double bond. In the present study, we have reported the nature of the interaction between hemoglobin (Hb) with harmine and harmaline by employing several multispectroscopic, calorimetric, and molecular docking approaches. Fluorescence spectroscopic studies have shown stronger interaction of harmine with Hb compared to that of almost structurally similar harmaline. Steady-state anisotropy experiments further show that the motional restriction of harmine in the presence of Hb is substantially higher than that of the harmaline-Hb complex. Circular dichroism (CD) study demonstrates no conformational change of Hb in the presence of both alkaloids, but CD study in 1-cm cuvette path length also demonstrates stronger affinity of harmine toward Hb compared to harmaline. From the thermal melting study, it has been found that both harmine and harmaline slightly affect the stability of Hb. From isothermal titration calorimetry (ITC), we have found that the binding process is exothermic and enthalpy driven. Molecular docking studies indicated that both harmine and harmaline prefer identical binding sites in Hb. This study helps us to understand that slight structural differences in harmine and harmaline can alter the interaction properties significantly, and this key information may help in the drug discovery processes.

Bedside to bench: the outlook for psychedelic research

There has recently been a resurgence of interest in psychedelic compounds based on studies demonstrating their potential therapeutic applications in treating post-traumatic stress disorder, substance abuse disorders, and treatment-resistant depression. Despite promising efficacy observed in some clinical trials, the full range of biological effects and mechanism(s) of action of these compounds have yet to be fully established. Indeed, most studies to date have focused on assessing the psychological mechanisms of psychedelics, often neglecting the non-psychological modes of action. However, it is important to understand that psychedelics may mediate their therapeutic effects through multi-faceted mechanisms, such as the modulation of brain network activity, neuronal plasticity, neuroendocrine function, glial cell regulation, epigenetic processes, and the gut-brain axis. This review provides a framework supporting the implementation of a multi-faceted approach, incorporating in silico, in vitro and in vivo modeling, to aid in the comprehensive understanding of the physiological effects of psychedelics and their potential for clinical application beyond the treatment of psychiatric disorders. We also provide an overview of the literature supporting the potential utility of psychedelics for the treatment of brain injury (e.g., stroke and traumatic brain injury), neurodegenerative diseases (e.g., Parkinson's and Alzheimer's diseases), and gut-brain axis dysfunction associated with psychiatric disorders (e.g., generalized anxiety disorder and major depressive disorder). To move the field forward, we outline advantageous experimental frameworks to explore these and other novel applications for psychedelics.

An inhibitor with GSK3β and DYRK1A dual inhibitory properties reduces Tau hyperphosphorylation and ameliorates disease in models of Alzheimer's disease

Since Alzheimer's disease (AD) is a complex and multifactorial neuropathology, the discovery of multi-targeted inhibitors has gradually demonstrated greater therapeutic potential. Neurofibrillary tangles (NFTs), the main neuropathologic hallmarks of AD, are mainly associated with hyperphosphorylation of the microtubule-associated protein Tau. The overexpression of GSK3β and DYRK1A has been recognized as an important contributor to hyperphosphorylation of Tau, leading to the strategy of using dual-targets inhibitors for the treatment of this disorder. ZDWX-12 and ZDWX-25, as harmine derivatives, were found good inhibition on dual targets in our previous study. Here, we firstly evaluated the inhibition effect of Tau hyperphosphorylation using two compounds by HEK293-Tau P301L cell-based model and okadaic acid (OKA)-induced mouse model. We found that ZDWX-25 was more effective than ZDWX-12. Then, based on comprehensively investigations on ZDWX-25 in vitro and in vivo, 1) the capability of ZDWX-25 to show a reduction in phosphorylation of multiple Tau epitopes in OKA-induced neurodegeneration cell models, and 2) the effect of reduction on NFTs by 3xTg-AD mouse model under administration of ZDWX-25, an orally bioavailable, brain-penetrant dual-targets inhibitor with low toxicity. Our data highlight that ZDWX-25 is a promising drug for treating AD.

A Comparative Study of the Impact of NO-Related Agents on MK-801- or Scopolamine-Induced Cognitive Impairments in the Morris Water Maze

Learning and memory deficits accompany numerous brain dysfunctions, including schizophrenia and Alzheimer’s disease (AD), and many studies point to the role of nitric oxide (NO) in these processes. The present investigations constitute the follow-up of our previous research, in which we investigated the activity of NO releasers and a selective inhibitor of neuronal NO synthase (nNOS) to prevent short-term memory deficits in novel object recognition and T-maze. Here, the ability of the compounds to prevent the induction of long-term memory deficits by MK-801 or scopolamine administration was investigated. The Morris Water Maze test, a reliable and valid test of spatial learning and memory, was used, in which escape latency in the acquisition phase and nine different parameters in the retention phase were measured. A fast NO releaser (spermine NONOate), a slow NO releaser (DETA NONOate), and a nNOS inhibitor, N(ω)-propyl-L-arginine (NPLA), were used. The compounds were administered i.p. at a dose range of 0.05–0.5 mg/kg. All compounds prevented learning deficits in the acquisition phase and reversed reference memory deficits in the retention phase of the scopolamine-treated mice. Spermine NONOate was the least effective. In contrast, the drugs poorly antagonised MK-801-induced deficits, and only the administration of DETA NONOate induced some improvements in the retention trial.

Natural Alkaloids as Multi-Target Compounds towards Factors Implicated in Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia in elderly people; currently, there is no efficient treatment. Considering the increase in life expectancy worldwide AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. A great amount of experimental and clinical evidence indicated that AD is a complex disorder characterized by widespread neurodegeneration of the CNS, with major involvement of the cholinergic system, causing progressive cognitive decline and dementia. The current treatment, based on the cholinergic hypothesis, is only symptomatic and mainly involves the restoration of acetylcholine (ACh) levels through the inhibition of acetylcholinesterase (AChE). Since the introduction of the Amaryllidaceae alkaloid galanthamine as an antidementia drug in 2001, alkaloids have been one of the most attractive groups for searching for new AD drugs. The present review aims to comprehensively summarize alkaloids of various origins as multi-target compounds for AD. From this point of view, the most promising compounds seem to be the β-carboline alkaloid harmine and several isoquinoline alkaloids since they can simultaneously inhibit several key enzymes of AD's pathophysiology. However, this topic remains open for further research on detailed mechanisms of action and the synthesis of potentially better semi-synthetic analogues.

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.

Harmine and 7,8-dihydroxyflavone synergistically suitable for amyotrophic lateral sclerosis management: An in silico study

Introduction: Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease characterized by progressive degeneration of both upper and lower motor neurons, resulting in paralysis and eventually leads to death from respiratory failure typically within 3 to 5 years of symptom onset. The aim of this work was to predict the pharmacokinetics and identify unique protein targets that are associated with potential anti-ALS phytochemicals and FDA-approved drugs, by in silico approaches.

Materials and methods: Standard computational tools (webserver and software) were used, and the methods used are clustering analysis, pharmacokinetics and molecular target predictions, and molecular docking simulation.

Results and discussion: The results show that riluzole, β-asarone, cryptotanshinone, harmine and 7,8-dihydroxyflavone have similar pharmacokinetics properties. Riluzole and harmine show 95% probability of target on norepinephrine transporter. Huperzine-A and cryptotanshinone show 100% probability of target on acetylcholinesterase. 7,8-dihydroxyflavone shows 35% probability of target on several carbonic anhydrases, 40% probability of target on CYP19A1, and 100% probability of target on inhibitor of nuclear factor kappa B kinase beta subunit and neurotrophic tyrosine kinase receptor type 2, respectively. Harmine also shows 95% probability of target on dual specificity tyrosine-phosphorylation-regulated kinases, threonine-protein kinases (haspin and PIM3), adrenergic receptors, cyclin-dependent kinases (CDK5 and CDK9), monoamine oxidase A, casein kinase I delta, serotonin receptors, dual specificity protein kinases (CLK1, CLK2, and CLK4), and nischarin, respectively. Also, the results of gene expression network show possible involvement of CDK1, CDK2, CDK4, ERK1, ERK2 and MAPK14 signaling pathways. This study shows that riluzole and harmine have closely similar physicochemical and pharmacokinetics properties as well as molecular targets, such as norepinephrine transporter (SLC6A2). Harmine, huperzine-A and cryptotanshinone could modulate acetylcholinesterase (AChE), which is involved in ALS-pathogenesis. The impact of 7,8-dihydroxyflavone on several carbonic anhydrases (CA) I, II, VII, IX, XII, and XIV, as well as CYP19A1, could help in remediating the respiratory failure associated with ALS.

Conclusion: Overall, harmine is found to be superior to riluzole, and the combination of harmine with 7,8-dihydroxyflavone can provide more effective treatment for ALS than the current regime. Further work is needed to validate the predicted therapeutic targets of harmine identified in this study on ALS model or clinical trials, using in silico, in vitro and in vivo techniques.

Graphical abstract:

Antioxidant, Antimicrobial, Phytochemical and FTIR Analysis of Peganum harmala (Fruit) Ethanolic Extract From Cholistan Desert, Pakistan

The aim of this study was to evaluate antioxidant and antimicrobial potential of Peganum harmala fruit. Ethanolic extract was prepared and phytochemical screening showed the presence of a lot of chemical compounds. Fourier transform infrared spectroscopy (FTIR) spectra indicated the presence of organic acids, hydroxyl and phenolic compounds, amino groups, aliphatic compounds, and functional groups such as amide, ketone, aldehyde, aromatics, and halogen compounds. Antioxidant activity of the ethanolic extract of P. harmala by the DPPH method showed 71.4% inhibition, whereas IC₅₀ ± SEM (μg/mL) was .406 ± .11. Antibacterial activity was performed against Escherichia coli, Bacillus subtilis, Bacillus pumilus, Micrococcus luteus, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Bordetella bronchiseptica. Maximum antibacterial activity was exhibited by Bacillus subtilis (24.33 ± 2 mm) and Bacillus pumilus (23.33 ± 2 mm). Zone of inhibition was 19 ± 2 mm by P. aeruginosa, and it was 18.33 ± 2 mm by Bordetella bronchiseptica. Staphylococcus aureus and Staphylococcus epidermidis had inhibitory effect in the range of 12.33 ± 2 mm and 13.66 ± 3 mm, respectively. 11.66 ± 2 mm and 10 ± 2 mm was zone of inhibition by Micrococcus luteus and E. coli, respectively. Antifungal activity was performed against Aspergillus terreus, Aspergillus fumigatus, Aspergillus flavus and Candida albicans. Ethanolic extract of P. harmala showed antifungal activity against Aspergillus flavus (5 ± 1 mm) and Candida albicans (4 ± 1 mm). Mild antifungal activity was reported by Aspergillus fumigatus (3 ± 1 mm), whereas no activity was exhibited by Aspergillus terreus. Further research is needed in order to evaluate the cytotoxic effects of P. harmala as well.

Harmine prevents 3-nitropropionic acid-induced neurotoxicity in rats via enhancing NRF2-mediated signaling: Involvement of p21 and AMPK

Oxidative stress induced neurotoxicity is increasingly perceived as an important neuropathologic mechanism underlying the motor and behavioral phenotypes associated with Huntington's disease (HD). Repeated exposure to 3-nitropropionic acid (3-NP) induces neurotoxic changes which closely simulate the neuropathological and behavioral characteristics of HD. This study aimed at evaluating the prophylactic effects of the dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) inhibitor "harmine" against 3-NP-indued neurotoxicity and HD-like symptoms. The potential prophylactic effect of harmine (10 mg/kg/day; intraperitoneal) was investigated on 3-NP-induced motor and cognitive HD-like deficits, nuclear factor erythroid 2 like 2 (NRF2), AMP kinase (AMPK) and p21 protein levels and the gene expression of haem oxygenase-1 (Ho-1), NAD(P)H: quinone oxidoreductase-1 (Nqo-1) and p62 in addition to redox imbalance and histological neurotoxic changes in the striatum, prefrontal cortex, and hippocampus of male Wistar rats. Harmine successfully increased the protein levels of NRF2, AMPK and p21 and the gene expression of Ho-1, Nqo-1 and p62, restored redox homeostasis, and reduced CASPASE-3 level. This was reflected in attenuation of 3-NP-induced neurodegenerative changes and improvement of rats' motor and cognitive performance. This study draws attention to the protective role of harmine against 3-NP-induced motor and cognitive dysfunction that could be mediated via enhancing NRF2-mediated signaling with subsequent amelioration of oxidative stress injury via NRF2 activators, p21 and AMPK, in the striatum, prefrontal cortex, and hippocampus which could offer a promising therapeutic tool to slow the progression of HD.

Therapeutic Properties of Ayahuasca Components in Ischemia/Reperfusion Injury of the Eye

Ischemic eye diseases are major causes of vision impairment. Thus, potential retinoprotective effects of N'N-dimethyltryptamine (DMT) were investigated. To inhibit its rapid breakdown by monoamine-oxidase A (MAO-A) enzyme, DMT was co-administered with harmaline, a β-carboline in the Amazonian Ayahuasca brew. Using ligation, 60 min of ischemia was provoked in eyes of rats, followed by 7 days of reperfusion whilst animals received harmaline alone, DMT + harmaline, or vehicle treatment. After 1 week of reperfusion, electroretinographical (ERG) measurements, histological analysis, and Western blot were performed. Harmaline alone exhibited retinoprotection in ischemia-reperfusion (I/R) which was, surprisingly, counterbalanced by DMT in case of co-administration. As both MAO-A inhibition and DMT increase serotoninergic tone synergistically, communicated to be anti-ischemic, thus, involvement of other pathways was investigated. Based on our experiments, DMT and harmaline exert opposite effects on important ocular proteins such as PARP1, NFκB, MMP9, or HSP70, each having a critical role in a different mechanism of eye-ischemia-related pathologies, e.g., cell death, inflammation, tissue destruction, and oxidative stress. Since DMT is proclaimed to be a promising drug candidate, its potentially undesirable effect on eye-ischemia should be further investigated. Meanwhile, this experiment revealed the potential therapeutic effect of MAO-A inhibitor harmaline in I/R-related eye diseases.

The Genus Alternanthera: Phytochemical and Ethnopharmacological Perspectives

Ethnopharmacological relevance: The genus Alternanthera (Amaranthaceae) comprises 139 species including 14 species used traditionally for the treatment of various ailments such as hypertension, pain, inflammation, diabetes, cancer, microbial and mental disorders.

Aim of the review: To search research gaps through critical assessment of pharmacological activities not performed to validate traditional claims of various species of Alternanthera. This review will aid natural product researchers in identifying Alternanthera species with therapeutic potential for future investigation.

Materials and methods: Scattered raw data on ethnopharmacological, morphological, phytochemical, pharmacological, toxicological, and clinical studies of various species of the genus Alternanthera have been compiled utilizing search engines like SciFinder, Google Scholar, PubMed, Science Direct, and Open J-Gate for 100 years up to April 2021.

Results: Few species of Alternanthera genus have been exhaustively investigated phytochemically, and about 129 chemical constituents related to different classes such as flavonoids, steroids, saponins, alkaloids, triterpenoids, glycosides, and phenolic compounds have been isolated from 9 species. Anticancer, antioxidant, antibacterial, CNS depressive, antidiabetic, analgesic, anti-inflammatory, and immunomodulator effects have been explored in the twelve species of the genus. A toxicity study has been conducted on 3 species and a clinical study on 2 species.

Conclusions: The available literature on pharmacological studies of Alternanthera species reveals that few species have been selected based on ethnobotanical surveys for scientific validation of their traditional claims. But most of these studies have been conducted on uncharacterized and non-standardized crude extracts. A roadmap of research needs to be developed for the isolation of new bioactive compounds from Alternanthera species, which can emerge out as clinically potential medicines.

Ayahuasca, a potentially rapid acting antidepressant: focus on safety and tolerability

INTRODUCTION

Ayahuasca is a psychedelic brew originally used by indigenous tribes from the Amazon Rainforest and in religious rituals. Pre-clinical and observational studies have demonstrated its possible potential as an antidepressant, and open and placebo-controlled clinical trials corroborated these results. For it to become an approved treatment for depression, its safety and tolerability need to be assessed and documented.

AREAS COVERED

We have gathered data regarding occurrence of adverse events (AEs) in all reported randomized, placebo-controlled trials with healthy and clinical populations involving ayahuasca administration (n = 108 ayahuasca administrations). We systematically categorized these results, recorded their prevalence and discussed the possible mechanisms related to their emergence.

EXPERT OPINION

: There were no reports of serious AEs, indicating a relative safety of ayahuasca administration in controlled settings. Most common AEs related to ayahuasca administration included nausea, vomiting, headaches and transient increases in cardiovascular measurements. Ayahuasca research is still in its infancy, especially concerning the absence of large and robust clinical trials to verify its antidepressant effects. Dose standardization, legal prohibition of the possession of its alkaloids and how traditional communities will be compensated if ayahuasca becomes an approved medicine are the biggest obstacles to overcome for its future use in the therapeutic context.

Potential Therapeutic Applications of Plant-Derived Alkaloids against Inflammatory and Neurodegenerative Diseases

Alkaloids are a type of natural compound possessing different pharmacological activities. Natural products, including alkaloids, which originate from plants, have emerged as potential protective agents against neurodegenerative disorders (NDDs) and chronic inflammations. A wide array of prescription drugs are used against these conditions, however, not free of limitations of potency, side effects, and intolerability. In the context of personalized medicine, further research on alkaloids to unravel novel therapeutic approaches in reducing complications is critical. In this review, a systematic survey was executed to collect the literature on alkaloids and their health complications, from which we found that majority of alkaloids exhibit anti-inflammatory action via nuclear factor-κB and cyclooxygenase-2 (COX-2), and neuroprotective interaction through acetylcholinesterase (AChE), COX, and β-site amyloid precursor protein activity. In silico ADMET and ProTox-II-related descriptors were calculated to predict the pharmacological properties of 280 alkaloids isolated from traditional medicinal plants towards drug development. Out of which, eight alkaloids such as tetrahydropalmatine, berberine, tetrandrine, aloperine, sinomenine, oxymatrine, harmine, and galantamine are found to be optimal within the categorical range when compared to nicotine. These alkaloids could be exploited as starting materials for novel drug synthesis or, to a lesser extent, manage inflammation and neurodegenerative-related complications.

DYRK1A inhibitors for disease therapy: Current status and perspectives

Dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) is a conserved protein kinase that plays essential roles in various biological processes. It is located in the region q22.2 of chromosome 21, which is involved in the pathogenesis of Down syndrome (DS). Moreover, DYRK1A has been shown to promote the accumulation of amyloid beta (Aβ) peptides leading to gradual Tau hyperphosphorylation, which contributes to neurodegeneration. Additionally, alterations in the DRK1A expression are also associated with cancer and diabetes. Recent years have witnessed an explosive increase in the development of DYRK1A inhibitors. A variety of novel DYRK1A inhibitors have been reported as potential treatments for human diseases. In this review, the latest therapeutic potential of DYRK1A for different diseases and the novel DYRK1A inhibitors discoveries are summarized, guiding future inhibitor development and structural optimization.

Insamgobonhwan Protects Neuronal Cells from Lipid ROS and Improves Deficient Cognitive Function

Iron is an essential element in the central nervous system that is involved in many of its important biological processes, such as oxygen transportation, myelin production, and neurotransmitter synthesis. Previous studies have observed the selective accumulation of iron in Aβ aggregates and neurofibrillary tangles in the brains of patients with Alzheimer's disease, and excess of this accumulation is associated with accelerated cognitive decline in Alzheimer's patients. Emerging evidence suggests that ferroptosis, cell death due to iron accumulation, is a potential therapeutic target for treating Alzheimer's disease. Insamgobonhwan (GBH) is a well-regarded traditional medicine from Donguibogam that possess antioxidant properties and has been suggested to slow the aging process. However, the neuroprotective role of GBH against lipid peroxidation-induced ferroptosis and its positive cognitive effects remain unexplored. Here, we investigated the ability of GBH to protect against RSL3-induced ferroptosis in vitro and to suppress amyloid-β-induced cognitive impairment in vivo. First, we treated HT22 cells with RSL3 to induce ferroptosis, which is an inhibitor of glutathione peroxidase 4 (GPX4) and induces lethal lipid hydroperoxide accumulation, reactive oxygen species (ROS) production, and ferroptotic cell death. GBH treatment inhibited cell death and lipid peroxidation, which were increased by RSL3 administration. In addition, GBH restored the expression of ferroptosis marker proteins, such as GPX4, HO-1 and COX-2, which were altered by RSL3. Next, we examined whether the protective ability of GBH in cells was reproduced in animals. We concluded that GBH treatment inhibited Aβ-induced lipid peroxidation and improved Aβ-induced cognitive impairment in mice.

Bee Venom Activates the Nrf2/HO-1 and TrkB/CREB/BDNF Pathways in Neuronal Cell Responses against Oxidative Stress Induced by Aβ1-42

Honeybee venom has recently been considered an anti-neurodegenerative agent, primarily due to its anti-inflammatory effects. The natural accumulation of amyloid-beta (Aβ) in the brain is reported to be the natural cause of aging neural ability downfall, and oxidative stress is the main route by which Aβ ignites its neural toxicity. Anti-neural oxidative stress is considered an effective approach for neurodegenerative therapy. To date, it is unclear how bee venom ameliorates neuronal cells in oxidative stress induced by Aβ. Here, we evaluated the neuroprotective effect of bee venom on Aβ-induced neural oxidative stress in both HT22 cells and an animal model. Our results indicate that bee venom protected HT22 cells against apoptosis induced by Aβ_1–42. This protective effect was explained by the increased nuclear translocation of nuclear factor erythroid 2-like 2 (Nrf2), consequently upregulating the production of heme oxygenase-1 (HO-1), a critical cellular instinct antioxidant enzyme that neutralizes excessive oxidative stress. Furthermore, bee venom treatment activated the tropomyosin-related kinase receptor B (TrkB)/cAMP response element-binding (CREB)/brain-derived neurotrophic factor (BDNF), which is closely related to the promotion of cellular antioxidant defense and neuronal functions. A mouse model with cognitive deficits induced by Aβ_1–42 intracerebroventricular (ICV) injections was also used. Bee venom enhanced animal cognitive ability and enhanced neural cell genesis in the hippocampal dentate gyrus region in a dose-dependent manner. Further analysis of animal brain tissue and serum confirmed that bee venom reduced oxidative stress, cholinergic system activity, and intercellular neurotrophic factor regulation, which were all adversely affected by Aβ_1–42. Our study demonstrates that bee venom exerts antioxidant and neuroprotective actions against neural oxidative stress caused by Aβ_1–42, thereby promoting its use as a therapeutic agent for neurodegenerative disorders.

Harmine Alleviated Sepsis-Induced Cardiac Dysfunction by Modulating Macrophage Polarization via the STAT/MAPK/NF-κB Pathway

Sepsis is a dysregulated systemic inflammatory response that often leads to cardiac dysfunction, which is termed sepsis-induced cardiomyopathy (SIC). Harmine, a natural β-carboline alkaloid compound, has been shown to exert pharmacological effects on several diseases. Here, we investigated whether harmine protected against SIC development and the underlying mechanisms. In vitro, the expression of the M1 phenotype markers iNOS and COX-2 was increased in RAW 264.7 cells stimulated with lipopolysaccharide (LPS), but this effect was reversed by the harmine intervention. Furthermore, LPS-induced increases in the levels of inflammatory cytokines, including IL-1β, IL-6, TNF-α, iNOS, COX-2, PGE2 and TXB2, generated by macrophages were suppressed when the cells were pretreated with harmine. Meanwhile, our findings showed that harmine administration effectively attenuated inflammation and apoptosis in H9c2 cells in the proinflammatory environment produced by macrophages, as evidenced by reductions in NLRP3 and cleaved caspase 3 levels and the p-NF-κB/NF-κB ratio. The western blot results indicated that the mechanisms underlying harmine-mediated inhibition of M1 polarization might be associated with suppression of STAT1/3, NF-κB and MAPK activation. Furthermore, an LPS injection induced cardiac dysfunction and decreased the survival rate of mice, which were alleviated by harmine treatment, and the relevant mechanism was possibly attributed to a drug-induced attenuation of the inflammatory and apoptotic processes in cardiomyocytes. Collectively, these results implied that harmine treatment protected against SIC by suppressing M1 phenotypic polarization and inflammation in macrophages.

Dynamic Changes of Endogenic or Exogenic β-Carboline Alkaloid Harmine in Different Mammals and Human in vivo at Developmental and Physiological States

OBJECTIVE

Several β-carboline alkaloids (βCBs), such as harmine, harmaline, harmane, and nor-harmane, are effective for Alzheimer's disease mouse models. They can be found in some plants, common foodstuffs, and blank plasma of various mammals. However, whether these compounds in mammals are exogenous or endogenous remain unclear.

METHODS

The exposure levels of βCBs and of neurotransmitters in plasma and tissues of pup rats, aging rats, mice of different physiological states, and healthy volunteers were detected by using UPLC-MS/MS. Plasma and tissue samples from 110 newborn rats up to 29 days old at 11 sampling points were collected and were analyzed to determine the concentration variation of βCBs in the developmental phase of newborn rats. The plasma of rats aged 2 to 18 months was used to detect the variation trend of βCBs and with some neurotransmitters. The plasma samples of normal C57BL/6 mice, APP/PS1 double transgenic mice, and scopolamine-induced memory impairment mice were collected and were analyzed to compare the difference of βCBs in different physiological states. The exposure levels of βCBs such as harmine, harmaline, and harmane in plasma of 550 healthy volunteers were also detected and analyzed on the basis of gender, race, and age.

RESULTS

Results showed that harmine was the main compound found in rats, mice, and human, which can be detected in a newborn rat plasma (0.16 ± 0.03 ng/ml) and brain (0.33 ± 0.14 ng/g) without any exogenous consumption. The concentration of harmine in rat plasma showed a decreasing trend similar to the exposure levels of neurotransmitters such as 5-hydroxytryptamine, acetylcholine chloride, glutamic acid, tyrosine, and phenylalanine during the growth period of 18 months. The harmine exposure in rats and human indicates high dependence on the physiological and pathological status such as aging, gender, and race.

CONCLUSION

The dynamic changes of harmine exposure in different animals and human, in vivo, at developmental and physiological states indicate that harmine is a naturally and widely distributed endogenous substance in different mammals and human. In addition to exogenous ingestion, spontaneous synthesis might be another important source of harmine in mammals, which should be verified by further experiment.

Antibacterial and antibiofilm activity of Peganum harmala seed extract against multidrug-resistant Pseudomonas aeruginosa pathogenic isolates and molecular mechanism of action

Biofilm formation of the opportunistic pathogen Pseudomonas (P). aeruginosa is one of the major global challenges to control nosocomial infections due to their high resistance to antimicrobials and host defense mechanisms. The present study aimed to assess the antibacterial and the antibiofilm activities of Peganum (P). harmala seed extract against multidrug-resistant P. aeruginosa isolates. Chemical identification of the active compound and determination of its molecular mechanism of action were also investigated. Results showed that P. harmala n-butanol "n-BuOH" extract exhibited antibacterial activity against multidrug-resistant P. aeruginosa isolates. This extract was even more active than conventional antibiotics cefazolin and vaamox when tested against three P. aeruginosa multidrug-resistant isolates. In addition, P. harmala n-BuOH extract exhibited potent bactericidal activity against PAO1 strain at MIC value corresponding to 500 µg/mL and attained 100% killing effect at 24 h of incubation. Furthermore, P. harmala n-BuOH extract showed an antibiofilm activity against P. aeruginosa PAO1 and exhibited 80.43% inhibition at sub-inhibitory concentration. The extract also eradicated 83.99% of the biofilm-forming bacteria. The active compound was identified by gas chromatography-mass spectrometry as an indole alkaloid harmaline. Transcriptomic analysis showed complete inhibition of the biofilm-related gene pilA when PAO1 cells were treated with harmaline. Our results revealed that P. harmala seed extract and its active compound harmaline could be considered as a candidate for a new treatment of multidrug-resistant P. aeruginosa pathogens-associated biofilm infections.

Roles of traditional chinese medicine regulating neuroendocrinology on AD treatment

The incidence of sporadic Alzheimer's disease (AD) is increasing in recent years. Studies have shown that in addition to some genetic abnormalities, the majority of AD patients has a history of long-term exposure to risk factors. Neuroendocrine related risk factors have been proved to be strongly associated with AD. Long-term hormone disorder can have a direct detrimental effect on the brain by producing an AD-like pathology and result in cognitive decline by impairing neuronal metabolism, plasticity and survival. Traditional Chinese Medicine(TCM) may regulate the complex process of endocrine disorders, and improve metabolic abnormalities, as well as the resulting neuroinflammation and oxidative damage through a variety of pathways. TCM has unique therapeutic advantages in treating early intervention of AD-related neuroendocrine disorders and preventing cognitive decline. This paper reviewed the relationship between neuroendocrine and AD as well as the related TCM treatment and its mechanism. The advantages of TCM intervention on endocrine disorders and some pending problems was also discussed, and new insights for TCM treatment of dementia in the future was provided.

Discovery of novel β-carboline derivatives as selective AChE inhibitors with GSK-3β inhibitory property for the treatment of Alzheimer's disease

The natural product harmine, a representative β-carboline alkaloid from the seeds of Peganum harmala L. (Zygophyllaceae), possesses a broad spectrum of biological activities. In this study, a novel series of harmine derivatives containing N-benzylpiperidine moiety were identified for the treatment of Alzheimer's disease (AD). The results showed that all the derivatives possessed significant anti-acetylcholinesterase (AChE) activity and good selectivity over butyrylcholinesterase (BChE). In particular, compound ZLWH-23 exhibited potent anti-AChE activity (IC₅₀ = 0.27 μM) and selective BChE inhibition (IC₅₀ = 20.82 μM), as well as acceptable glycogen synthase kinase-3 (GSK-3β) inhibition (IC₅₀ = 6.78 μM). Molecular docking studies and molecular dynamics simulations indicated that ZLWH-23 could form stable interaction with AChE and GSK-3β. Gratifyingly, ZLWH-23 exhibited good selectivity for GSK-3β over multi-kinases and very low cytotoxicity towards SH-SY5Y, HEK-293T, HL-7702, and HepG2 cell lines. Importantly, ZLWH-23 displayed efficient reduction against tau hyperphosphorylation on Ser-396 site in Tau (P301L) 293T cell model. Collectively, harmine-based derivatives could be considered as possible drug leads for the development of AD therapies.

The Pathophysiology and Treatment of Essential Tremor: The Role of Adenosine and Dopamine Receptors in Animal Models

Essential tremor (ET) is one of the most common neurological disorders that often affects people in the prime of their lives, leading to a significant reduction in their quality of life, gradually making them unable to independently perform the simplest activities. Here we show that current ET pharmacotherapy often does not sufficiently alleviate disease symptoms and is completely ineffective in more than 30% of patients. At present, deep brain stimulation of the motor thalamus is the most effective ET treatment. However, like any brain surgery, it can cause many undesirable side effects; thus, it is only performed in patients with an advanced disease who are not responsive to drugs. Therefore, it seems extremely important to look for new strategies for treating ET. The purpose of this review is to summarize the current knowledge on the pathomechanism of ET based on studies in animal models of the disease, as well as to present and discuss the results of research available to date on various substances affecting dopamine (mainly D3) or adenosine A1 receptors, which, due to their ability to modulate harmaline-induced tremor, may provide the basis for the development of new potential therapies for ET in the future.

Neuroprotective Activity of Melittin-The Main Component of Bee Venom-Against Oxidative Stress Induced by Aβ25-35 in In Vitro and In Vivo Models

Melittin, a 26-amino acid peptide, is the main component of the venom of four honeybee species and exhibits neuroprotective actions. However, it is unclear how melittin ameliorates neuronal cells in oxidative stress and how it affects memory impairment in an in vivo model. We evaluated the neuroprotective effect of melittin on Aβ_25–35-induced neuro-oxidative stress in both in vitro HT22 cells and in vivo animal model. Melittin effectively protected against HT22 cell viability and significantly deregulated the Aβ_25–35-induced overproduction of intracellular reactive oxygen species. Western blot analysis showed that melittin suppressed cell apoptosis and regulated Bax/Bcl-2 ratio, as well as the expression of proapoptotic related factors: Apoptosis-inducing factor (AIF), Calpain, Cytochrome c (CytoC), Cleaved caspase-3 (Cleacas3). Additionally, melittin enhanced the antioxidant defense pathway by regulating the nuclear translocation of nuclear factor erythroid 2-like 2 (Nrf2) thus upregulated the production of the heme oxygenase-1 (HO-1), a major cellular antioxidant enzyme combating neuronal oxidative stress. Furthermore, melittin treatment activated the Tropomyosin-related kinase receptor B (TrkB)/cAMP Response Element-Binding (CREB)/Brain-derived neurotrophic factor (BDNF), contributing to neuronal neurogenesis, and regulating the normal function of synapses in the brain. In our in vivo experiment, melittin was shown to enhance the depleted learning and memory ability, a novel finding. A mouse model with cognitive deficits induced by Aβ_25–35 intracerebroventricular injection was used. Melittin had dose-dependently enhanced neural-disrupted animal behavior and enhanced neurogenesis in the dentate gyrus hippocampal region. Further analysis of mouse brain tissue and serum confirmed that melittin enhanced oxidant–antioxidant balance, cholinergic system activity, and intercellular neurotrophic factors regulation, which were all negatively altered by Aβ_25–35. Our study shows that melittin exerts antioxidant and neuroprotective actions against neural oxidative stress. Melittin can be a potential therapeutic agent for neurodegenerative disorders.

Design, synthesis and biological evaluation of harmine derivatives as potent GSK-3β/DYRK1A dual inhibitors for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disease, characterized by irreversible cognitive impairment, memory loss and behavioral disturbances, ultimately leading to death. Glycogen synthase kinase 3β (GSK-3β) and dual-specificity tyrosine phosphorylation regulated kinase1A (DYRK1A) have gained a lot of attention for its role in tau pathology. To search for potential dual GSK-3β/DYRK1A inhibitors, we focused on harmine, a natural β-carboline alkaloid, which has been extensively studied for its various biological effects on the prevention of AD. In this study, a new series of harmine derivatives were designed, synthesized and evaluated as dual GSK-3β/DYRK1A inhibitors for their multiple biological activities. The in vitro results indicated that most of them displayed promising activity against GSK-3β and DYRK1A. Among them, compound ZDWX-25 showed potent inhibitory effects on GSK-3β and DYRK1A with IC50 values of 71 and 103 nM, respectively. Molecular modelling and kinetic studies verified that ZDWX-25 could interact with the ATP binding pocket of GSK-3β and DYRK1A. Western blot analysis revealed that ZDWX-25 inhibited hyperphosphorylation of tau protein in okadaic acid (OKA)-induced SH-SY5Y cells. In addition, ZDWX-25 showed good blood-brain barrier penetrability in vitro. More importantly, ZDWX-25 could ameliorate the impaired learning and memory in APP/PS1/Tau transgenic mice. These results indicated that the harmine-based compounds could be served as promising dual-targeted candidates for AD.

From psychiatry to neurology: Psychedelics as prospective therapeutics for neurodegenerative disorders

The studies of psychedelics, especially psychedelic tryptamines like psilocybin, are rapidly gaining interest in neuroscience research. Much of this interest stems from recent clinical studies demonstrating that they have a unique ability to improve the debilitating symptoms of major depressive disorder (MDD) long-term after only a single treatment. Indeed, the Food and Drug Administration (FDA) has recently designated two Phase III clinical trials studying the ability of psilocybin to treat forms of MDD with "Breakthrough Therapy" status. If successful, the use of psychedelics to treat psychiatric diseases like depression would be revolutionary. As more evidence appears in the scientific literature to support their use in psychiatry to treat MDD on and substance use disorders (SUD), recent studies with rodents revealed that their therapeutic effects might extend beyond treating MDD and SUD. For example, psychedelics may have efficacy in the treatment and prevention of brain injury and neurodegenerative diseases such as Alzheimer's Disease. Preclinical work has highlighted psychedelics' ability to induce neuroplasticity and synaptogenesis, and neural progenitor cell proliferation. Psychedelics may also act as immunomodulators by reducing levels of proinflammatory biomarkers, including IL-1β, IL-6, and tumor necrosis factor-α (TNF-α). Their exact molecular mechanisms, and induction of cellular interactions, especially between neural and glial cells, leading to therapeutic efficacy, remain to be determined. In this review, we discuss recent findings and information on how psychedelics may act therapeutically on cells within the central nervous system (CNS) during brain injuries and neurodegenerative diseases.

A preliminary study on the neurotoxic mechanism of harmine in Caenorhabditis elegans

Harmine is a beta-carboline and harmala alkaloid with extensive bioactivities. However, its toxicity, especially in neural system, is not systematically assessed and the toxic mechanism is not yet clear. Using Caenorhabditis elegans (C. elegans) as a model system, we found that harmine exhibited dosage dependent (0, 5, 10, 20, 40, 80, 160, and 320 μmol/L) toxic effect, such as growth inhibition, egg laying defects, shortened life span and increased mortality. Although harmine did not result in obvious structural alterations in neurite or death of neurons, it did show direct acetylcholinesterase inhibition activity. Further, we found that harmine treatment decreased worm pharyngeal pump rate and lowered the content of nitric oxide (NO) in worm body, implying foraging disorders, which is an indicator of acetylcholinergic neuron activity inhibition. Besides, network pharmacology and molecular docking reveals that acetylcholinesterase is one of the major neural toxicity targets as well. Above all, harmine can directly inhibit the activity of acetylcholinesterase, leading to excessive accumulation of acetylcholine, which may be one of the harmine neurotoxicity mechanisms.

Natural COX-2 Inhibitors as Promising Anti-inflammatory Agents: An Update

COX-2, a key enzyme that catalyzed the rate-limiting steps in the conversion of arachidonic acid to prostaglandins, played a pivotal role in the inflammatory process. Different from other family members, COX-2 was barely detectable in normal physiological conditions and highly inducible during the acute inflammatory response of human bodies to injuries or infections. Therefore, the therapeutic utilization of selective COX-2 inhibitors has already been considered as an effective approach for the treatment of inflammation with diminished side effects. Currently, both traditional and newer NSAIDs are the commonly prescribed medications that treat inflammatory diseases by targeting COX-2. However, due to the cardiovascular side-effects of the NSAIDs, finding reasonable alternatives for these frequently prescribed medicines are a hot spot in medicinal chemistry research. Naturallyoccurring compounds have been reported to inhibit COX-2, thereby possessing beneficial effects against inflammation and certain cell injury. The review mainly concentrated on recently identified natural products and derivatives as COX-2 inhibitors, the characteristics of their structural core scaffolds, their anti-inflammatory effects, molecular mechanisms for enzymatic inhibition, and related structure-activity relationships. According to the structural features, the natural COX-2 inhibitors were mainly divided into the following categories: natural phenols, flavonoids, stilbenes, terpenoids, quinones, and alkaloids. Apart from the anti-inflammatory activities, a few dietary COX-2 inhibitors from nature origin also exhibited chemopreventive effects by targeting COX-2-mediated carcinogenesis. The utilization of these natural remedies in future cancer prevention was also discussed. In all, the survey on the characterized COX-2 inhibitors from natural sources paves the way for the further development of more potent and selective COX-2 inhibitors in the future.

Peganum harmala enhanced GLP-1 and restored insulin signaling to alleviate AlCl3-induced Alzheimer-like pathology model

Peganum harmala (P. harmala) is a folk medicinal herb used in the Sinai Peninsula (Egypt) as a remedy for central disorders. The main constituents, harmine and harmaline, have displayed therapeutic efficacy against Alzheimer's disease (AD); however, the P. harmala potential on sensitizing central insulin to combat AD remains to be clarified. An AD-like rat model was induced by aluminum chloride (AlCl3; 50 mg/kg/day for six consecutive weeks; i.p), whereas a methanolic standardized P. harmala seed extract (187.5 mg/kg; p.o) was given to AD rats starting 2 weeks post AlCl3 exposure. Two additional groups of rats were administered either the vehicle to serve as the normal control or the vehicle + P. harmala seed extract to serve as the P. harmala control group. P. harmala enhanced cognition appraised by Y-maze and Morris water maze tests and improved histopathological structures altered by AlCl3. Additionally, it heightened the hippocampal contents of glucagon-like peptide (GLP)-1 and insulin, but abated insulin receptor substrate-1 phosphorylation at serine 307 (pS307-IRS-1). Besides, P. harmala increased phosphorylated Akt at serine 473 (pS473-Akt) and glucose transporter type (GLUT)4. The extract also curtailed the hippocampal content of beta amyloid (Aβ)42, glycogen synthase (GSK)-3β and phosphorylated tau. It also enhanced Nrf2, while reduced lipid peroxides and replenished glutathione. In conclusion, combating insulin resistance by P. harmala is a novel machinery in attenuating the insidious progression of AD by enhancing both insulin and GLP-1 trajectories in the hippocampus favoring GLUT4 production.

Role of natural plant products against Alzheimer's disease

Alzheimer's disease (AD) is one of the major neurodegenerative disorder. Deposition of amyloid fibrils and tau protein are associated with various pathological symptoms. Currently limited medication is available for AD treatment. Most of the drugs are basically cholinesterase inhibitors and associated with various side effects. Natural plant products have shown potential as a therapeutic agent for the treatment of AD symptoms. Variety of secondary metabolites like flavonoids, tannins, terpenoids, alkaloids and phenols are used to reduce the progression of the disease. Plant products have less or no side effect and are easily available. The present review gives a detailed account of the potential of natural plant products against the AD symptoms.

Agmatine has beneficial effect on harmaline-induced essential tremor in rat

Essential tremor (ET) is one of the most prevalent movement disorders and the most common cause of abnormal tremors. However, it cannot be treated efficiently with the currently available pharmacotherapy options. The pathophysiology of harmaline-induced tremor, most commonly used model of ET, involves various neurotransmitter systems including glutamate as well as ion channels. Agmatine, an endogenous neuromodulator, interacts with various glutamate receptor subtypes and ion channels, which have been associated with its' beneficial effects on several neurological disorders. The current study aims to assess the effect of agmatine on the harmaline model of ET. Two separate groups of male rats were injected either with saline or agmatine (40 mg/kg) 30 min prior to single intraperitoneal injection of harmaline (20 mg/kg). The percent duration, intensity and frequency of tremor and locomotor activity were evaluated by a custom-built tremor and locomotion analysis system. Pretreatment with agmatine reduced the percent tremor duration and intensity of tremor induced by harmaline, without affecting the tremor frequency. However, it did not affect the decreased spontaneous locomotor activity due to harmaline. This pattern of ameliorating effects of agmatine on harmaline-induced tremor provide the first evidence for being considered as a treatment option for ET.

Ficus erecta Thunb Leaves Alleviate Memory Loss Induced by Scopolamine in Mice via Regulation of Oxidative Stress and Cholinergic System

We examined the neuropharmacological effects of ethanol extract of Ficus erecta Thunb leaves (EEFE) on cognitive dysfunction in a scopolamine (SCO)-induced memory impairment animal model. Memory impairment was measured using the Y-maze test and passive avoidance task (PAT). For 19 days, EEFE (100 or 200 mg/kg) was treated through oral administration. Treatment with EEFE ameliorated memory impairment in behavioral tests, along with significant protection from neuronal oxidative stress and neuronal cell loss in the brain tissues of SCO-injected mice. Antioxidant and neuroprotective effects of EEFE were further confirmed using in vitro assays. Our findings indicate that the mechanisms of neuroprotection and antioxidation of EEFE are regulated by the cholinergic system, promotion of cAMP response element-binding protein (CREB) phosphorylation, and the nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase (HO)-1 signaling activation. The current study proposes that EEFE could be an encouraging plant resource and serve as a potent neuropharmacological drug candidate against neurodegenerative diseases.

Osthole-Loaded Nanoemulsion Enhances Brain Target in the Treatment of Alzheimer's Disease via Intranasal Administration

Osthole (OST) is a natural coumarin compound that exerts multiple pharmacologic effects. However, the poor water solubility and the low oral absorption of OST limit its clinical application for the treatment of neurologic diseases. A suitable preparation needs to be tailored to evade these unfavourable properties of OST. In this study, an OST nanoemulsion (OST-NE) was fabricated according to the pseudoternary phase diagram method, which was generally used to optimize the prescription in light of the solubility of OST in surfactants and cosurfactants. The final composition of OST-NE was 3.6% of ethyl oleate as oil phase, 11.4% of the surfactant (polyethylene glycol ester of 15-hydroxystearic acid: polyoxyethylene 35 castor oil = 1 : 1), 3% of polyethylene glycol 400 as cosurfactant, and 82% of the aqueous phase. The pharmacokinetic study of OST-NE showed that the brain-targeting coefficient of OST was larger by the nasal route than that by the intravenous route. Moreover, OST-NE inhibited cell death, decreased the apoptosis-related proteins (Bax and caspase-3), and enhanced the activity of antioxidant enzymes (superoxide dismutase and glutathione) in L-glutamate-induced SH-SY5Y cells. OST-NE improved the spatial memory ability, increased the acetylcholine content in the cerebral cortex, and decreased the activity of acetylcholinesterase in the hippocampus of Alzheimer's disease model mice. In conclusion, this study indicates that the bioavailability of OST was improved by using the OST-NE via the nasal route. A low dose of OST-NE maintained the neuroprotective effects of OST, such as inhibiting apoptosis and oxidative stress and regulating the cholinergic system. Therefore, OST-NE can be used as a possible alternative to improve its bioavailability in the prevention and treatment of Alzheimer's disease.

A review on β-carboline alkaloids and their distribution in foodstuffs: A class of potential functional components or not?

Pharmacologically active β-carboline alkaloids (βCs) such as harman, norharman and some others are naturally present in plants and occur in many foodstuffs. They have a lot of pharmacological properties, including antitumor, antioxidant, anti-inflammatory and antimicrobial effects, and possess the potential for treating Alzheimer's disease, Parkinson's disease, depression and other central nervous system diseases. Dietary intake is proven to be an important source of βCs. Therefore, it is important to know the amounts of βCs that can be gotten from daily diets. This review summarizes the pharmacological activities, toxicology and formation of βCs, and gives collective information on contents of βCs in different foodstuffs.

Parkinson's Disease Master Regulators on Substantia Nigra and Frontal Cortex and Their Use for Drug Repositioning

Parkinson's disease (PD) is among the most prevalent neurodegenerative diseases. Available evidences support the view of PD as a complex disease, being the outcome of interactions between genetic and environmental factors. In face of diagnosis and therapy challenges, and the elusive PD etiology, the use of alternative methodological approaches for the elucidation of the disease pathophysiological mechanisms and proposal of novel potential therapeutic interventions has become increasingly necessary. In the present study, we first reconstructed the transcriptional regulatory networks (TN), centered on transcription factors (TF), of two brain regions affected in PD, the substantia nigra pars compacta (SNc) and the frontal cortex (FCtx). Then, we used case-control studies data from these regions to identify TFs working as master regulators (MR) of the disease, based on region-specific TNs. Twenty-nine regulatory units enriched with differentially expressed genes were identified for the SNc, and twenty for the FCtx, all of which were considered MR candidates for PD. Three consensus MR candidates were found for SNc and FCtx, namely ATF2, SLC30A9, and ZFP69B. In order to search for novel potential therapeutic interventions, we used these consensus MR candidate signatures as input to the Connectivity Map (CMap), a computational drug repositioning webtool. This analysis resulted in the identification of four drugs that reverse the expression pattern of all three MR consensus simultaneously, benperidol, harmaline, tubocurarine chloride, and vorinostat, thus suggested as novel potential PD therapeutic interventions.

Pharmacological effects of harmine and its derivatives: a review

Harmine is isolated from the seeds of the medicinal plant, Peganum harmala L., and has been used for thousands of years in the Middle East and China. Harmine has many pharmacological activities including anti-inflammatory, neuroprotective, antidiabetic, and antitumor activities. Moreover, harmine exhibits insecticidal, antiviral, and antibacterial effects. Harmine derivatives exhibit pharmacological effects similar to those of harmine, but with better antitumor activity and low neurotoxicity. Many studies have been conducted on the pharmacological activities of harmine and harmine derivatives. This article reviews the pharmacological effects and associated mechanisms of harmine. In addition, the structure-activity relationship of harmine derivatives has been summarized.

Potential mechanisms of tremor tolerance induced in rats by the repeated administration of total alkaloid extracts from the seeds of Peganum harmala Linn

ETHNOPHARMACOLOGICAL RELEVANCE

The seeds of Peganum harmala Linn have been widely used for the treatment of nervous, cardiovascular, gastrointestinal, respiratory, and endocrine diseases and many other human ailments. However, tremor toxicity occurs after overdose and is tolerated following multiple dosing. Thus far, little is known about the underlying mechanisms of tremors and tremor tolerance.

AIM OF THE STUDY

To investigate the potential mechanisms of tremors and tremor tolerance induced in rats by the repeated administration of total alkaloid extracts from the seeds of P. harmala (TAEP).

MATERIALS AND METHODS

A tremor model was induced in male Wistar rats by administering TAEP at a dose of 150 mg/kg/day. To evaluate tremor action, behavioral assessment was conducted by using a custom-built tremor acquisition and analysis system. To investigate the relationships between tremors and neurotransmitter levels in the brain, various neurotransmitters were simultaneously quantified by an ultra-performance liquid chromatography combined with electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) system, and the association between these two parameters was analyzed using Pearson correlation coefficients. To further elucidate the potential mechanisms of the alterations of neurotransmitter levels in cortical tissues, the protein expression levels of several important enzymes and transporters that are closely related to neurotransmitter levels were investigated. In addition, neuropathological analysis was conducted to assess the effect of TAEP on neurons in the brain. To further clarify the potential mechanisms of TAEP-induced neurodegeneration in the brain, c-fos was subjected to immunohistochemical analysis, and oxidative stress markers were examined.

RESULTS

Tremors initially occurred in rats after the oral administration of TAEP at a dose of 150 mg/kg/day. However, they were tolerated following repeated dosing. The levels of 5-hydroxytryptamine (5-HT) and glycine (Gly) in cortical tissues were most likely associated with the tremor response. Tremor tolerance also likely resulted from the degeneration of cerebellar Purkinje cells. Furthermore, the alteration of 5-HT levels was mainly attributed to the downregulated expression of monoamine oxidase A (MAO-A). The degeneration of Purkinje neurons might have resulted from the overexpression of c-fos and increased oxidative stress in the cerebellum after the multiple dosing of TAEP.

CONCLUSION

The tremor response induced by TAEP at high doses is closely related to the concentrations of 5-HT and Gly in cortical tissues. Tremor tolerance may also be attributed to the degeneration of cerebellar Purkinje cells after the repeated dosing of TAEP. Further studies should be conducted to elucidate the interaction of the alkaloids on the neurotransmitter receptors, the expression of related neurotransmitter receptors, the specific signaling pathway involved in regulating MAO-A, and the mechanism of the loss and functional recovery of cerebellar Purkinje neurons.