Exploring the multifaceted neuroprotective actions of gallic acid: a review

Phytoconstituents Targeting the Serotonin 5-HT3 Receptor: Promising Therapeutic Strategies for Neurological Disorders

The 5-hydroxytryptamine-3 receptor (5-HT3R), a subtype of serotonin receptor, is a ligand-gated ion channel crucial in mediating fast synaptic transmission in the central and peripheral nervous systems. This receptor significantly influences various neurological activities, encompassing neurotransmission, mood regulation, and cognitive processing; hence, it may serve as an innovative target for neurological disorders. Multiple studies have revealed promising results regarding the beneficial effects of these phytoconstituents and extracts on conditions such as nausea, vomiting, neuropathic pain depression, anxiety, Alzheimer's disease, cognition, epilepsy, sleep, and dyskinesia via modulation of 5-HT3R in the pathophysiology of neurological disorder. The review delves into a detailed exploration of in silico, in vitro, and in vivo studies and clinical studies that discussed phytoconstituents acting on 5-HT3R and attenuates difficulties in neurological diseases. The diverse mechanisms by which plant-derived phytoconstituents influence 5-HT3R activity offer exciting avenues for developing innovative therapeutic interventions. Besides producing an agonistic or antagonistic effect, some phytoconstituents exert modulatory effects on 5-HT3R activity through multifaceted mechanisms. These include γ-aminobutyric acid and cholinergic neuronal pathways, interactions with neurokinin (NK)-1, NK2, serotonergic, and γ-aminobutyric acid(GABA)ergic systems, dopaminergic influences, and mediation of calcium ions release and inflammatory cascades. Notably, the phytoconstituent's capacity to reduce oxidative stress has also emerged as a significant factor contributing to their modulatory role. Despite the promising implications, there is currently a dearth of exploration needed to understand the effect of phytochemicals on the 5-HT3R. Comprehensive preclinical and clinical research is of the utmost importance to broaden our knowledge of the potential therapeutic benefits associated with these substances.

The genus Polygonum: An updated comprehensive review of its ethnomedicinal, phytochemical, pharmacological activities, toxicology, and phytopharmaceutical formulation

Polygonum is a plant genus that includes annual and perennial species and is found at various temperatures, from northern temperate regions to tropical and subtropical areas. The genus Polygonum has been used for centuries for various disorders, including hypertension, intestinal and stomach pain, dysuria, jaundice, toothaches, skin allergies, hemorrhoids, cardiac disorders, kidney stones, hemostasis, hyperglycemia, and others. Various databases, including Google Scholar, Scifinder, ScienceDirect, PubMed, Scopus, ResearchGate, and Web of Science, were utilized to collect pertinent scientific literature data. According to bibliographic studies, the Polygonum genus possesses various compounds from different families, including phenolic acids (gallic acid, caffeic acid, quinic acid, p-coumaric acid, ferulic acid, protocatechuic acid, chlorogenic acid, and many other compounds), flavonoids (quercetin, catechin, epicatechin, quercitrin, kaempferol, myricetin, etc.), tannins, stilbenes (polydatin and resveratrol), terpenes (α-pinene, β-caryophyllene and β-caryophyllene oxide, bisabolene, β-farnesene, etc.), fatty acids (decanoic acid, lauric acid, linoleic acid, oleic acid, palmitic acid, stearic acid, dodecanoic acid), polysaccharides, and others. Various chemical and biological activities (in vitro and in vivo), such as antioxidant, antimicrobial, anticancer, antitumor, anti-inflammatory, antidiabetic, antiparasitic, hepatoprotective, neuropharmacological, gastroprotective, diuretic, antipyretic, and others, have been described in several biological studies involving this species. An updated summary of Polygonum species and their ethnomedicinal, phytochemical, toxicological, pharmacological, and phytopharmaceutical formulations is necessary. Considering the numerous potentialities of the Polygonum species and their wide-ranging use, it is extremely essential to provide knowledge by compiling the accessible literature to identify the topics of intense investigation and the main gaps to better design future studies. The objective of this review is to give readers a better understanding, greater comprehension, and in-depth knowledge of the genus Polygonum's traditional applications, phytochemistry, pharmacology, toxicological features, and galenic formulation. Several species of this genus have been detailed in this review, including those that were frequently used in traditional medicine (P. minus, P. aviculare, P. hydropiper, P. cuspidatum, and P. multiflorum) and many of the genus' therapeutic species, like P. equisetiforme, which do not get enough attention.

Sweet basil (Ocimum basilicum) leaf and seed extracts alleviate neuronal dysfunction in aluminum chloride-induced neurotoxicity in Drosophila melanogaster Meigen model

Ocimum basilicum is an important medicinal plant and culinary herb generally known as sweet basil (SB). These plants are effective radical scavengers, that have been employed in treatment of nervous system disorders, and thus, could be beneficial for the management of neurodegenerative diseases (NDs). Current clinical treatments for NDs present several side effects, therefore, there is need to develop new treatments that can mitigate these deadly diseases. Hence, this study investigated the neuroprotective activities of SB leaf and seed in aluminum chloride (AlCl3)-induced toxicity in Drosophila melanogaster. HPLC characterization of the leaves and seeds were carried out. AlCl3-diet was used to induce neurodegeneration and treated flies received SB leaf and seed extracts-supplemented diet. Survival and locomotor performance activities/levels of oxidative biomarkers [reactive oxygen species (ROS), thiobarbituric acid reactive species (TBARS), total thiol, catalase, superoxide dismutase (SOD) and glutathione-S-transferase (GST)], enzymes linked with neurodegeneration (acetylcholinesterase (AChE) and monoamine oxidase (MAO)) were investigated. SB leaf had significantly (p < 0.05) higher polyphenol contents; gallic acid and P-coumaric acid were the most abundant polyphenol in the leaf and seed respectively. Percentage survival and locomotor rates, level/activities of total thiol, catalase, SOD and GST were significantly (p < 0.05) reduced while ROS, TBARS, AChE and MAO activities were significantly (p < 0.05) increased in AlCl3-diet-fed flies. Treatment with SB leaf and seed diet lessened these observed impairments. However, SB leaf had better neuroprotective activities that could be related to the observed higher phenolic constituents. Hence, SB leaf diet may offer improved therapeutic effect in NDs.

Neuroprotective properties of Betulin, Betulinic acid, and Ursolic acid as triterpenoids derivatives: a comprehensive review of mechanistic studies

Cognitive deficits are the main outcome of neurological disorders whose occurrence has risen over the past three decades. Although there are some pharmacologic approaches approved for managing neurological disorders, it remains largely ineffective. Hence, exploring novel nature-based nutraceuticals is a pressing need to alleviate the results of neurodegenerative diseases, such as Alzheimer's disease (AD) and other neurodegenerative disorders. Some triterpenoids and their derivates can be considered potential therapeutics against neurological disorders due to their neuroprotective and cognitive-improving effects. Betulin (B), betulinic acid (BA), and ursolic acid (UA) are pentacyclic triterpenoid compounds with a variety of biological activities, including antioxidative, neuroprotective and anti-inflammatory properties. This review focuses on the therapeutic efficacy and probable molecular mechanisms of triterpenoids in damage prevention to neurons and restoring cognition in neurodegenerative diseases. Considering few studies on this concept, the precise mechanisms that mediate the effect of these compounds in neurodegenerative disorders have remained unknown. The findings can provide sufficient information about the advantages of these compounds against neurodegenerative diseases.

Modification of cellulosic adsorbent via iron-based metal phenolic networks coating for efficient removal of chromium ion

Surface modification of durian rind cellulose (DCell) was done by utilizing the strong coordination effect of polyphenol-based metal phenolic networks (MPNs). MPNs from Fe(III)-tannic acid (FTN) and Fe(III)-gallic acid (FGN) were coated on DCell via a self-assembly reaction at pH 8, resulting in adsorbent composites of FTN@DCell and FGN@DCell for removal of Cr(VI). Batch adsorption experiments revealed that FTN coating resulted in an adsorbent composite with higher adsorption capacity than FGN coating, owing to the greater number of additional adsorption sites from phenolic hydroxyl groups of tannic acid. FTN@DCell exhibits an equilibrium adsorption capacity at 30°C of 110.9 mg/g for Cr(VI), significantly higher than FGN@DCell (73.63 mg/g); the adsorption capacity was increased at higher temperature (i.e., 155.8 and 116.8 mg/g at 50°C for FTN@DCell and FGN@DCell, respectively). Effects of pH, adsorbent dose, initial concentration, and coexisting ions on Cr(VI) removal were investigated. The kinetics fractal-based model Brouers-Sotolongo indicates the 1st and 2nd order reaction for Cr(VI) adsorption on FTN@DCell and FGN@DCell, respectively. The isotherm data can be described with a fractal-based model, which implies the heterogeneous nature of the adsorbent surface sites. The Cr(VI) adsorption via surface complexation with phenolic hydroxyl groups was confirmed by evaluating the functional groups shifting. FGN@DCell and FTN@DCell were found to have good reusability, maintaining over 50 % of their adsorption efficiency after four adsorption-desorption cycles. Environmental assessment with Arabidopsis thaliana demonstrated their potential in eliminating the Cr(VI) phytotoxic effect. Thus, this study has shown the efficient and economical conversion of durian waste into environmentally benign adsorbent for heavy metal treatment.

Natural Phenolic Compounds with Neuroprotective Effects

Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal cytotoxicity and degeneration. Huntington's (HD), Alzheimer's (AD), and Parkinson's (PD) diseases are three of the major neurodegenerative diseases. To date, researchers have found various natural phytochemicals that could potentially be used to treat neurodegenerative diseases. Particularly, the application of natural phenolic compounds has gained significant traction in recent years, driven by their various biological activities and therapeutic efficacy in human health. Polyphenols, by modulating different cellular functions, play an important role in neuroprotection and can neutralize the effects of oxidative stress, inflammation, and apoptosis in animal models. This review focuses on the current state of knowledge on phenolic compounds, including phenolic acids, flavonoids, stilbenes, and coumarins, as well as their beneficial effects on human health. We further provide an overview of the therapeutic potential and mechanisms of action of natural dietary phenolics in curing neurodegenerative diseases in animal models.

Effects of gallic acid on the release of aroma compounds in Moutai Baijiu

Due to the trace concentrations of gallic acid (GA), the interaction mechanism between GA and flavor compounds is limited, and the effects on the aroma compounds of Moutai Baijiu are even more unclear. In this study, the aroma compounds and phenolic compounds in Moutai Baijiu were investigated by stir bar sorptive extraction (SBSE), gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). A total of 63 volatiles and 10 phenolic compounds were identified, and 16 esters and 4 alcohols were identified as the important aroma substances (odor activity values ≥1). The effect of GA on the release of aroma compounds was investigated by sensory analysis and partition coefficient. The results showed that GA mainly inhibited the volatilization of alcohols, low concentrations of GA promoted the release of esters, and high concentrations slowed down or even inhibited the release effect affected by the hydrophobicity of aroma compounds. UV spectroscopy and thermodynamic analysis further revealed that the interaction of GA with 1-propanol was attributed mainly to hydrogen bonding and van der Waals forces, and the interaction with other compounds was mainly influenced by hydrophobic effects. These results show that gallic acid can effectively control the release of the aromas of Moutai Baijiu, highlight the important role of GA on the volatiles of baijiu, and provide theoretical support for further healthy improvement of the sensory quality of baijiu.

Mediterranean Shrub Species as a Source of Biomolecules against Neurodegenerative Diseases

Neurodegenerative diseases are associated with oxidative stress, due to an imbalance in the oxidation-reduction reactions at the cellular level. Various treatments are available to treat these diseases, although they often do not cure them and have many adverse effects. Therefore, it is necessary to find complementary and/or alternative drugs that replace current treatments with fewer side effects. It has been demonstrated that natural products derived from plants, specifically phenolic compounds, have a great capacity to suppress oxidative stress and neutralize free radicals thus, they may be used as alternative alternative pharmacological treatments for pathological conditions associated with an increase in oxidative stress. The plant species that dominate the Mediterranean ecosystems are characterized by having a wide variety of phenolic compound content. Therefore, these species might be important sources of neuroprotective biomolecules. To evaluate this potential, 24 typical plant species of the Mediterranean ecosystems were selected, identifying the most important compounds present in them. This set of plant species provides a total of 403 different compounds. Of these compounds, 35.7% are phenolic acids and 55.6% are flavonoids. The most relevant of these compounds are gallic, vanillic, caffeic, chlorogenic, p-coumaric, and ferulic acids, apigenin, kaempferol, myricitrin, quercetin, isoquercetin, quercetrin, rutin, catechin and epicatechin, which are widely distributed among the analyzed plant species (in over 10 species) and which have been involved in the literature in the prevention of different neurodegenerative pathologies. It is also important to mention that three of these plant species, Pistacea lentiscus, Lavandula stoechas and Thymus vulgaris, have most of the described compounds with protective properties against neurodegenerative diseases. The present work shows that the plant species that dominate the studied geographic area can provide an important source of phenolic compounds for the pharmacological and biotechnological industry to prepare extracts or isolated compounds for therapy against neurodegenerative diseases.

Emerging Role of Plant-Based Bioactive Compounds as Therapeutics in Parkinson's Disease

Neurological ailments, including stroke, Alzheimer's disease (AD), epilepsy, Parkinson's disease (PD), and other related diseases, have affected around 1 billion people globally to date. PD stands second among the common neurodegenerative diseases caused as a result of dopaminergic neuron loss in the midbrain's substantia nigra regions. It affects cognitive and motor activities, resulting in tremors during rest, slow movement, and muscle stiffness. There are various traditional approaches for the management of PD, but they provide only symptomatic relief. Thus, a survey for finding new biomolecules or substances exhibiting the therapeutic potential to patients with PD is the main focus of present-day research. Medicinal plants, herbal formulations, and natural bioactive molecules have been gaining much more attention in recent years as synthetic molecules orchestrate a number of undesired effects. Several in vitro, in vivo, and in silico studies in the recent past have demonstrated the therapeutic potential of medicinal plants, herbal formulations, and plant-based bioactives. Among the plant-based bioactives, polyphenols, terpenes, and alkaloids are of particular interest due to their potent anti-inflammatory, antioxidant, and brain-health-promoting properties. Further, there are no concise, elaborated articles comprising updated mechanism-of-action-based reviews of the published literature on potent, recently investigated (2019-2023) medicinal plants, herbal formulations, and plant based-bioactive molecules, including polyphenols, terpenes, and alkaloids, as a method for the management of PD. Therefore, we designed the current review to provide an illustration of the efficacious role of various medicinal plants, herbal formulations, and bioactives (polyphenols, terpenes, and alkaloids) that can become potential therapeutics against PD with greater specificity, target approachability, bioavailability, and safety to the host. This information can be further utilized in the future to develop several value-added formulations and nutraceutical products to achieve the desired safety and efficacy for the management of PD.

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.

Effects of Key Components on the Antioxidant Activity of Black Tea

Many components (such as tea polyphenols, catechins, theaflavins, theasinensins, thearubigins, flavonoids, gallic acid, etc.) in black tea have antioxidant activities. However, it is not clear which components have a greater influence on the antioxidant activity of black tea. In this study, the antioxidant activity and contents of tea polyphenols, catechins, theaflavins, thearubigins, theabrownins, TSA, total flavonoids, amino acids, caffeine, and total soluble sugar were analyzed in 51 black teas. Principal component analysis (PCA), orthogonal partial least-squares discrimination analysis (OPLS-DA), and the correlation analysis method were used for data analysis. The results showed that catechins in tea polyphenols were the most important components that determine the antioxidant activity of black tea. Among them, epicatechin gallate (ECG), epi-gallocatechin gallate (EGCG), epicatechin (EC), and epi-gallocatechin (EGC) were significantly positively correlated with the antioxidant activity of black tea, and theabrownin was negatively correlated with the antioxidant activity of black tea. Furthermore, this study analyzed the correlation between the changes in catechin and its oxidized polymers with antioxidant activity during black tea fermentation; it verified that catechins were significantly positively correlated with the antioxidant activity of black tea, and theabrownin showed a negative correlation. And the antioxidant activity of catechins and their oxidation products in vitro and their correlation in black tea processing were used as validation. This study provides a comparison method for comparing the antioxidant activity of black tea.

Gallic acid improves liver cirrhosis by reducing oxidative stress and fibrogenesis in the liver of rats induced by bile duct ligation

Disturbance in the production and excretion of bile acid causes cholestatic liver disease. Liver cirrhosis is a disease that occurs if cholestasis continues. This study evaluated the protective effect of gallic acid (GA) on liver damage caused by biliary cirrhosis. Rats were randomly divided into 4 groups, each with 8 subjects: 1) control, 2) BDL, 3) BDL + GA 20, and 4) BDL + GA 30. The rats were anesthetized 28 days after the BDL, followed by collecting their blood and excising their liver. Their serum was used to measure liver enzymes, and the liver was used for biochemical analysis, gene expression, and histopathological analysis. Serum levels of liver enzymes, total bilirubin, liver Malondialdehyde level (MDA), expression of inflammatory cytokines and caspase-3, necrosis of hepatocytes, bile duct proliferation, lymphocytic infiltration, and liver fibrosis showed an increase in the BDL group compared to the control group (p < 0.05). In addition, BDL decreased the activity of liver antioxidant enzymes and glutathione (GSH) levels compared to the control group (p < 0.05). The groups receiving GA indicated a decrease in liver enzymes, total bilirubin, MDA, the expression of inflammatory cytokines and caspase-3, and a reduction in liver tissue damage compared to the BDL group (p < 0.05). The level of GSH in the BDL + GA 20 group showed a significant increase compared to the BDL group (p < 0.05). Moreover, it was found that GA, with its anti-fibrotic and anti-inflammatory properties, reduces liver damage caused by biliary cirrhosis.

The effect of gallic acid on malondialdehyde, hydrogen peroxide and nitric oxide that influence viability of broiler blood cells at the high ambient temperatures

1. The objective of this study was to measure the effect of gallic acid on levels of ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and the viability of broiler blood cells (BBCs) when exposed to high ambient temperature.2. The BBCs were maintained at 41.5°C (control group, CG) or at ambient temperatures ranging from 41.5°C to 46°C. At 41.5°C to 46°C, BBCs were diluted with gallic acid at 0 (positive control group, PCG), 6.25, 12.5, 25 and 50 µmol, respectively. Ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and viability of BBCs were investigated.3. Hydrogen peroxide, malondialdehyde and nitric oxide for the CG was lower than PCG (P<0.05). However, the viability of CG was higher than PCG (P<0.05). At 41.5 to 46°C, malondialdehyde, hydrogen peroxide, and nitric oxide of BBCs diluted with gallic acid were lower compared to PCG (P<0.05). Viability of BBCs diluted with gallic acid was higher than PCG (P<0.05).4. These results indicated that gallic acid could reduce the adverse oxidative effects of high ambient temperature on BBCs, with an optimum dilution rate of 12.5 µmol.

Protective effects of vanillic acid on autistic-like behaviors in a rat model of maternal separation stress: Behavioral, electrophysiological, molecular and histopathological alterations

Compounds derived from herbs exhibit a range of biological properties, including anti-inflammatory, antioxidant, and neuroprotective properties. However, the exact mechanism of action of these compounds in various neurological disorders is not fully discovered yet. Herein, the present work detected the effect of Vanillic acid (VA), a widely-used flavoring agent derived from vanillin, on autistic-like behaviors to assess the probable underlying mechanisms that mediate behavioral, electrophysiological, molecular, and histopathological alterations in the rat model of maternal separation (MS) stress. Maternal separated rats were treated with VA (25, 50, and 100 mg/kg interperitoneally for 14 days). In addition, anxiety-like, autistic-like behaviors, and learning and memory impairment were evaluated using various behavioral tests. Hippocampus samples were assessed histopathologically by H&E staining. Levels of malondialdehyde (MDA) and antioxidant capacity (by the FRAP method), as well as nitrite levels, were measured in brain tissue. Moreover, gene expression of inflammatory markers (IL-1β, TLR-4, TNF-α, and NLRP3) was evaluated in the hippocampus. Electrophysiological alterations were also estimated in the hippocampus by long-term potentiation (LTP) assessments. Results showed that VA reversed the negative effects of MS on behavior. VA increased the diameter and decreased the percentage of dark neurons in the CA3 area. Accordingly, VA decreased MDA and nitrite levels and increased the antioxidant capacity in brain samples and decreased the expression of all inflammatory genes. VA treated rats showed significant improvements in all LTP parameters. This study provided evidence suggesting a possible role for VA in preventing autism spectrum disorder (ASD) by regulating immune signaling.

The Potential Use of Honey as a Neuroprotective Agent for the Management of Neurodegenerative Diseases

As the global population ages, there is an increasing research on managing neurodegenerative diseases that mainly affect the elderly. Honey is one of the natural products and functional foods widely studied for its neuroprotective properties. This review investigates honey's effectiveness as a neuroprotective agent through in vitro, in vivo, and clinical research. The articles were browsed from three databases (PubMed, ScienceDirect, and Scopus) between the years of 2012 and 2022 using the keywords "honey" crossed with "neurodegenerative". Out of the 16 articles, six in vitro, eight in vivo, one combination study, and one clinical intervention were compiled. Among the various types of honey studied, the Tualang and Thyme honey exhibited the highest antioxidant, anti-inflammatory, and anticholinesterase activity, leading to the prevention and management of multiple neurodegenerative diseases such as Alzheimer's disease. The neuroprotective properties of honey are primarily attributed to its high polyphenol content, with quercetin and gallic acid being the most prominent. This review compiled considerable evidence of the anti-neurodegenerative properties of honey presented by in vitro and in vivo studies. However, more clinical intervention studies are required to support these findings further.

Neurobiological effects of gallic acid: current perspectives

Gallic acid (GA) is a phenolic molecule found naturally in a wide range of fruits as well as in medicinal plants. It has many health benefits due to its antioxidant properties. This study focused on finding out the neurobiological effects and mechanisms of GA using published data from reputed databases. For this, data were collected from various sources, such as PubMed/Medline, Science Direct, Scopus, Google Scholar, SpringerLink, and Web of Science. The findings suggest that GA can be used to manage several neurological diseases and disorders, such as Alzheimer's disease, Parkinson's disease, strokes, sedation, depression, psychosis, neuropathic pain, anxiety, and memory loss, as well as neuroinflammation. According to database reports and this current literature-based study, GA may be considered one of the potential lead compounds to treat neurological diseases and disorders. More preclinical and clinical studies are required to establish GA as a neuroprotective drug.

Polyphenols Mediate Neuroprotection in Cerebral Ischemic Stroke-An Update

Stroke is one of the main causes of mortality and disability, and it is due to be included in monetary implications on wellbeing frameworks around the world. Ischemic stroke is caused by interference in cerebral blood flow, leading to a deficit in the supply of oxygen to the affected region. It accounts for nearly 80-85% of all cases of stroke. Oxidative stress has a significant impact on the pathophysiologic cascade in brain damage leading to stroke. In the acute phase, oxidative stress mediates severe toxicity, and it initiates and contributes to late-stage apoptosis and inflammation. Oxidative stress conditions occur when the antioxidant defense in the body is unable to counteract the production and aggregation of reactive oxygen species (ROS). The previous literature has shown that phytochemicals and other natural products not only scavenge oxygen free radicals but also improve the expressions of cellular antioxidant enzymes and molecules. Consequently, these products protect against ROS-mediated cellular injury. This review aims to give an overview of the most relevant data reported in the literature on polyphenolic compounds, namely, gallic acid, resveratrol, quercetin, kaempferol, mangiferin, epigallocatechin, and pinocembrin, in terms of their antioxidant effects and potential protective activity against ischemic stroke.

Non-Enzymatic Antioxidants against Alzheimer's Disease: Prevention, Diagnosis and Therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss and cognitive decline. Although substantial research has been conducted to elucidate the complex pathophysiology of AD, the therapeutic approach still has limited efficacy in clinical practice. Oxidative stress (OS) has been established as an early driver of several age-related diseases, including neurodegeneration. In AD, increased levels of reactive oxygen species mediate neuronal lipid, protein, and nucleic acid peroxidation, mitochondrial dysfunction, synaptic damage, and inflammation. Thus, the identification of novel antioxidant molecules capable of detecting, preventing, and counteracting AD onset and progression is of the utmost importance. However, although several studies have been published, comprehensive and up-to-date overviews of the principal anti-AD agents harboring antioxidant properties remain scarce. In this narrative review, we summarize the role of vitamins, minerals, flavonoids, non-flavonoids, mitochondria-targeting molecules, organosulfur compounds, and carotenoids as non-enzymatic antioxidants with AD diagnostic, preventative, and therapeutic potential, thereby offering insights into the relationship between OS and neurodegeneration.

An insight into the neuroprotective and anti-neuroinflammatory effects and mechanisms of Moringa oleifera

Neurodegenerative diseases (NDs) are sporadic maladies that affect patients' lives with progressive neurological disabilities and reduced quality of life. Neuroinflammation and oxidative reaction are among the pivotal factors for neurodegenerative conditions, contributing to the progression of NDs, such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS) and Huntington's disease (HD). Management of NDs is still less than optimum due to its wide range of causative factors and influences, such as lifestyle, genetic variants, and environmental aspects. The neuroprotective and anti-neuroinflammatory activities of Moringa oleifera have been documented in numerous studies due to its richness of phytochemicals with antioxidant and anti-inflammatory properties. This review highlights up-to-date research findings on the anti-neuroinflammatory and neuroprotective effects of M. oleifera, including mechanisms against NDs. The information was gathered from databases, which include Scopus, Science Direct, Ovid-MEDLINE, Springer, and Elsevier. Neuroprotective effects of M. oleifera were mainly assessed by using the crude extracts in vitro and in vivo experiments. Isolated compounds from M. oleifera such as moringin, astragalin, and isoquercitrin, and identified compounds of M. oleifera such as phenolic acids and flavonoids (chlorogenic acid, gallic acid, ferulic acid, caffeic acid, kaempferol, quercetin, myricetin, (-)-epicatechin, and isoquercitrin) have been reported to have neuropharmacological activities. Therefore, these compounds may potentially contribute to the neuroprotective and anti-neuroinflammatory effects. More in-depth studies using in vivo animal models of neurological-related disorders and extensive preclinical investigations, such as pharmacokinetics, toxicity, and bioavailability studies are necessary before clinical trials can be carried out to develop M. oleifera constituents into neuroprotective agents.

Transferrin-Functionalized Liposomes for the Delivery of Gallic Acid: A Therapeutic Approach for Alzheimer’s Disease

Senile plaques composed of amyloid β (Aβ) fibrils are considered the leading cause of Alzheimer’s disease (AD). Molecules with the ability to inhibit Aβ aggregation and/or promote Aβ clearance are thus a promising approach for AD therapy. Our group recently demonstrated that gallic acid (GA) has strong anti-amyloidogenic properties. In this study, stealth liposomes were prepared for the delivery of GA for AD therapy. The liposomes were functionalized with transferrin (Tf) to direct them to the brain, since Tf receptors are overexpressed in the endothelial cells of the blood–brain barrier. GA-loaded Tf-functionalized liposomes showed mean diameters of 130 nm, low polydispersity index values, and neutral zeta potential. Moreover, the produced nanocarriers promoted the sustained release of GA over 5 days and are physically stable for 1 month under storage conditions. Furthermore, GA-loaded Tf-functionalized liposomes showed a strong ability to interact with Aβ1-42 monomers, slowing down the Aβ monomer-to-oligomer and oligomer-to-fibril transitions and decreasing the number of fibrils formed by 56%. In addition, the NPs disaggregated approximately 30% of preformed Aβ fibrils. The presented results suggest that Tf-functionalized liposomes could be a viable platform for the brain delivery of GA for AD therapy. Studies with animal models of AD will be valuable for validating the therapeutic efficacy of this novel liposomal formulation.

Phikud Navakot extract attenuates lipopolysaccharide-induced inflammatory responses through inhibition of ERK1/2 phosphorylation in a coculture system of microglia and neuronal cells

ETHNOPHARMACOLOGICAL RELEVANCE

Phikud Navakot (PN), a mixture of nine herbal plants, is an ancient Thai traditional medicine used for relieving circulatory disorders and dizziness. PN has also shown anti-inflammatory effects in rats with acute myocardial infarction. Moreover, phytochemical-inhibiting neuroinflammation, including gallic acid, vanillic acid, ferulic acid, and rutin were detected in PN extract; however, the anti-neuroinflammatory activity of PN extract and its components in a coculture system of microglia and neuronal cells is limited.

OBJECTIVE

To investigate the anti-neuroinflammatory activities of PN on lipopolysaccharide (LPS)-induced inflammation in a coculture system of microglia and neuronal cells.

METHODS

ELISA and qRT-PCR were used to assess cytokine expression. The phosphorylation of mitogen-activated protein kinases (MAPKs) was determined by Western blotting. Microglia-mediated neuroinflammation was evaluated using a BV-2 microglia-N2a neuron transwell co-culture.

RESULTS

PN extract and its component, gallic acid, decreased LPS-induced the mRNA expression of interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS), as well as IL-6 protein levels in both microglial monoculture and coculture systems. This was accompanied by a reduction in neurodegeneration triggered by microglia in N2a neurons with increased neuronal integrity markers (βIII tubulin and tyrosine hydroxylase (TH)). These effects were caused by the ability of PN extract to inhibit extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) activation.

CONCLUSION

This is the first study to show that PN extract inhibits neurodegeneration in LPS-activated BV-2 microglia by targeting ERK signaling activity.

Identifying Drug Targets of Oral Squamous Cell Carcinoma through a Systems Biology Method and Genome-Wide Microarray Data for Drug Discovery by Deep Learning and Drug Design Specifications

In this study, we provide a systems biology method to investigate the carcinogenic mechanism of oral squamous cell carcinoma (OSCC) in order to identify some important biomarkers as drug targets. Further, a systematic drug discovery method with a deep neural network (DNN)-based drug–target interaction (DTI) model and drug design specifications is proposed to design a potential multiple-molecule drug for the medical treatment of OSCC before clinical trials. First, we use big database mining to construct the candidate genome-wide genetic and epigenetic network (GWGEN) including a protein–protein interaction network (PPIN) and a gene regulatory network (GRN) for OSCC and non-OSCC. In the next step, real GWGENs are identified for OSCC and non-OSCC by system identification and system order detection methods based on the OSCC and non-OSCC microarray data, respectively. Then, the principal network projection (PNP) method was used to extract core GWGENs of OSCC and non-OSCC from real GWGENs of OSCC and non-OSCC, respectively. Afterward, core signaling pathways were constructed through the annotation of KEGG pathways, and then the carcinogenic mechanism of OSCC was investigated by comparing the core signal pathways and their downstream abnormal cellular functions of OSCC and non-OSCC. Consequently, HES1, TCF, NF-κB and SP1 are identified as significant biomarkers of OSCC. In order to discover multiple molecular drugs for these significant biomarkers (drug targets) of the carcinogenic mechanism of OSCC, we trained a DNN-based drug–target interaction (DTI) model by DTI databases to predict candidate drugs for these significant biomarkers. Finally, drug design specifications such as adequate drug regulation ability, low toxicity and high sensitivity are employed to filter out the appropriate molecular drugs metformin, gefitinib and gallic-acid to combine as a potential multiple-molecule drug for the therapeutic treatment of OSCC.

Gallic and ascorbic acids supplementation alleviate cognitive deficits and neuropathological damage exerted by cadmium chloride in Wistar rats

Cadmium is a highly neurotoxic heavy metal that interferes with DNA repair mechanisms via generation of reactive oxygen species. The potentials of polyphenols and antioxidants as effective protective agents following heavy metal-induced neurotoxicity are emerging. We therefore explored the neuroprotective potentials of gallic and ascorbic acids in CdCl₂-induced neurotoxicity. Seventy-two Wistar rats were divided into six groups. Group A received distilled water, B: 3 mg/kg CdCl₂, C: 3 mg/kg CdCl₂ + 20 mg/kg gallic acid (GA), D: 3 mg/kg CdCl₂ + 10 mg/kg ascorbic acid (AA), E: 20 mg/kg GA and F: 10 mg/kg AA orally for 21 days. Depression, anxiety, locomotion, learning and memory were assessed using a battery of tests. Neuronal structure and myelin expression were assessed with histological staining and immunofluorescence. The Morris Water Maze test revealed significant increase in escape latency in CdCl₂ group relative to rats concurrently treated with GA or AA. Similarly, time spent in the target quadrant was reduced significantly in CdCl₂ group relative to other groups. Concomitant administration of gallic acid led to significant reduction in the durations of immobility and freezing that were elevated in CdCl₂ group during forced swim and open field tests respectively. Furthermore, GA and AA restored myelin integrity and neuronal loss observed in the CdCl₂ group. We conclude that gallic and ascorbic acids enhance learning and memory, decrease anxiety and depressive-like behavior in CdCl₂-induced neurotoxicity with accompanying myelin-protective ability.

Natural Antioxidant Compounds as Potential Pharmaceutical Tools against Neurodegenerative Diseases

Natural antioxidants are a very large diversified family of molecules classified by activity (enzymatic or nonenzymatic), chemical-physical properties (e.g., hydrophilic or lipophilic), and chemical structure (e.g., vitamins, polyphenols, etc.). Research on natural antioxidants in various fields, such as pharmaceutics, nutraceutics, and cosmetics, is among the biggest challenges for industry and science. From a biomedical point of view, the scavenging activity of reactive oxygen species (ROS) makes them a potential tool for the treatment of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, dementia, and amyotrophic lateral sclerosis (ALS). In addition to the purified phytochemical compounds, a variety of natural extracts characterized by a complex mixture of antioxidants and anti-inflammatory molecules have been successfully exploited to rescue preclinical models of these diseases. Extracts derived from Ginkgo biloba, grape, oregano, curcumin, tea, and ginseng show multitherapeutic effects by synergically acting on different biochemical pathways. Furthermore, the reduced toxicity associated with many of these compounds limits the occurrence of side effects. The support of nanotechnology for improving brain delivery, controlling release, and preventing rapid degradation and excretion of these compounds is of fundamental importance. This review reports on the most promising results obtained on in vitro systems, in vivo models, and in clinical trials, by exploiting natural-derived antioxidant compounds and extracts, in their free form or encapsulated in nanocarriers.

Gallic acid leads to cell death of Candida albicans by the apoptosis mechanism

Aim: To evaluate the antifungal activity of gallic acid (GA) against the strains of Candida spp. resistant to fluconazole and to determine its mechanism of action. Materials & methods: Antifungal activity was evaluated using the broth microdilution and flow cytometry techniques. Results: GA presented minimum inhibitory concentrations ranging from 16 to 72 μg/ml, causing alterations of the membrane integrity and mitochondrial transmembrane potential, production of reactive oxygen species and externalization of phosphatidylserine. Conclusion: GA has potential antifungal activity against Candida spp.

Separation of gallic acid from Cornus officinalis and its interactions with corn starch

D101 macroporous resin combined with high speed counter-current chromatography (D101 MR-HSCCC) was used to separate gallic acid (GA) from Cornus officinalis, and GA was added to starch-based products to improve food quality. The interaction and action mechanism of corn starch (CS) with GA were investigated for prediction and thereby controlling the structure and functions of starch-based foods. Results show that GA with 98.72% purity was successfully obtained using the D101 MR-HSCCC technique. HSCCC solvent system was composed of n-hexane-ethyl acetate-methanol-water (1:5:1:5, v/v/v/v). GA inhibited CS dissolution and improved CS swelling. Based on the particle size distribution, GA could enlarge the size of CS-GA complexes. FT-IR spectra exhibit that the interactions between CS and GA may comprise the intermolecular hydrogen bond and non-covalent bond. The results of XRD, LF-NMR and AFM show that the presence of GA could increase the relative crystallinity of CS, decrease the spin relaxation time (T₂)_, and change the surface morphology of CS via the modification of hydrogen bonds distribution. Finally, SEM analysis indicates that GA could change the microstructure of CS-GA complexes. These findings facilitate the development of CS-based products and utilization of CS.

Gold Nanomaterials-Based Electrochemical Sensors and Biosensors for Phenolic Antioxidants Detection: Recent Advances

Antioxidants play a central role in the development and production of food, cosmetics, and pharmaceuticals, to reduce oxidative processes in the human body. Among them, phenolic antioxidants are considered even more efficient than other antioxidants. They are divided into natural and synthetic. The natural antioxidants are generally found in plants and their synthetic counterparts are generally added as preventing agents of lipid oxidation during the processing and storage of fats, oils, and lipid-containing foods: All of them can exhibit different effects on human health, which are not always beneficial. Because of their relevant bioactivity and importance in several sectors, such as agro-food, pharmaceutical, and cosmetic, it is crucial to have fast and reliable analysis Rmethods available. In this review, different examples of gold nanomaterial-based electrochemical (bio)sensors used for the rapid and selective detection of phenolic compounds are analyzed and discussed, evidencing the important role of gold nanomaterials, and including systems with or without specific recognition elements, such as biomolecules, enzymes, etc. Moreover, a selection of gold nanomaterials involved in the designing of this kind of (bio)sensor is reported and critically analyzed. Finally, advantages, limitations, and potentialities for practical applications of gold nanomaterial-based electrochemical (bio)sensors for detecting phenolic antioxidants are discussed.

Spectroscopic and computational studies on the binding interaction between gallic acid and Pin1

Gallic acid (GA) is a natural ingredient in functional foods, which has various health-promoting and antitumour effects. Peptidyl-prolyl cis/trans isomerase Pin1 plays an important role in preventing the development of some malignant tumours. However, whether there was an interaction between Pin1 and GA remains unknown. In this work, the binding information of GA and Pin1 was investigated systematically using multiple spectral and computational methods. GA bound to Pin1 directly with moderate binding affinity in the order of 10⁴  mol/L, therefore decreasing the activity of Pin1. Also, the binding process of GA to Pin1 was driven through weak van der Waals forces, hydrogen bonds, and electrostatic forces. In addition, the important residues Lys63, Arg68, and Arg69 played a significant role in maintaining the binding stability between Pin1 and GA. Interestingly, GA reduced the activity of Pin1 by affecting its conformational characteristics. Our present work showed that GA binds to Pin1 and inhibits its activity, affecting its structural and functional properties, which may contribute to the therapy of Pin1-related diseases.

A Review of the Health Protective Effects of Phenolic Acids against a Range of Severe Pathologic Conditions (Including Coronavirus-Based Infections)

Phenolic acids comprise a class of phytochemical compounds that can be extracted from various plant sources and are well known for their antioxidant and anti-inflammatory properties. A few of the most common naturally occurring phenolic acids (i.e., caffeic, carnosic, ferulic, gallic, p-coumaric, rosmarinic, vanillic) have been identified as ingredients of edible botanicals (thyme, oregano, rosemary, sage, mint, etc.). Over the last decade, clinical research has focused on a number of in vitro (in human cells) and in vivo (animal) studies aimed at exploring the health protective effects of phenolic acids against the most severe human diseases. In this review paper, the authors first report on the main structural features of phenolic acids, their most important natural sources and their extraction techniques. Subsequently, the main target of this analysis is to provide an overview of the most recent clinical studies on phenolic acids that investigate their health effects against a range of severe pathologic conditions (e.g., cancer, cardiovascular diseases, hepatotoxicity, neurotoxicity, and viral infections—including coronaviruses-based ones).

LC-ESI-QTOF-MS/MS Analysis, Cytotoxic, Antiviral, Antioxidant, and Enzyme Inhibitory Properties of Four Extracts of Geranium pyrenaicum Burm. f.: A Good Gift from the Natural Treasure

This study focused on the biological evaluation and chemical characterization of Geranium pyrenaicum Burm. f. Different solvent extracts (hexane, ethyl acetate, methanol, and water extracts) were prepared. The phytochemical profile, antioxidant, and enzyme inhibitory activity were investigated. Cytotoxicity was assessed using VERO, FaDu, HeLa and RKO cells. The antiviral activity was carried out against HSV-1 (Herpes simplex virus 1) propagated in VERO cell line. The aqueous extract, possessing high phenolic content (170.50 mg gallic acid equivalent/g extract), showed the highest reducing capacity (613.27 and 364.10 mg Trolox equivalent/g extract, for cupric reducing antioxidant capacity and ferric reducing antioxidant power, respectively), radical scavenging potential (469.82 mg Trolox equivalent/g extract, against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), metal chelating ability (52.39 mg ethylenediaminetetraacetic acid equivalent/g extract) and total antioxidant capacity (3.15 mmol Trolox equivalent/g extract). Liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (LC-ESI-QTOF-MS/MS) alloved to tentatively identify a total of 56 compounds in the extracts, including ellagitannins, gallic acid and galloyl derivatives amongst others. The ethyl acetate extracts substantially depressed cholinesterase enzymes (4.49 and 12.26 mg galantamine equivalent/g extract against AChE and BChE, respectively) and α-amylase enzyme (1.04 mmol acarbose equivalent/g extract). On the other hand, the methanolic extract inhibited tyrosinase (121.42 mg kojic acid equivalent/g extract) and α-glucosidase (2.39 mmol acarbose equivalent/g extract) activities. The highest selectivity towards all cancer cell lines (SI 4.5-10.8) was observed with aqueous extract with the FaDu cells being the most sensitive (CC50 40.22 µg/mL). It can be concluded that the presence of certain bioactive antiviral molecules may be related to the high anti HSV-1 activity of the methanolic extract. This work has generated vital scientific data on this medicinal plant, which is a prospective candidate for the creation of innovative phyto-pharmaceuticals.

The Neuroprotective Effect of Tea Polyphenols on the Regulation of Intestinal Flora

Tea polyphenols (TPs) are the general compounds of natural polyhydroxyphenols extracted in tea. Although a large number of studies have shown that TPs have obvious neuroprotective and neuro repair effects, they are limited due to the low bioavailability in vivo. However, TPs can act indirectly on the central nervous system by affecting the “microflora–gut–brain axis”, in which the microbiota and its composition represent a factor that determines brain health. Bidirectional communication between the intestinal microflora and the brain (microbe–gut–brain axis) occurs through a variety of pathways, including the vagus nerve, immune system, neuroendocrine pathways, and bacteria-derived metabolites. This axis has been shown to influence neurotransmission and behavior, which is usually associated with neuropsychiatric disorders. In this review, we discuss that TPs and their metabolites may provide benefits by restoring the imbalance of intestinal microbiota and that TPs are metabolized by intestinal flora, to provide a new idea for TPs to play a neuroprotective role by regulating intestinal flora.

Antioxidant and Anticholinesterase Activities of Extracts and Phytochemicals of Syzygium antisepticum Leaves

Bioassay-guided separation of young leaves extracts of Syzygium antisepticum (Blume) Merr. & L.M. Perry led to the isolation of four triterpenoids (betulinic acid, ursolic acid, jacoumaric acid, corosolic acid) and one sterol glucoside (daucosterol) from the ethyl acetate extract, and three polyphenols (gallic acid, myricitrin, and quercitrin) from the methanol (MeOH) extract. The MeOH extract of S. antisepticum and some isolated compounds, ursolic acid and gallic acid potentially exhibited acetylcholinesterase activity evaluated by Ellman’s method. The MeOH extract and its isolated compounds, gallic acid, myricitrin, and quercitrin, also strongly elicited DPPH radical scavenging activity. In HEK-293 cells, the MeOH extract possessed cellular antioxidant effects by attenuating hydrogen peroxide (H₂O₂)-induced ROS production and increasing catalase, glutathione peroxidase-1 (GPx-1), and glutathione reductase (GRe). Furthermore, myricitrin and quercitrin also suppressed ROS production induced by H₂O₂ and induced GPx-1 and catalase production in HEK-293 cells. These results indicated that the young leaves of S. antisepticum are the potential sources of antioxidant and anticholinesterase agents. Consequently, S. antisepticum leaves are one of indigenous vegetables which advantage to promote the health and prevent diseases related to oxidative stress.

Delivery of Natural Agents by Means of Mesoporous Silica Nanospheres as a Promising Anticancer Strategy

Natural prodrugs derived from different natural origins (e.g., medicinal plants, microbes, animals) have a long history in traditional medicine. They exhibit a broad range of pharmacological activities, including anticancer effects in vitro and in vivo. They have potential as safe, cost-effective treatments with few side effects, but are lacking in solubility, bioavailability, specific targeting and have short half-lives. These are barriers to clinical application. Nanomedicine has the potential to offer solutions to circumvent these limitations and allow the use of natural pro-drugs in cancer therapy. Mesoporous silica nanoparticles (MSNs) of various morphology have attracted considerable attention in the search for targeted drug delivery systems. MSNs are characterized by chemical stability, easy synthesis and functionalization, large surface area, tunable pore sizes and volumes, good biocompatibility, controlled drug release under different conditions, and high drug-loading capacity, enabling multifunctional purposes. In vivo pre-clinical evaluations, a significant majority of results indicate the safety profile of MSNs if they are synthesized in an optimized way. Here, we present an overview of synthesis methods, possible surface functionalization, cellular uptake, biodistribution, toxicity, loading strategies, delivery designs with controlled release, and cancer targeting and discuss the future of anticancer nanotechnology-based natural prodrug delivery systems.

From Preclinical Stroke Models to Humans: Polyphenols in the Prevention and Treatment of Stroke

Polyphenols are an important family of molecules of vegetal origin present in many medicinal and edible plants, which represent important alimentary sources in the human diet. Polyphenols are known for their beneficial health effects and have been investigated for their potential protective role against various pathologies, including cancer, brain dysfunctions, cardiovascular diseases and stroke. The prevention of stroke promoted by polyphenols relies mainly on their effect on cardio- and cerebrovascular systems. However, a growing body of evidence from preclinical models of stroke points out a neuroprotective role of these molecules. Notably, in many preclinical studies, the polyphenolic compounds were effective also when administered after the stroke onset, suggesting their possible use in promoting recovery of patients suffering from stroke. Here, we review the effects of the major polyphenols in cellular and in vivo models of both ischemic and hemorrhagic stroke in immature and adult brains. The results from human studies are also reported.

Short-term exposure to the simple polyphenolic compound gallic acid induces neuronal hyperactivity in zebrafish larvae

A growing body of evidence suggests that the biological effects of polyphenols are not restricted to antioxidant activity, but they exert a wide range of modulatory effects on metabolic pathways, cellular signaling and gene expression. In this study, we tested the minimum safe concentration of gallic acid (GA) in 72 hpf zebrafish larvae in order to evaluate the effects on the central nervous system and the behavioral response. We showed that a short exposure (30 min) induces the depletion of the two main excitatory and inhibitory neurotransmitters, Glu and GABA, respectively, in the larval nervous system. The acute impairment of GABAergic-glutamatergic balance was paralleled by an increase of the fosab neuronal activity marker in specific brain areas, such as the forebrain, olfactory bulbs, pallial area, ventral midbrain, tegmentum, and the medulla oblongata ventral area. The neuronal excitation was mirrored by the increased cumulative motor response. The inhibition of the olfactory epithelium with brief cadmium exposition suggests a direct involvement of olfaction in the larvae response to GA. Our results demonstrate that a brief exposure to GA induces motoneuronal hyperexcitability in zebrafish. The behavioral response was probably elicited through the activation of an odorous, or chemical, stimulus. The specificity of the activated neuronal territories suggests the involvement of additional signaling pathways. Although the underlying molecular mechanisms remain to be elucidated, our data support the hypothesis that GA acts as an excitatory molecule, capable of inducing a specific nerve response. These results offer a new vision on potential effects of GA.

The Role of Natural Compounds and their Nanocarriers in the Treatment of CNS Inflammation

Neuroinflammation, which is involved in various inflammatory cascades in nervous tissues, can result in persistent and chronic apoptotic neuronal cell death and programmed cell death, triggering various degenerative disorders of the central nervous system (CNS). The neuroprotective effects of natural compounds against neuroinflammation are mainly mediated by their antioxidant, anti-inflammatory, and antiapoptotic properties that specifically promote or inhibit various molecular signal transduction pathways. However, natural compounds have several limitations, such as their pharmacokinetic properties and stability, which hinder their clinical development and use as medicines. This review discusses the molecular mechanisms of neuroinflammation and degenerative diseases of CNS. In addition, it emphasizes potential natural compounds and their promising nanocarriers for overcoming their limitations in the treatment of neuroinflammation. Moreover, recent promising CNS inflammation-targeted nanocarrier systems implementing lesion site-specific active targeting strategies for CNS inflammation are also discussed.

Citrus hystrix Extracts Protect Human Neuronal Cells against High Glucose-Induced Senescence

Citrus hystrix (CH) is a beneficial plant utilized in traditional folk medicine to relieve various health ailments. The antisenescent mechanisms of CH extracts were investigated using human neuroblastoma cells (SH-SY5Y). Phytochemical contents and antioxidant activities of CH extracts were analyzed using a gas chromatograph–mass spectrometer (GC-MS), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) assay. Effects of CH extracts on high glucose-induced cytotoxicity, reactive oxygen species (ROS) generation, cell cycle arrest and cell cycle-associated proteins were assessed using a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) assay, non-fluorescent 2′, 7′-dichloro-dihydrofluorescein diacetate (H₂DCFDA) assay, flow cytometer and Western blot. The extracts protected neuronal senescence by inhibiting ROS generation. CH extracts induced cell cycle progression by releasing senescent cells from the G1 phase arrest. As the Western blot confirmed, the mechanism involved in cell cycle progression was associated with the downregulation of cyclin D1, phospho-cell division cycle 2 (pcdc2) and phospho-Retinoblastoma (pRb) proteins. Furthermore, the Western blot showed that extracts increased Surtuin 1 (SIRT1) expression by increasing the phosphorylation of Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Collectively, CH extracts could protect high glucose-induced human neuronal senescence by inducing cell cycle progression and up-regulation of SIRT1, thus leading to the improvement of the neuronal cell functions.