Quercetin up-regulates mitochondrial complex-I activity to protect against programmed cell death in rotenone model of Parkinson’s disease in rats

Neuroprotective potential of traditionally used medicinal plants of Manipur against rotenone-induced neurotoxicity in SH-SY5Y neuroblastoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Alternanthera sessilis (L.) R. Br. ex DC., Eryngium foetidum L., and Stephania japonica (Thunb.) Miers plants are traditionally used to treat various central nervous system disorders like paralysis, epilepsy, seizure, convulsion, chronic pain, headache, sleep disturbances, sprain, and mental disorders. However, their possible neuroprotective effects have not been evaluated experimentally so far.

AIM OF THE STUDY

The study aims to examine the neuroprotective potential of the three plants against cytotoxicity induced by rotenone in SH-SY5Y neuroblastoma cells and assess its plausible mechanisms of neuroprotection.

MATERIALS AND METHODS

The antioxidant properties of the plant extracts were determined chemically by DPPH and ABTS assay methods. The cytotoxicity of rotenone and the cytoprotective activities of the extracts were evaluated using MTT assays. Microtubule-associated protein 2 (MAP2) expression studies in cells were performed to assess neuronal survival after rotenone and extract treatments. Mitochondrial membrane potential and intracellular levels of reactive oxygen species were evaluated using Rhodamine 123 and DCF-DA dye, respectively. Catalase, glutathione peroxidase, and superoxide dismutase activities were also measured. Apoptotic nuclei were examined using DAPI staining. Liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS) analysis of the plant extracts was also performed.

RESULTS

The methanol extracts of A. sessilis, S. japonica, and E. foetidum showed excellent free radical scavenging activities. MAP2 expression studies show that A. sessilis and S. japonica have higher neuroprotective effects against rotenone-induced neurotoxicity in SH-SY5Y cells than E. foetidum. Pre-treating cells with the plant extracts reverses the rotenone-induced increase in intracellular ROS. The plant extracts could also restore the reduced mitochondrial membrane potential induced by rotenone treatment and reinstate rotenone-induced increases in catalase, glutathione peroxidase, and superoxide dismutase activities. All the extracts inhibited rotenone-induced changes in nuclear morphology and DNA condensation, an early event of cellular apoptosis. LC-QTOF-MS analysis of the plant extracts shows the presence of neuroprotective compounds.

CONCLUSIONS

The plant extracts showed neuroprotective activities against rotenone-treated SH-SY5Y cells through antioxidant and anti-apoptotic mechanisms. These findings support the ethnopharmacological uses of these plants in treating neurological disorders. They probably are a good source of neuroprotective compounds that could be further explored to develop treatment strategies for neurodegenerative diseases like Parkinson's disease.

Flavonoids as Potential Therapeutics Against Neurodegenerative Disorders: Unlocking the Prospects

Neurodegeneration, the decline of nerve cells in the brain, is a common feature of neurodegenerative disorders (NDDs). Oxidative stress, a key factor in NDDs such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease can lead to neuronal cell death, mitochondria impairment, excitotoxicity, and Ca2+ stress. Environmental factors compromising stress response lead to cell damage, necessitating novel therapeutics for preventing or treating brain disorders in older individuals and an aging population. Synthetic medications offer symptomatic benefits but can have adverse effects. This research explores the potential of flavonoids derived from plants in treating NDDs. Flavonoids compounds, have been studied for their potential to enter the brain and treat NDDs. These compounds have diverse biological effects and are currently being explored for their potential in the treatment of central nervous system disorders. Flavonoids have various beneficial effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic, and antioxidant properties. Their potential to alleviate symptoms of NDDs is significant.

Effects of quercetin in preclinical models of Parkinson's disease: A systematic review

Parkinson's disease (PD) is a neurodegenerative disease that affects dopaminergic neurons, thus impairing dopaminergic signalling. Quercetin (QUE) has antioxidant and neuroprotective properties that are promising for the treatment of PD. This systematic review aimed to investigate the therapeutic effects of QUE against PD in preclinical models. The systematic search was performed in PubMed, Scopus and Web of Science. At the final screening stage, 26 articles were selected according to pre-established criteria. Selected studies used different methods for PD induction, as well as animal models. Most studies used rats (73.08%) and mice (23.08%), with 6-OHDA as the main strategy for PD induction (38.6%), followed by rotenone (30.8%). QUE was tested immersed in oil, nanosystems or in free formulations, in varied routes of administration and doses, ranging from 10 to 400 mg/kg and from 5 to 200 mg/kg in oral and intraperitoneal administrations, respectively. Overall, evidence from published data suggests a potential use of QUE as a treatment for PD, mainly through the inhibition of oxidative stress, neuroinflammatory response and apoptotic pathways.

Combating Parkinson's disease with plant-derived polyphenols: Targeting oxidative stress and neuroinflammation

Parkinson's disease (PD) is a devastating neurodegenerative disorder predominantly affecting the elderly, characterized by the loss of dopaminergic neurons in the substantia nigra. Reactive oxygen species (ROS) generation plays a central role in the pathogenesis of PD and other neurodegenerative diseases. An imbalance between cellular antioxidant activity and ROS production leads to oxidative stress, contributing to disease progression. Dopamine metabolism, mitochondrial dysfunction, and neuroinflammation in dopaminergic neurons have been implicated in the pathogenesis of Parkinson's disease. Consequently, there is a pressing need for therapeutic interventions capable of scavenging ROS. Current pharmacological approaches, such as L-dihydroxyphenylalanine (levodopa or L-DOPA) and other drugs, provide symptomatic relief but are limited by severe side effects. Researchers worldwide have been exploring alternative compounds with less toxicity to address the multifaceted challenges associated with Parkinson's disease. In recent years, plant-derived polyphenolic compounds have gained significant attention as potential therapeutic agents. These compounds exhibit neuroprotective effects by targeting pathophysiological responses, including oxidative stress and neuroinflammation, in Parkinson's disease. The objective of this review is to summarize the current understanding of the neuroprotective effects of various polyphenols in Parkinson's disease, focusing on their antioxidant and anti-inflammatory properties, and to discuss their potential as therapeutic candidates. This review highlights the progress made in elucidating the molecular mechanisms of action of these polyphenols, identifying potential therapeutic targets, and optimizing their delivery and bioavailability. Well-designed clinical trials are necessary to establish the efficacy and safety of polyphenol-based interventions in the management of Parkinson's disease.

Epigenetic Orchestration of Neurodegenerative Disorders: A Possible Target for Curcumin as a Therapeutic

Epigenetic modulations play a major role in gene expression and thus are responsible for various physiological changes including age-associated neurological disorders. Neurodegenerative diseases such as Alzheimer's (AD), Parkinson's (PD), Huntington's disease (HD), although symptomatically different, may share common underlying mechanisms. Most neurodegenerative diseases are associated with increased oxidative stress, aggregation of certain proteins, mitochondrial dysfunction, inactivation/dysregulation of protein degradation machinery, DNA damage and cell excitotoxicity. Epigenetic modulations has been reported to play a significant role in onset and progression of neurodegenerative diseases by regulating these processes. Previous studies have highlighted the marked antioxidant and neuroprotective abilities of polyphenols such as curcumin, by increased activity of detoxification systems like superoxide dismutase (SOD), catalase or glutathione peroxidase. The role of curcumin as an epigenetic modulator in neurological disorders and neuroinflammation apart from other chronic diseases have also been reported by a few groups. Nonetheless, the evidences for the role of curcumin mediated epigenetic modulation in its neuroprotective ability are still limited. This review summarizes the current knowledge of the role of mitochondrial dysfunction, epigenetic modulations and mitoepigenetics in age-associated neurological disorders such as PD, AD, HD, Amyotrophic Lateral Sclerosis (ALS), and Multiple Sclerosis (MS), and describes the neuroprotective effects of curcumin in the treatment and/or prevention of these neurodegenerative diseases by regulation of the epigenetic machinery.

Fischer's oligopeptide ratio in ischemic hypoxia: prophylactic amendment of sophoretin and melatonin supplementation

Aim: The fundamental pathophysiology of ischemic-hypoxia is oxygen depletion. Fischer's ratio is essential for monitoring hypoxia intensity. Methods: the current study highlighted the prophylactic role of sophoretin (QRC) and/or melatonin (MLN) versus sodium nitrite (SN) brain hypoxia. Results: Prophylactic treatment with sophoretin and MLN, was preceded with hypoxia-induction via sodium nitrite (60 mg/kg, S.C.). SN decreased hemoglobin (Hb), elevated HIF-α, HSP-70, IL-6 and TNF-α. Sophoretin and/or MLN restored the ameliorated inflammatory biomarkers, modulated norepinephrine, dopamine, serotonin and gamma-aminobutyric acid (GABA). Similarly, single-cell gel electrophoresis (SCGE or COMET) DNA damage assay confirmed this finding. Conclusion: Treatment via sophoretin and MLN was the most effective therapy for improving sodium nitrite-induced brain injury.

Quercetin's Restorative Properties in Male Mice with 3-Nitropropionic Acid-induced Huntington-like Symptoms: Molecular Docking, Behavioral, and Biochemical Assessment

The neurotoxicity of 3-Nitropropionic acid (3-NP) is well known. Herein, the prophylactic versus therapeutic effects of quercetin (QCT) were investigated against 3-NP-induced behavioral anomalies and oxidative neural damage. Thirty male mice were assigned into five groups; the negative control group, the QCT group (25 mg/kg/day, p.o. for 21 days), the 3-NP group (17 days), the prophylactic group (QCT administration for 14 consecutive days, and then 3-NP was administrated), the therapeutic group (3-NP was administrated and then QCT for 21 days). At the end of the animal treatment, behavioral studies were assessed. Subsequently, the brain sample tissues were assessed for oxidative stress-related parameters and histological evaluation. Moreover, the potential interaction between 3-NP and tumor necrosis factor-alpha (TNF-α) was evaluated by using a molecular docking study. 3-NP markedly led to neurotoxicity which was indicated by behavioral deficits (motor behavior, depression-like behavior, memory dysfunction, and passive avoidance) and oxidative damage. Blind and targeted molecular docking results showed good interaction between 3-NP and TNF-α. However, the prophylactic effects of QCT were superior to the therapeutic effects for attenuating 3-NP-induced neurobehavioral and oxidative neural changes in experimental mice, which histological changes of the brain's striatum region approved our findings. Taken together, the antioxidant activity of QCT remarkably could attenuate 3-NP-induced neurobehavioral deficits and mitochondrial dysfunctions in mice.

Oxidative Stress and Neurodegeneration: Insights and Therapeutic Strategies for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative condition marked by the gradual deterioration of dopaminergic neurons in the substantia nigra. Oxidative stress has been identified as a key player in the development of PD in recent studies. In the first part, we discuss the sources of oxidative stress in PD, including mitochondrial dysfunction, dopamine metabolism, and neuroinflammation. This paper delves into the possibility of mitigating oxidative stress as a potential treatment approach for PD. In addition, we examine the hurdles and potential of antioxidant therapy, including the challenge of delivering antioxidants to the brain and the requirement for biomarkers to track oxidative stress in PD patients. However, even if antioxidant therapy holds promise, further investigation is needed to determine its efficacy and safety in PD treatment.

Antioxidant responses driven by Hesperetin and Hesperidin counteract Parkinson's disease-like phenotypes in Drosophila melanogaster

The study investigated the protective effects of Hesperetin (HSP) and Hesperidin (HSD) on 1 methyl, 4 phenyl, 1,2,3,6 tetrahydropyridine hydrochloride (MPTP)-induced Parkinsonism in Drosophila melanogaster (D. melanogaster). After a lifespan study to select exposure time and concentrations, flies were co-exposed to MPTP (0.4 mg/g diet), Hesperetin (0.2 and 0.4 mg/g diet), and Hesperidin (0.1 and 0.4 mg/g) for 7 days. In addition to in vivo parameters, we assayed some markers of oxidative stress and antioxidant status (lipid peroxidation, protein carbonylation, thiol content, hydrogen peroxide, and nitrate/nitrite levels, mRNA expression of Keap-1 (Kelch-like ECH associated protein 1), /Nrf2 (Nuclear factor erythroid 2 related factor 2), catalase, and glutathione-S-transferase (GST) activities), and cholinergic (acetyl cholinesterase activity (AChE) and dopaminergic signaling content and the mRNA expression of tyrosine hydroxylase (TH), monoamine oxidase (MAO-like) activity). In addition to increasing the lifespan of flies, we found that both flavonoids counteracted the adverse effects of MPTP on survival, offspring emergence, and climbing ability of flies. Both flavonoids also reduced the oxidative damage on lipids and proteins and reestablished the basal levels of pro-oxidant species and activities of antioxidant enzymes in MPTP-exposed flies. These responses were accompanied by the normalization of the mRNA expression of Keap1/Nrf2 disrupted in flies exposed to MPTP. MPTP exposure also elicited changes in mRNA expression and content of TH as well as in MAO and AChE activity, which were reversed by HST and HSD. By efficiently hindering the oxidative stress in MPTP-exposed flies, our findings support the promising role of Hesperetin and Hesperidin as adjuvant therapy to manage Parkinsonism induced by chemicals such as MPTP.

Pharmacological Targeting of Senescence with Senolytics as a New Therapeutic Strategy for Neurodegeneration

Cellular senescence is a state of permanent cell-cycle arrest. Early in life, senescence has a physiologic role in tumor suppression and wound healing. However, gradually, as these senescent cells accumulate over the lifespan of an organism, they contribute to inflammation and the progression of age-related diseases, including neurodegeneration. Targeting senescent cells using a class of drugs known as "senolytics" holds great promise for the management of Alzheimer's and Parkinson's disease. Already, several senolytic compounds have been shown to ameliorate cognitive deficits across several preclinical models of neurodegeneration. Most of these senolytics (e.g., dasatinib) are repurposed clinical or experimental anticancer drugs, which trigger apoptosis of senescent cells by interfering with pro-survival pathways. However, outside of their senolytic function, many first-generation senolytics also have other less appreciated neuroprotective effects, such as potent antioxidant and anti-inflammatory activity. In addition, some senolytic drugs may also have negative dose-limiting toxicities, including thrombocytopenia. In this review, we discuss the various biologic pathways targeted by the leading senolytic drugs, namely dasatinib, quercetin, fisetin, and navitoclax. We further evaluate the clinical transability of these compounds for neurodegeneration, assessing their adverse effects, pharmacokinetic properties, and chemical structure. SIGNIFICANCE STATEMENT: Currently, there are no effective disease-modifying treatments for the most prevalent neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Some of the drugs currently available for treating these diseases are associated with unwanted side-effects and/or become less efficacious with time. Therefore, researchers have begun to explore new innovative treatments for these belligerent diseases, including senolytic drugs. These agents lead to the apoptosis of senescent cells thereby preventing their deleterious role in neurodegeneration.

Polyherbal and Multimodal Treatments: Kaempferol- and Quercetin-Rich Herbs Alleviate Symptoms of Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder impairing cognition and memory in the elderly. This disorder has a complex etiology, including senile plaque and neurofibrillary tangle formation, neuroinflammation, oxidative stress, and damaged neuroplasticity. Current treatment options are limited, so alternative treatments such as herbal medicine could suppress symptoms while slowing cognitive decline. We followed PRISMA guidelines to identify potential herbal treatments, their associated medicinal phytochemicals, and the potential mechanisms of these treatments. Common herbs, including Ginkgo biloba, Camellia sinensis, Glycyrrhiza uralensis, Cyperus rotundus, and Buplerum falcatum, produced promising pre-clinical results. These herbs are rich in kaempferol and quercetin, flavonoids with a polyphenolic structure that facilitate multiple mechanisms of action. These mechanisms include the inhibition of Aβ plaque formation, a reduction in tau hyperphosphorylation, the suppression of oxidative stress, and the modulation of BDNF and PI3K/AKT pathways. Using pre-clinical findings from quercetin research and the comparatively limited data on kaempferol, we proposed that kaempferol ameliorates the neuroinflammatory state, maintains proper cellular function, and restores pro-neuroplastic signaling. In this review, we discuss the anti-AD mechanisms of quercetin and kaempferol and their limitations, and we suggest a potential alternative treatment for AD. Our findings lead us to conclude that a polyherbal kaempferol- and quercetin-rich cocktail could treat AD-related brain damage.

Antiplatelet drugs: Potential therapeutic options for the management of neurodegenerative diseases

The blood platelet plays an important role but often remains under-recognized in several vascular complications and associated diseases. Surprisingly, platelet hyperactivity and hyperaggregability have often been considered the critical risk factors for developing vascular dysfunctions in several neurodegenerative diseases (NDDs) like Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. In addition, platelet structural and functional impairments promote prothrombotic and proinflammatory environment that can aggravate the progression of several NDDs. These findings provide the rationale for using antiplatelet agents not only to prevent morbidity but also to reduce mortality caused by NDDs. Therefore, we thoroughly review the evidence supporting the potential pleiotropic effects of several novel classes of synthetic antiplatelet drugs, that is, cyclooxygenase inhibitors, adenosine diphosphate receptor antagonists, protease-activated receptor blockers, and glycoprotein IIb/IIIa receptor inhibitors in NDDs. Apart from this, the review also emphasizes the recent developments of selected natural antiplatelet phytochemicals belonging to key classes of plant-based bioactive compounds, including polyphenols, alkaloids, terpenoids, and flavonoids as potential therapeutic candidates in NDDs. We believe that the broad analysis of contemporary strategies and specific approaches for plausible therapeutic treatment for NDDs presented in this review could be helpful for further successful research in this area.

Bioactive strawberry fruit (Arbutus unedo L.) extract remedies paraquat-induced neurotoxicity in the offspring prenatally exposed rats

Background

Paraquat (1,1'-dimethyl-4-4'-bipyridinium dichloride) exposure is well-established as a neurotoxic agent capable of causing neurological deficits in offspring. This study aimed to investigate therapeutic effects of Arbutus unedo L. aqueous extract (AU) against paraquat (PQ) exposure.

Methods

For that the phytoconstituents of AU was determined by LC/MS, and then its antioxidant potential was assessed by DPPH and ABTS assays. The assessment included its impact on cell viability and mitochondrial metabolism using N27 dopaminergic cells. Additionally, we evaluated the effects of prenatal PQ exposure on motor coordination, dopamine levels, trace element levels, and total antioxidant capacity (TAC) in rat progeny.

Results

The phytochemical profile of AU extract revealed the presence of 35 compounds, primarily phenolic and organic acids, and flavonoids. This accounted for its strong in vitro antioxidant activities against DPPH and ABTS radicals, surpassing the activities of vitamin C. Our findings demonstrated that AU effectively inhibited PQ-induced loss of N27 rat dopaminergic neural cells and significantly enhanced their mitochondrial respiration. Furthermore, daily post-treatment with AU during the 21 days of the rat's pregnancy alleviated PQ-induced motor deficits and akinesia in rat progeny. These effects inhibited dopamine depletion and reduced iron levels in the striatal tissues. The observed outcomes appeared to be mediated by the robust antioxidant activity of AU, effectively counteracting the PQ-induced decrease in TAC in the blood plasma of rat progeny. These effects could be attributed to the bioactive compounds present in AU, including phenolic acids such as gallic acid and flavonoids such as quercetin, rutin, apigenin, glucuronide, and kaempferol, all known for their potent antioxidant capacity.

Discussion

In conclusion, this preclinical study provided the first evidence of the therapeutic potential of AU extract against PQ-induced neurotoxicity. These findings emphasize the need for further exploration of the clinical applicability of AU in mitigating neurotoxin-induced brain damage.

Unravelling the Molecular Mechanisms of a Quercetin Nanocrystal for Treating Potential Parkinson's Disease in a Rotenone Model: Supporting Evidence of Network Pharmacology and In Silico Data Analysis

The prevalence of Parkinson's disease places a significant burden on society; therefore, there is an urgent need to develop more effective drugs. However, the development of these drugs is both expensive and risky. Quercetin (QUE) has potent pharmacological effects on neurodegenerative diseases, but its low solubility in water and poor bioavailability limit its use in pharmaceutical applications. In this study, Quercetin nanocrystals (QNC) were synthesized and compared to standard QUE. A network-pharmacology-based methodology was applied, including target prediction, network construction, a gene ontology (GO) analysis, a KEGG pathway enrichment analysis, and molecular docking. This study aimed to identify the targets of QUE relevant to the treatment of Parkinson's disease and investigate the associated pharmacological mechanisms. Most of the predicted targets are involved in dopamine uptake during synaptic transmission. QUE regulates the key targets DRD2 and DRD4, which significantly affect dopaminergic synapses. The molecular docking results showed that QUE had a better binding affinity than the standard drug l-Dopa. From these experiments, it can be concluded that QNC effectively reduced the adverse effects caused by rotenone-induced oxidative stress in biochemical, neurochemical, and histopathological alterations. Therefore, QNC can potentially treat Parkinson's disease, and its effectiveness should be assessed in future clinical trials.

Oxidative stress, the blood-brain barrier and neurodegenerative diseases: The critical beneficial role of dietary antioxidants

In recent years, growing awareness of the role of oxidative stress in brain health has prompted antioxidants, especially dietary antioxidants, to receive growing attention as possible treatments strategies for patients with neurodegenerative diseases (NDs). The most widely studied dietary antioxidants include active substances such as vitamins, carotenoids, flavonoids and polyphenols. Dietary antioxidants are found in usually consumed foods such as fresh fruits, vegetables, nuts and oils and are gaining popularity due to recently growing awareness of their potential for preventive and protective agents against NDs, as well as their abundant natural sources, generally non-toxic nature, and ease of long-term consumption. This review article examines the role of oxidative stress in the development of NDs, explores the 'two-sidedness' of the blood-brain barrier (BBB) as a protective barrier to the nervous system and an impeding barrier to the use of antioxidants as drug medicinal products and/or dietary antioxidants supplements for prevention and therapy and reviews the BBB permeability of common dietary antioxidant suplements and their potential efficacy in the prevention and treatment of NDs. Finally, current challenges and future directions for the prevention and treatment of NDs using dietary antioxidants are discussed, and useful information on the prevention and treatment of NDs is provided.

The multifaceted role of quercetin derived from its mitochondrial mechanism

Quercetin is a flavonoid with promising therapeutic applications; nonetheless, the phenotype exerted in some diseases is contradictory. For instance, anticancer properties may be explained by a cytotoxic mechanism, whereas antioxidant-related neuroprotection is a pro-survival process. According to the available literature, quercetin exerts a redox interaction with the electron transport chain (ETC) in the mitochondrion, affecting its membrane potential. It also affects ATP generation by oxidative phosphorylation, where ATP deprivation could partly explain its cytotoxic effect. Moreover, quercetin may support the generation of free radicals through redox reactions, causing a prooxidant effect. The nutrimental stress and prooxidant effect induced by quercetin might promote pro-survival properties such as antioxidant processes. Thus, in this review, we discuss the evidence supporting that quercetin redox interaction with the ETC could explain its beneficial and toxic properties.

Behavioral and biochemical investigations to explore the efficacy of quercetin and folacin in experimental diabetes induced vascular endothelium dysfunction and associated dementia in rats

OBJECTIVES

Vascular dementia (VaD), being strongly associated with metabolic conditions is a major health concern around the world. Diabetes is a major risk factor for the development of VaD. This study investigates the efficacy of quercetin and folacin in diabetes induced vascular endothelium dysfunction and related dementia.

METHODS

Single dose streptozotocin (STZ) (50 mg/kg i.p) was administered to albino Wistar rats (male, 200-250 g) by dissolving in citrate buffer. Morris water maze (MWM) and attentional set shifting tests were used to assess the spatial learning, memory, reversal learning, and executive functioning in animals. Body weight, serum glucose, serum nitrite/nitrate, vascular endothelial function, aortic superoxide anion, brains' oxidative markers (thiobarbituric acid reactive species-TBARS, reduced glutathione-GSH, superoxide dismutase-SOD, and catalase-CAT), mitochondrial enzyme complex (I, II, and IV), inflammatory markers (interleukin-IL-6, IL-10, tumor necrosis factor-TNF-α, and myeloperoxidase-MPO), and acetylcholinesterase activity-AChE were also assessed. Quercetin (30 mg kg-1/60 mg kg-1) and folacin (30 mg kg-1/60 mg kg-1) were used as the treatment drugs. Donepezil (0.5 mg kg-1) was used as a positive control.

RESULTS

STZ administered rats showed reduction in learning, memory, reversal learning, executive functioning, impairment in endothelial function, increase in brains' oxidative stress; inflammation; AChE activity, and decrease in mitochondrial complex (I, II, and IV) activity. Administration of quercetin and folacin in two different doses, significantly attenuated the STZ induced diabetes induced impairments in the behavioral, endothelial, and biochemical parameters.

CONCLUSIONS

STZ administration caused diabetes and VaD which was attenuated by the administration of quercetin and folacin. Therefore, these agents may be studied further for the assessment of their full potential in diabetes induced VaD conditions.

Combating Dopaminergic Neurodegeneration in Parkinson's Disease through Nanovesicle Technology

Parkinson's disease (PD) is characterized by dopaminergic neurodegeneration, resulting in dopamine depletion and motor behavior deficits. Since the discovery of L-DOPA, it has been the most prescribed drug for symptomatic relief in PD, whose prolonged use, however, causes undesirable motor fluctuations like dyskinesia and dystonia. Further, therapeutics targeting the pathological hallmarks of PD including α-synuclein aggregation, oxidative stress, neuroinflammation, and autophagy impairment have also been developed, yet PD treatment is a largely unmet success. The inception of the nanovesicle-based drug delivery approach over the past few decades brings add-on advantages to the therapeutic strategies for PD treatment in which nanovesicles (basically phospholipid-containing artificial structures) are used to load and deliver drugs to the target site of the body. The present review narrates the characteristic features of nanovesicles including their blood-brain barrier permeability and ability to reach dopaminergic neurons of the brain and finally discusses the current status of this technology in the treatment of PD. From the review, it becomes evident that with the assistance of nanovesicle technology, the therapeutic efficacy of anti-PD pharmaceuticals, phyto-compounds, as well as that of nucleic acids targeting α-synuclein aggregation gained a significant increment. Furthermore, owing to the multiple drug-carrying abilities of nanovesicles, combination therapy targeting multiple pathogenic events of PD has also found success in preclinical studies and will plausibly lead to effective treatment strategies in the near future.

Polyphenols and Their Impact on the Prevention of Neurodegenerative Diseases and Development

It is well known that neurodegenerative diseases' development and progression are accelerated due to oxidative stress and inflammation, which result in impairment of mitochondrial function, cellular damage, and dysfunction of DNA repair systems. The increased consumption of antioxidants can postpone the development of these disorders and improve the quality of patients' lives who have already been diagnosed with neurodegenerative diseases. Prolonging life span in developed countries contributes to an increase in the incidence ratio of chronic age-related neurodegenerative disorders, such as PD (Parkinson's disease), AD (Alzheimer's disease), or numerous forms of age-related dementias. Dietary supplementation with neuroprotective plant-derived polyphenols might be considered an important element of healthy aging. Some polyphenols improve cognition, mood, visual functions, language, and verbal memory functions. Polyphenols bioavailability differs greatly from one compound to another and is determined by solubility, degree of polymerization, conjugation, or glycosylation resulting from chemical structure. It is still unclear which polyphenols are beneficial because their potential depends on efficient transport across the BBB (blood-brain barrier), bioavailability, and stability in the CNS (central nervous system). Polyphenols improve brain functions by having a direct impact on cells and processes in the CNS. For a direct effect, polyphenolic compounds must be able to overcome the BBB and accumulate in brain tissue. In this review, the latest achievements in studies (animal models and clinical trials) on the effect of polyphenols on brain activity and function are described. The beneficial impact of plant polyphenols on the brain may be summarized by their role in increasing brain plasticity and related cognition improvement. As reversible MAO (monoamine oxidase) inhibitors, polyphenols are mood modulators and improve neuronal self-being through an increase in dopamine, serotonin, and noradrenaline amounts in the brain tissue. After analyzing the prohealth effects of various eating patterns, it was postulated that their beneficial effects result from synergistic interactions between individual dietary components. Polyphenols act on the brain endothelial cells and improve the BBB's integrity and reduce inflammation, thus protecting the brain from additional injury during stroke or autoimmune diseases. Polyphenolic compounds are capable of lowering blood pressure and improving cerebral blood flow. Many studies have revealed that a nutritional model based on increased consumption of antioxidants has the potential to ameliorate the cognitive impairment associated with neurodegenerative disorders. Randomized clinical trials have also shown that the improvement of cognitive functions resulting from the consumption of foods rich in flavonoids is independent of age and health conditions. For therapeutic use, sufficient quantities of polyphenols must cross the BBB and reach the brain tissue in active form. An important issue in the direct action of polyphenols on the CNS is not only their penetration through the BBB, but also their brain metabolism and localization. The bioavailability of polyphenols is low. The most usual oral administration also conflicts with bioavailability. The main factors that limit this process and have an effect on therapeutic efficacy are: selective permeability across BBB, gastrointestinal transformations, poor absorption, rapid hepatic and colonic metabolism, and systemic elimination. Thus, phenolic compounds have inadequate bioavailability for human applications to have any beneficial effects. In recent years, new strategies have been attempted in order to exert cognitive benefits and neuroprotective effects. Converting polyphenols into nanostructures is one of the theories proposed to enhance their bioavailability. The following nanoscale delivery systems can be used to encapsulate polyphenols: nanocapsules, nanospheres, micelles, cyclodextrins, solid lipid nanoparticles, and liposomes. It results in great expectations for the wide-scale and effective use of polyphenols in the prevention of neurodegenerative diseases. Thus far, only natural polyphenols have been studied as neuroprotectors. Perhaps some modification of the chemical structure of a given polyphenol may increase its neuroprotective activity and transportation through the BBB. However, numerous questions should be answered before developing neuroprotective medications based on plant polyphenols.

Analysis of bioactive compounds in cinnamon leaves and preparation of nanoemulsion and byproducts for improving Parkinson's disease in rats

Introduction

Cinnamomum osmophloeum Kanehira (C. osmophloeum), a broad-leaved tree species of Taiwan, contains phenolic acids, flavonoids, and phenylpropanoids such as cinnamaldehyde and cinnamic acid in leaves. Many reports have shown that the cinnamon leaf extract possesses anti-inflammatory, hypoglycemic, hypolipidemic and neuroprotective functions. This study aims to analyze bioactive compounds in C. osmophloeum (cinnamon leaves) by UPLC-MS/MS and prepare hydrosol, cinnamon leaf extract and cinnamon leaf nanoemulsion for comparison in improving Parkinson's disease (PD) in rats.

Methods

After extraction and determination of total phenolic and total flavonoid contents, cinnamaldehyde and the other bioactive compounds were analyzed in cinnamon leaves and hydrosol by UPLC-MS/MS. Cinnamon leaf nanoemulsion was prepared by mixing a suitable proportion of cinnamon leaf extract, soybean oil, lecithin, Tween 80 and deionized water, followed by characterization of particle size and polydispersity index by dynamic light scattering analyzer, particle size and shape by transmission electron microscope, encapsulation efficiency, as well as storage and heating stability. Fifty-six male Sprague-Dawley rats aged 8 weeks were divided into seven groups with group 1 as control (sunflower oil) and group 2 as induction (2 mg/kg bw rotenone in sunflower oil plus 10 mL/kg bw saline), while the other groups including rotenone injection (2 mg/kg bw) followed by high-dose of 60 mg/kg bw (group 3) or low-dose of 20 mg/kg bw (group 4) for tube feeding of cinnamon leaf extract or cinnamon leaf nanoemulsion at the same doses (groups 5 and 6) every day for 5 weeks as well as group 7 with rotenone plus hydrosol containing 0.5 g cinnamon leaf powder at a dose of 10 mL/kg bw. Biochemical analysis of brain tissue (striatum and midbrain) was done to determine dopamine, α-synuclein, tyrosine hydroxylase, superoxide dismutase, catalase, glutathione peroxidase and malondialdehyde contents by using commercial kits, while catalepsy performed by bar test.

Results and discussion

An extraction solvent of 80% ethanol was found to be the most optimal with a high yield of 15 bioactive compounds being obtained following UPLC analysis. A triple quadrupole tandem mass spectrometer with electrospray ionization mode was used for identification and quantitation, with cinnamaldehyde present at the highest amount (17985.2 µg/g). The cinnamon leaf nanoemulsion was successfully prepared with the mean particle size, zeta potential, polydispersity index and encapsulation efficiency being 30.1 nm, -43.1 mV, 0.149 and 91.6%, respectively. A high stability of cinnamon leaf nanoemulsion was shown over a 90-day storage period at 4 and heating at 100 for 2 h. Animal experiments revealed that the treatments of cinnamon leaf extract, nanoemulsion and hydrosol increased the dopamine contents from 17.08% to 49.39% and tyrosine hydroxylase levels from 17.07% to 25.59%, while reduced the α-synuclein levels from 17.56% to 15.95% in the striatum of rats. Additionally, in the midbrain of rats, an elevation of activities of superoxide dismutase (6.69-16.82%), catalase (8.56-16.94%), and glutathione peroxidase (2.09-16.94%) was shown, while the malondialdehyde content declined by 15.47-22.47%. Comparatively, the high-dose nanoemulsion exerted the most pronounced effect in improving PD in rats and may be a promising candidate for the development of health food or botanic drug.

Exploitation of Quercetin's Antioxidative Properties in Potential Alternative Therapeutic Options for Neurodegenerative Diseases

Oxidative stress (OS) is a condition in which there is an excess of reactive oxygen species (ROS) in the body, which can lead to cell and tissue damage. This occurs when there is an overproduction of ROS or when the body's antioxidant defense systems are overwhelmed. Quercetin (Que) is part of a group of compounds called flavonoids. It is found in high concentrations in vegetables, fruits, and other foods. Over the past decade, a growing number of studies have highlighted the therapeutic potential of flavonoids to modulate neuronal function and prevent age-related neurodegeneration. Therefore, Que has been shown to have antioxidant, anticancer, and anti-inflammatory properties, both in vitro and in vivo. Due to its antioxidant character, Que alleviates oxidative stress, thus improving cognitive function, reducing the risk of neurodegenerative diseases. On the other hand, Que can also help support the body's natural antioxidant defense systems, thus being a potentially practical supplement for managing OS. This review focuses on experimental studies supporting the neuroprotective effects of Que in Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and epilepsy.

A critical analysis on the concentrations of phenolic compounds tested using in vitro and in vivo Parkinson's disease models

Phenolic compounds (PCs) have neuroprotective effects with potential to prevent or slower the progression of Parkinson's disease (PD). However, whether the PCs neuroprotective effects can be observed under their dietary concentrations remains unclear. Therefore, we searched for the most cited articles in density on PCs and PD in the Web of Science Core Collection and All-Database (WoS-CC/AD) and selected the articles based on our eligibility criteria. From these 81 articles selected, we extracted information on experimental design, compounds tested, concentration and/or dose administered, route of administration, and main results obtained. We compared the concentrations of PCs evaluated in vitro with the concentrations bioavailable in the human bloodstream. Further, after extrapolation to humans, we compared the doses administered to animals in vivo with the daily consumed amounts of PCs. Concentrations evaluated in 21 in vitro laboratory studies were higher than those bioavailable in the bloodstream. In the case of in vivo laboratory studies, only one study administered doses of PCs in normal daily amount. The results of the comparisons demonstrate that the neuroprotective effects of the selected articles are mainly associated with concentrations, amounts and routes of administration that do not correspond to the consumption of phenolic compounds through the diet.

A transcriptome based approach to predict candidate drug targets and drugs for Parkinson's disease using an in vitro 6-OHDA model

The most common treatment strategies for Parkinson's disease (PD) aim to slow down the neurodegeneration process or control the symptoms. In this study, using an in vitro PD model we carried out a transcriptome-based drug target prediction strategy. We identified novel drug target candidates by mapping genes upregulated in 6-OHDA-treated cells on a human protein-protein interaction network. Among the predicted targets, we show that AKR1C3 and CEBPB are promising in validating our bioinformatics approach since their known ligands, rutin and quercetin, respectively, act as neuroprotective drugs that effectively decrease cell death, and restore the expression profiles of key genes upregulated in 6-OHDA-treated cells. We also show that these two genes upregulated in our in vitro PD model are downregulated to basal levels upon drug administration. As a further validation of our methodology, we further confirm that the potential target genes identified with our bioinformatics approach are also upregulated in post-mortem transcriptome samples of PD patients from the literature. Therefore, we propose that this methodology predicts novel drug targets AKR1C3 and CEBPB, which are relevant to future clinical applications as potential drug repurposing targets for PD. Our systems-based computational approach to predict candidate drug targets can be employed in identifying novel drug targets in other diseases without a priori assumption.

Neuropharmacological interventions of quercetin and its derivatives in neurological and psychological disorders

Quercetin is a naturally occurring bioactive flavonoid abundant in many plants and fruits. Quercetin and its derivatives have shown an array of pharmacological activities in preclinical tests against various illnesses and ailments. Owing to its protective role against oxidative stress and neuroinflammation, quercetin is a possible therapeutic choice for the treatment of neurological disorders. Quercetin and its derivatives can modulate a variety of signal transductions, including neuroreceptor, neuroinflammatory receptor, and redox signaling events. The research on quercetin and its derivatives in neurology-related illnesses mainly focused on the targets, such as redox stress, neuroinflammation, and signaling pathways; however, the function of quercetin and its derivatives on specific molecular targets, such as nuclear receptors and proinflammatory mediators are yet to be explored. Findings showed that various molecular targets of quercetin and its derivatives have therapeutic potential against psychological and neurodegenerative disorders.

Analysis of phenolic compounds in Parkinson's disease: a bibliometric assessment of the 100 most cited papers

Objective

The aim of this study was to identify and characterize the 100 most cited articles on Parkinson's disease (PD) and phenolic compounds (PCs).

Methods

Articles were selected in the Web of Science Core Collection up to June 2022 based on predetermined inclusion criteria, and the following bibliometric parameters were extracted: the number of citations, title, keywords, authors, year, study design, tested PC and therapeutic target. MapChart was used to create worldwide networks, and VOSviewer software was used to create bibliometric networks. Descriptive statistical analysis was used to identify the most researched PCs and therapeutic targets in PD.

Results

The most cited article was also the oldest. The most recent article was published in 2020. Asia and China were the continent and the country with the most articles in the list (55 and 29%, respectively). In vitro studies were the most common experimental designs among the 100 most cited articles (46%). The most evaluated PC was epigallocatechin. Oxidative stress was the most studied therapeutic target.

Conclusion

Despite the demonstrations in laboratorial studies, the results obtained point to the need for clinical studies to better elucidate this association.

Protective Effects of Currants (Vitis vinifera) on Corticolimbic Serotoninergic Alterations and Anxiety-like Comorbidity in a Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of nigral dopaminergic neurons. Increasing evidence supports that PD is not simply a motor disorder but a systemic disease leading to motor and non-motor symptoms, including memory loss and neuropsychiatric conditions, with poor management of the non-motor deficits by the existing dopaminergic medication. Oxidative stress is considered a contributing factor for nigrostriatal degeneration, while antioxidant/anti-inflammatory properties of natural phyto-polyphenols have been suggested to have beneficial effects. The present study aimed to determine the contribution of monoaminergic neurotransmission on the anxiety-like phenotype in a rat rotenone PD model and evaluate the possible neuroprotective effects of black Corinthian currant, Vitis vinifera, consisting of antioxidant polyphenols. Rotenone-treated rats showed anxiety-like behavior and exploratory deficits, accompanied by changes in 5-HT, SERT and β₂-ARs expression in the prefrontal cortices, hippocampus and basolateral amygdala. Importantly, the motor and non-motor behavior, as well as 5-HT, SERT and β₂-ARs expression patterns of the PD-like phenotype were partially recovered by a supplementary diet with currants. Overall, our results suggest that the neuroprotective effects of Corinthian currants in rotenone-induced anxiety-like behavior may be mediated via corticolimbic serotonergic transmission.

New Insights into the Gut Microbiota in Neurodegenerative Diseases from the Perspective of Redox Homeostasis

An imbalance between oxidants and antioxidants in the body can lead to oxidative stress, which is one of the major causes of neurodegenerative diseases. The gut microbiota contains trillions of beneficial bacteria that play an important role in maintaining redox homeostasis. In the last decade, the microbiota-gut-brain axis has emerged as a new field that has revolutionized the study of the pathology, diagnosis, and treatment of neurodegenerative diseases. Indeed, a growing number of studies have found that communication between the brain and the gut microbiota can be accomplished through the endocrine, immune, and nervous systems. Importantly, dysregulation of the gut microbiota has been strongly associated with the development of oxidative stress-mediated neurodegenerative diseases. Therefore, a deeper understanding of the relationship between the gut microbiota and redox homeostasis will help explain the pathogenesis of neurodegenerative diseases from a new perspective and provide a theoretical basis for proposing new therapeutic strategies for neurodegenerative diseases. In this review, we will describe the role of oxidative stress and the gut microbiota in neurodegenerative diseases and the underlying mechanisms by which the gut microbiota affects redox homeostasis in the brain, leading to neurodegenerative diseases. In addition, we will discuss the potential applications of maintaining redox homeostasis by modulating the gut microbiota to treat neurodegenerative diseases, which could open the door for new therapeutic approaches to combat neurodegenerative diseases.

Plant based food bioactives: A boon or bane for neurological disorders

Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.

Europinidin Inhibits Rotenone-Activated Parkinson's Disease in Rodents by Decreasing Lipid Peroxidation and Inflammatory Cytokines Pathways

Background: Europinidin is a derivative of delphinidin obtained from the plants Plumbago Europea and Ceratostigma plumbaginoides. This herb has wide medicinal applications in treating various diseases but there are very few studies available on this bioactive compound. Considering this background, the present study is designed for the evaluation of Europinidin against Parkinson’s disease. Aim: The investigation aims to assess the effect of Europinidin in the rotenone-activated Parkinson’s paradigm. Methods: To evaluate neuroprotective activity, rotenone (1.5 mg/kg s.c) and europinidin (10 mg/kg and 20 mg/kg) was administered in rats for 21 days. The behavioural parameters were performed before sacrificing the rats. On the 22nd day, all the rats were assessed for biochemical markers (SOD, GSH, MDA, Catalase), neurotransmitter levels (Dopamine, 5-HIAA, DOPAC, and HVA levels), and neuroinflammatory markers (IL-6, IL-1β and TNF-α). Results: It was found that rotenone produced significant (p < 0.001) oxidative damage, a cholinergic deficit, dopaminergic loss, and a rise in neuroinflammatory markers in rats. Conclusion: The study concludes that europinidin possesses anti-oxidant and anti-inflammatory properties. The results suggest the therapeutic role of europinidin against rotenone-activated behavioural, biochemical, and neuroinflammatory alterations in rats.

Hypericum Genus as a Natural Source for Biologically Active Compounds

Hypericum L. genus plants are distributed worldwide, with numerous species identified throughout all continents, except Antarctica. These plant species are currently used in various systems of traditional medicine to treat mild depression, wounds and burns, diarrhea, pain, fevers, and their secondary metabolites previously shown, and the in vitro and/or in vivo cytotoxic, antimicrobial, anti-inflammatory, antioxidant, antihyperglycemic, and hepatoprotective activities, as well as the acetylcholinesterase and monoamine oxidase inhibitory activities. We conducted a systematic bibliographic search according to the Cochrane Collaboration guidelines to answer the question: "What is known about plants of Hypericum genus as a source of natural products with potential clinical biological activity?" We documented 414 different natural products with confirmed in vitro/in vivo biological activities, and 58 different Hypericum plant species as sources for these natural products. Phloroglucinols, acylphloroglucinols, xanthones, and benzophenones were the main chemical classes identified. The selective cytotoxicity against tumor cells, cell protection, anti-inflammatory, antimicrobial, antidepressant, anti-Alzheimer's, and adipogenesis-inhibition biological activities are described. Acylphloroglucinols were the most frequent compounds with anticancer and cell-protection mechanisms. To date, no work has been published with a full descriptive list directly relating secondary metabolites to their species of origin, plant parts used, extraction methodologies, mechanisms of action, and biological activities.

Molecular understanding of the translational models and the therapeutic potential natural products of Parkinson's disease

Parkinson's disease is the second most prevalent neurodegenerative disease after Alzheimer's disease, mostly happened in the elder population and the prevalence gradually increased with age. Parkinson's disease is a movement disorder that severely affects patients' daily life. The mechanism of Parkinson's disease still remains unknown, however, studies already proved that the damage or absence of dopaminergic neurons located in the substantia nigra and the decreased dopamine in the striatum are significantly related to Parkinson's disease. To date, the mainstream treatment of Parkinson's disease has been achieved by alleviating its associated morbid symptoms, such as the use of levodopa, carbidopa, dopamine receptor agonists, monoamine oxidase type B inhibitors, anticholinergic drugs, etc. However, strong side effects, even toxicity, have been reported after using these drugs, with reduced effectiveness over time. Plant compounds have shown good therapeutic effects in neurodegenerative diseases as a less toxic treatment. In this review, we have compiled several natural plant compounds and classified the currently reported compounds for therapeutic use based on their structural parent nuclei and constituent elements. We wish to inspire new ideas for the treatment of Parkinson's disease by summarizing their mechanisms.

Therapeutic application of quercetin in aging-related diseases: SIRT1 as a potential mechanism

Quercetin, a naturally non-toxic flavonoid within the safe dose range with antioxidant, anti-apoptotic and anti-inflammatory properties, plays an important role in the treatment of aging-related diseases. Sirtuin 1 (SIRT1), a member of NAD+-dependent deacetylase enzyme family, is extensively explored as a potential therapeutic target for attenuating aging-induced disorders. SIRT1 possess beneficial effects against aging-related diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), Depression, Osteoporosis, Myocardial ischemia (M/I) and reperfusion (MI/R), Atherosclerosis (AS), and Diabetes. Previous studies have reported that aging increases tissue susceptibility, whereas, SIRT1 regulates cellular senescence and multiple aging-related cellular processes, including SIRT1/Keap1/Nrf2/HO-1 and SIRTI/PI3K/Akt/GSK-3β mediated oxidative stress, SIRT1/NF-κB and SIRT1/NLRP3 regulated inflammatory response, SIRT1/PGC1α/eIF2α/ATF4/CHOP and SIRT1/PKD1/CREB controlled phosphorylation, SIRT1-PINK1-Parkin mediated mitochondrial damage, SIRT1/FoxO mediated autophagy, and SIRT1/FoxG1/CREB/BDNF/Trkβ-catenin mediated neuroprotective effects. In this review, we summarized the role of SIRT1 in the improvement of the attenuation effect of quercetin on aging-related diseases and the relationship between relevant signaling pathways regulated by SIRT1. Moreover, the functional regulation of quercetin in aging-related markers such as oxidative stress, inflammatory response, mitochondrial function, autophagy and apoptosis through SIRT1 was discussed. Finally, the prospects of an extracellular vesicles (EVs) as quercetin loading and delivery, and SIRT1-mediated EVs as signal carriers for treating aging-related diseases, as well as discussed the ferroptosis alleviation effects of quercetin to protect against aging-related disease via activating SIRT1. Generally, SIRT1 may serve as a promising therapeutic target in the treatment of aging-related diseases via inhibiting oxidative stress, reducing inflammatory responses, and restoring mitochondrial dysfunction.

Evidence for Oxidative Pathways in the Pathogenesis of PD: Are Antioxidants Candidate Drugs to Ameliorate Disease Progression?

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that arises due to a complex and variable interplay between elements including age, genetic, and environmental risk factors that manifest as the loss of dopaminergic neurons. Contemporary treatments for PD do not prevent or reverse the extent of neurodegeneration that is characteristic of this disorder and accordingly, there is a strong need to develop new approaches which address the underlying disease process and provide benefit to patients with this debilitating disorder. Mitochondrial dysfunction, oxidative damage, and inflammation have been implicated as pathophysiological mechanisms underlying the selective loss of dopaminergic neurons seen in PD. However, results of studies aiming to inhibit these pathways have shown variable success, and outcomes from large-scale clinical trials are not available or report varying success for the interventions studied. Overall, the available data suggest that further development and testing of novel therapies are required to identify new potential therapies for combating PD. Herein, this review reports on the most recent development of antioxidant and anti-inflammatory approaches that have shown positive benefit in cell and animal models of disease with a focus on supplementation with natural product therapies and selected synthetic drugs.

Brain polar phenol content, behavioural and neurochemical effects of Corinthian currant in a rotenone rat model of Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of nigral dopaminergic neurons, leading to reduced motor control. A contributing factor for the nigrostriatal degeneration is known to be oxidative stress, while antioxidant/anti-inflammatory properties of natural polyphenols have been suggested to show beneficial effects. The present study questioned the potential neuroprotective effects of supplementary diet with Corinthian currant, using a rat rotenone PD model.

METHODS

The alterations in motor activity, brain Corinthian currant polar phenols' accumulation, expression patterns of tyrosine hydroxylase (TH), dopamine transporter (DAT) and brain-derived neurotrophic factor (BDNF) in the nigrostriatal dopaminergic system were determined in rotenone-treated, currant-diet rats and matching controls.

RESULTS

Rotenone treatment resulted in motor deficits and TH expression decreases in the nigrostriatal pathway, exhibiting PD-like behavioural motor and neurochemical phenotypes. Interestingly, 38 days Corinthian currant consumption resulted in differential accumulation of polar phenols in mesencephalon and striatum and had a significant effect on attenuating motor deficits and dopaminergic cell loss in substantia nigra pars compacta. In addition, it induced up-regulation of BDNF expression in the nigrostriatal dopaminergic system.

DISCUSSION

Taken all together, evidence is provided for the potential neuroprotective influences of Corinthian currant consumption, involving the neurotrophic factor BDNF, in rescuing aspects of PD-like phenotype.

Neuroprotective effects of catechin and quercetin in experimental Parkinsonism through modulation of dopamine metabolism and expression of IL-1β, TNF-α, NF-κB, IκKB, and p53 genes in male Wistar rats

The neurobehavioral, brain redox-stabilizing and neurochemical modulatory properties of catechin and quercetin in rotenone-induced Parkinsonism, and the involvement of NF-κB-mediated inflammation, were investigated. Male Wistar rats subcutaneously administered with multiple doses of 1.5mg/kg rotenone were post-treated with 5-20mg/kg catechin or quercetin. This was followed by neurobehavioral evaluation, biochemical estimations, and assessment of neurotransmitter metabolism in the striatum. Expression of genes involved in the canonical pathway for the activation of NF-κB mediated inflammation (IL-1β, TNF-α, NF-κB, and IκKB) and the pro-apoptotic gene, p53, in the striatum was determined by RT-qPCR. Catechin and quercetin mitigated neurobehavioral deficits caused by rotenone. Both flavonoids attenuated striatal redox stress and neurochemical dysfunction, optimized disturbed dopamine metabolism, and improved depletion of neuron density caused by rotenone toxicity. While administration of catechin produced a more pronounced attenuating effect on IL-1β, TNF-α, and p53 genes, the attenuating effect of quercetin (20mg/kg) was more pronounced on NF-κB and IκKB gene expressions when compared to the group administered with rotenone only. Comparatively, quercetin demonstrated superior protection against rotenone neurotoxicity. It is concluded that catechin and quercetin have potential relevance in Parkinson's disease therapy through amelioration of redox stress, optimization of dopamine metabolism, and modulation of anti-inflammatory and anti-apoptotic pathways.

Protective effects of functional foods against Parkinson's disease: A narrative review on pharmacology, phytochemistry, and molecular mechanisms

In Persian Medicine (PM), PD (brain-based tremor) is a known CNS disorder with several therapeutic and preventive options. In their medical textbooks and pharmacopeias, Persian great scientists such as Rhazes (854-925 AD), Avicenna (980-1037 AD), and Jorjani (1042-1136 AD), have discussed pharmacological and nutritional strategies for the prevention, slowing progression, and treatment of PD. In the present study, we surveyed plant- and animal-based foods recommended by PM for the prevention and treatment of CNS-related tremors. In vivo and in-vitro pharmacological evidence supporting the beneficial effects of PM-recommended foods in prevention and alleviating PD, major active phytochemicals along with the relevant mechanisms of action were studied. Several PM plants possess potent antioxidant, antiinflammatory, and PD preventing properties. Garlic and allicin, cabbage and isothiocyanates, chickpea seed and its O-methylated isoflavones biochanin A and formononetin, cinnamon, and cinnamaldehyde, saffron and its crocin, crocetin, and safranal, black cumin and its thymoquinone, black pepper and piperine, pistachio and genistein and daidzein, and resveratrol are among the most effective dietary itemsagainst PD. They act through attenuating neurotoxin-induced memory loss and behavioral impairment, oxidative stress, and dopaminergic cell death. PM-recommended foods can help alleviate PD progression and also discovering and developing new neuroprotective anti-PD pharmaceuticals.

Potential innovation against Alzheimer's disorder: a tricomponent combination of natural antioxidants (vitamin E, quercetin, and basil oil) and the development of its intranasal delivery

Alzheimer's disorder (AD) is very difficult to manage and treat. The complexity of the brain, the blood-brain barrier influencing a multitude of parameters/biomarkers, as well as numerous other factors involved often contribute to the decline in the chances of treatment success. Development of the new drug moiety also takes time, being necessary to consider both its toxicity and related issues. As a strategic plan, a combined strategy is being developed and considered to address AD pathology using several approaches. A combination of vitamin E, quercetin, and basil oil in a nano-based formulation is designed to be administered nasally. The antioxidant present in these natural-based products helps to treat and alleviate AD if a synergistic approach is considered. The three active substances mentioned above are well known for the treatment of neurodegenerative disorders. The nanoformulation helps the co-delivery of the drug moiety to the brain through the intranasal route. In this review, a correlation and use of vitamin E, quercetin, and basil oil in a nano-based formulation is described as an effective way to treat AD. The intranasal administration of drugs is a promising approach for the treatment of neurodegenerative and mental disorders, as this route is non-invasive, enhances the bioavailability, allows a drug dose reduction, bypasses the blood-brain barrier, and reduces the systemic undesired effect. The use of natural products is generally considered to be just as safe; therefore, by using this combined approach, the level of toxicity can be minimized.

Neurodegenerative Diseases and Flavonoids: Special Reference to Kaempferol

Neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, Multiple Sclerosis and Ischemic stroke have become a major health problem worldwide. Pre-clinical studies have demonstrated the beneficial effects of flavonoids on neurodegenerative diseases and suggest them to be used as therapeutic agents. Kaempferol is found in many plants such as tea, beans, broccoli, strawberries, and neuroprotective effects against the development of many neurodegenerative diseases such as Parkinson, Alzheimer's disease and Huntington's disease. The present study summarizes the neuroprotective effects of kaempferol in various models of neurodegenerative diseases. Kaempferol delays the initiation as well as the progression of neurodegenerative disorders by acting as a scavenger of free radicals and preserving the activity of various antioxidant enzymes. Kaempferol can cross the Blood-Brain Barrier (BBB), and therefore results in an enhanced protective effect. The multi-target property of kaempferol makes it a potential dietary supplement in preventing and treating neurodegenerative diseases.

Neuroprotective Effects of Resveratrol in In vivo and In vitro Experimental Models of Parkinson's Disease: a Systematic Review

Parkinson's disease (PD) is currently the second most common neurodegenerative disease, being characterized by motor and non-motor symptoms. The therapeutic options available for its treatment are limited, do not slow the progression of the disease, and have serious side effects. For this reason, many studies have sought to find compounds with neuroprotective properties that bring additional benefits to current therapy. In this context, resveratrol is a phenolic compound, found in many plant species, capable of crossing the blood-brain barrier and having multiple biological properties. Experimental studies in vitro and in vivo have shown that it can prevent or slow the progression of a variety of diseases, including PD. In this systematic review, we summarize the effects of resveratrol in experimental in vivo and in vitro models of PD and discuss the molecular mechanisms involved in its action. The bibliographic search was performed in the databases of PubMed, Web of Science, SciELO, and Google Scholar, and based on the inclusion criteria, 41 articles were selected and discussed. Most of the included studies have demonstrated neuroprotective effects of resveratrol. In general, resveratrol prevented behavioral and/or neurological disorders, improved antioxidant defenses, reduced neuroinflammatory processes, and inhibited apoptosis. In summary, this systematic review offers important scientific evidence of neuroprotective effects of resveratrol in PD and also provide valuable information about its mechanism of action that can support future clinical studies.

Investigation of the peripheral inflammation (neutrophil-lymphocyte ratio) in two neurodegenerative diseases of the central nervous system

INTRODUCTION

Alzheimer's disease (AD), and idiopathic Parkinson's disease (IPD) are the neurodegenerative diseases of the central nervous system (CNS). Cognitive impairment is on the forefront in AD. However, IPD is a movement disorder. Inflammation was suggested to have an effect in the pathophysiology of these two diseases. Neutrophil-lymphocyte ratio (NLR) was shown to be a possible marker showing the peripheral inflammation. We aimed to investigate the NLR of patiens with the diagnosis of AD, and IPD, and individuals with no neurodegenerative disease.

MATERIALS AND METHODS

A total of 100 patients with the diagnosis of IPD, and 94 with diagnosis of AD, and 61 healthy controls were included into the study. All the demographic, clinical, and laboratory data were retrospectively obtained from the hospital automated database system.

RESULTS

The NLR in the IPD group was found statistically significantly higher compared with the control group and the AD group (p < 0.001, p = 0.04, respectively). The age-adjusted values were statistically analyzed because of age difference. No statistically significant difference was detected between AD and control groups in terms of NLR (p = 0.6). The age-adjusted NLR value in the Parkinson's group was found significantly higher compared to the control group (p = 0.02) and Alzheimer's group (p = 0.03).

DISCUSSION

Chronic inflammation has an important role in the emergence and progression of the chronic neurodegenerative diseases of the CNS. Our results show that the inflammation in the peripheral blood in IPD was more significant compared with the inflammation in AD.

Nanotechnology-Based Drug Delivery Strategies to Repair the Mitochondrial Function in Neuroinflammatory and Neurodegenerative Diseases

Mitochondria are vital organelles in eukaryotic cells that control diverse physiological processes related to energy production, calcium homeostasis, the generation of reactive oxygen species, and cell death. Several studies have demonstrated that structural and functional mitochondrial disturbances are involved in the development of different neuroinflammatory (NI) and neurodegenerative (ND) diseases (NI&NDDs) such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Remarkably, counteracting mitochondrial impairment by genetic or pharmacologic treatment ameliorates neurodegeneration and clinical disability in animal models of these diseases. Therefore, the development of nanosystems enabling the sustained and selective delivery of mitochondria-targeted drugs is a novel and effective strategy to tackle NI&NDDs. In this review, we outline the impact of mitochondrial dysfunction associated with unbalanced mitochondrial dynamics, altered mitophagy, oxidative stress, energy deficit, and proteinopathies in NI&NDDs. In addition, we review different strategies for selective mitochondria-specific ligand targeting and discuss novel nanomaterials, nanozymes, and drug-loaded nanosystems developed to repair mitochondrial function and their therapeutic benefits protecting against oxidative stress, restoring cell energy production, preventing cell death, inhibiting protein aggregates, and improving motor and cognitive disability in cellular and animal models of different NI&NDDs.

Targeting Mitochondria by Plant Secondary Metabolites: A Promising Strategy in Combating Parkinson's Disease

Parkinson’s disease (PD) is one of the most prevalent and debilitating neurodegenerative conditions, and is currently on the rise. Several dysregulated pathways are behind the pathogenesis of PD; however, the critical targets remain unclear. Accordingly, there is an urgent need to reveal the key dysregulated pathways in PD. Prevailing reports have highlighted the importance of mitochondrial and cross-talked mediators in neurological disorders, genetic changes, and related complications of PD. Multiple pathophysiological mechanisms of PD, as well as the low efficacy and side effects of conventional neuroprotective therapies, drive the need for finding novel alternative agents. Recently, much attention has been paid to using plant secondary metabolites (e.g., flavonoids/phenolic compounds, alkaloids, and terpenoids) in the modulation of PD-associated manifestations by targeting mitochondria. In this line, plant secondary metabolites have shown promising potential for the simultaneous modulation of mitochondrial apoptosis and reactive oxygen species. This review aimed to address mitochondria and multiple dysregulated pathways in PD by plant-derived secondary metabolites.

Quercetin exhibits potent antioxidant activity, restores motor and non-motor deficits induced by rotenone toxicity

The rotenone-induced animal model of Parkinson's disease (PD) has been used to investigate the pathogenesis of PD. Oxidative stress is one of the main contributors of neurodegeneration in PD. Flavonoids have the potential to modulate neuronal function and combat various neurodegenerative diseases. The pre- and post-supplementation of quercetin (50 mg/kg, p.o) was done in rats injected with rotenone (1.5 mg/kg, s.c). After the treatment, behavioral activities were monitored for motor activity, depression-like behavior, and cognitive changes. Rats were decapitated after behavioral analysis and the brain samples were dissected out for neurochemical and biochemical estimation. Results showed that supplementation of quercetin significantly (p<0.01) restored rotenone-induced motor and non-motor deficits (depression and cognitive impairments), enhanced antioxidant enzyme activities (p<0.01), and attenuated neurotransmitter alterations (p<0.01). It is suggested that quercetin supplementation improves neurotransmitter levels by mitigating oxidative stress via increasing antioxidant enzyme activity and hence improves motor activity, cognitive functions, and reduces depressive behavior. The results of the present study showed that quercetin pre-supplementation produced more significant results as compared to post-supplementation. These findings show that quercetin can be a potential therapeutic agent to reduce the risk and progression of PD.

Quercetin attenuates neurotoxicity induced by iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) have been proposed as targeted carriers to deliver therapeutic molecules in the central nervous system (CNS). However, IONPs may damage neural tissue via free iron accumulation, protein aggregation, and oxidative stress. Neuroprotective effects of quercetin (QC) have been proven due to its antioxidant and anti-inflammatory properties. However, poor solubility and low bioavailability of QC have also led researchers to make various QC-involved nanoparticles to overcome these limitations. We wondered how high doses or prolonged treatment with quercetin conjugated superparamagnetic iron oxide nanoparticles (QCSPIONs) could improve cognitive dysfunction and promote neurogenesis without any toxicity. It can be explained that the QC inhibits protein aggregation and acts against iron overload via iron-chelating activity, iron homeostasis genes regulation, radical scavenging, and attenuation of Fenton/Haber-Weiss reaction. In this review, first, we present brain iron homeostasis, molecular mechanisms of iron overload that induced neurotoxicity, and the role of iron in dementia-associated diseases. Then by providing evidence of IONPs neurotoxicity, we discuss how QC neutralizes IONPs neurotoxicity, and finally, we make a brief comparison between QC and conventional iron chelators. In this review, we highlight that QC as supplementation and especially in conjugated form reduces iron oxide nanoparticles neurotoxicity in clinical application.

Inhibition of γH2AX, COX-2 and regulation of antioxidant enzymes in MPP+-exposed SH-SY5Y cells pre-treated with rutin

Many plant-derived bioactive compounds such as rutin are reportedly effective in attenuating neuronal death in most neurodegenerative disorders. Parkinson's disease (PD) is characterized by the gradual degeneration of dopaminergic neurons in the substantia nigra of the midbrain, and has previously been modelled in-vitro through the specific neurotoxic activity of 1-methyl-4-phenylpyridinium (MPP⁺) on dopaminergic neurons. Rutin is a bioflavonoid with multiple pharmacological effects, and this study investigated the neuroprotective effects of rutin in the human dopaminergic SH-SY5Y cell line using the neurotoxin MPP⁺. SH-SY5Y cells pretreated with rutin, were exposed to MPP⁺ and evaluated for cell viability, nitric oxide (NO), reactive oxygen species (ROS) and antioxidant enzymes activities. In addition, western blot techniques were used to determine the protein expression levels of γH2AX and COX-2. Rutin significantly attenuated MPP⁺-induced loss of cell viability, mitigated ROS and NO production and inhibited the disruption of antioxidant enzymes activity. It was also observed that rutin significantly reduced protein expression levels of γH2AX and COX-2 in SH-SY5Y cells treated with MPP⁺. Taken together, findings from this study tend to suggest that rutin is a promising neuroprotective compound for the treatment of PD through its effects on some of the mechanisms that characterize this neurodegenerative disease.

Quercetin inhibiting the PD-1/PD-L1 interaction for immune-enhancing cancer chemopreventive agent

Targeting the PD-1/PD-L1 immune checkpoints has achieved significant positive results in the treatment of multiple cancers. Quercetin is one of the most abundant dietary flavonoids found in various vegetables and fruits, and has a wide range of biological activities including immunomodulation. Here we report that quercetin dihydrate was screened and shown to inhibit the PD-1/PD-L1 interaction. Treatment with quercetin dihydrate promoted the killing activity of T cells on MDA-MB-231 and NCI-H460 cancer cells. Experiments using the xenograft mouse model showed that the growth rate of tumor volumes and masses in the quercetin dihydrate-treated mice were decreased. Immunohistochemistry of the tumors showed that CD8, GZMB, and IFN-γ were increased in the quercetin dihydrate-treated mice. These results suggest that quercetin dihydrate attenuates the inhibitory effect of PD-L1 on T cells by inhibiting the PD-1/PD-L1 interaction, which has an exciting potential to be used as a cancer chemopreventive agent.