Flavonoids as Therapeutic Agents in Alzheimer's and Parkinson's Diseases: A Systematic Review of Preclinical Evidences

Exploring the potential of quercetin in Alzheimer's Disease: Pharmacodynamics, Pharmacokinetics, and Nanodelivery systems

Alzheimer's disease (AD) is a primary cause of dementia that affects millions of people worldwide and its prevalence is likely to increase largely in the coming decades. Multiple complex pathways, such as oxidative stress, tau and amyloid-beta (Aβ) pathology, and cholinergic dysfunction, are involved in the pathogenesis of Alzheimer's disease. The conventional treatments provide only symptomatic relief and not a complete cure for the disease. On the other hand, recent studies have looked into the possibility of flavonoids as an effective therapeutic strategy for treating AD. Quercetin, a well-known flavonol, has been extensively studied for AD treatment. Therefore, this review mainly focuses on the pharmacokinetics properties of quercetin and its modes of action, such as antioxidant, anti-inflammatory, anti-amyloidogenic, and neuroprotective properties, which are beneficial in treating AD. It also highlights the nano delivery systems of quercetin, including liposomes, nanostructures lipid carriers, solid lipid nanoparticles, nanoemulsions, microemulsions, self-emulsifying drug delivery systems, and nanoparticles reported for AD treatment. The remarkable potential of quercetin nanocarriers has been reflected in enhancing its bioavailability and therapeutic efficacy. Therefore, clinical studies must be conducted to explore it as a therapeutic strategy for Alzheimer's disease.

Revealing Comprehensive Food Functionalities and Mechanisms of Action through Machine Learning

Foods possess a range of unexplored functionalities; however, fully identifying these functions through empirical means presents significant challenges. In this study, we have proposed an in silico approach to comprehensively predict the functionalities of foods, encompassing even processed foods. This prediction is accomplished through the utilization of machine learning on biomedical big data. Our focus revolves around disease-related protein pathways, wherein we statistically evaluate how the constituent compounds collaboratively regulate these pathways. The proposed method has been employed across 876 foods and 83 diseases, leading to an extensive revelation of both food functionalities and their underlying operational mechanisms. Additionally, this approach identifies food combinations that potentially affect molecular pathways based on interrelationships between food functions within disease-related pathways. Our proposed method holds potential for advancing preventive healthcare.

Teaghrelin protected dopaminergic neurons in MPTP-induced Parkinson's disease animal model by promoting PINK1/Parkin-mediated mitophagy and AMPK/SIRT1/PGC1-α-mediated mitochondrial biogenesis

Mitochondrial dysfunction, a common cellular hallmark in both familial and sporadic forms of Parkinson's disease (PD), is assumed to play a significant role in pathologic development and progression of the disease. Teaghrelin, a unique bioactive compound in some oolong tea varieties, has been demonstrated to protect SH-SY5Y cells against 1-methyl-4-phenylpyridinium induced neurotoxicity by binding to the ghrelin receptor to activate the AMPK/SIRT1/PGC-1α pathway. In this study, an animal model was established using a neurotoxin, 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP), a byproduct of a prohibited drug, to evaluate the oral efficacy of teaghrelin on PD by monitoring motor dysfunction of mice in open field, pole, and bean walking tests. The results showed that MPTP-induced motor dysfunction of mice was significantly attenuated by teaghrelin supplementation. Tyrosine hydroxylase and dopamine transporter protein were found reduced in the striatum and midbrain of MPTP-treated mice, and significantly mitigated by teaghrelin supplementation. Furthermore, teaghrelin administration enhanced mitophagy and mitochondria biogenesis, which maintained cell homeostasis and prevented the accumulation of αSyn and apoptosis-related proteins. It seemed that teaghrelin protected dopaminergic neurons in MPTP-treated mice by increasing PINK1/Parkin-mediated mitophagy and AMPK/SIRT1/PGC-1α-mediated mitochondria biogenesis, highlighting its potential therapeutic role in maintaining dopaminergic neurons function in PD. Mitochondrial dysfunction, a common cellular hallmark in both familial and sporadic forms of Parkinson's disease (PD), is assumed to play a significant role in pathologic development and progression of the disease. Teaghrelin, a unique bioactive compound in some oolong tea varieties, has been demonstrated to protect SH-SY5Y cells against 1-methyl-4-phenylpyridinium induced neurotoxicity by binding to the ghrelin receptor to activate the AMPK/SIRT1/PGC-1α pathway. In this study, an animal model was established using a neurotoxin, 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP), a byproduct of a prohibited drug, to evaluate the oral efficacy of teaghrelin on PD by monitoring motor dysfunction of mice in open field, pole, and bean walking tests. The results showed that MPTP-induced motor dysfunction of mice was significantly attenuated by teaghrelin supplementation. Tyrosine hydroxylase and dopamine transporter protein were found reduced in the striatum and midbrain of MPTP-treated mice, and significantly mitigated by teaghrelin supplementation. Furthermore, teaghrelin administration enhanced mitophagy and mitochondria biogenesis, which maintained cell homeostasis and prevented the accumulation of αSyn and apoptosis-related proteins. It seemed that teaghrelin protected dopaminergic neurons in MPTP-treated mice by increasing PINK1/Parkin-mediated mitophagy and AMPK/SIRT1/PGC-1α-mediated mitochondria biogenesis, highlighting its potential therapeutic role in maintaining dopaminergic neurons function in PD.

Experimental Parkinson models and green chemistry approach

Parkinson's is the most common neurodegenerative disease after Alzheimer's. Motor findings in Parkinson's occur as a result of the degeneration of dopaminergic neurons starting in the substantia nigra pars compacta and ending in the putamen and caudate nucleus. Loss of neurons and the formation of inclusions called Lewy bodies in existing neurons are characteristic histopathological findings of Parkinson's. The disease primarily impairs the functional capacity of the person with cardinal findings such as tremor, bradykinesia, etc., as a result of the loss of dopaminergic neurons in the substantia nigra. Experimental animal models of Parkinson's have been used extensively in recent years to investigate the pathology of this disease. These models are generally based on systemic or local(intracerebral) administration of neurotoxins, which can replicate many features of Parkinson's mammals. The development of transgenic models in recent years has allowed us to learn more about the modeling of Parkinson's. Applying animal modeling, which shows the most human-like effects in studies, is extremely important. It has been demonstrated that oxidative stress increases in many neurodegenerative diseases such as Parkinson's and various age-related degenerative diseases in humans and that neurons are sensitive to it. In cases where oxidative stress increases and antioxidant systems are inadequate, natural molecules such as flavonoids and polyphenols can be used as a new antioxidant treatment to reduce neuronal reactive oxygen species and improve the neurodegenerative process. Therefore, in this article, we examined experimental animal modeling in Parkinson's disease and the effect of green chemistry approaches on Parkinson's disease.

Protein aggregation and therapeutic strategies in SOD1- and TDP-43- linked ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with severe socio-economic impact. A hallmark of ALS pathology is the presence of aberrant cytoplasmic inclusions composed of misfolded and aggregated proteins, including both wild-type and mutant forms. This review highlights the critical role of misfolded protein species in ALS pathogenesis, particularly focusing on Cu/Zn superoxide dismutase (SOD1) and TAR DNA-binding protein 43 (TDP-43), and emphasizes the urgent need for innovative therapeutic strategies targeting these misfolded proteins directly. Despite significant advancements in understanding ALS mechanisms, the disease remains incurable, with current treatments offering limited clinical benefits. Through a comprehensive analysis, the review focuses on the direct modulation of the misfolded proteins and presents recent discoveries in small molecules and peptides that inhibit SOD1 and TDP-43 aggregation, underscoring their potential as effective treatments to modify disease progression and improve clinical outcomes.

Therapeutic potential of berries in age-related neurological disorders

Aging significantly impacts several age-related neurological problems, such as stroke, brain tumors, oxidative stress, neurodegenerative diseases (Alzheimer's, Parkinson's, and dementia), neuroinflammation, and neurotoxicity. Current treatments for these conditions often come with side effects like hallucinations, dyskinesia, nausea, diarrhea, and gastrointestinal distress. Given the widespread availability and cultural acceptance of natural remedies, research is exploring the potential effectiveness of plants in common medicines. The ancient medical system used many botanical drugs and medicinal plants to treat a wide range of diseases, including age-related neurological problems. According to current clinical investigations, berries improve motor and cognitive functions and protect against age-related neurodegenerative diseases. Additionally, berries may influence signaling pathways critical to neurotransmission, cell survival, inflammation regulation, and neuroplasticity. The abundance of phytochemicals in berries is believed to contribute to these potentially neuroprotective effects. This review aimed to explore the potential benefits of berries as a source of natural neuroprotective agents for age-related neurological disorders.

From network pharmacology to molecular docking analysis of sterubin targets for Alzheimer

Sterubin (7-O-Methyleriodicytol), a flavanone compound isolated from the leaves of Eriodicyton californicum and Eriodicyton angustifolium, has neuroprotective, anti-inflammatory, and antioxidant properties. Therefore, it is of interest to identify the potential targets for Alzheimer disease using network pharmacology. We report 25 overlapping targets among 100 potential targets of sterubin and 673 known targets of Alzheimer. APP, BACE-1, and AChE were among the ten hub targets enriched in biological processes and pathways relevant to Alzheimer's disease. Subsequent, molecular docking analysis shows that sterubin have optimal binding features with these hub gene targets for further consideration.

Therapeutic potential of clinically proven natural products in the management of dementia

Dementia is a common neurodegenerative disorder connected to damage to nerve cells in the brain. Although some conventional drugs are available for dementia treatments and are still sanctified for dementia patients, their short- and long-term side effects and other limitations make treating patients more challenging. The authors aimed to explain novel options for treating dementia with natural products and unravel some clinically proven natural products. This article systematically reviewed recent studies that have investigated the role of natural products and their bioactive compounds for dementia. PubMed Central, Scopus, and Google Scholar databases of articles were collected, and abstracts were reviewed for relevance to the subject matter.In this review, we provide mechanistic insights of clinically validated natural products, including like- Yokukansan, Souvenaid, BDW, Hupergene, Bacopa monnier, Omega-3, Tramiprostate and Palmitoylethanolamide with which have therapeutic efficacy against dementia in the management of dementia. As shown by studies, certain natural ingredients could be used to treat and prevent dementia. We strongly believe that the medicinal plants and phytoconstituents alone or in combination with other compounds would be effective treatments against dementia with lesser side effects as compared to currently available treatments. Moreover, these products should be studied further in order to develop novel dementia medications.

Protective Effects of Plant-Derived Compounds Against Traumatic Brain Injury

Inflammation in the nervous system is one of the key features of many neurodegenerative diseases. It is increasingly being identified as a critical pathophysiological primitive mechanism associated with chronic neurodegenerative diseases following traumatic brain injury (TBI). Phytochemicals have a wide range of clinical properties due to their antioxidant and anti-inflammatory effects. Currently, there are few drugs available for the treatment of neurodegenerative diseases other than symptomatic relief. Numerous studies have shown that plant-derived compounds, in particular polyphenols, protect against various neurodegenerative diseases and are safe for consumption. Polyphenols exert protective effects on TBI via restoration of nuclear factor kappa B (NF-κB), toll-like receptor-4 (TLR4), and Nod-like receptor family proteins (NLRPs) pathways. In addition, these phytochemicals and their derivatives upregulate the phosphatidylinositol-3-Kinase/Protein Kinase B (PI3K/AKT) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways, which have critical functions in modulating TBI symptoms. There is supporting evidence that medicinal plants and phytochemicals are protective in different TBI models, though future clinical trials are needed to clarify the precise mechanisms and functions of different polyphenolic compounds in TBI.

Exploring the mechanisms of kaempferol in neuroprotection: Implications for neurological disorders

Kaempferol, a flavonoid compound found in various fruits, vegetables, and medicinal plants, has garnered increasing attention due to its potential neuroprotective effects in neurological diseases. This research examines the existing literature concerning the involvement of kaempferol in neurological diseases, including stroke, Parkinson's disease, Alzheimer's disease, neuroblastoma/glioblastoma, spinal cord injury, neuropathic pain, and epilepsy. Numerous in vitro and in vivo investigations have illustrated that kaempferol possesses antioxidant, anti-inflammatory, and antiapoptotic properties, contributing to its neuroprotective effects. Kaempferol has been shown to modulate key signaling pathways involved in neurodegeneration and neuroinflammation, such as the PI3K/Akt, MAPK/ERK, and NF-κB pathways. Moreover, kaempferol exhibits potential therapeutic benefits by enhancing neuronal survival, attenuating oxidative stress, enhancing mitochondrial calcium channel activity, reducing neuroinflammation, promoting neurogenesis, and improving cognitive function. The evidence suggests that kaempferol holds promise as a natural compound for the prevention and treatment of neurological diseases. Further research is warranted to elucidate the underlying mechanisms of action, optimize dosage regimens, and evaluate the safety and efficacy of this intervention in human clinical trials, thereby contributing to the advancement of scientific knowledge in this field.

Systems pharmacology and multi-scale mechanism of Enicostema axillare bioactives in treating Alzheimer disease

As a progressive neurological disease with increased morbidity and mortality, Alzheimer Disease (AD) is characterized by neuron damage that controls memory and mental functions. Enicostema axillare (EA), an herb with a history of combativeness and effectiveness in treating Rheumatoid Arthritis, Cancer, and Diabetes, is used in Indian folk medicine from a holistic point of view. Though the herb is used for many illnesses, the molecular mechanism of its bioactive on AD has not been deciphered by intricate research. A unique pharmacology approach based on ADME drug screening and targeting, pathway enrichment (GO and KEGG), and network pharmacology, was established to explore the molecular mechanisms of E. axillare (EA) bioactive compounds for the treatment of AD. In brief, we bring to light the three active compounds of EA and seven potential molecular targets of AD, which are mainly implicated in four signaling pathways, i.e., MAPK, Apoptosis, neurodegeneration, and the TNF pathway. Moreover, the network analysis of the active compounds, molecular targets, and their pathways reveals the pharmacological nature of the compounds. Further, molecular docking studies were carried out to explore the interactions between the EA bioactive compounds and the targets and examine the binding affinity. The outcome of the work reflects the potential therapeutic effects of the compounds for treating AD through the modulation of the key proteins, which further corroborates the reliability of our network pharmacology analysis. This study not only helps in understanding the molecular mechanism of the drugs but also helps in finding and sorting new drugs for the treatment of AD, and other complex diseases through modern medicine.

Exploring the Efficient Natural Products for the Therapy of Parkinson's Disease via Drosophila Melanogaster (Fruit Fly) Models

Parkinson's disease (PD) is a severe neurodegenerative disorder, partly attributed to mutations, environmental toxins, oxidative stress, abnormal protein aggregation, and mitochondrial dysfunction. However, the precise pathogenesis of PD and its treatment strategy still require investigation. Fortunately, natural products have demonstrated potential as therapeutic agents for alleviating PD symptoms due to their neuroprotective properties. To identify promising lead compounds from herbal medicines' natural products for PD management and understand their modes of action, suitable animal models are necessary. Drosophila melanogaster (fruit fly) serves as an essential model for studying genetic and cellular pathways in complex biological processes. Diverse Drosophila PD models have been extensively utilized in PD research, particularly for discovering neuroprotective natural products. This review emphasizes the research progress of natural products in PD using the fruit fly PD model, offering valuable insights into utilizing invertebrate models for developing novel anti-PD drugs.

Pathogenesis of Neurodegenerative Diseases and the Protective Role of Natural Bioactive Components

Neurodegenerative diseases are a serious problem throughout the world. There are several causes of neurodegenerative diseases; these include genetic predisposition, accumulation of misfolded proteins, oxidative stress, neuroinflammation, and excitotoxicity. Oxidative stress increases the production of reactive oxygen species (ROS) that advance lipid peroxidation, DNA damage, and neuroinflammation. The cellular antioxidant system (superoxide dismutase, catalase, peroxidase, and reduced glutathione) plays a crucial role in scavenging free radicals. An imbalance in the defensive actions of antioxidants and overproduction of ROS intensify neurodegeneration. The formation of misfolded proteins, glutamate toxicity, oxidative stress, and cytokine imbalance promote the pathogenesis of Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Antioxidants are now attractive molecules to fight against neurodegeneration. Certain vitamins (A, E, C) and polyphenolic compounds (flavonoids) show excellent antioxidant properties. Diet is the major source of antioxidants. However, diet medicinal herbs are also rich sources of numerous flavonoids. Antioxidants prevent ROS-mediated neuronal degeneration in post-oxidative stress conditions. The present review is focused on the pathogenesis of neurodegenerative diseases and the protective role of antioxidants. KEY TEACHING POINTSThis review shows that multiple factors are directly or indirectly associated with the pathogenesis of neurodegenerative diseases.Failure to cellular antioxidant capacity increases oxidative stress that intensifies neuroinflammation and disease progression.Different vitamins, carotenoids, and flavonoids, having antioxidant capacity, can be considered protective agents.

Insights from molecular network analysis to docking of sterubin with potential targets

The use of a flavonoid compound sterubin in drug discovery is gaining momentum. Hence, it is of interest to document the molecular network analysis to docking of sterubin with potential targets to glean insights. We identified 32 target genes and (or) gene products for sterubin using DAVID tools for GO, KEGG pathway enrichment analyses and the STRING database. Further, molecular docking analysis data of sterubin with these targets is documented for further consideration in broad-spectrum drug discovery.

Quercetin as a possible complementary therapy in multiple sclerosis: Anti-oxidative, anti-inflammatory and remyelination potential properties

Multiple sclerosis (MS) is a complex autoimmune disorder of the central nervous system (CNS) which causes various symptoms such as fatigue, dyscoordination weakness and visual weakness. The intricacy of the immune system and obscure etiology are the main reasons for the lack of a definite treatment for MS. Oxidative stress is one of the most important key factors in MS pathogenesis. It can enhance inflammation, neurodegeneration and autoimmune-mediated processes, which can lead to excessive demyelination and axonal disruption. Recently, promising effects of Quercetin as a non-pharmacological anti-oxidant therapy have been reported in preclinical studies of MS disease. In this review, we provide a compendium of preclinical and clinical studies that have investigated the effects of Quercetin on MS disease to evaluate its potential utility as a complementary therapy in MS. Quercetin treatment in MS disease not only protects the CNS against oxidative stress and neuroinflammation, but it also declines the demyelination process and promotes remyelination potential. The present study clarifies the reported knowledge on the beneficial effects of Quercetin against MS, with future implication as a neuroprotective complementary therapy.

Therapeutic potential of flavonoids in the management of obesity-induced Alzheimer's disease: an overview of preclinical and clinical studies

Obesity is a global epidemic that affects people of all ages, genders, and backgrounds. It can lead to a plethora of disorders, including diabetes mellitus, renal dysfunction, musculoskeletal problems, metabolic syndrome, cardiovascular, and neurodegenerative abnormalities. Obesity has also been linked to neurological diseases such as cognitive decline, dementia, and Alzheimer's disease (AD), caused by oxidative stress, pro-inflammatory cytokines, and the production of reactive oxygen free radicals (ROS). Secretion of insulin hormone is impaired in obese people, leading to hyperglycaemia and increased accumulation of amyloid-β in the brain. Acetylcholine, a key neurotransmitter necessary for forming new neuronal connections in the brain, decreases in AD patients. To alleviate acetylcholine deficiency, researchers have proposed dietary interventions and adjuvant therapies that enhance the production of acetylcholine and assist in the management of AD patients. Such measures include dietary intervention with antioxidant and anti-inflammatory flavonoid-rich diets, which have been found to bind to tau receptors, reduce gliosis, and reduce neuroinflammatory markers in animal models. Furthermore, flavonoids like curcumin, resveratrol, epigallocatechin-3-gallate, morin, delphinidins, quercetin, luteolin, and oleocanthal have shown to cause significant reductions in interleukin-1β, increase BDNF levels, stimulate hippocampal neurogenesis and synapse formation, and ultimately prevent the loss of neurons in the brain. Thus, flavonoid-rich nutraceuticals can be a potential cost-effective therapeutic option for treating obesity-induced AD, but further well-designed, randomized, and placebo-controlled clinical studies are needed to assess their optimal dosages, efficacy, and long-term safety of flavonoids in humans. The main objectives of this review are to underscore the therapeutic potential of different nutraceuticals containing flavonoids that can be added in the daily diet of AD patients to enhance acetylcholine and reduce neuronal inflammation in the brain.

Effects of aerobic exercise and dietary flavonoids on cognition: a systematic review and meta-analysis

Introduction: Studies have shown that exercise increases angiogenesis and perfusion in the hippocampus, activates neurogenesis in the dentate gyrus and increases synaptic plasticity, as well as increases the complexity and number of dendritic spines, all of which promote memory function and protect against cognitive decline. Flavonoids are gaining attention as antioxidants in health promotion due to their rich phenolic content, particularly for their modulating role in the treatment of neurodegenerative diseases. Despite this, there has been no comprehensive review of cognitive improvement supplemented with flavonoid and prescribed with exercise or a combination of the two interventions has been conducted. The purpose of this review is to determine whether a combined intervention produces better results when given together than when given separately. Methods: Relevant articles assessing the effect of physical exercise, flavonoid or in combination on cognitive related biomarkers and neurobehavioral assessments within the timeline of January 2011 until June 2023 were searched using three databases; PubMed, PROQUEST and SCOPUS. Results: A total of 705 articles were retrieved and screened, resulting in 108 studies which are in line with the objective of the current study were included in the analysis. Discussion: The selected studies have shown significant desired effect on the chosen biomarkers and neurobehavioral assessments. Systematic Review Registration: identifier: [CRD42021271001].

The role of redox active copper(II) on antioxidant properties of the flavonoid baicalein: DNA protection under Cu(II)-Fenton reaction and Cu(II)-ascorbate system conditions

The antioxidant properties of flavonoids are mediated by their functional hydroxyl groups, which are capable of both chelating redox active metals such as iron, copper and scavenging free radicals. In this paper, the antioxidant vs. prooxidant and DNA protecting properties of baicalein and Cu(II)-baicalein complexes were studied under the conditions of the Copper-Fenton reaction and of the Copper-Ascorbate system. From the relevant EPR spectra, the interaction of baicalein with Cu(II) ions was confirmed, while UV-vis spectroscopy demonstrated a greater stability over time of Cu(II)-baicalein complexes in DMSO than in methanol and PBS and Phosphate buffers. An ABTS study confirmed a moderate ROS scavenging efficiency, at around 37%, for both free baicalein and Cu(II)-baicalein complexes (in the ratios 1:1 and 1:2). The results from absorption titrations are in agreement with those from viscometric studies and confirmed that the binding mode between DNA and both free baicalein and Cu-baicalein complexes, involves hydrogen bonds and van der Waals interactions. The DNA protective effect of baicalein has been investigated by means of gel electrophoresis under the conditions of the Cu-catalyzed Fenton reaction and of the Cu-Ascorbate system. In both cases, it was found that, at sufficiently high concentrations, baicalein offers some protection to cells from DNA damage caused by ROS (singlet oxygen, hydroxyl radicals and superoxide radical anions). Accordingly, baicalein may be useful as a therapeutic agent in diseases with a disturbed metabolism of redox metals such as copper, for example Alzheimer's disease, Wilson's disease and various cancers. While therapeutically sufficient concentrations of baicalein may protect neuronal cells from Cu-Fenton-induced DNA damage in regard to neurological conditions, conversely, in the case of cancers, low concentrations of baicalein do not inhibit the pro-oxidant effect of copper ions and ascorbate, which can, in turn, deliver an effective damage to DNA in tumour cells.

Buckwheat tartary regulates the Gsk-3β/β-catenin pathway to prevent neurobehavioral impairments in a rat model of surgical menopause

Menopause is a natural aging process characterized by decreased levels of sex hormones in females. Deprivation of estrogen following menopause results in alterations of dendritic arborization of the neuron that leads to neurobehavioral complications. Hormone replacement therapy is in practice to manage postmenopausal conditions but is associated with a lot of adverse effects. In the present study, the efficacy of buckwheat tartary (Fagopyrum tataricum) whole seed extract was investigated against the neurobehavioral complication in middle-aged ovariectomized rats, which mimic the clinical postmenopausal condition. Hydroalcoholic extraction (80% ethanol) was done, and quantification of major marker compounds in the extract was performed using HPLC. Oral treatment of the extract following the critical window period rescued the reconsolidation process of spatial and recognition memory, as well as depression-like behavior. Gene expression analysis disclosed elevated oxidative stress and neuroinflammation that largely disturb the integrity of the blood-brain barrier in ovariectomized rats. Gfap and Pparγ expression also showed reactive astrogliosis in the rats subjected to ovariectomy. The extract treatment reverted the elevated oxidative stress, neuroinflammation and expression of the studied genes. Furthermore, protein expression analysis revealed that Gsk-3β was activated differentially in the brain, as suggested by β-catenin protein expression, which was normalized following the treatment with extract and rescued the altered neurobehavioral process. The results of the current study concluded that Fagopyrum tataricum seed extract is better option to overcome the neurobehavioral complications associated with the menopause.

Mapping new pharmacological interventions for cognitive function in Alzheimer's disease: a systematic review of randomized clinical trials

Background and Objective: Alzheimer's disease (AD) is a progressive neurodegenerative disorder, that is, characterized by cognitive decline. To date, there are no effective treatments for AD. Therefore, the objective of this study was to map new perspectives on the effects of pharmacological treatment on cognitive function and the overall psychological state in patients with AD. Methods: Two independent researchers searched for randomized clinical trials (RCTs) exploring new pharmacological approaches related to cognition in Alzheimer's disease in adults from 2018 to 2023 in PubMed, Web of Science, Scopus, and Cochrane Library databases. A total of 17 RCTs were included in this review. Results: The results show that in recent years, new drugs have been tested in patients with Alzheimer's disease, including masitinib, methylphenidate, levetiracetam, Jiannao Yizhi, and Huannao Yicong formulas. Most studies have been conducted in populations with mild to moderate Alzheimer's disease. Conclusion: Although some of the drugs found suggested improvement in cognitive function, the scarcity of available studies highlights the need for further research in this area. Systematic review registration: [www.crd.york.ac.uk/prospero], identifier [CRD42023409986].

Molecular insights into the inhibition of early stage of Aβ peptide aggregation and destabilization of Alzheimer's Aβ protofibril by dipeptide D-Trp-Aib: A molecular modelling approach

Amyloid beta (Aβ) peptide aggregates rapidly into the soluble oligomers, protofibrils and fibrils to form senile plaques, a neurotoxic component and pathological hallmark of Alzheimer's disease (AD). Experimentally, it has been demonstrated the inhibition of an early stages of Aβ aggregation by a dipeptide D-Trp-Aib inhibitor, but its molecular mechanism is still unclear. Hence, in the present study, we used molecular docking and molecular dynamics (MD) simulations to explore the molecular mechanism of inhibition of an early oligomerization and destabilization of preformed Aβ protofibril by D-Trp-Aib. Molecular docking study showed that the D-Trp-Aib binds at the aromatic (Phe19, Phe20) region of Aβ monomer, Aβ fibril and hydrophobic core of Aβ protofibril. MD simulations revealed the binding of D-Trp-Aib at the aggregation prone region (Lys16-Glu22) resulted in the stabilization of Aβ monomer by π-π stacking interactions between Tyr10 and indol ring of D-Trp-Aib, which decreases the β-sheet content and increases the α-helices. The interaction between Lys28 of Aβ monomer to D-Trp-Aib could be responsible to block the initial nucleation and may impede the fibril growth and elongation. The loss of hydrophobic contacts between two β-sheets of Aβ protofibril upon binding of D-Trp-Aib at the hydrophobic cavity resulted in the partial opening of β-sheets. This also disrupts a salt bridge (Asp23-Lys28) leading to the destabilization of Aβ protofibril. Binding energy calculations revealed that van der Waals and electrostatic interactions maximally favours the binding of D-Trp-Aib to Aβ monomer and Aβ protofibril respectively. The residues Tyr10, Phe19, Phe20, Ala21, Glu22, Lys28 of Aβ monomer, whereas Leu17, Val18, Phe19, Val40, Ala42 of protofibril contributing for the interactions with D-Trp-Aib. Thus, the present study provides structural insights into the inhibition of an early oligomerization of Aβ peptides and destabilization of Aβ protofibril, which could be useful to design novel inhibitors for the treatment of AD.

Change in habitual intakes of flavonoid-rich foods and mortality in US males and females

BACKGROUND

Higher baseline intakes of flavonoid-rich foods and beverages are associated with a lower risk of chronic disease and mortality in observational studies. However, associations between changes in intakes and mortality remain unclear. We aimed to evaluate associations between 8-year changes in intakes of (1) individual flavonoid-rich foods and (2) a composite measure (termed the 'flavodiet') of foods and beverages that are known to be main contributors to flavonoid intake and subsequent total and cause-specific mortality.

METHODS

We evaluated associations between 8-year changes in intakes of (1) individual flavonoid-rich foods and (2) a novel 'flavodiet' score and total and cause-specific mortality. We included 55,786 females from the Nurses' Health Study (NHS) and 29,800 males from the Health Professionals Follow-up Study (HPFS), without chronic disease at baseline in our analyses. Using multivariable-adjusted Cox proportional hazard models, we examined associations of 8-year changes in intakes of (1) flavonoid-rich foods and (2) the flavodiet score with subsequent 2-year lagged 6-year risk of mortality adjusting for baseline intakes. Data were pooled using fixed-effects meta-analyses.

RESULTS

We documented 15,293 deaths in the NHS and 8988 deaths in HPFS between 1986 and 2018. For blueberries, red wine and peppers, a 5%, 4% and 9% lower risk of mortality, respectively, was seen for each 3.5 servings/week increase in intakes while for tea, a 3% lower risk was seen for each 7 servings/week increase [Pooled HR (95% CI) for blueberries; 0.95 (0.91, 0.99); red wine: 0.96 (0.93, 0.99); peppers: 0.91 (0.88, 0.95); and tea: 0.97 (0.95, 0.98)]. Conversely, a 3.5 servings/week increase in intakes of onions and grapefruit plus grapefruit juice was associated with a 5% and 6% higher risk of total mortality, respectively. An increase of 3 servings per day in the flavodiet score was associated with an 8% lower risk of total mortality [Pooled HR: 0.92 (0.89, 0.96)], and a 13% lower risk of neurological mortality [Pooled HR: 0.87 (0.79, 0.97)], after multivariable adjustments.

CONCLUSIONS

Encouraging an increased intake of specific flavonoid-rich foods and beverages, namely tea, blueberries, red wine, and peppers, even in middle age, may lower early mortality risk.

Preliminary study to identify CXCR4 inhibitors as potential therapeutic agents for Alzheimer's and Parkinson's diseases

Neurodegenerative disorders (NDDs) are known to exhibit genetic overlap and shared pathophysiology. This study aims to find the shared genetic architecture of Alzheimer's disease (AD) and Parkinson's disease (PD), two major age-related progressive neurodegenerative disorders. The gene expression profiles of GSE67333 (containing samples from AD patients) and GSE114517 (containing samples from PD patients) were retrieved from the Gene Expression Omnibus (GEO) functional genomics database managed by the National Center for Biotechnology Information. The web application GREIN (GEO RNA-seq Experiments Interactive Navigator) was used to identify differentially expressed genes (DEGs). A total of 617 DEGs (239 upregulated and 379 downregulated) were identified from the GSE67333 dataset. Likewise, 723 DEGs (378 upregulated and 344 downregulated) were identified from the GSE114517 dataset. The protein-protein interaction networks of the DEGs were constructed, and the top 50 hub genes were identified from the network of the respective dataset. Of the four common hub genes between two datasets, C-X-C chemokine receptor type 4 (CXCR4) was selected due to its gene expression signature profile and the same direction of differential expression between the two datasets. Mavorixafor was chosen as the reference drug due to its known inhibitory activity against CXCR4 and its ability to cross the blood-brain barrier. Molecular docking and molecular dynamics simulation of 51 molecules having structural similarity with Mavorixafor was performed to find two novel molecules, ZINC49067615 and ZINC103242147. This preliminary study might help predict molecular targets and diagnostic markers for treating Alzheimer's and Parkinson's diseases. Insight Box Our research substantiates the therapeutic relevance of CXCR4 inhibitors for the treatment of Alzheimer's and Parkinson's diseases. We would like to disclose the following insights about this study. We found common signatures between Alzheimer's and Parkinson's diseases at transcriptional levels by analyzing mRNA sequencing data. These signatures were used to identify putative therapeutic agents for these diseases through computational analysis. Thus, we proposed two novel compounds, ZINC49067615 and ZINC103242147, that were stable, showed a strong affinity with CXCR4, and exhibited good pharmacokinetic properties. The interaction of these compounds with major residues of CXCR4 has also been described.

Protective effects of baicalin against L-glutamate-induced oxidative damage in HT-22 cells by inhibiting NLRP3 inflammasome activation via Nrf2/HO-1 signaling

Objectives

To explore the ability and underlying molecular mechanisms involved in the protective effects of Baicalin (BA) against L-Glutamate-induced mouse hippocampal neuron cell line HT-22.

Materials and Methods

The cell injury model of HT-22 cells was induced by L-glutamate, and cell viability and damage were detected by CCK-8 and LDH assays. Generation of intracellular reactive oxygen species (ROS) was measured by DCFH-DA in situ fluorescence method. The SOD activity and MDA concentration in the supernatants were determined by WST-8 and colorimetric method, respectively. Furthermore, Western blot and real-time qPCR analysis were utilized to detect the expression levels of the Nrf2/HO-1 signaling pathway and NLRP3 inflammasome proteins and genes.

Results

L-Glutamate exposure induced cell injuries in HT-22 cells, and the concentration of 5 mM L-Glutamate was chosen to be the modeling condition. Co-treatment with BA significantly promoted cell viability and reduced LDH release in a dose-dependent manner. In addition, BA attenuated the L-Glutamate-induced injuries by decreasing the ROS production and MDA concentration, while increasing the SOD activity. Moreover, we also found that BA treatment up-regulated the gene and protein expression of Nrf2 and HO-1, and then inhibited the expression of NLRP3.

Conclusion

Our study found that BA could relieve oxidative stress damage of HT-22 cells induced by L-Glutamate, and the mechanism might be related to the activation of Nrf2/HO-1 and inhibition of NLRP3 inflammasome.

A Comprehensive Review of Herbal Supplements Used for Persistent Symptoms Attributed to Lyme Disease

Context

Lyme disease is the most common, tick-borne disease in the USA. While most patients successfully recover with antibiotics, some patients experience persistent symptoms for months to years. Patients who attribute chronic symptoms to Lyme disease commonly use herbal supplements. The complexity, variability in dose and formulation, and lack of data for these herbal compounds make it difficult to assess their efficacy and safety.

Objective

This review examines the evidence for the antimicrobial activity, safety, and drug-drug interactions of 18 herbal supplements that patients commonly use for treatment of persistent symptoms attributed to Lyme disease.

Design

The research team performed a narrative review by searching the PubMed, Embase, Scopus, Natural Medicines databases, and NCCIH website. The search used the keywords for 18 herbal compounds: (1) andrographis (Andrographis paniculate), (2) astragalus (Astragalus propinquus), (3) berberine, (4) cat's claw bark (Uncaria tomentosa), (5) cordyceps (Cordyceps sinensis), (6) cryptolepis (Cryptolepis sanguinolenta), (7) Chinese skullcap (Scutellaria baicalensis), (8) garlic (Allium sativum), (9) Japanese knotwood (Polygonum cuspidatum), (10) reishi mushrooms (Ganoderma lucidum), (11) sarsaparilla (Smilax medica), (12) Siberian ginseng (Eleutherococcus senticosus), (13) sweet wormwood (Artemisia annua), (14) teasle root (Dipsacus fullonum), (15) lemon balm (Melissa officinalis), (16) oil of oregano (Origanum vulgare), (17) peppermint (Mentha x piperita), and (18) thyme (Thymus vulgaris). The team also searched for terms related to protocols, including Dr. Rawls' protocol and the Buhner protocol.

Setting

University of Maryland Medical Center, Baltimore MD.

Results

Seven of the 18 herbs reviewed had evidence for in-vitro activity against B. burgdorferi. These compounds included: (1) cat's claw (2) cryptolepis, (3) Chinese skullcap, (4) Japanese knotweed, (5) sweet wormwood, (6) thyme, and (7) oil of oregano. With the exception of oil of oregano these compounds also have anti-inflammatory activity. In vivo data and clinical trials are lacking. Clinicians should be cautious as many of the identified compounds have drug interactions and additive effects that could lead to increased risks for bleeding, hypotension, and hypoglycemia.

Conclusions

Many of the herbs that alternative and integrative practitioners use to treat Lyme disease have anti-inflammatory effects that may contribute to patients' perceptions of symptomatic improvement. Some herbs have limited demonstrated anti-borrelial activity in vitro, but in-vivo data and clinical trial data is lacking. Further research is required to determine the efficacy, safety and appropriate use of these herbs for this patient population.

Neuroprotective potential of cinnamoyl derivatives against Parkinson's disease indicators in Drosophila melanogaster and in silico models

Parkinson's disease (PD) is a movement disorder resulting from the loss of dopaminergic neurons over time. While there is no cure for PD, available conventional therapies aid to manage the motor symptoms. Natural products (NPs) derived from plants are among the most potent alternative therapies for PD. This study explored the neuroprotective potential of selected cinnamoyl derivatives namely toussaintine A (1), E-toussaintine E (2), asperphenamate (3) and julocrotine (4) against PD indicators using rotenone-challenged Drosophila melanogaster and in silico models. The compounds were first assessed for their toxicity preceding treatment experiments. Adult flies (aged 1-4 days) were exposed to varying concentrations of the compounds for 7 days. During the experiment, the mortality of flies was observed, and the lethal concentration (LC₅₀) of each tested compound was determined. The LC₅₀ values were found to be 50.1, 55.6, 513.5, and 101.0 µM for compounds 1, 2, 3, and 4, respectively. For seven days, we exposed flies to 500 µM of rotenone and co-fed with a chosen dose of 40 µM of each test compound in the diet. Using a negative geotaxis test, rotenone-challenged flies exhibited compromised climbing ability in comparison to control flies, the condition that was reversed by the action of studied compounds. Rotenone exposure also elevated malondialdehyde levels in the brain tissues, as measured by lipid peroxidation, when compared to control flies. In flies exposed to rotenone and co-fed with the compounds, this effect was lessened. In flies exposed to rotenone, mRNA levels of antioxidant enzymes such as superoxide dismutase and catalase were raised but were normalized in flies treated with the investigated compounds. Moreover, in-silico studies examined the inhibitory ability of compounds 1-4 against selected PD molecular targets, revealing the strong power of toussaintine A (1) against Adenosine receptor 2 (A2AR) and monoamine oxidase B. Thus, our findings suggest that cinnamoyl derivatives have neuroprotective potential via reducing the oxidative burden and improving locomotor ability after toxin invectives. In particular, compound 1 at lower doses can simultaneously be a potential inhibitor of A2AR and an anti-oxidative mediator in the development of anti-PD agents.

The Neuroprotective Potentiality of Flavonoids on Alzheimer's Disease

Alzheimer's disease (AD), due to its spread, has become a global health priority, and is characterized by senile dementia and progressive disability. The main cause of AD and other neurodegenerations (Huntington, Parkinson, Amyotrophic Lateral Sclerosis) are aggregated protein accumulation and oxidative damage. Recent research on secondary metabolites of plants such as polyphenols demonstrated that they may slow the progression of AD. The flavonoids' mechanism of action in AD involved the inhibition of acetylcholinesterase, butyrylcholinesterase, Tau protein aggregation, β-secretase, oxidative stress, inflammation, and apoptosis through modulation of signaling pathways which are implicated in cognitive and neuroprotective functions, such as ERK, PI3-kinase/Akt, NFKB, MAPKs, and endogenous antioxidant enzymatic systems. This review focuses on flavonoids and their role in AD, in terms of therapeutic potentiality for human health, antioxidant potential, and specific AD molecular targets.

The Flavonol Quercitrin Hinders GSK3 Activity and Potentiates the Wnt/β-Catenin Signaling Pathway

The Wnt/β-catenin signaling pathway dictates cell proliferation and differentiation during embryonic development and tissue homeostasis. Its deregulation is associated with many pathological conditions, including neurodegenerative disease, frequently downregulated. The lack of efficient treatment for these diseases, including Alzheimer’s disease (AD), makes Wnt signaling an attractive target for therapies. Interestingly, novel Wnt signaling activating compounds are less frequently described than inhibitors, turning the quest for novel positive modulators even more appealing. In that sense, natural compounds are an outstanding source of potential drug leads. Here, we combine different experimental models, cell-based approaches, neuronal culture assays, and rodent behavior tests with Xenopus laevis phenotypic analysis to characterize quercitrin, a natural compound, as a novel Wnt signaling potentiator. We find that quercitrin potentiates the signaling in a concentration-dependent manner and increases the occurrence of the Xenopus secondary axis phenotype mediated by Xwnt8 injection. Using a GSK3 biosensor, we describe that quercitrin impairs GSK3 activity and increases phosphorylated GSK3β S9 levels. Treatment with XAV939, an inhibitor downstream of GSK3, impairs the quercitrin-mediated effect. Next, we show that quercitrin potentiates the Wnt3a-synaptogenic effect in hippocampal neurons in culture, which is blocked by XAV939. Quercitrin treatment also rescues the hippocampal synapse loss induced by intracerebroventricular injection of amyloid-β oligomers (AβO) in mice. Finally, quercitrin rescues AβO-mediated memory impairment, which is prevented by XAV939. Thus, our study uncovers a novel function for quercitrin as a Wnt/β-catenin signaling potentiator, describes its mechanism of action, and opens new avenues for AD treatments.

Model yeast as a versatile tool to examine the antioxidant and anti-ageing potential of flavonoids, extracted from medicinal plants

The demand for the production of herbal extracts for cosmetics, food, and health supplements, known as plant-based medicine, is rising globally. Incorporating herbal extracts could help to create higher value products due to the functional properties of bioactive compounds. Because the phytochemical composition could vary depending on the processing methods, a simple bioassay of herbal bioactive compounds is an important screening method for the purposes of functional characterization and quality assurance. As a simplified eukaryotic model, yeast serves as a versatile tool to examine functional property of bioactive compounds and to gain better understanding of fundamental cellular processes, because they share similarities with the processes in humans. In fact, aging is a well-conserved phenomenon between yeast and humans, making yeast a powerful genetic tool to examine functional properties of key compounds obtained from plant extracts. This study aimed to apply a well-established model yeast, Saccharomyces cerevisiae, to examine the antioxidant and anti-aging potential of flavonoids, extracted from medicinal plants, and to gain insight into yeast cell adaptation to oxidative stress. Some natural quercetin analogs, including morin, kaempferol, aromadendrin, and steppogenin, protected yeast cells against oxidative stress induced by acetic acid, as shown by decreased cell sensitivity. There was also a reduction in intracellular reactive oxygen species following acetic acid treatment. Using the chronological aging assay, quercetin, morin, and steppogenin could extend the lifespan of wild-type S. cerevisiae by 15%–25%. Consistent with the fact that oxidative stress is a key factor to aging, acetic acid resistance was associated with increased gene expression of TOR1, which encodes a key growth signaling kinase, and MSN2 and MSN4, which encode stress-responsive transcription factors. The addition of the antioxidant morin could counteract this increased expression, suggesting a possible modulatory role in cell signaling and the stress response of yeast. Therefore, yeast represents a versatile model organism and rapid screening tool to discover potentially rejuvenescent molecules with anti-aging and anti-oxidant potential from natural resources and to advance knowledge in the molecular study of stress and aging.

Protective Effects of Flavonoids against Alzheimer's Disease: Pathological Hypothesis, Potential Targets, and Structure-Activity Relationship

Alzheimer’s disease (AD) is a neurodegenerative disease with high morbidity and mortality, for which there is no available cure. Currently, it is generally believed that AD is a disease caused by multiple factors, such as amyloid-beta accumulation, tau protein hyperphosphorylation, oxidative stress, and inflammation. Multitarget prevention and treatment strategies for AD are recommended. Interestingly, naturally occurring dietary flavonoids, a class of polyphenols, have been reported to have multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this review, we summarize and discuss the existing multiple pathogenic factors of AD. Moreover, we further elaborate on the biological activities of natural flavonoids and their potential mode of action and targets in managing AD by presenting a wide range of experimental evidence. The gathered data indicate that flavonoids can be regarded as prophylactics to slow the advancement of AD or avert its onset. Different flavonoids have different activities and varying levels of activity. Further, this review summarizes the structure–activity relationship of flavonoids based on the existing literature and can provide guidance on the design and selection of flavonoids as anti-AD drugs.

Free radical biology in neurological manifestations: mechanisms to therapeutics interventions

Recent advancements and growing attention about free radicals (ROS) and redox signaling enable the scientific fraternity to consider their involvement in the pathophysiology of inflammatory diseases, metabolic disorders, and neurological defects. Free radicals increase the concentration of reactive oxygen and nitrogen species in the biological system through different endogenous sources and thus increased the overall oxidative stress. An increase in oxidative stress causes cell death through different signaling mechanisms such as mitochondrial impairment, cell-cycle arrest, DNA damage response, inflammation, negative regulation of protein, and lipid peroxidation. Thus, an appropriate balance between free radicals and antioxidants becomes crucial to maintain physiological function. Since the 1brain requires high oxygen for its functioning, it is highly vulnerable to free radical generation and enhanced ROS in the brain adversely affects axonal regeneration and synaptic plasticity, which results in neuronal cell death. In addition, increased ROS in the brain alters various signaling pathways such as apoptosis, autophagy, inflammation and microglial activation, DNA damage response, and cell-cycle arrest, leading to memory and learning defects. Mounting evidence suggests the potential involvement of micro-RNAs, circular-RNAs, natural and dietary compounds, synthetic inhibitors, and heat-shock proteins as therapeutic agents to combat neurological diseases. Herein, we explain the mechanism of free radical generation and its role in mitochondrial, protein, and lipid peroxidation biology. Further, we discuss the negative role of free radicals in synaptic plasticity and axonal regeneration through the modulation of various signaling molecules and also in the involvement of free radicals in various neurological diseases and their potential therapeutic approaches. The primary cause of free radical generation is drug overdosing, industrial air pollution, toxic heavy metals, ionizing radiation, smoking, alcohol, pesticides, and ultraviolet radiation. Excessive generation of free radicals inside the cell R1Q1 increases reactive oxygen and nitrogen species, which causes oxidative damage. An increase in oxidative damage alters different cellular pathways and processes such as mitochondrial impairment, DNA damage response, cell cycle arrest, and inflammatory response, leading to pathogenesis and progression of neurodegenerative disease other neurological defects.

Flavonoids as Promising Neuroprotectants and Their Therapeutic Potential against Alzheimer’s Disease

Alzheimer's disease (AD) is one of the serious and progressive neurodegenerative disorders in the elderly worldwide. Various genetic, environmental, and lifestyle factors are associated with its pathogenesis that affect neuronal cells to degenerate over the period of time. AD is characterized by cognitive dysfunctions, behavioural disability, and psychological impairments due to the accumulation of amyloid beta (Aβ) peptides and neurofibrillary tangles (NFT). Several research reports have shown that flavonoids are the polyphenolic compounds that significantly improve cognitive functions and inhibit or delay the amyloid beta aggregation or NFT formation in AD. Current research has uncovered that dietary use of flavonoid-rich food sources essentially increases intellectual abilities and postpones or hinders the senescence cycle and related neurodegenerative problems including AD. During AD pathogenesis, multiple signalling pathways are involved and to target a single pathway may relieve the symptoms but not provides the permanent cure. Flavonoids communicate with different signalling pathways and adjust their activities, accordingly prompting valuable neuroprotective impacts. Flavonoids likewise hamper the movement of obsessive indications of neurodegenerative disorders by hindering neuronal apoptosis incited by neurotoxic substances. In this short review, we briefly discussed about the classification of flavonoids and their neuroprotective properties that could be used as a potential source for the treatment of AD. In this review, we also highlight the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production.

Neurohormetic phytochemicals in the pathogenesis of neurodegenerative diseases

The world population is progressively ageing, assuming an enormous social and health challenge. As the world ages, neurodegenerative diseases are on the rise. Regarding the progressive nature of these diseases, none of the neurodegenerative diseases are curable at date, and the existing treatments can only help relieve the symptoms or slow the progression. Recently, hormesis has increased attention in the treatment of age-related neurodegenerative diseases. The concept of hormesis refers to a biphasic dose-response phenomenon, where low levels of the drug or stress exert protective of beneficial effects and high doses deleterious or toxic effects. Neurohormesis, as the adaptive aspect of hormetic dose responses in neurons, has been shown to slow the onset of neurodegenerative diseases and reduce the damages caused by aging, stroke, and traumatic brain injury. Hormesis was also observed to modulate anxiety, stress, pain, and the severity of seizure. Thus, neurohormesis can be considered as a potentially innovative approach in the treatment of neurodegenerative and other neurologic disorders. Herbal medicinal products and supplements are often considered health resources with many applications. The hormesis phenomenon in medicinal plants is valuable and several studies have shown that hormetic mechanisms of bioactive compounds can prevent or ameliorate the neurodegenerative pathogenesis in animal models of Alzheimer’s and Parkinson’s diseases. Moreover, the hormesis activity of phytochemicals has been evaluated in other neurological disorders such as Autism and Huntington’s disease. In this review, the neurohormetic dose–response concept and the possible underlying neuroprotection mechanisms are discussed. Different neurohormetic phytochemicals used for the better management of neurodegenerative diseases, the rationale for using them, and the key findings of their studies are also reviewed.

Advances on Therapeutic Strategies for Alzheimer’s Disease: From Medicinal Plant to Nanotechnology

Alzheimer’s disease (AD) is a chronic dysfunction of neurons in the brain leading to dementia. It is characterized by gradual mental failure, abnormal cognitive functioning, personality changes, diminished verbal fluency, and speech impairment. It is caused by neuronal injury in the cerebral cortex and hippocampal area of the brain. The number of individuals with AD is growing at a quick rate. The pathology behind AD is the progress of intraneuronal fibrillary tangles, accumulation of amyloid plaque, loss of cholinergic neurons, and decrease in choline acetyltransferase. Unfortunately, AD cannot be cured, but its progression can be delayed. Various FDA-approved inhibitors of cholinesterase enzyme such as rivastigmine, galantamine, donepezil, and NDMA receptor inhibitors (memantine), are available to manage the symptoms of AD. An exhaustive literature survey was carried out using SciFinder’s reports from Alzheimer’s Association, PubMed, and Clinical Trials.org. The literature was explored thoroughly to obtain information on the various available strategies to prevent AD. In the context of the present scenario, several strategies are being tried including the clinical trials for the treatment of AD. We have discussed pathophysiology, various targets, FDA-approved drugs, and various drugs in clinical trials against AD. The goal of this study is to shed light on current developments and treatment options, utilizing phytopharmaceuticals, nanomedicines, nutraceuticals, and gene therapy.

A Newly Synthesized Derivative and a Natural Parent Molecule: Which Would Be More Beneficial as a Future Antitumor Candidate? Docking and In Vivo Study

Seeking for new effectual anticancer drugs is of great importance. In this study, a newly synthesized and well-characterized chromene derivative (ethyl 2-amino-4-phenyl-4H-benzo(h)chromene-3-carboxylate) "C" was prepared. Molecular docking studies were done. The new compound "C" in compare to the natural parent Quercetin "Q," as a well-known natural chromene derivative with antioxidant and antitumor activities, were tested for their antitumor activity against Ehrlich ascites carcinoma (EAC)-bearing mice. Both reduced ascites volume, decreased viable EAC cells, and prolonged EAC-bearing mice life span. They normalized troponin, creatine kinase-MB, lactate dehydrogenase, and urea levels, reversed liver enzyme activities towards normal, and increased antioxidant levels while reduced tumor necrosis factor-alpha (TNF-α) levels. Compared to each other, the new synthetic derivative "C" showed stronger antineoplastic effects than the natural parent "Q" may via the anti-inflammatory activities. Therefore, the newly synthesized chromene derivative is more promising as a future antitumor candidate than the natural parent molecule "Quercetin." Finally, our results encourage researchers to pay more attention to developing more novel natural-based derivatives that would be more beneficial as future therapeutics than their natural parents.

(–)-Epicatechin Provides Neuroprotection in Sodium Iodate-Induced Retinal Degeneration

Oxidative stress, mitochondrial impairment, and pathological amyloid beta (Aβ) deposition are involved in the pathogenesis of dry age-related macular degeneration (AMD). The natural flavonoid (–)-epicatechin (EC) is known to be an antioxidant and neuroprotective compound. Whether EC plays a therapeutic role in AMD is unknown. In this work, we aimed to assess the efficacy and molecular mechanisms of EC against sodium iodate (NaIO₃)-induced retinal degeneration in C57BL/6 mice via bioinformatic, morphological, and functional methods. We demonstrated that EC had no toxic effects on the retina and could ameliorate retinal deformation and thinning. EC treatment prevented outer retinal degeneration, reduced drusen-like deposits, increased b-wave amplitude in electroretinography, blocked retinal gliosis, and increased the number and quality of mitochondria. Importantly, EC increased the protein expression of OPA1 and decreased the expression of PINK1, indicating the role of EC in mitochondrial fusion that impaired by NaIO₃. Moreover, EC downregulated APP and TMEM97 levels, upregulated PGRMC1 levels, and reduced subretinal Aβ accumulation. This study illustrated that EC, which may become a promising therapeutic strategy for AMD, prevented NaIO₃-induced retinal degeneration, and this improvement may be associated with the mitochondrial quality control and the TMEM97/PGRMC1/Aβ signaling pathway.

Chrysin-Loaded Chitosan Nanoparticle-Mediated Neuroprotection in Aβ1-42-Induced Neurodegenerative Conditions in Zebrafish

Amyloid β plaques and neurofibrillary tangles are the characteristic features of Alzheimer's disease (AD). Plaques of amyloid β play a pivotal role in affecting cognitive functions and memory. Alzheimer's disease is a progressive neurodegenerative disease and is one of the leading causes of dementia worldwide. Several treatment strategies focusing on the amyloid cascade have been implemented to treat AD. The blood-brain barrier (BBB) poses the main obstructive barrier by refraining drugs from penetrating the brain. Nanotechnology is a promising research field for brain drug delivery using nanosized particles. Zebrafish is emerging as a model of interest to elaborate on brain targeting and nanotechnology-based therapeutics for neurodegenerative diseases. In the current study, we have synthesized and characterized chrysin-loaded chitosan nanoparticles (Chr-Chi NPs) and evaluated them for neuroprotection against amyloid-β-induced toxicity. We find that treatment with Chr-Chi NPs helps to retain memory, cognition, and synaptic connections, which are otherwise compromised due to Aβ_1-42 toxicity. The NPs further help in reducing aggregates of amyloid β, thus decreasing neuronal death and generation of reactive oxygen species (ROS). Taken together, our study brings to light a novel strategy for treating AD by a combined action on the neurons and amyloid aggregates mediated by chrysin and chitosan, respectively. Chr-Chi NPs, therefore, have the potential to provide a beneficial combinatorial treatment strategy for AD.

Neuroprotective Effects and Therapeutic Potential of the Citrus Flavonoid Hesperetin in Neurodegenerative Diseases

Neurodegenerative disorders affect more than fifty million Americans each year and represent serious health threats as the population ages. Neuroinflammation and oxidative stress are critical in the onset, progression, and pathogenesis of neurodegenerative diseases such as Alzheimer’s (AD), Parkinson’s (PD), and amyotrophic lateral sclerosis (ALS). A wide range of natural compounds has been investigated because of their antioxidant, anti-inflammatory, and neuroprotective properties. The citrus flavonoid hesperetin (HPT), an aglycone of hesperidin found in oranges, mandarins, and lemons, has been extensively reported to exert neuroprotective effects in experimental models of neurogenerative diseases. This review has compiled multiple studies on HPT in both in vivo and in vitro models to study neurodegeneration. We focused on the modulatory effects of hesperetin on the release of cellular anti-inflammatory and antioxidative stress mediators. Additionally, this review discusses the hesperetin effect in maintaining the levels of microRNA (miRNA) and modulating autophagy as it relates to hesperetin’s protective mechanisms against neurodegeneration. Moreover, this review is focused on providing experimental data for hesperetin’s potential as a neuroprotective compound and discusses reported evidence that HPT crosses the blood–brain barrier. In summary, this review shows the evidence available in the literature to indicate the efficacy of hesperetin in delaying the onset of neurodegenerative diseases.

Polydatin as a therapeutic alternative for central nervous system disorders: A systematic review of animal studies

Polydatin, or piceid, is a natural stilbene found in grapes, peanuts, and wines. Polydatin presents pharmacological activities, including neuroprotective properties, exerting preventive and/or therapeutic effects in central nervous system (CNS) disorders. In the present study, we summarize and discuss the neuroprotective effects of polydatin in CNS disorders and related pathological conditions in preclinical animal studies. A systematic review was performed by searching online databases, returning a total of 110 records, where 27 articles were selected and discussed here. The included studies showed neuroprotective effects of polydatin in experimental models of neurological disorders, including cerebrovascular disorders, Parkinson's disease, traumatic brain injuries, diabetic neuropathy, glioblastoma, and neurotoxicity induced by chemical agents. Most studies were focused on stroke (22.2%) and conducted in male rodents. The intervention protocol with polydatin was mainly acute (66.7%), with postdamage induction treatment being the most commonly used regimen (55.2%). Overall, polydatin ameliorated behavioral dysfunctions and/or promoted neurological function by virtue of its antioxidant and antiinflammatory properties. In summary, this review offers important scientific evidence for the neuroprotective effects and distinct pharmacological mechanisms of polydatin that not only enhances the present understanding but is also useful for the development of future preclinical and clinical investigations.

Phytochemicals and Nano-Phytopharmaceuticals Use in Skin, Urogenital and Locomotor Disorders: Are We There?

Nanomedicines emerged from nanotechnology and have been introduced to bring advancements in treating multiple diseases. Nano-phytomedicines are synthesized from active phytoconstituents or plant extracts. Advancements in nanotechnology also help in the diagnosis, monitoring, control, and prevention of various diseases. The field of nanomedicine and the improvements of nanoparticles has been of keen interest in multiple industries, including pharmaceutics, diagnostics, electronics, communications, and cosmetics. In herbal medicines, these nanoparticles have several attractive properties that have brought them to the forefront in searching for novel drug delivery systems by enhancing efficacy, bioavailability, and target specificity. The current review investigated various therapeutic applications of different nano-phytopharmaceuticals in locomotor, dermal, reproductive, and urinary tract disorders to enhance bioavailability and efficacy of phytochemicals and herbal extracts in preclinical and in vitro studies. There is a lack of clinical and extensive preclinical studies. The research in this field is expanding but strong evidence on the efficacy of these nano-phytopharmaceuticals for human use is still limited. The long-term efficacy and safety of nano-phytopharmaceuticals must be ensured with priority before these materials emerge as common human therapeutics. Overall, this review provides up-to-date information on related contemporary research on nano-phytopharmaceuticals and nano-extracts in the fields of dermatological, urogenital, and locomotor disorders.

Yeast as a Model to Find New Drugs and Drug Targets for VPS13-Dependent Neurodegenerative Diseases

Mutations in human VPS13A-D genes result in rare neurological diseases, including chorea-acanthocytosis. The pathogenesis of these diseases is poorly understood, and no effective treatment is available. As VPS13 genes are evolutionarily conserved, the effects of the pathogenic mutations could be studied in model organisms, including yeast, where one VPS13 gene is present. In this review, we summarize advancements obtained using yeast. In recent studies, vps13Δ and vps13-I2749 yeast mutants, which are models of chorea-acanthocytosis, were used to screen for multicopy and chemical suppressors. Two of the suppressors, a fragment of the MYO3 and RCN2 genes, act by downregulating calcineurin activity. In addition, vps13Δ suppression was achieved by using calcineurin inhibitors. The other group of multicopy suppressors were genes: FET4, encoding iron transporter, and CTR1, CTR3 and CCC2, encoding copper transporters. Mechanisms of their suppression rely on causing an increase in the intracellular iron content. Moreover, among the identified chemical suppressors were copper ionophores, which require a functional iron uptake system for activity, and flavonoids, which bind iron. These findings point at areas for further investigation in a higher eukaryotic model of VPS13-related diseases and to new therapeutic targets: calcium signalling and copper and iron homeostasis. Furthermore, the identified drugs are interesting candidates for drug repurposing for these diseases.

Insights into the inhibitory mechanism of skullcapflavone II against α-synuclein aggregation and its mediated cytotoxicity

The dangerous self-assembled and infectious seeds of α-synuclein (αSN) play primary roles in Parkinson's disease. Accordingly, the inhibition of αSN fibrillation and elimination of toxic aggregates are the main therapeutic strategies. Skullcapflavone II (S.FII), a compound isolated from S. pinnatifida, has shown multiple neuroprotective features. Herein, we demonstrated that S.FII inhibited αSN aggregation with IC50 of 7.2 μM. It increased nucleation time and decreased fibril elongation rate and the species formed in the presence of S.FII were unable to act as seeds. Additionally, S.FII inhibited both secondary nucleation and seeding of αSN and disaggregated the mature preformed fibrils as well. The species formed in the presence of S.FII showed less toxicity. It also preserved neurite length and dopamine content of SH-SY5Y cells and attenuated the inflammatory responses in mixed glial cells. The Localized Surface Plasmon Resonance (LSPR) analysis indicated that S.FII interacts with αSN. Docking simulation studies on αSN fibrils revealed that S.FII could interact with the key residues of the salt bridges and glutamine ladder, which might lead to the destruction of fibril's structures. We also showed that S.FII passes through the blood-brain barrier in vitro and in vivo. Overall, these findings elucidate the neuroprotective roles of S.FII in reducing αSN pathogenicity.

Potential of flavonoids as anti-Alzheimer's agents: bench to bedside

Developing therapies for neurodegenerative diseases are challenging because of the presence of blood-brain barrier and Alzheimer being one of the commonest and uprising neurodegenerative disorders possess the need for developing novel therapies. Alzheimer's is attributed to be the sixth leading cause of death in the USA and the number of cases is estimated to be increased from 58 million in 2021 to 88 million by 2050. Natural drugs have benefits of being cost-effective, widely available, fewer side effects, and immuno-booster can be useful in managing Alzheimer. Flavonoids can slow the neuronal degeneration as they have shown activity in central nervous system and are able to cross the blood-brain barrier. These can be easily extracted from fruits, vegetable, and plants. In Alzheimer disease, flavonoids scavenges the reactive oxygen species and reduces the production of amyloid beta protein. Agents from sub-classes of flavonoids such as flavanones, flavanols, flavones, flavonols, anthocyanins, and isoflavones having pharmacological action in treating Alzheimer disease are discussed in this review.

Intake of Flavonoids and Flavonoid-Rich Foods and Mortality Risk Among Individuals With Parkinson Disease: A Prospective Cohort Study

BACKGROUND AND OBJECTIVES

Although flavonoids have the potential to exert neuroprotective benefits, evidence of their role in improving survival rates among individuals with Parkinson disease (PD) remains lacking. We aimed to prospectively study the association between prediagnosis and postdiagnosis flavonoid intakes and risk of mortality among individuals with PD identified from 2 large ongoing cohorts of US men and women.

METHODS

Included in the current analysis were 599 women from the Nurses' Health Study and 652 men from the Health Professionals Follow-Up Study who were newly diagnosed with PD during follow-up. Dietary intakes of total flavonoid and its subclasses, together with major flavonoid-rich foods (tea, apples, berries, orange and orange juice, and red wine), were repeatedly assessed with a validated food frequency questionnaire every 4 years. Mortality was ascertained via the National Death Index and state vital statistics records.

RESULTS

We documented 944 deaths during 32 to 34 years of follow-up. A higher total flavonoid intake before PD diagnosis was associated with a lower future risk for all-cause mortality in men (hazard ratio [HR] comparing 2 extreme quartiles 0.53, 95% confidence interval [CI] 0.39, 0.71; p for trend < 0.001) but not in women (HR 0.93, 95% CI 0.68, 1.28; p for trend = 0.69) after adjustment for age, smoking status, total energy intake, and other covariates. The pooled HR comparing the extreme quartiles was 0.70 (95% CI 0.40, 1.22; p for trend = 0.25) with significant heterogeneity (p = 0.01). For flavonoid subclasses, the highest quartile of anthocyanins, flavones, and flavan-3-ols intakes before diagnosis had a lower mortality risk compared to the lowest quartile (pooled HR 0.66, 0.78, and 0.69, respectively; p < 0.05 for all); for berries and red wine, participants consuming ≥3 servings per week had a lower risk (pooled HR 0.77, 95% CI 0.58, 1.02; and pooled HR 0.68, 95% CI 0.51, 0.91, respectively) compared to <1 serving per month. After PD diagnosis, greater consumptions of total flavonoid, subclasses including flavonols, anthocyanins, flavan-3-ols, and polymers, and berries and red wine were associated with lower mortality risk (p < 0.05 for all).

DISCUSSION

Among individuals with PD, higher consumption of flavonoids, especially anthocyanins and flavan-3-ols, and flavonoid-rich food such as berries and red wine was likely to be associated with a lower risk of mortality.

An ethnopharmacological review on the therapeutical properties of flavonoids and their mechanisms of actions: A comprehensive review based on up to date knowledge

Flavonoids -a class of low molecular weight secondary metabolites- are ubiquitous and cornucopia throughout the plant kingdom. Structurally, the main structure consists of C6-C3-C6 rings with different substitution patterns so that many sub-classes are obtained, for example: flavonols, flavonolignans, flavonoid glycosides, flavans, anthocyanidins, aurones, anthocyanidins, flavones, neoflavonoids, chalcones, isoflavones, flavones and flavanones. Flavonoids are evaluated to have drug like nature since they possess different therapeutic activities, and can act as cardioprotective, antiviral, antidiabetic, anti-inflammatory, antibacterial, anticancer, and also work against Alzheimer's disease and others. However, information on the relationship between their structure and biological activity is scarce. Therefore, the present review tries to summarize all the therapeutic activities of flavonoids, their mechanisms of action and the structure activity relationship.

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Latest updated ethnopharmacological review of the therapeutic effects of flavonoids.

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Flavonoids are attracting attention because of their therapeutic properties.

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Flavonoids are valuable candidates for drug development against many dangerous diseases.

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This overview summarizes the most important therapeutic effect and mechanism of action of flavonoids.

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General knowledge about the structure activity relationship of flavonoids is summarized.

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Substitution of chemical groups in the structure of flavonoids can significantly change their biological and chemical properties.

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The chemical properties of the basic flavonoid structure should be considered in a drug-based structural program.

The Citrus Flavonoid Hesperetin Encounters Diabetes-Mediated Alzheimer-Type Neuropathologic Changes through Relieving Advanced Glycation End-Products Inducing Endoplasmic Reticulum Stress

The present study investigates whether hesperetin, a citrus flavonoid, can encounter advanced glycation end-product (AGE)-induced Alzheimer’s disease-like pathophysiological changes with the underlying mechanisms. SH-SY5Y cells pretreated with hesperetin before stimulation with AGEs (200 μg/mL) were assessed in the following experiments. Hesperetin (40 μmol/L) elevated the reduced cell viability induced by AGEs. Hesperetin ameliorated reactive oxygen species overproduction and the downregulation of superoxide dismutase, glutathione peroxidase, and catalase, triggered by AGEs. Amyloid precursor protein upregulation, accompanied by the increased production of Aβ, caused by AGEs, was reversed by hesperetin. However, hesperetin lowered β-site APP-cleaving enzyme 1 expression, inducing insulin-degrading and neprilysin expression. In addition, hesperetin downregulated the expressions of the AGEs-induced endoplasmic reticulum (ER) stress proteins, including 78-kDa glucose-regulated protein and C/EBP homologous protein, and lowered the phosphorylation of protein kinase R-like ER kinase and activating transcription factor 4. Hesperetin-pretreated cells had a minor apoptotic DNA fragmentation. Hesperetin is able to upregulate Bcl-2 protein expression, downregulate Bax expression, and decrease caspase-12/-9/-3 activity as well, indicating that it inhibits ER stress-mediated neuronal apoptosis. There is a similar effect between hesperetin and positive rosiglitazone control against Aβ aggravation of SH-SY5Y cell injury induced by AGEs. Thus, hesperetin might be a potential agent for treating glycation-induced Aβ neurotoxicity.

Phytochemicals as inhibitors of tumor necrosis factor alpha and neuroinflammatory responses in neurodegenerative diseases

Inflammatory processes and proinflammatory cytokines have a key role in the cellular processes of neurodegenerative diseases and are linked to the pathogenesis of functional and mental health disorders. Tumor necrosis factor alpha has been reported to play a major role in the central nervous system in Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis and many other neurodegenerative diseases. Therefore, a potent proinflammatory/proapoptotic tumor necrosis factor alpha could be a strong candidate for targeted therapy. Plant derivatives have now become promising candidates as therapeutic agents because of their antioxidant and chemical characteristics, and anti-inflammatory features. Recently, phytochemicals including flavonoids, terpenoids, alkaloids, and lignans have generated interest as tumor necrosis factor alpha inhibitor candidates for a number of diseases involving inflammation within the nervous system. In this review, we discuss how phytochemicals as tumor necrosis factor alpha inhibitors are a therapeutic strategy targeting neurodegeneration.

Ginsenoside F1 Protects the Brain against Amyloid Beta-Induced Toxicity by Regulating IDE and NEP

Ginsenoside F1, the metabolite of Rg1, is one of the most important constituents of Panax ginseng. Although the effects of ginsenosides on amyloid beta (Aβ) aggregation in the brain are known, the role of ginsenoside F1 remains unclear. Here, we investigated the protective effect of ginsenoside F1 against Aβ aggregation in vivo and in vitro. Treatment with 2.5 μM ginsenoside F1 reduced Aβ-induced cytotoxicity by decreasing Aβ aggregation in mouse neuroblastoma neuro-2a (N2a) and human neuroblastoma SH-SY5Y neuronal cell lines. Western blotting, real-time PCR, and siRNA analysis revealed an increased level of insulin-degrading enzyme (IDE) and neprilysin (NEP). Furthermore, liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis confirmed that ginsenoside F1 could pass the blood-brain barrier within 2 h after administration. Immunostaining results indicate that ginsenoside F1 reduces Aβ plaques in the hippocampus of APPswe/PSEN1dE9 (APP/PS1) double-transgenic Alzheimer's disease (AD) mice. Consistently, increased levels of IDE and NEP protein and mRNA were observed after the 8-week administration of 10 mg/kg/d ginsenoside F1. These data indicate that ginsenoside F1 is a promising therapeutic candidate for AD.