Quercetin and Related Chromenone Derivatives as Monoamine Oxidase Inhibitors: Targeting Neurological and Mental Disorders

Gold Nanoparticles in Parkinson's Disease Therapy: A Focus on Plant-Based Green Synthesis

Parkinson's disease (PD) is a progressive neurodegenerative disease that affects approximately 1% of people over the age of 60 and 5% of those over the age of 85. Current drugs for Parkinson's disease mainly affect the symptoms and cannot stop its progression. Nanotechnology provides a solution to address some challenges in therapy, such as overcoming the blood-brain barrier (BBB), adverse pharmacokinetics, and the limited bioavailability of therapeutics. The reformulation of drugs into nanoparticles (NPs) can improve their biodistribution, protect them from degradation, reduce the required dose, and ensure target accumulation. Furthermore, appropriately designed nanoparticles enable the combination of diagnosis and therapy with a single nanoagent. In recent years, gold nanoparticles (AuNPs) have been studied with increasing interest due to their intrinsic nanozyme activity. They can mimic the action of superoxide dismutase, catalase, and peroxidase. The use of 13-nm gold nanoparticles (CNM-Au8®) in bicarbonate solution is being studied as a potential treatment for Parkinson's disease and other neurological illnesses. CNM-Au8® improves remyelination and motor functions in experimental animals. Among the many techniques for nanoparticle synthesis, green synthesis is increasingly used due to its simplicity and therapeutic potential. Green synthesis relies on natural and environmentally friendly materials, such as plant extracts, to reduce metal ions and form nanoparticles. Moreover, the presence of bioactive plant compounds on their surface increases the therapeutic potential of these nanoparticles. The present article reviews the possibilities of nanoparticles obtained by green synthesis to combine the therapeutic effects of plant components with gold.

Investigating the mechanism of Sinisan formula in depression treatment: a comprehensive analysis using GEO datasets, network pharmacology, and molecular docking

The herbal formula Sinisan (SNS) is a commonly used treatment for depression; however, its mechanism of action remains unclear. This article uses a combination of the GEO database, network pharmacology and molecular docking technologies to investigate the mechanism of action of SNS. The aim is to provide new insights and methods for future depression treatments. The study aims to extract effective compounds and targets for the treatment of depression from the T CMSP database. Relevant targets were searched using the GEO, Disgenet, Drugbank, PharmGKB and T T D databases, followed by screening of core targets. In addition, GO and KEGG pathway enrichment analyses were performed to explore potential pathways for the treatment of depression. Molecular docking was used to evaluate the potential targets and compounds and to identify the optimal core protein-compound complex. Molecular dynamics was used to further investigate the dynamic variability and stability of the complex. The study identified 118 active SNS components and 208 corresponding targets. Topological analysis of P P I networks identified 11 core targets. GO and KEGG pathway enrichment analyses revealed that the mechanism of action for depression involves genes associated with inflammation, apoptosis, oxidative stress, and the MAP K3 and P I3K-Akt signalling pathways. Molecular docking and dynamics simulations showed a strong binding affinity between these compounds and the screened targets, indicating promising biological activity. The present study investigated the active components, targets and pathways of SNS in the treatment of depression. Through a preliminary investigation, key signalling pathways and compounds were identified. These findings provide new directions and ideas for future research on the therapeutic mechanism of SNS and its clinical application in the treatment of depression.Communicated by Ramaswamy H. Sarma.

Natural Products as Monoamine Oxidase Inhibitors: Potential Agents for Neurological Disorders

The role of medicinal plants has been advantageous due to their manifestation through various cellular and molecular mechanisms. Inhibition of the monoamine oxidase enzyme is suspected to be a highly effective treatment for various neurological illnesses like Alzheimer's disease, Parkinson's disease, depression, social phobia, and panic disorders. The study of phytochemicals and plant extracts used as a traditional source of medication revealed that they possess the vast potential for monoamine oxidase inhibition. Thus, the article focuses on the potential use of plant extracts and phytochemicals as sources of novel MAO inhibitors for treating neurological disorders. Exhaustive literature search revealed that a variety of phytochemicals from the categories such as flavonoids, alkaloids, glycosides, alkyl phenyl ketones, coumarin derivatives and essential oils have displayed potential MAO inhibition. This review highlights the progress made in the discovery and development of plant-based MAO inhibitors and aims to provide medicinal chemists with an overview of this information to aid in the development of clinically viable drugs.

Pyrazoline Derivatives as Promising MAO-A Targeting Antidepressants: An Update

Depression is one of the key conditions addressed by the Mental Health Gap Action Programme (mhGAP) of WHO that can lead to self-harm and suicide. Depression is associated with low levels of neurotransmitters, which eventually play a key role in the progression and development of mental illness. The nitrogen-containing heterocyclic compounds exhibit the most prominent pharmacological profile as antidepressants. Pyrazoline, a dihydro derivative of pyrazole, is a well-known five-membered heterocyclic moiety that exhibits a broad spectrum of biological activities. Many researchers have reported pyrazoline scaffold-containing molecules as potential antidepressant agents with selectivity for monoamine oxidase enzyme (MAO) isoforms. Several studies indicated a better affinity of pyrazoline-based moiety as (monoamine oxidase inhibitors) MAOIs. In this review, we have focused on the recent advancements (2019-2023) in the development of pyrazoline-containing derivatives exhibiting promising inhibition of MAO-A enzyme to treat depression. This review provides structural insights on pyrazoline-based molecules along with their SAR analysis, in silico exploration of binding interactions between pyrazoline derivatives and MAO-A enzyme, and clinical trial status of various drug molecules against depression. The in-silico exploration of potent pyrazoline derivatives at the active site of the MAOA enzyme will provide further insights into the development of new potential MAO-A inhibitors for the treatment of depression.

Role of Flavonoids in Modulation of Mitochondria Dynamics during Oxidative Stress

BACKGROUND

Flavonoids are a widespread category of naturally occurring polyphenols distinguished by the flavan nucleus in plant-based foods and beverages, known for their various health benefits. Studies have suggested that consuming 150-500 mg of flavonoids daily is beneficial for health. Recent studies suggest that flavonoids are involved in maintaining mitochondrial activity and preventing impairment of mitochondrial dynamics by oxidative stress.

OBJECTIVE

This review emphasized the significance of studying the impact of flavonoids on mitochondrial dynamics, oxidative stress, and inflammatory response.

METHODS

This review analysed and summarised the findings related to the impact of flavonoids on mitochondria from publicly available search engines namely Pubmed, Scopus, and Web of Science.

DESCRIPTION

Any disruption in mitochondrial dynamics can contribute to cellular dysfunction and diseases, including cancer, cardiac conditions, and neurodegeneration. Flavonoids have been shown to modulate mitochondrial dynamics by regulating protein expression involved in fission and fusion events. Furthermore, flavonoids exhibit potent antioxidant properties by lowering the production of ROS and boosting the performance of antioxidant enzymes. Persistent inflammation is a characteristic of many different disorders. This is because flavonoids also alter the inflammatory response by controlling the expression of numerous cytokines and chemokines involved in the inflammatory process. Flavonoids exhibit an impressive array of significant health effects, making them an effective therapeutic agent for managing various disorders. Further this review summarised available mechanisms underlying flavonoids' actions on mitochondrial dynamics and oxidative stress to recognize the optimal dose and duration of flavonoid intake for therapeutic purposes.

CONCLUSION

This review may provide a solid foundation for developing targeted therapeutic interventions utilizing flavonoids, ultimately benefiting individuals afflicted with various disorders.

Targeting Nrf2 signaling pathway by quercetin in the prevention and treatment of neurological disorders: An overview and update on new developments

BACKGROUND

Neurological disorders (NLDs) are widely acknowledged as a significant public health concern worldwide. Stroke, Alzheimer's disease (AD), and traumatic brain injury (TBI) are three of these disorders that have sparked major study attention. Neurological dysfunction, protein buildup, oxidation and neuronal injury, and aberrant mitochondria are all prevalent neuropathological hallmarks of these disorders. The signaling cascade of nuclear factor erythroid 2 related factor 2 (Nrf2) shares all of them as a common target. Several studies have found that overexpression of Nrf2 is a promising treatment method in NLDs. Effective treatment of these disorders continues to be a universal concern regardless of various medicines. In order to treat a variety of neurological problems, organic remedies may provide an alternative treatment. It has been demonstrated that polyphenols like quercetin (Que) offer considerable capabilities for treating NLDs. One of Que's greatest key targets, Nrf2, has the capacity to control the production of a number of cytoprotective enzymes that exhibit neuroprotective, detoxifying, and antioxidative effects. Additionally, Que enhanced the expression of Nrf2 and inhibited alterations in the shape and death of neurons in the hippocampus.

OBJECTIVE

In this review, we have focused on Que's medicinal prospects as a neuroprotective drug.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar were used to search articles for this study.

RESULTS

The findings of this research demonstrate that (1) Que protected the blood-brain barrier via stimulating Nrf2 in animal stroke, which alleviated ischemic reperfusion and motor dysfunction. (2) By triggering the Nrf2 pathway, Que reduced the neuroinflammation and oxidative damage brought on by TBI in the cortex. (3) In an experimental model of AD, Que enhanced cognitive function by decreasing A1-4, antioxidant activity, and Nrf2 levels in the brain.

CONCLUSION

We discuss recent research on Que-mediated Nrf2 expression in the management of several NLDs in this paper.

Pharmacokinetic and pharmacodynamic herb-drug interactions-part I. Herbal medicines of the central nervous system

Unlike conventional drug substances, herbal medicines are composed of a complex of biologically active compounds. Therefore, the potential occurrence of herb-drug interactions is even more probable than for drug-drug interactions. Interactions can occur on both the pharmacokinetic and pharmacodynamic level. Herbal medicines may affect the resulting efficacy of the concomitantly used (synthetic) drugs, mainly on the pharmacokinetic level, by changing their absorption, distribution, metabolism, and excretion. Studies on the pharmacodynamic interactions of herbal medicines and conventional drugs are still very limited. This interaction level is related to the mechanism of action of different plant constituents. Herb-drug interactions can cause changes in drug levels and activities and lead to therapeutic failure and/or side effects (sometimes toxicities, even fatal). This review aims to provide a summary of recent information on the potential drug interactions involving commonly used herbal medicines that affect the central nervous system (Camellia, Valeriana, Ginkgo, Hypericum, Humulus, Cannabis) and conventional drugs. The survey databases were used to identify primary scientific publications, case reports, and secondary databases on interactions were used later on as well. Search keywords were based on plant names (botanical genera), officinal herbal drugs, herbal drug preparations, herbal drug extracts.

Mechanistic prospective and pharmacological attributes of quercetin in attenuation of different types of arthritis

Arthritis is a frequent autoimmune disease with undefined etiology and pathogenesis. Scientific community constantly fascinating quercetin (QUR), as it is the best-known flavonoid among others for curative and preventive properties against a wide range of diseases. Due to its multifaceted activities, the implementation of QUR against various types of arthritis namely, rheumatoid arthritis (RA), osteoarthritis (OA), gouty arthritis (GA) and psoriotic arthritis (PsA) has greatly increased in recent years. Many research evidenced that QUR regulates a wide range of pathways for instance NF-κB, MAK, Wnt/β-catenine, Notch, etc., that are majorly associated with the inflammatory mechanisms. Besides, the bioavailability of QUR is a major constrain to its therapeutic potential, and drug delivery techniques have experienced significant development to overcome the problem of its limited application. Hence, this review compiled the cutting-edge experiments on versatile effects of QUR on inflammatory diseases like RA, OA, GA and PsA, sources and bioavailability, therapeutic challenges, pharmacokinetics, clinical studies as well as toxicological impacts. The use of QUR in a health context would offer a tearing and potential therapeutic method, supporting the advancement of public health, particularly, of arthritic patients worldwide.

Inhibitory Effect of Quercetin on Oxidative Endogen Enzymes: A Focus on Putative Binding Modes

Oxidative stress is defined as an imbalance between the production of free radicals and reactive oxygen species (ROS) and the ability of the body to neutralize them by anti-oxidant defense systems. Cells can produce ROS during physiological processes, but excessive ROS can lead to non-specific and irreversible damage to biological molecules, such as DNA, lipids, and proteins. Mitochondria mainly produce endogenous ROS during both physiological and pathological conditions. Enzymes like nicotinamide adenine dinucleotide phosphate oxidase (NOX), xanthine oxidase (XO), lipoxygenase (LOX), myeloperoxidase (MPO), and monoamine oxidase (MAO) contribute to this process. The body has enzymatic and non-enzymatic defense systems to neutralize ROS. The intake of bioactive phenols, like quercetin (Que), can protect against pro-oxidative damage by quenching ROS through a non-enzymatic system. In this study, we evaluate the ability of Que to target endogenous oxidant enzymes involved in ROS production and explore the mechanisms of action underlying its anti-oxidant properties. Que can act as a free radical scavenger by donating electrons through the negative charges in its phenolic and ketone groups. Additionally, it can effectively inhibit the activity of several endogenous oxidative enzymes by binding them with high affinity and specificity. Que had the best molecular docking results with XO, followed by MAO-A, 5-LOX, NOX, and MPO. Que's binding to these enzymes was confirmed by subsequent molecular dynamics, revealing different stability phases depending on the enzyme bound. The 500 ns simulation showed a net evolution of binding for NOX and MPO. These findings suggest that Que has potential as a natural therapy for diseases related to oxidative stress.

A Concise Review of the Recent Structural Explorations of Chromones as MAO-B Inhibitors: Update from 2017 to 2023

Monoamine oxidases (MAOs) are a family of flavin adenine dinucleotide-dependent enzymes that catalyze the oxidative deamination of a wide range of endogenous and exogenous amines. Multiple neurological conditions, including Parkinson's disease (PD) and Alzheimer's disease (AD), are closely correlated with altered biogenic amine concentrations in the brain caused by MAO. Toxic byproducts of this oxidative breakdown, including hydrogen peroxide, reactive oxygen species, and ammonia, can cause oxidative damage and mitochondrial dysfunction in brain cells. Certain MAO-B blockers have been recognized as effective treatment options for managing neurological conditions, including AD and PD. There is still a pressing need to find potent therapeutic molecules to fight these disorders. However, the focus of neurodegeneration studies has recently increased, and certain compounds are now in clinical trials. Chromones are promising structures for developing therapeutic compounds, especially in neuronal degeneration. This review focuses on the MAO-B inhibitory potential of several synthesized chromones and their structural activity relationships. Concerning the discovery of a novel class of effective chromone-based selective MAO-B-inhibiting agents, this review offers readers a better understanding of the most recent additions to the literature.

Biological Activity of Genus Hypericum Sect. Hypericum Species-H. tetrapterum, H. maculatum subsp. immaculatum, H. triquetrifolium

St. John's wort (Hypericum perforatum, Hypericaceae) has long been used in traditional medicine as a potent remedy, while many other species of this genus have not been thoroughly investigated. The study aimed to detect the biological activity, including antioxidant, antihyperglycemic, anticholinergic, antimicrobial and monoaminoxidase inhibitory potential, of water-alcoholic extracts of three species autochthonous for Serbia and Greece from plant genus Hypericum (section Hypericum-H. tetrapterum, H. maculatum ssp. immaculatum and H. triquetrifolium), followed by phytochemical profiling. The highest amount of phenolics was recorded in H. maculatum subsp. immaculatum extract, while the highest abundance of flavonoids was characteristic of H. tetrapterum extract. Hypericin and hyperforin, quercetin, and its flavonoid, rutin, were present in all of the evaluated species. The evaluated species were good scavengers of DPPH, OH and NO radicals, as well as potent reducers of ferric ions in FRAP assay. Furthermore, the evaluated species were shown as potent inhibitors of monoaminoxidase A and α-glucosidase and modest inhibitors of acetylcholinesterase, monoaminoxidase B and α-amylase. No anti-Candida activity was recorded, but the extracts were effective against MRSA Staphylococcus aureus and Enterococcus sp., as well as against Proteus mirabilis. The obtained results strongly highlight the need for further in vivo studies in order to better define the potential of the medicinal application of the studied species.

Analysis of Antioxidant Constituents of Filtering Infusions from Oak (Quercus sideroxyla Bonpl. and Quercus eduardii Trel.) and Yerbaniz (Tagetes lucida (Sweet) Voss) as Monoamine Oxidase Inhibitors

The antioxidant constituents of ancestral products with ethnobotanical backgrounds are candidates for the study of filtering infusions to aid in pharmacotherapies focused on the treatment of depression and anxiety. Monoamine oxidase A (MAO-A) is an enzyme that regulates the metabolic breakdown of serotonin and noradrenaline in the nervous system. The goal of this study was to evaluate in vitro and in silico the effect of antioxidant constituents of filtering infusions from yerbaniz (Tagetes lucida (Sweet) Voss) and oak (Quercus sideroxyla Bonpl. and Quercus eduardii Trel.) as monoamine oxidase inhibitors. Materials were dried, ground, and mixed according to a simplex-centroid mixture design for obtaining infusions. Differential analysis of the phenolic constituent's ratio in the different infusions indicates that among the main compounds contributing to MAO-A inhibition are the gallic, chlorogenic, quinic, and shikimic acids, quercetin glucuronide and some glycosylated derivatives of ellagic acid and ellagic acid methyl ether. Infusions of Q. sideroxyla Bonpl. leaves, because of their content (99.45 ± 5.17 µg/mg) and synergy between these constituents for MAO-A inhibition (52.82 ± 3.20%), have the potential to treat depression and anxiety. Therefore, future studies with pharmacological approaches are needed to validate them as therapeutic agents with applications in mental health care.

Bioisosteric replacement based on 1,2,4-oxadiazoles in the discovery of 1H-indazole-bearing neuroprotective MAO B inhibitors

Following a hybridization strategy, a series of 5-substituted-1H-indazoles were designed and evaluated in vitro as inhibitors of human monoamine oxidase (hMAO) A and B. Among structural modifications, the bioisostere-based introduction of 1,2,4-oxadiazole ring returned the most potent and selective human MAO B inhibitor (compound 20, IC₅₀ = 52 nM, SI > 192). The most promising inhibitors were studied in cell-based neuroprotection models of SH-SY5Y and astrocytes line against H₂O₂. Moreover, preliminary drug-like features (aqueous solubility at pH 7.4; hydrolytic stability at acidic and neutral pH) were assessed for selected 1,2,4-oxadiazoles and compared to amide analogues through RP-HPLC methods. Molecular docking simulations highlighted the crucial role of molecular flexibility in providing a better shape complementarity for compound 20 within MAO B enzymatic cleft than rigid analogue 18. Enzymatic kinetics analysis along with thermal stability curves (T_m shift = +2.9 °C) provided clues of a tight-binding mechanism for hMAO B inhibition by 20.

Flavonols in Action: Targeting Oxidative Stress and Neuroinflammation in Major Depressive Disorder

Major depressive disorder is one of the most common mental illnesses that highly impairs quality of life. Pharmacological interventions are mainly focused on altered monoamine neurotransmission, which is considered the primary event underlying the disease's etiology. However, many other neuropathological mechanisms that contribute to the disease's progression and clinical symptoms have been identified. These include oxidative stress, neuroinflammation, hippocampal atrophy, reduced synaptic plasticity and neurogenesis, the depletion of neurotrophic factors, and the dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis. Current therapeutic options are often unsatisfactory and associated with adverse effects. This review highlights the most relevant findings concerning the role of flavonols, a ubiquitous class of flavonoids in the human diet, as potential antidepressant agents. In general, flavonols are considered to be both an effective and safe therapeutic option in the management of depression, which is largely based on their prominent antioxidative and anti-inflammatory effects. Moreover, preclinical studies have provided evidence that they are capable of restoring the neuroendocrine control of the HPA axis, promoting neurogenesis, and alleviating depressive-like behavior. Although these findings are promising, they are still far from being implemented in clinical practice. Hence, further studies are needed to more comprehensively evaluate the potential of flavonols with respect to the improvement of clinical signs of depression.

Neurotherapeutic Effects of Quercetin and Its Metabolite Compounds on Cognitive Impairment and Parkinson's Disease: An In Silico Study

BACKGROUND AND OBJECTIVE

Little is known about the metabolomic profile of quercetin and its biological effects. This study aimed to determine the biological activities of quercetin and its metabolite products, as well as the molecular mechanisms of quercetin in cognitive impairment (CI) and Parkinson's disease (PD).

METHODS

Key methods used were MetaTox, PASS Online, ADMETlab 2.0, SwissADME, CTD MicroRNA MIENTURNE, AutoDock, and Cytoscape.

RESULTS

A total of 28 quercetin metabolite compounds were identified by phase I reactions (hydroxylation and hydrogenation reactions) and phase II reactions (methylation, O-glucuronidation, and O-sulfation reactions). Quercetin and its metabolites were found to inhibit cytochrome P450 (CYP) 1A, CYP1A1, and CYP1A2. The studied compounds demonstrated significant gastrointestinal absorption and satisfied Lipinsky's criterion. Due to their high blood-brain barrier permeability, P-glycoprotein inhibition, anticancer, anti-inflammatory, and antioxidant capabilities, quercetin and its metabolite products have been proposed as promising molecular targets for the therapy of CI and PD. By regulating the expression of crucial signaling pathways [mitogen-activated protein kinase (MAPK) signaling pathway, and neuroinflammation and glutamatergic signaling], genes [brain derived neurotrophic factor (BDNF), human insulin gene (INS), and dopamine receptor D2 (DRD2), miRNAs (hsa-miR-16-5p, hsa-miR-26b-5p, hsa-miR-30a-5p, hsa-miR-125b-5p, hsa-miR-203a-3p, and hsa-miR-335-5p], and transcription factors [specificity protein 1 (SP1), v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA), and nuclear factor Kappa B subunit 1 (NFKB1)], quercetin exhibited its neurotherapeutic effects in CI and PD. In addition to inhibiting β-N-acetylhexosaminidase, quercetin also showed robust interactions and binding affinities with heme oxygenase 1 (HMOX1), superoxide dismutase 2 (SOD2), tumor necrosis factor (TNF), nitric oxide synthase 2 (NOS2), brain-derived neurotrophic factor (BDNF), INS, DRD2, and γ-aminobutyric acid type A (GABAa).

CONCLUSION

This study identified 28 quercetin metabolite products. The metabolites have similar characteristics to quercetin such as physicochemical properties, absorption, distribution, metabolism, and excretion (ADME), and biological activities. More research, especially clinical trials, is needed to find out how quercetin and its metabolites protect against CI and PD.

Alcohol-Induced Headache with Neuroinflammation: Recent Progress

Ethanol and other congeners in alcoholic beverages and foods are known triggers of alcohol-induced headaches (AIHs). Recent studies implicate AIHs as an important underlying factor for neuroinflammation. Studies show the relationship between alcoholic beverages, AIH agents, neuroinflammation, and the pathway they elicit. However, studies elucidating specific AIH agents’ pathways are scarce. Works reviewing their pathways can give invaluable insights into specific substances’ patterns and how they can be controlled. Hence, we reviewed the current understanding of how AIH agents in alcoholic beverages affect neuroinflammation and their specific roles. Ethanol upregulates transient receptor potential cation channel subfamily V member 1 (TRPV1) and Toll-like receptor 4 (TLR4) expression levels; both receptors trigger a neuroinflammation response that promotes AIH manifestation—the most common cause of AIHs. Other congeners such as histamine, 5-HT, and condensed tannins also upregulate TRPV1 and TLR4, neuroinflammatory conditions, and AIHs. Data elucidating AIH agents, associating pathways, and fermentation parameters can help reduce or eliminate AIH inducers and create healthier beverages.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.

Monoamine oxidase A: An emerging therapeutic target in prostate cancer

Monoamine oxidase A (MAOA), a mitochondrial enzyme degrading biogenic and dietary amines, has been studied in the contexts of neuropsychiatry and neurological disorders for decades, but its importance in oncology, as best exemplified in prostate cancer (PC) to date, was only realized recently. PC is the most commonly diagnosed non-skin cancer and the second deadliest malignancy for men in the United States. In PC, the increased expression level of MAOA is correlated with dedifferentiated tissue microarchitecture and a worse prognosis. A wealth of literature has demonstrated that MAOA promotes growth, metastasis, stemness and therapy resistance in PC, mainly by increasing oxidative stress, augmenting hypoxia, inducing epithelial-to-mesenchymal transition, and activating the downstream principal transcription factor Twist1-dictated multiple context-dependent signaling cascades. Cancer-cell-derived MAOA also enables cancer-stromal cell interaction involving bone stromal cells and nerve cells by secretion of Hedgehog and class 3 semaphorin molecules respectively to modulate the tumor microenvironment in favor of invasion and metastasis. Further, MAOA in prostate stromal cells promotes PC tumorigenesis and stemness. Current studies suggest that MAOA functions in PC in both cell autonomous and non-autonomous manners. Importantly, clinically available monoamine oxidase inhibitors have shown promising results against PC in preclinical models and clinical trials, providing a great opportunity to repurpose them as a PC therapy. Here, we summarize recent advances in our understanding of MAOA roles and mechanisms in PC, present several MAOA-targeted strategies that have been nominated for treating PC, and discuss the unknowns of MAOA function and targeting in PC for future exploration.

Integrated network pharmacology and hepatic metabolomics to reveal the mechanism of Acanthopanax senticosus against major depressive disorder

Objective:Acanthopanax senticosus (Rupr. et Maxim.) Harms (ASH) is a traditional herbal medicine widely known for its antifatigue and antistress effects, as well as tonifying qi, invigorating spleen and kidney, and tranquilizing the mind. Recent evidence suggests that ASH has a therapeutic effect on major depressive disorder (MDD), but its mechanism is still unclear. The current study aimed to investigate the effect of ASH on MDD and potential therapeutic mechanisms.

Materials and Methods: The chemical compound potential target network was predicted based on network pharmacology. Simultaneously, chronic unpredictable mild stress (CUMS) model mice were orally administrated ASH with three dosages (400, 200, and 100 mg/kg) for 6 weeks, and hepatic metabolomics based on gas chromatography–mass spectrometry (GC–MS) was carried out to identify differential metabolites and related metabolic pathways. Next, the integrated analysis of metabolomics and network pharmacology was applied to find the key target. Finally, molecular docking technology was employed to define the combination of the key target and the corresponding compounds.

Results: A total of 13 metabolites and four related metabolic pathways were found in metabolomics analysis. From the combined analysis of network pharmacology and metabolomics, six targets (DAO, MAOA, MAOB, GAA, HK1, and PYGM) are the overlapping targets and two metabolic pathways (glycine, serine, and threonine metabolism and starch and sucrose metabolism) are the most related pathways. Finally, DAO, MAOA, MAOB, GAA, HK1, and PYGM were verified bounding well to their corresponding compounds including isofraxidin, eleutheroside B1, eleutheroside C, quercetin, kaempferol, and acacetin.

Conclusion: Based on these results, it was implied that the potential mechanism of ASH on MDD was related to the regulation of metabolism of several excitatory amino acids and carbohydrates, as well as the expression of DAO, MAOA, MAOB, GAA, HK1, and PYGM.

Neuroprotective Effects of Quercetin on Ischemic Stroke: A Literature Review

Ischemic stroke (IS) is characterized by high recurrence and disability; however, its therapies are very limited. As one of the effective methods of treating acute attacks of IS, intravenous thrombolysis has a clear time window. Quercetin, a flavonoid widely found in vegetables and fruits, inhibits immune cells from secreting inflammatory cytokines, thereby reducing platelet aggregation and limiting inflammatory thrombosis. In pre-clinical studies, it has been shown to exhibit neuroprotective effects in patients with ischemic brain injury. However, its specific mechanism of action remains unknown. Therefore, this review aims to use published data to elucidate the potential value of quercetin in patients with ischemic brain injury. This article also reviews the plant sources, pharmacological effects, and metabolic processes of quercetin in vivo, thus focusing on its mechanism in inhibiting immune cell activation and inflammatory thrombosis as well as promoting neuroprotection against ischemic brain injury.

Antidepressant Potential of Quercetin and its Glycoside Derivatives: A Comprehensive Review and Update

Depression is a global health problem with growing prevalence rates and serious impacts on the daily life of patients. However, the side effects of currently used antidepressants greatly reduce the compliance of patients. Quercetin is a flavonol present in fruits, vegetables, and Traditional Chinese medicine (TCM) that has been proved to have various pharmacological effects such as anti-depressant, anti-cancer, antibacterial, antioxidant, anti-inflammatory, and neuroprotective. This review summarizes the evidence for the pharmacological application of quercetin to treat depression. We clarified the mechanisms of quercetin regulating the levels of neurotransmitters, promoting the regeneration of hippocampal neurons, improving hypothalamic-pituitary-adrenal (HPA) axis dysfunction, and reducing inflammatory states and anti-oxidative stress. We also summarized the antidepressant effects of some quercetin glycoside derivatives to provide a reference for further research and clinical application.

Recent advancements in chromone as a privileged scaffold towards the development of small molecules for neurodegenerative therapeutics

Neurodegenerative disorders, i.e., Alzheimer's or Parkinson's disease, involve progressive degeneration of the central nervous system, resulting in memory loss and cognitive impairment. The intensification of neurodegenerative research in recent years put some molecules into clinical trials, but still there is an urgent need to develop effective therapeutic molecules to combat these diseases. Chromone is a well-identified privileged structure for the design of well-diversified therapeutic molecules of potential pharmacological interest, particularly in the field of neurodegeneration. In this short review, we focused on the recent advancements and developments of chromones for neurodegenerative therapeutics. Different small molecules were reviewed as multi-target-directed ligands (MTDLs) with potential inhibition of AChE, BuChE, MAO-A, MAO-B, Aβ plaque formation and aggregation. Recently developed MTDLs emphasized that the chromone scaffold has the potential to develop new molecules for the treatment of neurodegenerative diseases.

Quercetin Mitigates Methamphetamine-Induced Anxiety-Like Behavior Through Ameliorating Mitochondrial Dysfunction and Neuroinflammation

Methamphetamine (MA) abuse results in neurotoxic outcomes, including increased anxiety and depression. Studies have reported an association between MA exposure and anxiety, nonetheless, the underlying mechanism remains elusive. In the present study, we developed a mouse model of anxiety-like behavior induced by MA administration. RNA-seq was then performed to profile the gene expression patterns of hippocampus (HIPP), and the differentially expressed genes (DEGs) were significantly enriched in signaling pathways related to psychiatric disorders and mitochondrial function. Based on these, mitochondria was hypothesized to be involved in MA-induced anxiety. Quercetin, as a mitochondrial protector, was used to investigate whether to be a potential treatment for MA-induced anxiety; accordingly, it alleviated anxiety-like behavior and improved mitochondrial impairment in vivo. Further experiments in vitro suggested that quercetin alleviated the dysfunction and morphological abnormalities of mitochondria induced by MA, via decreasing the levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and increasing the oxygen consumption rate (OCR) and ATP production. Moreover, the study examined the effect of quercetin on astrocytes activation and neuroinflammation, and the results indicated that it significantly attenuated the activation of astrocytes and reduced the levels of IL-1β, TNFα but not IL-6. In light of these findings, quantitative evidence is presented in the study supporting the view that MA can evoke anxiety-like behavior via the induction of mitochondrial dysfunction. Quercetin exerted antipsychotic activity through modulation of mitochondrial function and neuroinflammation, suggesting its potential for further therapeutic development in MA-induced anxiety.

A Major Diplotaxis harra-Derived Bioflavonoid Glycoside as a Protective Agent against Chemically Induced Neurotoxicity and Parkinson's Models; In Silico Target Prediction; and Biphasic HPTLC-Based Quantification

Oxidative stress and chronic inflammation have a role in developing neurodegenerative diseases such as Parkinson’s disease (PD) and inflammatory movement disorders such as rheumatoid arthritis that affect millions of populations. In searching for antioxidant and anti-inflammatory molecules from natural sources that can counteract neurodegenerative diseases and arthritis, the flavonoid-rich extract of Diplotaxis harra (DHE) was selected based on its in vitro antioxidant and anti-inflammatory activities. DHE could inhibit the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in the lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages from 100% to the level of 28.51 ± 18.67 and 30.19 ± 5.00% at 20 μg/mL, respectively. A TLC bioautography of DHE fractions using 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) led to the isolation of a major antioxidant compound which was identified by X-ray diffraction analysis as isorhamnetin-3-O-β-D-glucoside (IR3G). IR3G also exhibited a potent anti-inflammatory activity, particularly by suppressing the upregulation of iNOS expression, similar to that of dexamethasone (DEX) at 10 μM to the level of 35.96 ± 7.80 and 29.34 ± 6.34%, respectively. Moreover, IR3G displayed a strong neuroprotectivity (>60% at 1.0−4−1.0−3 μM) against 6-hydroxydopamine (6-OHDA)-challenged SHSY5Y neuroblastoma, an in vitro model of dopaminergic neurons for Parkinson’s disease (PD) research. Accordingly, the in vivo anti-Parkinson potentiality was evaluated, where it was found that IR3G successfully reversed the 6-OHDA-induced locomotor deficit in a zebrafish model. A study of molecular docking and molecular dynamic (MD) simulation of IR3G and its aglycone isorhamnetin (IR) against human acetylcholine esterase (AChE), monoamine oxidase B (MAO-B), and Polo-like kinase-2 (PLK2) was performed and further outlined a putative mechanism in modulating neurodegenerative diseases such as PD. The free radical scavenging, anti-inflammatory through anti-iNOS and anti-COX-2 expression, and neuroprotective activities assessed in this study would present partial evidence for the potentiality of D. harra-derived IR3G as a promising natural therapeutic agent against neurodegenerative diseases and inflammatory arthritis. Finally, a biphasic HPTLC method was developed to estimate the biomarker IR3G in D. harra quantitatively.

Inhibition of Human Monoamine Oxidases A and B by Specialized Metabolites Present in Fresh Common Fruits and Vegetables

Diets rich in fruits and vegetables are associated with better psychological wellbeing and cognitive functions, although it is unclear which molecules and mechanisms are involved. One potential explanation is the inhibition of monoamine oxidases (MAOs), which have been linked to several neurological disorders. The present study investigated the ability of kiwifruit to inhibit MAO-A and MAO-B, refining an in vitro assay to avoid confounding effects. Ultra-performance liquid chromatography/mass spectrometry (UPLC-QTOF) and nuclear magnetic resonance spectroscopy (NMR) were used to select individual kiwifruit metabolites for further analysis. Moreover, extracts of other common fruits and vegetables were screened to identify promising candidate inhibitors. Multiple extracts and compounds inhibited both enzymes, and the selective inhibition of MAO-B by the major kiwifruit specialized metabolite D-(−)-quinic acid was observed. These results suggest that fruits and vegetables contain metabolites that inhibit the activity of MAO-A and -B, offering a potential natural option for the treatment of neurological disorders, in which MAOs are involved.

Neuroprotective and anxiolytic potential of green rooibos (Aspalathus linearis) polyphenolic extract

South African rooibos (Aspalathus linearis) tea is globally consumed for its health benefits and caffeine free nature, but no information is available on the neuroprotective capacity of (unfermented) green rooibos. Our aim was to investigate the cytoprotective activity of green rooibos in neuronal cells, including probing antioxidant and enzyme inhibitory properties that could explain observed effects in these cells. We also investigated the anxiolytic potential of green rooibos using zebrafish larval models. Green rooibos extract (Green oxithin™) was assessed for its neuroprotective potential in Neuro-2a cells treated with different concentrations of the extract (12.5-25-50-100 μg mL^-1) and different concentrations of hydrogen peroxide (250 or 125 μM) as oxidizing agent. Cell viability (MTT) and redox status (intracellular ROS) were also quantified in these cells. Antioxidant properties of the extract were quantified using cell-free systems (DPPH, ORAC and xanthine/xanthine oxidase), and potential neuroprotection evaluated in terms of its potential to inhibit key enzymes of the CNS (monoamine oxidase A (MOA-A), acetylcholinesterase (AChE) and tyrosinase (TYR)). Results demonstrated that green rooibos extract exerted significant cytoprotective properties in Neuro-2a cells, particularly when exposed to lethal 250 μM hydrogen peroxide, increasing cell survival by more than 100%. This may be ascribed (at least partially) to its capacity to limit intracellular ROS accumulation in these cells. Data from cell-free systems confirmed that green rooibos was able to scavenge free radicals (synthetic and physiological) in a dose dependent manner with a similar profile activity to vitamins C and E. Green rooibos also acted as a moderate MAO-A inhibitor, but had no significant effect on AChE or TYR. Finally, zebrafish larvae treated with lower doses of green rooibos demonstrated a significant anxiolytic effect in the light-dark anxiety model. Using the PTZ excitotoxicity model, green rooibos was shown to rescue GABA receptor signalling, which together with its demonstrated inhibition of MAO-A, may account for the anxiolytic outcome. Current data confirms that green rooibos could be considered a "functional brain food" and may be a good option as starting ingredient in the development of new nutraceuticals.

Nutritional therapy can reduce the burden of depression management in low income countries: A review

Depression is a serious mental and mood disorder with global health and economic burden. This burden may be overwhelming in low income countries, although there are insufficient data. Most antidepressant formulations are predicated on the monoamine, neuroendocrine and neuro-inflammation hypotheses, with little or no cognizance to other neurochemicals altered in depression. A nutritional strategy with or without conventional antidepressants is recommended, as nutrition plays vital roles in the onset, severity and duration of depression, with poor nutrition contributing to its pathogenesis. This review discusses nutritional potentials of utilizing omega-3 fatty acids, proteins, vitamins, minerals and herbs or their phytochemicals in the management of depression with the aim of reducing depression burden. Literature search of empirical data in books and journals in data bases including but not limited to PubMed, Scopus, Science Direct, Web of Science and Google Scholar that might contain discussions of sampling were sought, their full text obtained, and searched for relevant content to determine eligibility. Omega-3 fatty and amino acids had significant positive anti-depression outcomes, while vitamins and minerals although essential, enhanced omega-3 fatty and amino acids activities. Some herbs either as whole extracts or their phytochemicals/metabolites had significant positive anti-depression efficacy. Nutrition through the application of necessary food classes or herbs as well as their phytochemicals, may go a long way to effectively manage depression. This therefore will provide inexpensive, natural, and non-invasive therapeutic means with reduced adverse effects that can also be applied alongside clinical management. This nutritional strategy should be given more attention in research, assessment and treatment for those with depression and other mental illness in low income countries, especially in Africa.

Dismantling Parkinson's disease with herbs: MAO-B inhibitory activity and quantification of chemical constituents using HPLC-MS/MS of Egyptian local market plants

Withania somnifera, Angelica sinensis, Glycyrrhiza glabra, and Simmondsia chinensis were acquired from the Egyptian market, profiled for their chemical constituents, screened for the in-vitro MAO-B inhibitory activity and evaluated for the total phenolic content. Thirty compounds were characterized in the selected herbs using HPLC-MS/MS. In-vitro MAO-B inhibitory activity and total phenolic content of the acquired herbs were compared with those of a prepared herbal formula consisting of a mixture of equal amounts of the four mentioned herbs. The most potent MAO-B inhibitory activity was exerted by the methanol extract of the prepared formula (IC₅₀ of 712.19 ± 13.90 ng/mL) compared to selegiline (IC₅₀ of 581.69 ± 11.35 ng/mL). The highest value of the total phenolic content was shown by Angelica sinensis methanolic extract (76.15 ± 0.1 mg/g) followed by Glycyrrhiza glabra methanolic extract (65.74 ± 0.1 mg/g), then the mixture's methanolic extract of the four herbs (37.04 ± 0.1 mg/g).

Quercetin reverses chronic unpredictable mild stress-induced depression-like behavior in vivo by involving nuclear factor-E2-related factor 2

Quercetin is a flavonoid compound rich in many natural plants with a wide range of pharmacological effects and nutritional value. Although previous studies have initially shown the antidepressant effect of quercetin in some models. However, the exact mechanism of the antidepressant effect of quercetin on the depression model induced by chronic unpredictable mild stress (CUMS) is still unclear or has not been clearly elucidated. The present study aimed to investigate the antidepressant effect of quercetin in vivo on a CUMS-induced depression model that is closest to human depression, and to explore its mechanism of action around nuclear factor-E2-related factor 2 (Nrf2) related signaling pathways, for the first time. Our results demonstrated that CUMS for 21 consecutive days caused significant decreases in the sucrose preference, and the horizontal score and vertical score in the open field test of mice respectively by 22.6%, 34.4%, and 66.6% (all P < 0.01), and a significant increase in the immobility time during the forced swimming test by 110.5% (P < 0.01), but fortunately, after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 26.2%, 40.1%, 152.7%, 43.5% (all P < 0.01). Further western blot analysis showed that CUMS caused the phosphorylation or expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), Nrf2 and heme oxygenase-1 (HO-1) proteins in the hippocampus of mice to significantly down-regulate by 60.0%, 72.1%, 90.0% and 50.1% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of these proteins were significantly up-regulated by 85.8%, 182.0%, 325.1% and 60.3% (all P < 0.01). In addition, CUMS also caused significant reduction in the levels of antioxidants including superoxide dismutase (SOD) and glutathione-s transferase (GST) in the mice hippocampus by 51.3%, 40.3% (both P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 69.2% and 49.5% (both P < 0.01), as well as significant elevation in the levels of lipid peroxide malondialdehyde (MDA), inflammation medium nitric oxide (NO) and inducible nitric oxide synthase (iNOS) by 156.4%, 255.4% and 72.7% (all P < 0.01), while after chronic oral administration of high dose quercetin at 40 mg/kg, the abnormalities of the above indicators were significantly reversed by 45.9%, 26.8% and 55.2% (all P < 0.01). The medium dose of quercetin (20 mg/kg) only reversed some of the above indicators, while the low dose of quercetin (10 mg/kg) had no reversal effect on the above indicators. Collectively, the present study confirmed for the first time that quercetin weakened CUMS-induced depression in vivo, and its mechanism was at least partially attributable to the upregulation of hippocampal Nrf2 and the inhibition of iNOS, thereby correcting the central inflammatory response, and the imbalance between oxidation and antioxidant.

Novel thiazolyl-hydrazone derivatives including piperazine ring: synthesis, in vitro evaluation, and molecular docking as selective MAO-A inhibitor

MAO-A inhibitors are used in the treatment of depression. There are many studies showing that the thiazolyl-hydrazone structure is a pharmacophore structure for the MAO enzyme. In previous studies by our team, activity studies were carried out with thiazolyl-hydrazone derivatives containing pyrrolidine, morpholine, and piperazine. All of them were displayed MAO-A selective inhibition profile. Additionally, derivatives containing piperazine ring were most active. For this purpose, thiazolyl-hydrazone derivatives containing piperazine were synthesized, but this time an active group, formyl group, was added to the piperazine ring as a substituent. Based on this view, new thiazolyl-hydrazone compounds were synthesized, characterized, and screened for their hMAO-A and hMAO-B inhibitory activity by an in vitro fluorometric method. The structure of the compound was tried to be fully elucidated using 2D NMR technique. The compound including 2,4-dimethyl substituent (3i) were found to be the most effective agents in the series against MAO-A enzyme with the IC₅₀ value of 0.080 ± 0.003 µM. The docking study of compound 3i revealed that there is a strong interaction between the active sites of hMAO-A and analyzed compound.

Lifestyle Adjustments in Long-COVID Management: Potential Benefits of Plant-Based Diets

Purpose of Review

The SARS-CoV-2-pandemic has caused mortality and morbidity at an unprecedented global scale. Many patients infected with SARS-CoV-2 continue to experience symptoms after the acute phase of infection and report fatigue, sleep difficulties, anxiety, and depression as well as arthralgia and muscle weakness. Summarized under the umbrella term “long-COVID,” these symptoms may last weeks to months and impose a substantial burden on affected individuals. Dietary approaches to tackle these complications have received comparably little attention. Although plant-based diets in particular were shown to exert benefits on underlying conditions linked to poor COVID-19 outcomes, their role with regard to COVID-19 sequelae is yet largely unknown. Thus, this review sought to investigate whether a plant-based diet could reduce the burden of long-COVID.

Recent Findings

The number of clinical trials investigating the role of plant-based nutrition in COVID-19 prevention and management is currently limited. Yet, there is evidence from pre-pandemic observational and clinical studies that a plant-based diet may be of general benefit with regard to several clinical conditions that can also be found in individuals with COVID-19. These include anxiety, depression, sleep disorders, and musculoskeletal pain. Adoption of a plant-based diet leads to a reduced intake in pro-inflammatory mediators and could be one accessible strategy to tackle long-COVID associated prolonged systemic inflammation.

Summary

Plant-based diets may be of general benefit with regard to some of the most commonly found COVID-19 sequelae. Additional trials investigating which plant-based eating patterns confer the greatest benefit in the battle against long-COVID are urgently warranted.

Insights into the Mechanism of the Therapeutic Potential of Herbal Monoamine Oxidase Inhibitors in Neurological Diseases

Monoamine oxidase (MAO) is an enzyme that catalyzes the deamination of monoamines and other proteins. MAO's hyperactivation results in the massive generation of reactive oxygen species, which leads to a variety of neurological diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and depression-like disorders. Although synthetic MAO inhibitors are clinically available, they are associated with side effects such as hepatotoxicity, cheese reaction, hypertensive crisis, and so on, necessitating the investigation of alternative MAO inhibitors from a natural source with a safe profile. Herbal medications have a significant impact on the prevention of many diseases; additionally, they have fewer side effects and serve as a precursor for drug development. This review discusses the potential of herbal MAO inhibitors as well as their associated mechanism of action, with an aim to foster future research on herbal MAO inhibitors as potential treatment for neurological diseases.

Monoamine Oxidase Inhibitors (MAOIs) in Psychiatric Practice: How to Use them Safely and Effectively

Monoamine oxidase inhibitors (MAOIs) were among the first licensed pharmacological treatments for patients with depression but over time have fallen out of mainstream clinical use. This has led to a loss of clinician training opportunities and reduced availability of MAOIs for prescribing. This article provides a concise and practical overview of how to use MAOIs safely and effectively in psychiatric practice. We consider the history of MAOIs, why they are not used more frequently, their mechanisms of action, availability, indications and efficacy, general tolerability, withdrawal symptoms, and safety considerations (including hypertensive reactions and serotonin syndrome). Practical advice is given in terms of dietary restrictions, interactions with other medications (both prescribed and non-prescribed), and how prescribers can stop and switch MAOIs, both within the drug class and outside of it. We also provide advice on choice of MAOI and treatment sequencing. Lastly, we consider emerging directions and potential additional indications.

Potential Implications of Quercetin in Autoimmune Diseases

Autoimmune diseases are a worldwide health problem with growing rates of morbidity, and are characterized by breakdown and dysregulation of the immune system. Although their etiology and pathogenesis remain unclear, the application of dietary supplements is gradually increasing in patients with autoimmune diseases, mainly due to their positive effects, relatively safety, and low cost. Quercetin is a natural flavonoid that is widely present in fruits, herbs, and vegetables. It has been shown to have a wide range of beneficial effects and biological activities, including anti-inflammation, anti-oxidation, and neuroprotection. In several recent studies quercetin has reportedly attenuated rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, and systemic lupus erythematosus in humans or animal models. This review summarizes the evidence for the pharmacological application of quercetin for autoimmune diseases, which supports the view that quercetin may be useful for their prevention and treatment.

Myricetin improves metabolic outcomes but not cognitive deficit associated to metabolic syndrome in male mice

Myricetin is a flavonol highly prevalent in edible vegetables and fruits, with recognized hypoglycemic and anti-obesity effects, besides great antioxidant capacity. Thus, this study sought to investigate whether myricetin is able to improve metabolic and behavioral outcomes found in monosodium l-glutamate (MSG) obese mice, a model of metabolic syndrome characterized by early hyperinsulinemia associated to obesity, dyslipidemia, hepatic steatosis, anxiety and cognitive deficit. Newborn male mice received MSG (4 mg kg-1 day-1, s.c.) on alternate days during the first 10 days of life for obesity induction, while control pups received equimolar saline solution. From postnatal day 90 to 135, MSG mice were orally treated with myricetin (50 mg kg-1 day-1) or distilled water, while control animals received vehicle. During the last week of treatment, all groups were submitted to behavioral tests: open field maze, elevated plus maze and Morris water maze. At the end of treatment, animals were euthanized for collection of liver, serum and adipose tissue fat pads. Myricetin treatment reduced the elevated serum levels of glucose and triglycerides, typically found in MSG mice, as well as restored peripheral insulin sensitivity and liver steatosis. Moreover, myricetin ameliorated the lack of thigmotaxis and exploratory behavior, but did not improve the cognitive deficit presented by MSG mice. Therefore, this study contributes to the pharmacological validation of myricetin as an affordable and healthy therapeutic adjuvant for the treatment of metabolic syndrome and most of its comorbidities.

Pharmacogenetic-based management of depression: Role of traditional Persian medicine

Depression is one of the most common mental disorders worldwide. The genetic factors are linked to depression and anti-depressant outcomes. Traditional Persian medicine (TPM) manuscripts have provided various anti-depressant remedies, which may be useful in depression management. This review has studied the bioactive compounds, underlying mechanisms, and treatment outcomes of the medicinal plants traditionally mentioned effective for depression from "The storehouse of medicament" (a famous pharmacopeia of TPM) to merge those with the novel genetics science and serve new scope in depression prevention and management. This review paper has been conducted in two sections: (1) Collecting medicinal plants and their bioactive components from "The storehouse of medicament," "Physician's Desk Reference (PDR) for Herbal Medicines," and "Google scholar" database. (2) The critical key factors and genes in depression pathophysiology, prevention, and treatment were clarified. Subsequently, the association between bioactive components' underlying mechanism and depression treatment outcomes via considering polymorphisms in related genes was derived. Taken together, α-Mangostin, β-carotene, β-pinene, apigenin, caffeic acid, catechin, chlorogenic acid, citral, ellagic acid, esculetin, ferulic acid, gallic acid, gentiopicroside, hyperoside, kaempferol, limonene, linalool, lycopene, naringin, protocatechuic acid, quercetin, resveratrol, rosmarinic acid, and umbelliferone are suitable for future pharmacogenetics-based studies in the management of depression.

The role of monoamine oxidase enzymes in the pathophysiology of neurological disorders

Monoamine oxidase enzymes are responsible for the degredation of serotonin, dopamine, and norepinephrine in the central neurvous system. Although it has been nearly 100 years since they were first described, we are still learning about their role in the healthy brain and how they are altered in various disease states. The present review provides a survey of our current understanding of monoamine oxidases, with a focus on their contributions to neuropsychiatric, neurodevelopmental, and neurodegenerative disease. Important species differences in monoamine oxidase function and development in the brain are highlighted. Sex-specific monoamine oxidase regulatory mechanisms and their implications for various neurological disorders are also discussed. While our understanding of these critical enzymes has expanded over the last century, gaps exist in our understanding of sex and species differences and the roles monoamine oxidases may play in conditions often comorbid with neurological disorders.

Synergistic protective effect of Beta vulgaris with meso-2,3-dimercaptosuccinic acid against lead-induced neurotoxicity in male rats

Lead (Pb) toxicity is one of the most prevalent causes of human neurotoxicity. The available chelator drugs used now have many adverse effects. So, in this study, the protective role of Beta vulgaris juice (BVJ) on rat neurotoxicity induced by Pb was evaluated and the results were compared with the results of dimercaptosuccinic acid (DMSA, as used drug). Additionally, the synergistic effect of BVJ and DMSA against Pb-induced neurotoxicity was assessed. The study focused on the determination of the antioxidant, anti-inflammatory, and neurological potential of BVJ (alone, and with DMSA) towards lead-induced neurotoxicity. Also, the characterization of BVJ was studied. The results showed that BVJ contains considerable quantities of polyphenols, triterpenoids, and betalains which play an important role as antioxidants and anti-inflammatory. BVJ exhibited a protective effect against neurotoxicity via the reduction of Pb levels in blood and brain. Moreover, BVJ decreased the oxidative stress, inflammation, and cell death induced by Pb. Also, BVJ regulated the activities of acetylcholine esterase and monoamine oxidase-A which changed by Pb toxicity. BVJ and DMSA combination displayed a synergistic antineurotoxic effect (combination index ˂ 1). These results were in harmony with brain histopathology. Conclusion: BVJ has a powerful efficacy in the protection from brain toxicity via diminishing Pb in the brain and blood circulation, resulting in the prevention of the oxidative and inflammatory stress. Treatment with BVJ in combination with DMSA revealed a synergistic effect in the reduction of neurotoxicity induced by Pb. Also, the antioxidant and anti-inflammatory effects of the BVJ lead to the improvement of DMSA therapy.

Quercetin: Antiviral Significance and Possible COVID-19 Integrative Considerations

Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases and aging processes in humans, and its antiviral properties have been investigated in numerous studies. In silico and in vitro studies demonstrated that quercetin can interfere with various stages of the coronavirus entry and replication cycle such as PLpro, 3CLpro, and NTPase/helicase. Due to its pleiotropic activities and lack of systemic toxicity, quercetin and its derivatives may represent target compounds to be tested in future clinical trials to enrich the drug arsenal against coronavirus infections. There is evidence that quercetin in combination with, for example, vitamins C and D, may exert a synergistic antiviral action that may provide either an alternative or additional therapeutic/preventive option due to overlapping antiviral and immunomodulatory properties. This review summarizes the antiviral significance of quercetin and proposes a possible strategy for the effective utilization of natural polyphenols in our daily diet for the prevention of viral infection.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Therapeutic Potential of Quercetin as an Antiatherosclerotic Agent in Atherosclerotic Cardiovascular Disease: A Review

Atherosclerotic cardiovascular disease (ASCVD) is one of the diseases with the highest morbidity and mortality globally. It causes a huge burden on families and caregivers and high costs for medicine and surgical interventions. Given expensive surgeries and failures of most conventional treatments, medical community tries to find a more cost-effective cure. Thus, attentions have been primarily focused on food or herbs. Quercetin (Qu) extracted from food, a flavonoid component, develops potentials of alternative or complementary medicine in atherosclerosis. Due to the wide range of health benefits, researchers have considered to apply Qu as a natural compound in therapy. This review is aimed to identify the antiatherosclerosis functions of Qu in treating ASCVD such as anti-inflammatory, antioxidant properties, effects on endothelium-dependent vasodilation, and blood lipid-lowering.

Antidepressant-Like Activities of Hispidol and Decursin in Mice and Analysis of Neurotransmitter Monoamines

The antidepressant activities of hispidol and decursin (both potent monoamine oxidase A (MAO-A) inhibitors) were evaluated using the forced swimming test (FST) and the tail suspension test (TST) in mice, and thereafter, levels of neurotransmitter monoamines and metabolites in brain tissues were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hispidol (15 mg/kg) caused less or comparable immobility than fluoxetine (15 mg/kg; the positive control) in immobility time, as determined by FST (9.6 vs 32.0 s) and TST (53.1 vs 48.7 s), respectively, and its effects were dose-dependent and significant. Decursin (15 mg/kg) also produced immobility comparable to that of fluoxetine as determined by FST (47.0 vs 43.4 s) and TST (55.6 vs 63.4 s), and its effects were also dose-dependent and significant. LC-MS/MS analysis after FST showed that hispidol (15 mg/kg) greatly increased dopamine (DA) and serotonin levels dose-dependently in brain tissues as compared with the positive control. Decursin (15 mg/kg) dose-dependently increased DA level after TST. Slight changes in norepinephrine and 3,4-dihydroxyphenylacetic acid levels were observed after FST and TST in hispidol- or decursin-treated animals. It was observed that hispidol and decursin were effective and comparable to fluoxetine in immobility tests. These immobility and monoamine level results suggest that hispidol and decursin are potential antidepressant agents for the treatment of depression, and that they act mainly through serotonergic and/or dopaminergic systems.

Molecular docking utilising the OliveNet™ library reveals novel phenolic compounds which may potentially target key proteins associated with major depressive disorder

The antidepressant medications that are currently prescribed to patients suffering from major depressive disorder (MDD) have limitations and as a result, there is an urgent need to increase the options that are available. A number of studies have found that natural polyphenols have neuroprotective properties and there is evidence to suggest that they modulate neurotransmitter systems. There are more than 200 phenolic compounds that have been identified in Olea europaea, many of which have not yet been investigated for their potential biological effects. In this study, in silico methods were used to screen the phenolic library from the OliveNet™ database and identify novel lead compounds for proteins implicated in the pathophysiology of MDD. The molecular docking results revealed that the monoamine oxidase enzyme isoforms (MAO-A/MAO-B) had binding specificities for certain phenolic subclasses. The lead ligands that were identified from these subclasses were positioned near the flavin adenine dinucleotide (FAD) cofactor, interacting in a similar manner as known inhibitors. In addition to the MAO enzymes, several phenolic compounds were docked to neurotransmitter transporters and postsynaptic receptors, as well as proteins involved in neuroinflammation, oxidative stress and the endocannabinoid system. Based on the binding affinity, position, orientation and interactions of the lead phenolic compounds identified in this study, it is predicted that they may have antidepressant properties. The results should be validated further using molecular dynamics (MD) simulations, as well as in vivo and in vitro techniques.