The Effects of Ellagic Acid upon Brain Cells: A Mechanistic View and Future Directions

Exploring the synergistic potential of pomegranate fermented juice compounds against oxidative stress-induced neurotoxicity through computational docking and experimental analysis in human neuroblastoma cells

This study explored the neuroprotective potential of fermented pomegranate (PG-F) against hydrogen peroxide (H2O2)-induced neurotoxicity in human neuroblastoma SH-SY5Y cells and elucidated the underlying molecular mechanisms. The fermentation process, involving probiotics, transforms the hydrolyzable tannins in pomegranate juice into ellagic acid (EA) and gallic acid (GA), which are believed to contribute to its health benefits. Molecular docking simulations confirmed the stable interactions between EA, GA, and proteins associated with the antioxidant and anti-apoptotic pathways. PG-F significantly enhanced the viability of H2O2-treated cells, as evidenced by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, cell morphology observations, and Hoechst 33342 staining. PG-F mitigated the H2O2-induced intracellular reactive oxygen species (ROS) levels, restored mitochondrial membrane potential, and upregulated antioxidant gene expression. The PG-F treatment also attenuated the H2O2-induced imbalance in the Bax/Bcl-2 ratio and reduced the cleaved caspase-3, caspase-7, and caspase-9 levels, suppressing the apoptotic pathways. Further insights showed that PG-F inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) and facilitated the nuclear translocation of nuclear factor-erythroid 2-related factor (Nrf2), highlighting its role in modulating the key signaling pathways. A combined treatment with equivalent concentrations of EA and GA, as found in PG-F, induced remarkable cellular protection. Drug combination analysis using the Chou-Talalay method revealed a synergistic effect between EA and GA, emphasizing their combined efficacy. In conclusion, PG-F has significant neuroprotective effects against H2O2-induced neurotoxicity by modulating the antioxidant and anti-apoptotic pathways. The synergistic action of EA and GA suggests the therapeutic potential of PG-F in alleviating oxidative stress-associated neurodegenerative diseases.

Brazil Nut-Enriched Diet Modulates Enteric Glial Cells and Gut Microbiota in an Experimental Model of Chronic Kidney Disease

Introduction: Chronic kidney disease (CKD) promotes gut dysbiosis, and enteric glial reactivity, a feature of intestinal inflammation. Brazil nut modulated enteric glial profile in healthy animals and could modulate these cells in 5/6 nephrectomized rats.Methods: A 5/6 nephrectomy-induced CKD and Sham-operated rats were divided as follows: CKD and Sham received a standard diet and CKD-BN and Sham-BN received a 5% Brazil nut enriched-diet. The protein content of glial fibrillary acid protein (GFAP), enteric glial marker, and GPx protein content and activity were assessed in the colon. The major phyla of gut microbiota were assessed.Results: CKD-BN group presented a decrease in GFAP content (p = 0.0001). The CKD-BN group modulated the abundance of Firmicutes, increasing its proportion compared to the CKD group. The CKD-BN group showed increased GPx activity in the colon (p = 0.0192), despite no significant difference in protein content.Conclusion: Brazil nut-enriched diet consumption decreased enteric glial reactivity and modulated gut microbiota in the CKD experimental model.

A Critical Appraisal of the Protective Activity of Polyphenolic Antioxidants against Iatrogenic Effects of Anticancer Chemotherapeutics

Polyphenolic compounds, encompassing flavonoids (e.g., quercetin, rutin, and cyanidin) and non-flavonoids (e.g., gallic acid, resveratrol, and curcumin), show several health-related beneficial effects, which include antioxidant, anti-inflammatory, hepatoprotective, antiviral, and anticarcinogenic properties, as well as the prevention of coronary heart diseases. Polyphenols have also been investigated for their counteraction against the adverse effects of common anticancer chemotherapeutics. This review evaluates the outcomes of clinical studies (and related preclinical data) over the last ten years, with a focus on the use of polyphenols in chemotherapy as auxiliary agents acting against oxidative stress toxicity induced by antitumor drugs. While further clinical studies are needed to establish adequate doses and optimal delivery systems, the improvement in polyphenols' metabolic stability and bioavailability, through the implementation of nanotechnologies that are currently being investigated, could improve therapeutic applications of their pharmaceutical or nutraceutical preparations in tumor chemotherapy.

Synthetic and Natural Bioactive Molecules in Balancing the Crosstalk among Common Signaling Pathways in Alzheimer's Disease: Understanding the Neurotoxic Mechanisms for Therapeutic Intervention

The structure and function of the brain greatly rely on different signaling pathways. The wide variety of biological processes, including neurogenesis, axonal remodeling, the development and maintenance of pre- and postsynaptic terminals, and excitatory synaptic transmission, depends on combined actions of these molecular pathways. From that point of view, it is important to investigate signaling pathways and their crosstalk in order to better understand the formation of toxic proteins during neurodegeneration. With recent discoveries, it is established that the modulation of several pathological events in Alzheimer's disease (AD) due to the mammalian target of rapamycin (mTOR), Wnt signaling, 5'-adenosine monophosphate activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), and sirtuin 1 (Sirt1, silent mating-type information regulator 2 homologue 1) are central to the key findings. These include decreased amyloid formation and inflammation, mitochondrial dynamics control, and enhanced neural stability. This review intends to emphasize the importance of these signaling pathways, which collectively determine the fate of neurons in AD in several ways. This review will also focus on the role of novel synthetic and natural bioactive molecules in balancing the intricate crosstalk among different pathways in order to prolong the longevity of AD patients.

Ellagic acid through attenuation of neuro-inflammatory response exerted antidepressant-like effects in socially isolated mice

Recent studies have been demonstrated that neuroinflammation plays a crucial role in the pathophysiology of depression. Therefore, anti-inflammatory medications could be regarded as a potentially effective treatments for depression. Ellagic acid (EA) is a natural polyphenol with antioxidant and anti-inflammatory properties. This study aimed to evaluate the antidepressant-like effect of EA in a mouse model of social isolation stress (SIS), considering its potential anti-neuroinflammatory properties. In this study, 48 male mice were divided into six groups (n = 8), including saline-treated control (socially conditioned (SC)) group and SIS (isolation conditioned (IC)) groups treated with saline or EA at doses of 12.5, 25, 50, and 100 mg/kg, respectively. Saline and EA were administrated intraperitoneally for 14 constant days. Immobility time in the forced swimming test (FST) and grooming activity time in the splash test were measured. The gene expression of inflammatory cytokines relevant to neuroinflammation was assessed in the hippocampus by real-time PCR. Results showed that SIS significantly increased immobility time in the FST and reduced grooming activity time in the splash test. In addition, the expression of inflammatory genes, including TNF-α, IL-1β, and TLR4 increased in IC mice's hippocampi. Findings showed that EA decreased immobility time in the FST and increased grooming activity time in the splash test. Moreover, EA attenuated neuroimmune-response in the hippocampus. In conclusion, finding determined that EA, through attenuation of neuroinflammation in the hippocampus, partially at least, exerted an antidepressant-like effect in the mouse model of SIS.

Oral ellagic acid attenuated LPS-induced neuroinflammation in rat brain: MEK1 interaction and M2 microglial polarization

Ellagic acid, the marker component of peels of Punica granatum L., is known traditionally to treat traumatic hemorrhage. In this study, the cellular mechanism underlying ellagic acid-induced anti-inflammation was investigated using lipopolysaccharides (LPSs) as a neuroinflammation inducer. Our in vitro data showed that LPS (1 μg/mL) consistently phosphorylated ERK and induced neuroinflammation, such as elevation in tumor necrosis factor-α (TNF-α) and nitric oxide production in treated BV-2 cells. Incubation of ellagic acid significantly inhibited LPS-induced ERK phosphorylation and subsequent neuroinflammation in treated BV-2 cells. Furthermore, our in vivo study of neuroinflammation employed an intranigral infusion of LPS that resulted in a time-dependent elevation in phosphorylated ERK levels in the infused substantia nigra (SN). Oral administration of ellagic acid (100 mg/kg) significantly attenuated LPS-induced ERK phosphorylation. A four-day treatment of ellagic acid did not alter LPS-induced ED-1 elevation but ameliorated LPS-induced reduction in CD206 and arginase-1 (two biomarkers of M2 microglia). A seven-day treatment of ellagic acid abolished LPS-induced increases in heme-oxygenase-1, cyclo-oxygenase 2, and α-synuclein trimer levels (a pathological hallmark) in the infused SN. At the same time, ellagic acid attenuated LPS-induced increases in active caspase 3 and receptor-interacting protein kinase-3 levels (respective biomarkers of apoptosis and necroptosis) as well as reduction in tyrosine hydroxylase-positive cells in the infused SN. In silico analysis showed that ellagic acid binds to the catalytic site of MEK1. Our data suggest that ellagic acid is capable of inhibiting MEK1-ERK signaling and then attenuated LPS-induced neuroinflammation, protein aggregation, and programmed cell deaths. Moreover, M2 microglial polarization is suggested as a novel antineuroinflammatory mechanism in the ellagic acid-induced neuroprotection.

Synergistic effect of ellagic acid and gabapentin in a rat model of neuropathic pain

BACKGROUND

Neuropathic pain is a subtype of chronic pain characterized by a primary lesion or dysfunction of the peripheral or central nervous system. The current pain management of neuropathic pain is inadequate and needs new medications.

AIM

We studied the effects of 14 days of intraperitoneal ellagic acid (EA) and gabapentin administration in a rat model of neuropathic pain induced by chronic constriction injury (CCI) of the right sciatic nerve.

METHODS

Rats were divided into six groups: (1) control, (2) CCI, (3) CCI + EA (50 mg/kg), 4) CCI + EA (100 mg/kg), 5) CCI + gabapentin (100 mg/kg), and 6) CCI + EA (100 mg/kg) + gabapentin (100 mg/kg). Behavioral tests, including mechanical allodynia, cold allodynia, and thermal hyperalgesia, were conducted on days - 1(pre-operation), 7, and 14 post-CCI. In addition, at day 14 post-CCI, spinal cord segments were collected to measure the expression of inflammatory markers, including tumor necrosis factor-alpha (TNF-α), nitric oxide (NO), and oxidative stress markers, including malondialdehyde (MDA) and thiol.

RESULTS

CCI increased mechanical allodynia, cold allodynia, and thermal hyperalgesia in rats which were reduced by treatment with EA (50 or 100 mg/kg), gabapentin, or their combination. CCI increased TNF-α, NO, and MDA levels and decreased thiol content in the spinal cord, which all were reverted by administration of EA (50 or 100 mg/kg), gabapentin, or their combination.

CONCLUSION

This is the first report on ellagic acid's ameliorative effect in rats' CCI-induced neuropathic pain. This effect can be attributed to its anti-oxidative and anti-inflammatory, thus making it potentially useful as an adjuvant to conventional treatment.

Protective effects of pomegranate (Punica granatum) and its main components against natural and chemical toxic agents: A comprehensive review

BACKGROUND

Different chemical toxicants or natural toxins can damage human health through various routes such as air, water, fruits, foods, and vegetables.

PURPOSE

Herbal medicines may be safe and selective for the prevention of toxic agents due to their active ingredients and various pharmacological properties. According to the beneficial properties of pomegranate, this paper summarized the protective effects of this plant against toxic substances.

STUDY DESIGN

In this review, we focused on the findings of in vivo and in vitro studies of the protective effects of pomegranate (Punica granatum) and its active components including ellagic acid and punicalagin, against natural and chemical toxic agents.

METHODS

We collected articles from the following databases or search engines such as Web of Sciences, Google Scholar, Pubmed and Scopus without a time limit until the end of September 2022.

RESULTS

P. granatum and its constituents have shown protective effects against natural toxins such as aflatoxins, and endotoxins as well as chemical toxicants for instance arsenic, diazinon, and carbon tetrachloride. The protective effects of these compounds are related to different mechanisms such as the prevention of oxidative stress, and reduction of inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), cyclooxygenase-2(COX-2) and nuclear factor ĸB (NF-ĸB) as well as the modulation of apoptosis, mitogen-activated protein kinase (MAPK) signaling pathways and improvement of liver or cardiac function via regulation of enzymes.

CONCLUSION

In this review, different in vitro and in vivo studies have shown that P. granatum and its active constituents have protective effects against natural and chemical toxic agents via different mechanisms. There are no clinical trials on the protective effects of P. granatum against toxic agents.

Potential implications of polyphenolic compounds in neurodegenerative diseases

Neurodegenerative diseases are common chronic diseases related to progressive damage to the nervous system. Current neurodegenerative diseases present difficulties and despite extensive research efforts to develop new disease-modifying therapies, there is still no effective treatment for halting the neurodegenerative process. Polyphenols are biologically active organic compounds abundantly found in various plants. It has been reported that plant-derived dietary polyphenols may improve some disease states and promote health. Emerging pieces of evidence indicate that polyphenols are associated with neurodegenerative diseases. This review aims to overview the potential neuroprotective roles of polyphenols in most common neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and ischemic stroke.

Ellagic Acid and Its Anti-Aging Effects on Central Nervous System

Aging is an unavoidable biological process that leads to the decline of human function and the reduction in people’s quality of life. Demand for anti-aging medicines has become very urgent. Many studies have shown that ellagic acid (EA), a phenolic compound widely distributed in dicotyledonous plants, has powerful anti-inflammation and antioxidant properties. Moreover, it has been demonstrated that EA can enhance neuronal viability, reduce neuronal defects, and alleviate damage in neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and cerebral ischemia. This paper reviews the biochemical functions and neuroprotective effects of EA, showing the clinical value of its application.

Ellagic Acid: A Review on Its Natural Sources, Chemical Stability, and Therapeutic Potential

Ellagic acid (EA) is a bioactive polyphenolic compound naturally occurring as secondary metabolite in many plant taxa. EA content is considerable in pomegranate (Punica granatum L.) and in wood and bark of some tree species. Structurally, EA is a dilactone of hexahydroxydiphenic acid (HHDP), a dimeric gallic acid derivative, produced mainly by hydrolysis of ellagitannins, a widely distributed group of secondary metabolites. EA is attracting attention due to its antioxidant, anti-inflammatory, antimutagenic, and antiproliferative properties. EA displayed pharmacological effects in various in vitro and in vivo model systems. Furthermore, EA has also been well documented for its antiallergic, antiatherosclerotic, cardioprotective, hepatoprotective, nephroprotective, and neuroprotective properties. This review reports on the health-promoting effects of EA, along with possible mechanisms of its action in maintaining the health status, by summarizing the literature related to the therapeutic potential of this polyphenolic in the treatment of several human diseases.

Brazil Nut (Bertholletia excelsa H.B.K) Retards Gastric Emptying and Modulates Enteric Glial Cells in a Dose-Dependent Manner

BACKGROUND

The role of food and nutrients in the regulation of enteric glial cell functions is unclear. Some foods influence enteric neurophysiology and can affect glial cell functions that include regulation of the intestinal barrier, gastric emptying, and colonic transit. Brazil nuts are the most abundant natural source of selenium, unsaturated fatty acids, fibers, and polyphenols.

OBJECTIVE

The study investigated the effects of a Brazil nut-enriched diet on enteric glial cells and gastrointestinal transit.

METHODS

Two-month-old male Wistar rats were randomized to a standard diet (control group, CG), standard diet containing 5% (wt/wt) Brazil nut (BN5), and standard diet containing 10% (wt/wt) Brazil nut (BN10) (n = 9 per group). After eight weeks, the animals underwent constipation and gastric emptying tests to assess motility. Evaluations of colonic immunofluorescence staining for glial fibrillary acidic protein (GFAP) and myenteric ganglia area were performed.

RESULTS

The BN5 group showed increased weight gain while the BN10 group did not (p < 0.0001). The BN10 group showed higher gastric residue amounts compared to the other groups (p = 0.0008). The colon exhibited an increase in GFAP immunoreactivity in the BN5 group compared to that in the other groups (p = 0.0016), and the BN10 group presented minor immunoreactivity compared to the CG (p = 0.04). The BN10 group presented a minor ganglia area compared to the CG (p = 0.0155).

CONCLUSION

The Brazil nut-enriched diet modified the gastric residual, colonic GFAP immunoreactivity, and myenteric ganglia area after eight weeks in healthy male Wistar rats.

Ellagic Acid Prevents α-Synuclein Aggregation and Protects SH-SY5Y Cells from Aggregated α-Synuclein-Induced Toxicity via Suppression of Apoptosis and Activation of Autophagy

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopamine neurons and the deposition of misfolded proteins known as Lewy bodies (LBs), which contain α-synuclein (α-syn). The causes and molecular mechanisms of PD are not clearly understood to date. However, misfolded proteins, oxidative stress, and impaired autophagy are believed to play important roles in the pathogenesis of PD. Importantly, α-syn is considered a key player in the development of PD. The present study aimed to assess the role of Ellagic acid (EA), a polyphenol found in many fruits, on α-syn aggregation and toxicity. Using thioflavin and seeding polymerization assays, in addition to electron microscopy, we found that EA could dramatically reduce α-syn aggregation. Moreover, EA significantly mitigated the aggregated α-syn-induced toxicity in SH-SY5Y cells and thus enhanced their viability. Mechanistically, these cytoprotective effects of EA are mediated by the suppression of apoptotic proteins BAX and p53 and a concomitant increase in the anti-apoptotic protein, BCL-2. Interestingly, EA was able to activate autophagy in SH-SY5Y cells, as evidenced by normalized/enhanced expression of LC3-II, p62, and pAKT. Together, our findings suggest that EA may attenuate α-syn toxicity by preventing aggregation and improving viability by restoring autophagy and suppressing apoptosis.

Presynaptic Release-Regulating Alpha2 Autoreceptors: Potential Molecular Target for Ellagic Acid Nutraceutical Properties

Polyphenol ellagic acid (EA) possesses antioxidant, anti-inflammatory, anti-carcinogenic, anti-diabetic and cardio protection activities, making it an interesting multi-targeting profile. EA also controls the central nervous system (CNS), since it was proven to reduce the immobility time of mice in both the forced swimming and the tail-suspension tests, with an efficiency comparable to that of classic antidepressants. Interestingly, the anti-depressant-like effect was almost nulled by the concomitant administration of selective antagonists of the noradrenergic receptors, suggesting the involvement of these cellular targets in the central effects elicited by EA and its derivatives. By in silico and in vitro studies, we discuss how EA engages with human α_2A-ARs and α_2C-AR catalytic pockets, comparing EA behaviour with that of known agonists and antagonists. Structurally, the hydrophobic residues surrounding the α_2A-AR pocket confer specificity on the intermolecular interactions and hence lead to favourable binding of EA in the α_2A-AR, with respect to α_2C-AR. Moreover, EA seems to better accommodate within α_2A-ARs into the TM5 area, close to S200 and S204, which play a crucial role for activation of aminergic GPCRs such as the α₂-AR, highlighting its promising role as a partial agonist. Consistently, EA mimics clonidine in inhibiting noradrenaline exocytosis from hippocampal nerve endings in a yohimbine-sensitive fashion that confirms the engagement of naïve α₂-ARs in the EA-mediated effect.

Neuroprotective Potential of Ellagic Acid: A Critical Review

Ellagic acid (EA) is a dietary polyphenol present in various fruits, vegetables, herbs, and nuts. It exists either independently or as part of complex structures, such as ellagitannins, which release EA and several other metabolites including urolithins following absorption. During the past few decades, EA has drawn considerable attention because of its vast range of biological activities as well as its numerous molecular targets. Several studies have reported that the oxidative stress-lowering potential of EA accounts for its broad-spectrum pharmacological attributes. At the biochemical level, several mechanisms have also been associated with its therapeutic action, including its efficacy in normalizing lipid metabolism and lipidemic profile, regulating proinflammatory mediators, such as IL-6, IL-1β, and TNF-α, upregulating nuclear factor erythroid 2-related factor 2 and inhibiting NF-κB action. EA exerts appreciable neuroprotective activity by its free radical-scavenging action, iron chelation, initiation of several cell signaling pathways, and alleviation of mitochondrial dysfunction. Numerous in vivo studies have also explored the neuroprotective attribute of EA against various neurotoxins in animal models. Despite the increasing number of publications with experimental evidence, a critical analysis of available literature to understand the full neuroprotective potential of EA has not been performed. The present review provides up-to-date, comprehensive, and critical information regarding the natural sources of EA, its bioavailability, metabolism, neuroprotective activities, and underlying mechanisms of action in order to encourage further studies to define the clinical usefulness of EA for the management of neurological disorders.

Ellagic acid prevents 3-nitropropionic acid induced symptoms of Huntington's disease

Mitochondrial abnormalities and redox imbalance are major pathogenic factors in progression of Huntington's disease (HD), manifested clinically by affective, motor, cognitive, and psychiatric incompetence. Antioxidants behold much promise in mitigation of several pathological facets in HD. Ellagic acid (EA) is a naturally derived polyphenol acknowledged for potent neuroprotective abilities that enabled its significance amongst popular brain tonics. The present study is aimed to examine the outcome of EA pre-treatment in 3-nitropropionic acid (3-NP) rat prototype of HD. Separate rat groups were pre-treated with EA (25, 50, and 100 mg/kg, p.o.) for 21 days and 3-NP (10 mg/kg, i.p.) was given for 14 days alongside to induce symptoms of HD. The physical/motor functions (narrow beam paradigm, footprint study, hanging-wire assessment) and cognitive abilities using elevated plus maze and novel object recognition task were evaluated. Entire brain was isolated and succinate dehydrogenase activity and parameters of oxido-nitrosative stress were assessed in mitochondrial fraction. 3-NP accrued oxido-nitrosative stress and significant decrease in succinate dehydrogenase activity caused motor and cognitive deficits in rats. EA pre-treatment resurrected succinate dehydrogenase activity in 3-NP treated rats that indicated preservation of mitochondrial function. A significant decrease in thiobarbituric acid reactive substances and nitrite levels and increase in glutathione and catalase activity by EA in 3-NP treated rats was noted. EA protected the rats against 3-NP triggered cognitive insufficiency and motor disturbances. It can be inferred that ellagic acid protects against 3-NP induced mitochondrial dysfunction and oxido-nitrosative stress in the brain. EA supplements or nutraceuticals might possess protective potential against symptoms of HD.

Identification of SARS-CoV-2 Receptor Binding Inhibitors by In Vitro Screening of Drug Libraries

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) global pandemic. The first step of viral infection is cell attachment, which is mediated by the binding of the SARS-CoV-2 receptor binding domain (RBD), part of the virus spike protein, to human angiotensin-converting enzyme 2 (ACE2). Therefore, drug repurposing to discover RBD-ACE2 binding inhibitors may provide a rapid and safe approach for COVID-19 therapy. Here, we describe the development of an in vitro RBD-ACE2 binding assay and its application to identify inhibitors of the interaction of the SARS-CoV-2 RBD to ACE2 by the high-throughput screening of two compound libraries (LOPAC^®1280 and DiscoveryProbeTM). Three compounds, heparin sodium, aurintricarboxylic acid (ATA), and ellagic acid, were found to exert an effective binding inhibition, with IC50 values ranging from 0.6 to 5.5 µg/mL. A plaque reduction assay in Vero E6 cells infected with a SARS-CoV-2 surrogate virus confirmed the inhibition efficacy of heparin sodium and ATA. Molecular docking analysis located potential binding sites of these compounds in the RBD. In light of these findings, the screening system described herein can be applied to other drug libraries to discover potent SARS-CoV-2 inhibitors.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Ellagic Acid Prevents Dopamine Neuron Degeneration from Oxidative Stress and Neuroinflammation in MPTP Model of Parkinson's Disease

Parkinson's disease (PD) is one of the most common neurodegenerative diseases and is characterized by progressive dopaminergic neurodegeneration in the substantia nigra pars compacta area. In the present study, treatment of EA for 1 week at a dose of 10 mg/kg body weight prior to MPTP (25 mg/kg body weight) was carried out. MPTP administration caused oxidative stress, as evidenced by decreased activities of superoxide dismutase and catalase, and the depletion of reduced glutathione with a concomitant rise in the lipid peroxidation product, malondialdehyde. It also significantly increased the pro-inflammatory cytokines and elevated the inflammatory mediators like cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the striatum. Immunohistochemical analysis revealed a loss of dopamine neurons in the SNc area and a decrease in dopamine transporter in the striatum following MPTP administration. However, treatment with EA prior to MPTP injection significantly rescued the dopaminergic neurons and dopamine transporter. EA treatment further restored antioxidant enzymes, prevented the depletion of glutathione and inhibited lipid peroxidation, in addition to the attenuation of pro-inflammatory cytokines. EA also reduced the levels of COX-2 and iNOS. The findings of the present study demonstrate that EA protects against MPTP-induced PD and the observed neuroprotective effects can be attributed to its potent antioxidant and anti-inflammatory properties.

Oxidative Stress, Antioxidant Capabilities, and Bioavailability: Ellagic Acid or Urolithins?

Oxidative stress (OS), triggered by overproduction of reactive oxygen and nitrogen species, is the main mechanism responsible for several human diseases. The available one-target drugs often face such illnesses, by softening symptoms without eradicating the cause. Differently, natural polyphenols from fruits and vegetables possess multi-target abilities for counteracting OS, thus representing promising therapeutic alternatives and adjuvants. Although in several in vitro experiments, ellagitannins (ETs), ellagic acid (EA), and its metabolites urolithins (UROs) have shown similar great potential for the treatment of OS-mediated human diseases, only UROs have demonstrated in vivo the ability to reach tissues to a greater extent, thus appearing as the main molecules responsible for beneficial activities. Unfortunately, UROs production depends on individual metabotypes, and the consequent extreme variability limits their potentiality as novel therapeutics, as well as dietary assumption of EA, EA-enriched functional foods, and food supplements. This review focuses on the pathophysiology of OS; on EA and UROs chemical features and on the mechanisms of their antioxidant activity. A discussion on the clinical applicability of the debated UROs in place of EA and on the effectiveness of EA-enriched products is also included.

Synthesis, Characterization, Molecular Docking, and Biological Activities of Some Natural and Synthetic Urolithin Analogs

Urolithins (that is, hydroxy substituted benzo[c]chromen-6-one derivatives) are formed within the gastrointestinal tract following to the exposure to various ellagitannin rich diet, particularly involving pomegranate, nuts, and berries. Regarding the bioavailability deficiency of ellagitannins, the biological activities obtained through the extracts of these dietaries are attributed to the urolithin compounds, since they are bioavailable. Particularly, there are studies indicating the importance of ellagitannin-rich food for protective and alternative treatment of Alzheimer's Disease (AD). From this perspective, within this study, the major urolithins (that is, urolithins A and B), their methyl ether metabolites, as well as some synthetic urolithin analogs have been synthesized and screened for their biological activities in various enzyme inhibition (acetylcholinesterase, butyrylcholinesterase, monoamine oxidase B, cyclooxygenase 1, and cyclooxygenase 2) and antioxidant (DPPH radical scavenging) assay systems. The results pointed out the potential of urolithins to act as inhibitors on these receptors. Docking studies were also performed to investigate the possible interactions.

The Ethyl Acetate Extract of Leaves of Ugni molinae Turcz. Improves Neuropathological Hallmarks of Alzheimer's Disease in Female APPswe/PS1dE9 Mice Fed with a High Fat Diet

The most common type of dementia is Alzheimer's disease (AD), a progressive neurodegenerative disease characterized by impairment in cognitive performance in aged individuals. Currently, there is no effective pharmacological treatment that cures the disease due to the lack of knowledge on the actual mechanisms involved in its pathogenesis. In the last decades, the amyloidogenic hypothesis has been the most studied theory trying to explain the origin of AD, yet it does not address all the concerns relating to its development. In the present study, a possible new preclinical treatment of AD was evaluated using the ethyl acetate extract (EAE) of leaves of Ugni molinae Turcz. (synonym Myrtus ugni Molina Family Myrtacea). The effects were assessed on female transgenic mice from a preclinical model of familial AD (APPswe/PS1dE9) combined with a high fat diet. This preclinical model was selected due to the already available experimental and observational data proving the relationship between obesity, gender, metabolic stress, and cognitive dysfunction; related to characteristics of sporadic AD. According to chemical analyses, EAE would contain polyphenols such as tannins, flavonoid derivatives, and phenolic acids, as well as pentacyclic triterpenoids that exhibit neuroprotective, anti-inflammatory, and antioxidant effects. In addition, the treatment evidenced its capacity to prevent deterioration of memory capacity and reduction of progression speed of AD neuropathology.

Ellagic acid improves muscle dysfunction in cuprizone-induced demyelinated mice via mitochondrial Sirt3 regulation

Sirt3 enzyme and mitochondrial abnormality can be related to excess fatigue or muscular dysfunction in multiple sclerosis (MS).Ellagic acid (EA) has a mitochondrial protector, iron chelator, antioxidant, and axon regenerator in neurons.In this study the effect of EAon muscle dysfunction, its mitochondria, and Sirt3 enzyme incuprizone-induced model of MSwas examined. Demyelination was induced by a diet containing 0.2% w/w cuprizone (Cup) for 42 days and EA administered daily (5, 50, and 100 mg/kg P.O) either with or without cuprizone in mice. Behavioral tests were assessed, and muscle tissue markers ofoxidative stress, mitochondrial parameters, mitochondrial respiratory chain activity, the Sirt3 protein level, and Sirt3 expression were also determined. Luxol fast blue staining and the behavioral tests were performed toassess the implemented model. In Cup group an increased oxidative stress in their muscle tissues was observed. Also, muscle mitochondria exhibited mitochondria dysfunction, lowered mitochondrial respiratory chain activity, Sirt3 protein level, and Sirt3 expression.EA prevented most of these anomalous alterations. Sub-chronicEA co-treatment dose-dependently ameliorated behavioral and muscular impairment in mice that received Cup.EA can effectively protect muscle tissue against cuprizone-induced demeylination via the mitochondrial protection, oxidative stress prevention and Sirt3 overexpression.

Implication of NMDA-NO pathway in the antidepressant-like effect of ellagic acid in male mice

Depression is one the common psychiatric disorders through the world. Nitric oxide (NO) and N-methyl-d-aspartate receptor (NMDA-R) are involved in the pathophysiology of depression. Previous studies have been reported various pharmacological properties for ellagic acid (EA). We aimed to evaluate possible involvement of NMDA-NO pathway in the antidepressant-like effect of EA. To do this, we used relevant behavioral tests to evaluate depressive-like behavior. In order to find effective and sub-effective doses of agents, mice treated with EA (6.25, 12.5, 25, 50 and 100 mg/kg), L-NAME (5 and 10 mg/kg), L-arg (25 and 50 mg/kg), NMDA (75 and 150 mg/kg) and ketamine (0.25 and 0.5 mg/kg). Furthermore, mice were treated with combination of sub-effective dose of EA plus sub-effective doses of L-NAME and/or ketamine as well as treated with effective dose of EA in combination of effective doses of L-arg and/or NMDA. Level of NO and gene expression of NR2A and NR2B subunits of NMDA-R were assessed in the hippocampus. Results showed that EA dose dependently provoked antidepressant-like effects and also decreased the hippocampal NO level as well as expression of NMDA-Rs. Co-administration of sub-effective doses of L-NAME or ketamine with sub-effective dose of EA potentiated the effect of EA on behaviors, NO level as well as NMDA-Rs gene expression in the hippocampus. However, co-treatment of effective dose of EA with effective doses of L-arg or NMDA mitigated effects of EA. In conclusion, our data suggested that NMDA-NO, partially at least, are involved in the antidepressant-like effect of EA.

Pharmacological safety of Plinia cauliflora (Mart.) Kausel in rabbits

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Fruit peels of Plinia cauliflora are widely used in Brazilian traditional medicine.

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No studies have proved the safety of its pharmacological effects.

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We assessed the safety pharmacology of P. cauliflora extract (EEPC) in rabbits.

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EEPC did not cause any significant changes in several physiological systems.

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These data provide important safety data for its clinical use.

Fruit peels of Plinia cauliflora (Mart.) Kausel are widely used in Brazilian traditional medicine, but no studies have proved the safety of its pharmacological effects on the respiratory, cardiovascular, and central nervous systems. The present study assessed the safety pharmacology of P. cauliflora in New Zealand rabbits. First, an ethanol extract (EEPC) was selected for the pharmacological experiments and chemical characterization. Then, different groups of rabbits were orally treated with EEPC (200 and 2000 mg/kg) or vehicle. Acute behavioral and physiological alterations in the modified Irwin test, respiratory rate, arterial blood gas, and various cardiovascular parameters (i.e., heart rate, blood pressure, and electrocardiography) were evaluated. The main secondary metabolites that were identified in EEPC were ellagic acid, gallic acid, O-deoxyhexosyl quercetin, and the anthocyanin O-hexosyl cyanidin. No significant behavioral or physiological changes were observed in any of the groups. None of the doses of EEPC affected respiratory rate or arterial blood gas, with no changes on blood pressure or electrocardiographic parameters. The present study showed that EEPC did not cause any significant changes in respiratory, cardiovascular, or central nervous system function. These data provide scientific evidence of the effects of this species and important safety data for its clinical use.

Ellagic acid protects against diabetes-associated behavioral deficits in rats: Possible involved mechanisms

AIMS

Diabetes mellitus (DM), a chronic metabolic disease, is associated with behavioral deficits. It has been suggested that ellagic acid (EA), a natural polyphenol compound, has potent anti-diabetic, anti-inflammatory, and neuroprotective properties. The present study was aimed to explore the potential protective effects of EA against diabetes-associated behavioral deficits and verified possible involved mechanisms.

MAIN METHODS

Fifty adult male Wistar rats were randomly divided into five groups: i.e., CON: normal rats treated with vehicle (5 ml/kg/day; P.O.), EA: normal rats treated with EA (50 mg/kg/day; P.O.), STZ: diabetic rats treated with vehicle (5 ml/kg/day; P.O.), STZ + INS: diabetic rats treated with insulin (6 IU/rat/day; S.C.), STZ + EA: diabetic rats treated with EA (50 mg/kg/day; P.O.). All the groups were under treatment for eight consecutive weeks. During the seventh and eighth weeks, behavioral functions of the rats were assessed by commonly used behavioral tests. Subsequently, pro- and anti-inflammatory cytokines, neurotrophic factors, and also histological changes were evaluated in both cerebral cortex and hippocampus of the rats.

KEY FINDINGS

Chronic EA treatment attenuated anxiety/depression-like behaviors, improved exploratory/locomotor activities, and ameliorated cognitive deficits in diabetic rats. These results were accompanied by decreased blood glucose levels, modulation of inflammation status, improved neurotrophic support, and amelioration of neuronal loss in diabetic rats. In some aspects, treatment with EA was even more effective than insulin therapy.

SIGNIFICANCE

The current work's data confirms that EA could potentially serve as a novel, promising, and accessible protective agent against diabetes-associated behavioral deficits, owing to its anti-hyperglycemic, anti-inflammatory, and neurotrophic properties.

Small Molecule Natural Products and Alzheimer's Disease

Alzheimer's disease (AD) is a progressive and deadly neurodegenerative disease that is characterized by memory loss, cognitive impairment and dementia. Several hypotheses have been proposed for the pathogenesis based on the pathological changes in the brain of AD patients during the last few decades. Unfortunately, there is no effective agents/therapies to prevent or control AD at present. Currently, only a few drugs, which function as acetylcholinesterase (AChE) inhibitors or N-methyl-Daspartate (NMDA) receptor antagonists, are available to alleviate symptoms. Since many small molecule natural products have shown their functions as agonists or antagonists of receptors, as well as inhibitors of enzymes and proteins in the brain during the development of central nervous system (CNS) drugs, it is likely that natural products will play an important role in anti-AD drug development. We review recent papers on using small molecule natural products as drug candidates for the treatment of AD. These natural products possess antioxidant, anti-inflammatory, anticholinesterase, anti-amyloidogenic and neuroprotective activities. Moreover, bioactive natural products intended to be used for preventing AD, reducing the symptoms of AD and the new targets for treatment of AD are summarized.

Ellagic acid in suppressing in vivo and in vitro oxidative stresses

Oxidative stress is a biological condition produced by a variety of factors, causing several chronic diseases. Oxidative stress was, therefore, treated with natural antioxidants, such as ellagic acid (EA). EA has a major role in protecting against different diseases associated with oxidative stress. This review critically discussed the antioxidant role of EA in biological systems. The in vitro and in vivo studies have confirmed the protective role of EA in suppressing oxidative stress. The review also discussed the mechanism of EA in suppressing of oxidative stress, which showed that EA activates specific endogenous antioxidant enzymes and suppresses specific genes responsible for inflammation, diseases, or disturbance of biochemical systems. The amount of EA used and duration, which plays a significant role in the treatment of oxidative stress has been discussed. In conclusion, EA is a strong natural antioxidant, which possesses the suppressing power of oxidative stress in biological systems.

Antioxidative, anti-inflammatory and anti-apoptotic effects of ellagic acid in liver and brain of rats treated by D-galactose

Accumulating evidence has suggested that oxidative stress and apoptosis are involved in the ageing process. D-galactose (gal) has been reported to cause symptoms of ageing in rats, accompanied by liver and brain injuries. Our study aimed to investigate the potential antioxidative, anti-inflammatory and anti-apoptotic effects of ellagic acid and to explore how these effects act on rats in a D-gal-induced ageing model. Ageing was induced by subcutaneous injection of D-gal (100 mg/kg/d for 8 weeks). Ellagic acid was simultaneously administered to the D-gal-induced ageing rats once daily by intragastric gavage. Finally, the mental condition, body weight, organ index, levels of inflammatory cytokines, antioxidative enzymes, and liver function, as well as the expression of pro- and anti-apoptotic proteins, were monitored. Our results showed that ellagic acid could improve the mental condition, body weight, organ index and significantly decrease the levels of inflammatory cytokines, normalize the activities of antioxidative enzymes, and modulate the expression of apoptotic protein in ageing rats. In conclusion, the results of this study illustrate that ellagic acid was suitable for the treatment of some ageing-associated problems, such as oxidative stress, and had beneficial effects for age-associated diseases.

Chronic administration of ellagic acid improved the cognition in middle-aged overweight men

This study aimed to investigate if ellagic acid has beneficial effects on cognitive deficits in middle-aged overweight individuals and to propose a possible mechanism. A total of 150 middle-aged male participants, including 76 normal-weight and 74 overweight men, aged between 45 to 55 years, were recruited for this study. Both normal-weight and overweight participants were administered either 50 mg ellagic acid or placebo cellulose daily for 12 weeks. Blood lipids, peripheral brain-derived neurotrophic factor (BDNF), and saliva cortisol were assessed on the last day of the procedure to investigate the effects induced by ellagic acid. The results revealed that ellagic acid treatment improved the levels of blood lipid metabolism with a 4.7% decline in total cholesterol, 7.3% decline in triglycerides, 26.5% increase in high-density lipoprotein, and 6.5% decline in low-density lipoprotein. Additionally, ellagic acid increased plasma BDNF by 21.2% in the overweight group and showed no effects on normal-weight participants. Moreover, the increased saliva cortisol level in overweight individuals was inhibited by 22.7% in a 12-week ellagic acid treatment. Also, compared with placebo, overweight individuals who consumed ellagic acid showed enhanced cognitive function as measured by the Wechsler Adult Intelligence Scale-Revised and the Montreal Cognitive Assessment. To the best of our knowledge, this is the first report showing that ellagic acid prevents cognitive deficits through normalization of lipid metabolism, increase in plasma BDNF level, and reduction of saliva cortisol concentration. These results indicate that ellagic acid has a potential to restore cognitive performance related to mild age-related declines.

A novel DSC approach for evaluating protectant drugs efficacy against dementia

Differential scanning calorimetry was applied to evaluate the efficacy of preventive treatments with biologically active compounds of plant origin against neurodegenerative disorder in mice. As we reported recently, large differences exist between the heat capacity profiles of water-soluble brain proteome fractions from healthy animals and from animals with scopolamine-induced dementia: the profiles for healthy animals displayed well expressed exothermic event peaking at 40-45°C, by few degrees above body temperature, but still preceding in temperature the proteome endothermic denaturational transitions; the low-temperature exotherm was completely abolished by the scopolamine treatment. Here we explored this signature difference in the heat capacity profiles to assess the efficacy of preventive treatments with protectant drugs anticipated to slow down or block progression of dementia (myrtenal, ellagic acid, lipoic acid and their combinations, including also ascorbic acid). We found that these neuroprotectants counteract the scopolamine effect and partially or completely preserve the 'healthy' thermogram, and specifically the low-temperature exotherm. These results well correlate with the changes in the cognitive functions of the animals assessed using the Step Through Test for learning and memory. The exothermic event is deemed to be associated with a reversible process of fibrillization and/or aggregation of specific water-soluble brain protein fractions preceding their denaturation. Most importantly, the results demonstrate that the effect of scopolamine and its prevention by protectant substances are clearly displayed in the heat capacity profiles of the brain proteome, thus identifying DSC as a powerful method in drug testing and discovery.

Ellagic acid protects against neuron damage in ischemic stroke through regulating the ratio of Bcl-2/Bax expression

An oxygen-glucose deprivation and reoxygenation model in primary cultured rat cortical neurons was developed for this study to investigate the effects of ellagic acid (EA), a low-molecular-weight polyphenol, on neuron cells and their function, and to evaluate whether EA can be safely utilized by humans as a functional food or therapeutic agent. Administration of EA significantly decreased the volume of cerebrum infarction and the neurological deficit scores of the rats; EA treatment also increased the number of Bcl-2-positive cells and the ratio of Bcl-2-positive to Bax-positive neurons in the semidarkness zone near the brain ischemic focus in the photothrombotic cerebral ischemia model. Treatment of EA resulted in increased neuron viability, cell nuclear integrity, and the ratio of Bcl-2/Bax expression in the primary cultured neuron model; EA treatment also lead to a decrease in the number of apoptotic cells. Our results therefore suggest a specific mechanism for the beneficial effects of EA, providing new insights into how it provides neuroprotection. To the best of our knowledge, these results represent new insights on the mechanisms of the brain cell protective activity of EA. Thus, EA may be used in functional foods or medicines to help treat nerve dysfunction, neurodegenerative disease, and aging.

Neuroprotective Effects of Bioavailable Polyphenol-Derived Metabolites against Oxidative Stress-Induced Cytotoxicity in Human Neuroblastoma SH-SY5Y Cells

Oxidative stress is involved in cell death in neurodegenerative diseases. Dietary polyphenols can exert health benefits, but their direct effects on neuronal cells are debatable because most phenolics are metabolized and do not reach the brain as they occur in the dietary sources. Herein, we evaluate the effects of a panel of bioavailable polyphenols and derived metabolites at physiologically relevant conditions against H₂O₂-induced apoptosis in human neuroblastoma SH-SY5Y cells. Among the 19 metabolites tested, 3,4-dihydroxyphenylpropionic acid, 3,4-dihydroxyphenylacetic acid, gallic acid, ellagic acid, and urolithins prevented neuronal apoptosis via attenuation of ROS levels, increased REDOX activity, and decreased oxidative stress-induced apoptosis by preventing the caspase-3 activation via the mitochondrial apoptotic pathway in SH-SY5Y cells. This suggests that dietary sources containing the polyphenol precursors of these molecules such as cocoa, berries, walnuts, and tea could be potential functional foods to reduce oxidative stress associated with the onset and progress of neurodegenerative diseases.

Ellagic acid improves endogenous neural stem cells proliferation and neurorestoration through Wnt/β-catenin signaling in vivo and in vitro

SCOPE

The aim of this study is to research the effects of the polyphenol ellagic acid (EA) on brain cells and to explore its mechanism of action, and to evaluate whether EA can be safely utilized by humans as a functional food or therapeutic agent.

METHODS AND RESULTS

A photothrombosis-induced model of brain injury in rats was created, and EA was administered intragastrically to rats on 7 consecutive days post-venous ischemia. An oxygen-glucose deprivation and re-perfusion model was established in neural stem cells in order to research the effects on proliferation after 2 days of EA treatment in vitro. The administration of EA improved the rats' nerve-related abilities, remedied infarct volumes and morphological changes in the brain, and enhanced the content of nestin protein in the brain semidarkness zone. The proliferation of NSCs and the expression of β-catenin and Cyclin D1 genes were also increased in primary cultured NSCs.

CONCLUSIONS

EA administration can improve brain injury outcomes and increase the proliferation of NSCs through the Wnt/β-catenin signaling pathway. The presented results represent new insights on the mechanisms of the brain cell protective activity of EA. Thus, EA may be used in functional foods or medicines to help treat nerve dysfunction, neurodegenerative disease and aging.