Naringin modulates oxidative stress and inflammation in 3-nitropropionic acid-induced neurodegeneration through the activation of nuclear factor-erythroid 2-related factor-2 signalling pathway

Effectiveness of Flavonoid-Rich Diet in Alleviating Symptoms of Neurodegenerative Diseases

Over the past decades, there has been a significant increase in the burden of neurological diseases, including neurodegenerative disorders, on a global scale. This is linked to a widespread demographic trend in which developed societies are aging, leading to an increased proportion of elderly individuals and, concurrently, an increase in the number of those afflicted, posing one of the main public health challenges for the coming decades. The complex pathomechanisms of neurodegenerative diseases and resulting varied symptoms, which differ depending on the disease, environment, and lifestyle of the patients, make searching for therapies for this group of disorders a formidable challenge. Currently, most neurodegenerative diseases are considered incurable. An important aspect in the fight against and prevention of neurodegenerative diseases may be broadly understood lifestyle choices, and more specifically, what we will focus on in this review, a diet. One proposal that may help in the fight against the spread of neurodegenerative diseases is a diet rich in flavonoids. Flavonoids are compounds widely found in products considered healthy, such as fruits, vegetables, and herbs. Many studies indicated not only the neuroprotective effects of these compounds but also their ability to reverse changes occurring during the progression of diseases such as Alzheimer's, Parkinson's and amyotrophic lateral sclerosis. Here, we present the main groups of flavonoids, discussing their characteristics and mechanisms of action. The most widely described mechanisms point to neuroprotective functions due to strong antioxidant and anti-inflammatory effects, accompanied with their ability to penetrate the blood-brain barrier, as well as the ability to inhibit the formation of protein aggregates. The latter feature, together with promoting removal of the aggregates is especially important in neurodegenerative diseases. We discuss a therapeutic potential of selected flavonoids in the fight against neurodegenerative diseases, based on in vitro studies, and their impact when included in the diet of animals (laboratory research) and humans (population studies). Thus, this review summarizes flavonoids' actions and impacts on neurodegenerative diseases. Therapeutic use of these compounds in the future is potentially possible but depends on overcoming key challenges such as low bioavailability, determining the therapeutic dose, and defining what a flavonoid-rich diet is and determining its potential negative effects. This review also suggests further research directions to address these challenges.

Exploring role of natural compounds in molecular alterations associated with brain ageing: A perspective towards nutrition for ageing brain

Aging refers to complete deterioration of physiological integrity and function. By midcentury, adults over 60 years of age and children under 15 years will begin to outnumber people in working age. This shift will bring multiple global challenges for economy, health, and society. Eventually, aging is a natural process playing a vital function in growth and development during pediatric stage, maturation during adult stage, and functional depletion. Tissues experience negative consequences with enhanced genomic instability, deregulated nutrient sensing, mitochondrial dysfunction, and decline in performance on cognitive tasks. As brain ages, its volume decreases, neurons & glia get inflamed, vasculature becomes less developed, blood pressure increases with a risk of stroke, ischemia, and cognitive deficits. Diminished cellular functions leads to progressive reduction in functional and emotional capacity with higher possibility of disease and finally death. This review overviews cellular as well as molecular aspects of aging, biological pathway related to accelerated brain aging, and strategies minimizing cognitive aging. Age-related changes include altered bioenergetics, decreased neuroplasticity and flexibility, aberrant neural activity, deregulated Ca2+ homeostasis in neurons, buildup of reactive oxygen species, and neuro-inflammation. Unprecedented progress has been achieved in recent studies, particularly in terms of how herbal or natural substances affect genetic pathways and biological functions that have been preserved through evolution. Herein, the present work provides an overview of ageing and age-related disorders and explore the molecular mechanisms that underlie therapeutic effects of herbal and natural chemicals on neuropathological signs of brain aging.

The Role of NRF2 in Trinucleotide Repeat Expansion Disorders

Trinucleotide repeat expansion disorders, a diverse group of neurodegenerative diseases, are caused by abnormal expansions within specific genes. These expansions trigger a cascade of cellular damage, including protein aggregation and abnormal RNA binding. A key contributor to this damage is oxidative stress, an imbalance of reactive oxygen species that harms cellular components. This review explores the interplay between oxidative stress and the NRF2 pathway in these disorders. NRF2 acts as the master regulator of the cellular antioxidant response, orchestrating the expression of enzymes that combat oxidative stress. Trinucleotide repeat expansion disorders often exhibit impaired NRF2 signaling, resulting in inadequate responses to excessive ROS production. NRF2 activation has been shown to upregulate antioxidative gene expression, effectively alleviating oxidative stress damage. NRF2 activators, such as omaveloxolone, vatiquinone, curcumin, sulforaphane, dimethyl fumarate, and resveratrol, demonstrate neuroprotective effects by reducing oxidative stress in experimental cell and animal models of these diseases. However, translating these findings into successful clinical applications requires further research. In this article, we review the literature supporting the role of NRF2 in the pathogenesis of these diseases and the potential therapeutics of NRF2 activators.

Naringin activates semaphorin 3A to ameliorate TGF-β-induced endothelial-to-mesenchymal transition related to atrial fibrillation

The loss of semaphorin 3A (Sema3A), which is related to endothelial-to-mesenchymal transition (EndMT) in atrial fibrosis, is implicated in the pathogenesis of atrial fibrillation (AF). To explore the mechanisms by which EndMT affects atrial fibrosis and assess the potential of a Sema3A activator (naringin) to prevent atrial fibrosis by targeting transforming growth factor-beta (TGF-β)-induced EndMT, we used human atria, isolated human atrial endocardial endothelial cells (AEECs), and used transgenic mice expressing TGF-β specifically in cardiac tissues (TGF-β transgenic mice). We evaluated an EndMT marker (Twist), a proliferation marker (proliferating cell nuclear antigen; PCNA), and an endothelial cell (EC) marker (CD31) through triple immunohistochemistry and confirmed that both EndMT and EC proliferation contribute to atrial endocardial fibrosis during AF in TGF-β transgenic mice and AF patient tissue sections. Additionally, we investigated the impact of naringin on EndMT and EC proliferation in AEECs and atrial fibroblasts. Naringin exhibited an antiproliferative effect, to which AEECs were more responsive. Subsequently, we downregulated Sema3A in AEECs using small interfering RNA to clarify a correlation between the reduction in Sema3A and the elevation of EndMT markers. Naringin treatment induced the expression of Sema3A and a concurrent decrease in EndMT markers. Furthermore, naringin administration ameliorated AF and endocardial fibrosis in TGF-β transgenic mice by stimulating Sema3A expression, inhibiting EndMT markers, reducing atrial fibrosis, and lowering AF vulnerability. This suggests therapeutic potential for naringin in AF treatment.

Azilsartan Attenuates 3-Nitropropinoic Acid-Induced Neurotoxicity in Rats: The Role of IĸB/NF-ĸB and KEAP1/Nrf2 Signaling Pathways

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder characterized by motor, psychiatric and cognitive symptoms. Injection of 3-nitropropionic acid (3-NP) is a widely used experimental model for induction of HD. The current study aimed to inspect the potential neuroprotective properties of azilsartan (Azil), an angiotensin II type 1 receptor blocker (ATR1), in 3-NP-induced striatal neurotoxicity in rats. Rats were randomly allocated into five groups and treated for 14 days as follows: group I received normal saline; group II received Azil (10 mg/kg, p.o.); group III received 3-NP (10 mg/kg, i.p); group IV and V received Azil (5 or 10 mg/kg, p.o, respectively) 1 h prior to 3-NP injection. Both doses of Azil markedly attenuated motor and behavioural dysfunction as well as striatal histopathological alterations caused by 3-NP. In addition, Azil balanced striatal neurotransmitters levels as evidenced by the increase of striatal gamma-aminobutyric acid content and the decrease of glutamate content. Azil also amended neuroinflammation and oxidative stress via modulating IĸB/NF-ĸB and KEAP1/Nrf2 downstream signalling pathways, as well as reducing iNOS and COX2 levels. Moreover, Azil demonstrated an anti-apoptotic activity by reducing caspase-3 level and BAX/BCL2 ratio. In conclusion, the present study reveals the neuroprotective potential of Azil in 3-NP-induced behavioural, histopathological and biochemical changes in rats. These findings might be attributed to inhibition of ATR1/NF-κB signalling, modulation of Nrf2/KEAP1 signalling, anti-inflammatory, anti-oxidant and anti-apoptotic properties.

Biological activities, Molecular mechanisms, and Clinical application of Naringin in Metabolic syndrome

Metabolic syndrome has become major health problems in recent decades, and natural compounds receive considerable attention in the management of metabolic syndrome. Among them, naringin is abundant in citrus fruits and tomatoes. Many studies have investigated the therapeutic effects of naringin in metabolic syndrome. This review discusses in vitro and in vivo studies on naringin and implications for clinical trials on metabolic syndrome such as diabetes mellitus, obesity, nonalcoholic fatty liver disease, dyslipidemia, and hypertension over the past decades, overviews the molecular mechanisms by which naringin targets metabolic syndrome, and analyzes possible correlations between the different mechanisms. This review provides a theoretical basis for the further application of naringin in the treatment of metabolic syndrome.

A clinical study and future prospects for bioactive compounds and semi-synthetic molecules in the therapies for Huntington's disease

A neurodegenerative disorder (ND) refers to Huntington's disease (HD) which affects memory loss, weight loss, and movement dysfunctions such as chorea and dystonia. In the striatum and brain, HD most typically impacts medium-spiny neurons. Molecular genetics, excitotoxicity, oxidative stress (OS), mitochondrial, and metabolic dysfunction are a few of the theories advanced to explicit the pathophysiology of neuronal damage and cell death. Numerous in-depth studies of the literature have supported the therapeutic advantages of natural products in HD experimental models and other treatment approaches. This article briefly discusses the neuroprotective impacts of natural compounds against HD models. The ability of the discovered natural compounds to suppress HD was tested using either in vitro or in vivo models. Many bioactive compounds considerably lessened the memory loss and motor coordination brought on by 3-nitropropionic acid (3-NP). Reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and enhanced mitochondrial energy generation have profoundly decreased the biochemical change. It is significant since histology showed that therapy with particular natural compounds lessened damage to the striatum caused by 3-NP. Moreover, natural products displayed varying degrees of neuroprotection in preclinical HD studies because of their antioxidant and anti-inflammatory properties, maintenance of mitochondrial function, activation of autophagy, and inhibition of apoptosis. This study highlighted about the importance of bioactive compounds and their semi-synthetic molecules in the treatment and prevention of HD.

Impact of NQO1 dysregulation in CNS disorders

NAD(P)H Quinone Dehydrogenase 1 (NQO1) plays a pivotal role in the regulation of neuronal function and synaptic plasticity, cellular adaptation to oxidative stress, neuroinflammatory and degenerative processes, and tumorigenesis in the central nervous system (CNS). Impairment of the NQO1 activity in the CNS can result in abnormal neurotransmitter release and clearance, increased oxidative stress, and aggravated cellular injury/death. Furthermore, it can cause disturbances in neural circuit function and synaptic neurotransmission. The abnormalities of NQO1 enzyme activity have been linked to the pathophysiological mechanisms of multiple neurological disorders, including Parkinson's disease, Alzheimer's disease, epilepsy, multiple sclerosis, cerebrovascular disease, traumatic brain injury, and brain malignancy. NQO1 contributes to various dimensions of tumorigenesis and treatment response in various brain tumors. The precise mechanisms through which abnormalities in NQO1 function contribute to these neurological disorders continue to be a subject of ongoing research. Building upon the existing knowledge, the present study reviews current investigations describing the role of NQO1 dysregulations in various neurological disorders. This study emphasizes the potential of NQO1 as a biomarker in diagnostic and prognostic approaches, as well as its suitability as a target for drug development strategies in neurological disorders.

Pre-clinical Evidence-based Neuroprotective Potential of Naringin against Alzheimer's Disease-like Pathology: A Comprehensive Review

Neurodegenerative disorders (NDs) are a group of progressive, chronic, and disabling disorders that are highly prevalent and the incidence is on a constant rise globally. Alzheimer's disease (AD), one of the most common neurodegenerative disorders is hallmarked by cognitive impairment, amyloid-β (Aβ) deposition, hyperphosphorylation of tau protein, cholinergic dysfunction, mitochondrial toxicity, and neurodegeneration. Available therapeutic agents only provide symptomatic relief and their use are limited due to serious side effects. Recent research has recognized flavonoids as potential multi-target biomolecules that can reduce the pathogenesis of AD. Naringin, a natural citrus flavonoid has been traditionally used to treat various NDs including AD, and has gained special attention because exhibits a neuroprotective effect by affecting numerous signaling pathways with minimum adverse effects. Naringin reduces deposition of Aβ, hyperphosphorylation of tau protein, cholinergic dysfunction, oxidative stress burden, mitochondrial toxicity, the activity of glutamate receptors, and apoptosis of the neuronal cells. Additionally, it reduces the expression of phosphorylated-P38/P38 and the NF-κB signaling pathway, showing that a wide range of molecular targets is involved in naringin's neuroprotective action. The present study describes the possible pharmacological targets, signaling pathways, and molecular mechanisms of naringin involved in neuroprotection against AD-like pathology. Based on the above pre-clinical reports it can be concluded that naringin could be an alternative therapeutic agent for the management of AD-like manifestation. Thus, there is a strong recommendation to perform more preclinical and clinical studies to develop naringin as a novel molecule that could be a multi-target drug to counteract AD.

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.

Regulation of Keap1-Nrf2 axis in temporal lobe epilepsy-hippocampal sclerosis patients may limit the seizure outcomes

BACKGROUND

Accumulation of reactive oxygen species (ROS) exacerbates neuronal loss during seizure-induced excitotoxicity. Keap1 (Kelch-like ECH-associated protein1)-nuclear factor erythroid 2-related factor 2 (Nrf2) axis is one of the known active antioxidant response mechanisms. Our study focused on finding the factors influencing Keap1-Nrf2 axis regulation in temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS) patients.

METHODS

Based on post-surgical follow-up data, patient samples (n = 26) were categorized into class 1 (completely seizure-free) and class 2 (only focal-aware seizures/auras), as suggested by International League Against Epilepsy (ILAE). For molecular analyses, double immunofluorescence assay and Western blot analysis were employed.

RESULTS

A significant decrease in expression of Nrf2 (p < 0.005), HO-1; p < 0.02) and NADPH Quinone oxidoreductase1 (NQO1; p < 0.02) was observed in ILAE class 2. Keap1 (p < 0.02) and histone methyltransferases (HMTs) like SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) (p < 0.009) and enhancer of zeste homolog 2 (EZH2; p < 0.02) and methylated histones viz., H3K4me1 (p < 0.001), H3K9me3 (p < 0.001), and H3K27me3 (p < 0.001) was upregulated in ILAE class 2. Nrf2-interacting proteins viz., p21 (p < 0.001) and heat shock protein 90 (HSP90; p < 0.03) increased in class 1 compared to class 2 patients.

CONCLUSION

Upregulation of HMTs and methylated histones can limit phase II antioxidant enzyme expression. Also, HSP90 and p21 that interfere with Keap1-Nrf2 interaction could contribute to a marginal increase in HO-1 and NQO1 expression despite histone methylation and Keap1. Based on our findings, we conclude that TLE-HS patients prone to seizure recurrence were found to have dysfunctional antioxidant response, in part, owing to Keap1-Nrf2 axis. The significance of Keap1-Nrf2 signaling mechanism in generation of phase II antioxidant response. Keap1-Nrf2 controls antioxidant response through regulation of phase II antioxidant enzymes like HO-1 (heme oxygenase-1), NQO1 (NADPH-Quinone Oxidoreductase1), and glutathione S-transferase (GST). Release of Nrf2 from negative regulation by Keap1 causes its translocation into nucleus, forming a complex with cAMP response-element binding protein (CBP) and small Maf proteins (sMaf). This complex subsequently binds antioxidant response element (ARE) and elicits and antioxidant response involving expression of phase II antioxidant enzymes. Reactive oxygen species (ROS) modify Cysteine 151 residue, p62 (sequsetosome-1), and interacts with Nrf2- binding site in Keap 1. p21 and HSP90 prevent Nrf2 interaction with Keap1. At transcriptional level, histone methyltransferases like EZH2 (enhancer of zeste homologue2), and SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) and corresponding histone targets viz., H3K27me3, H3K9me3, and H3K4me1 influence Nrf2 and Keap1 expression respectively.

In Vitro Anti-Inflammatory Activity of Methyl Derivatives of Flavanone

Inflammation plays an important role in the immune defense against injury and infection agents. However, the inflammatory chronic process may lead to neurodegenerative diseases, atherosclerosis, inflammatory bowel diseases, or cancer. Flavanones present in citrus fruits exhibit biological activities, including anti-oxidative and anti-inflammatory properties. The beneficial effects of flavanones have been found based on in vitro cell cultures and animal studies. A suitable in vitro model for studying the inflammatory process are macrophages (RAW264.7 cell line) because, after stimulation using lipopolysaccharide (LPS), they release inflammatory cytokines involved in the immune response. We determined the nitrite concentration in the macrophage cell culture and detected ROS using chemiluminescence. Additionally, we measured the production of selected cytokines using the Bio-Plex Magnetic Luminex Assay and the Bio-PlexTM 200 System. For the first time, we have shown that methyl derivatives of flavanone inhibit NO and chemiluminescence generated via LPS-stimulated macrophages. Moreover, the tested compounds at 1-20 µM dose-dependently modulate proinflammatory cytokine production (IL-1β, IL-6, IL-12p40, IL-12p70, and TNF-α) in stimulated RAW264.7 cells. The 2'-methylflavanone (5B) and the 3'-methylflavanone (6B) possess the strongest anti-inflammatory activity among all the tested flavanone derivatives. These compounds reduce the concentration of IL-6, IL-12p40, and IL12p70 compared to the core flavanone structure. Moreover, 2'-methylflavanone reduces TNF-α, and 3'-methylflavanone reduces IL-1β secreted by RAW264.7 cells.

Review of Phytochemical Potency as a Natural Anti-Helicobacter pylori and Neuroprotective Agent

Phytochemicals are plant secondary metabolites that show health benefits for humans due to their bioactivity. There is a huge variety of phytochemicals that have already been identified, and these compounds can act as antimicrobial and neuroprotection agents. Due to their anti-microbial activity and neuroprotection, several phytochemicals might have the potency to be used as natural therapeutic agents, especially for Helicobacter pylori infection and neurodegenerative disease, which have become a global health concern nowadays. According to previous research, there are some connections between H. pylori infection and neurodegenerative diseases, especially Alzheimer's disease. Hence, this comprehensive review examines different kinds of phytochemicals from natural sources as potential therapeutic agents to reduce H. pylori infection and improve neurodegenerative disease. An additional large-scale study is needed to establish the connection between H. pylori infection and neurodegenerative disease and how phytochemicals could improve this condition.

The untapped potential of targeting NRF2 in neurodegenerative disease

Since its initial discovery almost three decades ago, the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) has been shown to regulate a host of downstream transcriptional responses and play a critical role in preventing or promoting disease progression depending on the context. Critically, while the importance of proper nuclear factor erythroid 2-related factor 2 function has been demonstrated across a variety of pathological settings, the ability to progress NRF2-targeted therapeutics to clinic has remained frustratingly elusive. This is particularly true in the case of age-related pathologies, where nuclear factor erythroid 2-related factor 2 is a well-established mitigator of many of the observed pathogenic effects, yet options to target this pathway remain limited. Along these lines, loss of nuclear factor erythroid 2-related factor 2 function has clearly been shown to enhance neuropathological outcomes, with enhancing nuclear factor erythroid 2-related factor 2 pathway activation to prevent neurodegenerative/neurological disease progression continuing to be an active area of interest. One critical obstacle in generating successful therapeutics for brain-related pathologies is the ability of the compound to cross the blood brain barrier (BBB), which has also hampered the implementation of several promising nuclear factor erythroid 2-related factor 2 inducers. Another limitation is that many nuclear factor erythroid 2-related factor 2 activators have undesirable off-target effects due to their electrophilic nature. Despite these constraints, the field has continued to evolve, and several viable means of targeting nuclear factor erythroid 2-related factor 2 in a neuropathological context have emerged. In this perspective, we will briefly discuss the key findings and promising therapeutic options that have been discovered to date, as well as highlight emerging areas of NRF2-neurodegeneration research that provide hope for successfully targeting this pathway in the future.

Inhibition of Enzymes Involved in Neurodegenerative Disorders and Aβ1-40 Aggregation by Citrus limon Peel Polyphenol Extract

Alzheimer's (AD) and Parkinson's diseases (PD) are multifactorial neurogenerative disorders of the Central Nervous System causing severe cognitive and motor deficits in elderly people. Because treatment of AD and PD by synthetic drugs alleviates the symptoms often inducing side effects, many studies have aimed to find neuroprotective properties of diet polyphenols, compounds known to act on different cell signaling pathways. In this article, we analyzed the effect of polyphenols obtained from the agro-food industry waste of Citrus limon peel (LPE) on key enzymes of cholinergic and aminergic neurotransmission, such as butyryl cholinesterase (BuChE) and monoamine oxidases (MAO)-A/B, on Aβ1-40 aggregation and on superoxide dismutase (SOD) 1/2 that affect oxidative stress. In our in vitro assays, LPE acts as an enzyme inhibitor on BuChE (IC50 ~ 73 µM), MAO-A/B (IC50 ~ 80 µM), SOD 1/2 (IC50 ~ 10-20 µM) and interferes with Aβ1-40 peptide aggregation (IC50 ~ 170 µM). These results demonstrate that LPE behaves as a multitargeting agent against key factors of AD and PD by inhibiting to various extents BuChE, MAOs, and SODs and reducing Aβ-fibril aggregation. Therefore, LPE is a promising candidate for the prevention and management of AD and PD symptoms in combination with pharmacological therapies.

Global Impacts of Western Diet and Its Effects on Metabolism and Health: A Narrative Review

The Western diet is a modern dietary pattern characterized by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy, sweets, fried foods, conventionally raised animal products, high-fat dairy products, and high-fructose products. The present review aims to describe the effect of the Western pattern diet on the metabolism, inflammation, and antioxidant status; the impact on gut microbiota and mitochondrial fitness; the effect of on cardiovascular health, mental health, and cancer; and the sanitary cost of the Western diet. To achieve this goal, a consensus critical review was conducted using primary sources, such as scientific articles, and secondary sources, including bibliographic indexes, databases, and web pages. Scopus, Embase, Science Direct, Sports Discuss, ResearchGate, and the Web of Science were used to complete the assignment. MeSH-compliant keywords such "Western diet", "inflammation", "metabolic health", "metabolic fitness", "heart disease", "cancer", "oxidative stress", "mental health", and "metabolism" were used. The following exclusion criteria were applied: (i) studies with inappropriate or irrelevant topics, not germane to the review's primary focus; (ii) Ph.D. dissertations, proceedings of conferences, and unpublished studies. This information will allow for a better comprehension of this nutritional behavior and its effect on an individual's metabolism and health, as well as the impact on national sanitary systems. Finally, practical applications derived from this information are made.

Naringenin: A flavanone with anti-inflammatory and anti-infective properties

Although a growing body of research has recently shown how crucial inflammation and infection are to all major diseases, several of the medications currently available on the market have various unfavourable side effects, necessitating the development of alternative therapeutic choices. Researchers are increasingly interested in alternative medications or active components derived from natural sources. Naringenin is a commonly consumed flavonoid found in many plants, and since it was discovered to have nutritional benefits, it has been utilized to treat inflammation and infections caused by particular bacteria or viruses. However, the absence of adequate clinical data and naringenin's poor solubility and stability severely restrict its usage as a medicinal agent. In this article, we discuss naringenin's effects and mechanisms of action on autoimmune-induced inflammation, bacterial infections, and viral infections based on recent research. We also present a few suggestions for enhancing naringenin's solubility, stability, and bioavailability. This paper emphasizes the potential use of naringenin as an anti-inflammatory and anti-infective agent and the next prophylactic substance for the treatment of various inflammatory and infectious diseases, even though some mechanisms of action are still unclear, and offers some theoretical support for its clinical application.

Biological Activities and Solubilization Methodologies of Naringin

Naringin (NG), a natural flavanone glycoside, possesses a multitude of pharmacological properties, encompassing anti-inflammatory, sedative, antioxidant, anticancer, anti-osteoporosis, and lipid-lowering functions, and serves as a facilitator for the absorption of other drugs. Despite these powerful qualities, NG's limited solubility and bioavailability primarily undermine its therapeutic potential. Consequently, innovative solubilization methodologies have received considerable attention, propelling a surge of scholarly investigation in this arena. Among the most promising solutions is the enhancement of NG's solubility and physiological activity without compromising its inherent active structure, therefore enabling the formulation of non-toxic and benign human body preparations. This article delivers a comprehensive overview of NG and its physiological activities, particularly emphasizing the impacts of structural modification, solid dispersions (SDs), inclusion compound, polymeric micelle, liposomes, and nanoparticles on NG solubilization. By synthesizing current research, this research elucidates the bioavailability of NG, broadens its clinical applicability, and paves the way for further exploration and expansion of its application spectrum.

Herbal/Natural Compounds Resist Hallmarks of Brain Aging: From Molecular Mechanisms to Therapeutic Strategies

Aging is a complex process of impaired physiological integrity and function, and is associated with increased risk of cardiovascular disease, diabetes, neurodegeneration, and cancer. The cellular environment of the aging brain exhibits perturbed bioenergetics, impaired adaptive neuroplasticity and flexibility, abnormal neuronal network activity, dysregulated neuronal Ca²⁺ homeostasis, accumulation of oxidatively modified molecules and organelles, and clear signs of inflammation. These changes make the aging brain susceptible to age-related diseases, such as Alzheimer's and Parkinson's diseases. In recent years, unprecedented advances have been made in the study of aging, especially the effects of herbal/natural compounds on evolutionarily conserved genetic pathways and biological processes. Here, we provide a comprehensive review of the aging process and age-related diseases, and we discuss the molecular mechanisms underlying the therapeutic properties of herbal/natural compounds against the hallmarks of brain aging.

Morin post-treatment surpassed calpeptin in ameliorating 3-NP-induced cortical neurotoxicity via modulation of glutamate/calpain axis, Kidins220, and BDNF/TrkB/AKT/CREB trajectory

The neuroprotective capacity of morin hydrate (MH), a potent antioxidant flavonoid, and calpeptin (CP), a calpain inhibitor, was documented against different insults but not Huntington's disease (HD). Accordingly, we aim to assess the neuroprotective potential of MH and/or CP in a 3-nitropropionic acid (3-NP)-induced HD model. The 3-NP-treated rats were post-treated with saline, MH, CP, or MH + CP for a week. Post-treatment with MH and/or CP amended motor function (beam walking test) and short-/ long-term spatial memory (novel object recognition test) and improved cortical microscopic architecture. On the molecular level, MH, and to a lesser extent CP, inhibited the cortical content/expression of glutamate, calpain, and Kidins220 and abated the inflammatory molecules, nuclear factor (NF)-κB, tumor necrosis factor-α, and interleukin-1β, as well as lipid peroxidation. However, MH, but barely CP, activated the molecules of the neuroprotective trajectory; viz., brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase receptor B (TrkB), protein kinase B (AKT), and cAMP response element-binding protein (CREB). Compared to the single treatments, the combination regimen mediated further reductions in the cortical contents of glutamate, calpain, and Kidins220, effects that extended to entail the anti-inflammatory/anti-oxidant potentials of MH and to a greater extent CP. However, the combination of MH strengthened the fair effect of CP on the survival signaling pathway BDNF/TrkB/AKT/CREB. In conclusion, MH, CP, and especially their combination, afforded neuroprotection against HD through curbing the glutamate/calpain axis, Kidins220, as well as NF-κB-mediated neuroinflammation/oxidative stress, besides activating the BDNF/TrkB/AKT/CREB hub that was partly dependent on calpain inhibition.

Evidence of Flavonoids on Disease Prevention

A growing body of evidence highlights the properties of flavonoids in natural foods for disease prevention. Due to their antioxidative, anti-inflammatory, and anti-carcinogenic activities, flavonoids have been revealed to benefit skeletal muscle, liver, pancreas, adipocytes, and neural cells. In this review, we introduced the basic classification, natural sources, and biochemical properties of flavonoids, then summarize the experimental results and underlying molecular mechanisms concerning the effects of flavonoid consumption on obesity, cancers, and neurogenerative diseases that greatly threaten public health. Especially, the dosage and duration of flavonoids intervening in these diseases are discussed, which might guide healthy dietary habits for people of different physical status.

Targeting the Nrf2 signaling pathway using phytochemical ingredients: A novel therapeutic road map to combat neurodegenerative diseases

BACKGROUND

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a classical nuclear transcription factor that regulates the system's anti-oxidative stress response. The activation of Nrf2 induces the expression of antioxidant proteins and improves the system's anti-oxidative stress ability. Accumulating evidence suggests that Nrf2-centered signaling pathways may be a key pharmacological target for the treatment of neurodegenerative diseases (NDDs). However, phytochemicals as new therapeutic agents against NDDs have not been clearly delineated.

PURPOSE

To review the therapeutic effects of phytochemical ingredients on NDDs by activating Nrf2 and reducing oxidative stress injury.

METHODS

A comprehensive search of published articles was performed using various literature databases including PubMed, Google Scholar, and China National Knowledge Infrastructure. The search terms included "Nrf2", "phytochemical ingredients", "natural bioactive agents", "neurodegenerative diseases", "Antioxidant", "Alzheimer's disease", "Parkinson's disease", "Huntington's disease", "amyotrophic lateral sclerosis" "multiple sclerosis", "toxicity", and combinations of these keywords. A total of 769 preclinical studies were retrieved until August 2022, and we included 39 of these articless on phytochemistry, pharmacology, toxicology and other fields.

RESULTS

Numerous in vivo and in vitro studies showed that phytochemical ingredients could act as an Nrf2 activator in the treatment of NDDs through the antioxidant defense mechanism. These phytochemical ingredients, such as salidroside, naringenin, resveratrol, sesaminol, ellagic acid, ginsenoside Re, tanshinone I, sulforaphane, curcumin, naringin, tetramethylpyrazine, withametelin, magnolol, piperine, and myricetin, had the potential to improve Nrf2 signaling, thereby combatting NDDs.

CONCLUSION

As Nrf2 activators, phytochemical ingredients may provide a novel potential strategy for the treatment of NDDs. Here, we reviewed the interaction between phytochemical ingredients, Nrf2, and its antioxidant damaging pathway in NDDs and explored the advantages of phytochemical ingredients in anti-oxidative stress, which provides a reliable basis for improving the treatment of NDDs. However, further clinical trials are needed to determine the safety and efficacy of Nrf2 activators for NDDs.

Naringin and Naringenin Polyphenols in Neurological Diseases: Understandings from a Therapeutic Viewpoint

The glycosides of two flavonoids, naringin and naringenin, are found in various citrus fruits, bergamots, tomatoes, and other fruits. These phytochemicals are associated with multiple biological functions, including neuroprotective, antioxidant, anticancer, antiviral, antibacterial, anti-inflammatory, antiadipogenic, and cardioprotective effects. The higher glutathione/oxidized glutathione ratio in 3-NP-induced rats is attributed to the ability of naringin to reduce hydroxyl radical, hydroperoxide, and nitrite. However, although progress has been made in treating these diseases, there are still global concerns about how to obtain a solution. Thus, natural compounds can provide a promising strategy for treating many neurological conditions. Possible therapeutics for neurodegenerative disorders include naringin and naringenin polyphenols. New experimental evidence shows that these polyphenols exert a wide range of pharmacological activity; particular attention was paid to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, as well as other neurological conditions such as anxiety, depression, schizophrenia, and chronic hyperglycemic peripheral neuropathy. Several preliminary investigations have shown promising evidence of neuroprotection. The main objective of this review was to reflect on developments in understanding the molecular mechanisms underlying the development of naringin and naringenin as potential neuroprotective medications. Furthermore, the configuration relationships between naringin and naringenin are discussed, as well as their plant sources and extraction methods.

Naringin attenuates fructose-induced NAFLD progression in rats through reducing endogenous triglyceride synthesis and activating the Nrf2/HO-1 pathway

Background: Excessive fructose consumption causes hepatic lipid accumulation via increased triglyceride (TG) synthesis, leading to the development and progression of non-alcoholic fatty liver disease (NALFD). Naringin, a flavanone glycoside found in citrus fruit, has antioxidant and hypolipidemic properties. Therefore, the aim of this study was to investigate the effect of naringin on fructose-induced NAFLD in rats and the possible underlying mechanism. Methods: Male Sprague Dawley rats were given 10% (w/v) fructose in drinking water for 12 weeks. Naringin (100 mg/kg/day) was administered orally to rats for the last 4 weeks of fructose overload. After 12 weeks of treatment, the hepatic lipid content was determined. In addition, the expression of proteins involved in de novo lipogenesis (DNL) and TG synthesis as well as antioxidant and inflammatory mediators in the liver were examined by western blot analysis. Results: Treatment of fructose-fed rats with naringin significantly decreased the hepatic TG and cholesterol content as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities. Naringin treatment also decreased the hepatic expression of carbohydrate response element binding protein (ChREBP), sterol regulatory element-binding protein-1c (SREBP-1c) and nuclear SREBP-1c (nSREBP-1c) as well as enzymes involved in DNL (acetyl CoA carboxylase [ACC] and fatty acid synthase [FAS]) and an enzyme involved in TG synthesis (glycerol-3-phosphate acyltransferase 1 [GPAT-1] and diacylglycerol acyltransferase2 [DGAT2]) in fructose-fed rats. In addition, naringin induced a significant decrease in the hepatic expression of nuclear factor kappa B (NF-κB) and tumor necrosis factor α (TNF-α). Furthermore, naringin administration restored the expression of the antioxidant mediators nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) in the liver of fructose-fed rats. Conclusion: These results demonstrate that oral administration of naringin protects against fructose-induced hepatic steatosis by decreasing DNL and TG synthesis. In addition, naringin could prevent NAFLD progression via targeting the Nrf2/HO-1 and the NF-κB/TNF-α pathways.

Nrf2 Pathway in Huntington's Disease (HD): What Is Its Role?

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease that occurs worldwide. Despite some progress in understanding the onset of HD, drugs that block or delay symptoms are still not available. In recent years, many treatments have been proposed; among them, nuclear transcriptional factor-2 (Nrf2) enhancer compounds have been proposed as potential therapeutic agents to treat HD. Nrf2 triggers an endogenous antioxidant pathway activated in different neurodegenerative disorders. Probably, the stimulation of Nrf2 during either the early phase or before HD symptoms' onset, could slow or prevent striatum degeneration. In this review, we present the scientific literature supporting the role of Nrf2 in HD and the potential prophylactic and therapeutic role of this compound.

Naringenin: A prospective therapeutic agent for Alzheimer's and Parkinson's disease

Neurodegenerative disorders (NDs) are a cluster of progressive, severe, and disabling disorders that affect millions of people worldwide and are on the surge. These disorders are characterized by the gradual loss of a selectively vulnerable group of neurons. Due to the complex pathophysiological mechanisms behind neurodegeneration and despite enormous efforts and understanding of the occurrence and progression of NDs, there is still a lack of an effective treatment for such diseases. Therefore, the development of a new therapeutic strategy for NDs is an unmet clinical need. Various natural compounds extracted from medicinal plants or fruits have shown promising activities in treating different types of NDs by targeting multiple signaling pathways. Among natural entities, flavonoids have incited a rise in public and scientific interest in recent years because of their purported health-promoting effects. Dietary supplementation of flavonoids has been shown to mitigate the severity of NDs such as Parkinson's disease (PD), Alzheimer's disease (AD), and dementia by their antioxidant effects. Naringenin is a citrus flavonoid that is known to possess numerous biological activities like antioxidant, anti-proliferative, and anti-inflammatory activities. Therefore, naringenin has emerged as a potential therapeutic agent that exerts preventive and curative effects on several neurological disorders. Increasing evidence has attained special attention on the variety of therapeutic targets along with complex signaling pathways of naringenin, which suggest its possible therapeutic applications in several NDs. Derived from the results of several pre-clinical research and considering the therapeutic effects of this compound, this review focuses on the potential role of naringenin as a pharmacological agent for the treatment and management of Alzheimer's and Parkinson's disease. The overall neuroprotective effects and different possible underlying mechanisms related to naringenin are discussed. In the light of substantial evidence for naringenin's neuroprotective efficacy in several experimental paradigms, this review suggests that this molecule should be investigated further as a viable candidate for the management of Alzheimer's and Parkinson's disease, with an emphasis on mechanistic and clinical trials to determine its efficacy. PRACTICAL APPLICATIONS: Naringenin is a flavanone, aglycone of Naringin, predominantly found in citrus fruits with a variety of pharmacological actions. Naringenin has been shown to exhibit remarkable therapeutic efficacy and has emerged as a potential therapeutic agent for the management of a variety of diseases such as various heart, liver, and metabolic disorders. Similarly, it has shown efficacy in neurodegenerative illnesses. Therefore, this review enables us to better understand the neuroprotective effects and different possible underlying mechanisms of naringenin. Also, this review provides a new indication to manage the symptoms of NDs like AD and PD. Furthermore, naringenin will be useful in the field of medicine as a new active ingredient for the treatment of neurodegenerative disorders like AD and PD.

GSK-3β-mediated regulation of Nrf2/HO-1 signaling as a new therapeutic approach in the treatment of movement disorders

Movement disorders are neurological conditions characterized by involuntary motor movements, such as dystonia, ataxia, chorea myoclonus, tremors, Huntington's disease (HD), and Parkinson's disease (PD). It is classified into two categories: hypokinetic and hyperkinetic movements. Globally, movement disorders are a major cause of death. The pathophysiological process is initiated by excessive ROS generation, mitochondrial dysfunction, neuroinflammation, and neurotransmitters imbalance that lead to motor dysfunction in PD and HD patients. Several endogenous targets including Nrf2 maintain oxidative balance in the body. Activation of Nrf2 signaling is regulated by the enzyme glycogen synthase kinase (GSK-3β). In the cytoplasm, inhibition of GSK-3β regulates cellular proliferation, homeostasis, and apoptotic process by stimulating the nuclear factor erythroid 2 (Nrf2) pathway which is involved in the elevation of the cellular antioxidant enzymes which controls the ROS generation. The activation of Nrf2 increases the expression of antioxidant response elements (ARE), such as (Hemeoxygenase-1) HO-1, which decreases excessive cellular stress, mitochondrial dysfunction, apoptosis, and neuronal degeneration, which is the major cause of motor dysfunction. The present review explores the GSK-3β-mediated neuroprotection in various movement disorders through the Nrf2/HO-1 antioxidant pathway. This review provides a link between GSK-3β and the Nrf2/HO-1 signaling pathway in the treatment of PD and HD. In addition to that it highlights various GSK-3β inhibitors and the Nrf2/HO-1 activators, which exert robust neuroprotection against motor disorders. Therefore, the present review will help in the discovery of new therapy for PD and HD patients.

Aerobic Training with Naringin Supplementation Improved Spatial Cognition via H2S Signaling Pathway in Alzheimer's Disease Model Rats

OBJECTIVES

This study examined the effects of one-month naringin administration and exercise training on cognitive impairment and H₂S signaling pathway in an Amyloid β (Aβ)-injected rat.

METHODS

Rats were divided into four groups: control group; rats underwent Aβ microinjection surgery, exercise group; rats underwent Aβ microinjection surgery and trained by treadmill for four weeks, naringin group; rats underwent Aβ microinjection surgery, and rats orally administrated 80 mg.kg^-1 naringin for four weeks, naringin+exercise group; rats underwent Aβ microinjection surgery and were trained by treadmill for four weeks, and also, rats orally administrated 80 mg.kg^-1 naringin for four weeks. After one month of treatment, spatial learning and memory were measured, and then hippocampi were sampled. S-adenosylmethionine (SAM), cystathionine-β-synthase (CBS), hydrogen sulfide (H₂S) levels, and neuronal death were detected in the hippocampi of rats.

RESULTS

Naringin and exercise improved spatial learning (latency time, P < .001) and memory (P < .001) in the Morris Water Maze test in Aβ-injected rats compared with the control group. SAM (P < .01), CBS (P < .001), and H₂S (P < .01) levels are increased in the naringin+exercise group compared with the control group.

CONCLUSION

The result of this study supports the effect of exercise and/or naringin to improve cognitive dysfunction and cell death through the production of H₂S.

Protective effect of naringin against oxaliplatin-induced peripheral neuropathy in rats: A behavioral and molecular study

Oxaliplatin (OXL) is a chemotherapeutic drug used for metastatic and other types of cancer, but it causes peripheral neuropathy as a dose-limiting side effect. Herein, we used the rat model of OXL-induced peripheral neuropathy to demonstrate the protective effects of naringin (NRG) in this neuropathy. In this study, rats were injected with OXL (4 mg/kg, body weight, i.p.) in 5% glucose solution 30 min after oral administration of NRG (50 and 100 mg/kg, body weight) on the 1st, 2nd, 5th, and 6th days. OXL caused sensory and motor neuropathy (as revealed by the hot plate, tail flick, rota-rod, and cold hyperalgesia tests) in the sciatic nerve of rats. Coadministration of oral NRG alleviated OXL-induced sensory and motor neuropathy. Levels of superoxide dismutase, catalase, glutathione peroxidase, nuclear factor erythroid 2-related factor 2, Heme oxygenase-1, nuclear factor-κ B, tumor necrosis factor-α, interleukin-1β, Bax, Bcl-2, caspase-3, paraoxonase, mitogen-activated protein kinase 14, neuronal nitric oxide synthase (nNOS), acetylcholinesterase, and arginase 2 in the sciatic nerve tissues were assessed by real-time polymerase chain reaction. Moreover, the protein levels of caspase-3, Bax, Bcl-2, intercellular adhesion molecules-1, glial fibrillary acidic protein, and nNOS were examined by Western blot analysis. NRG treatment significantly improved all the above-mentioned parameters and reduced OXL-induced oxidative stress, inflammation, and apoptosis in the sciatic nerve tissue. In conclusion, this study demonstrated that NRG significantly attenuated OXL-induced peripheral neuropathy and might be considered as a new protective agent to prevent the OXL-induced peripheral neuropathy.

Concise total syntheses of two flavans and structure revision assisted by quantum NMR calculations

A two-step protecting-group-free protocol for the synthesis of 3'-hydroxy-5,7-dimethoxy-4-O-2'-cycloflavan (1) and concise total synthesis of 4'-hydroxy-5,7-dimethoxy-4-O-2'-cycloflavan (8) enabled by a PTSA triggered bioinspired olefin isomerization/hemiacetalization/dehydration/[3 + 3]-type cycloaddition cascade reaction are reported. The successful synthesis of cycloflavan 8 along with GIAO ¹³C NMR calculations of flavan-4-ol 9 and cycloflavan 8 indicated the misassignment of the flavonoid isolated previously and realized the revision of its actual structure.

Drug Discovery of Plausible Lead Natural Compounds That Target the Insulin Signaling Pathway: Bioinformatics Approaches

The growing smooth talk in the field of natural compounds is due to the ancient and current interest in herbal medicine and their potentially positive effects on health. Dozens of antidiabetic natural compounds were reported and tested in vivo, in silico, and in vitro. The role of these natural compounds, their actions on the insulin signaling pathway, and the stimulation of the glucose transporter-4 (GLUT4) insulin-responsive translocation to the plasma membrane (PM) are all crucial in the treatment of diabetes and insulin resistance. In this review, we collected and summarized a group of available in vivo and in vitro studies which targeted isolated phytochemicals with possible antidiabetic activity. Moreover, the in silico docking of natural compounds with some of the insulin signaling cascade key proteins is also summarized based on the current literature. In this review, hundreds of recent studies on pure natural compounds that alleviate type II diabetes mellitus (type II DM) were revised. We focused on natural compounds that could potentially regulate blood glucose and stimulate GLUT4 translocation through the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. On attempt to point out potential new natural antidiabetic compounds, this review also focuses on natural ingredients that were shown to interact with proteins in the insulin signaling pathway in silico, regardless of their in vitro/in vivo antidiabetic activity. We invite interested researchers to test these compounds as potential novel type II DM drugs and explore their therapeutic mechanisms.

Potential nephroprotective phytochemicals: Mechanism and future prospects

ETHNOPHARMACOLOGICAL RELEVANCE

Kidney disease (KD) is one of the serious health issues, which causes worrisome morbidity and economic burden. Therapeutic strategies are available however majority of them are associated with severe adverse effects and poor patient compliance and adherence. This explorative article was undertaken to provide a holistic review of known nephroprotective (NP) phytoconstituents along with their research-based evidences on mechanism, sources, and clinical trials that may play essential role in prevention and cure of KD.

AIM OF THE STUDY

The present systematic review aimed to provide in-depth and better evidences of the global burden of KD, phytoconstituents as NP with emphasis on mechanism of action both in vitro and in vivo, their wide biological sources as well as their clinical efficacy in management of kidney disease and its related disorders.

MATERIAL AND METHODS

Comprehensive information was searched systematically from electronic databases, namely, PubMed, Sciencedirect, Wiley, Scopus, Google scholar and Springer until February 2021 to find relevant data for publication on phytoconstituents with nephroprotective potential.

RESULTS

In total, 24,327 articles were screened in first search for "phytoconstituents and medicinal plants for nephroprotection and kidney disorder". On the basis of exclusion and inclusion criteria, 24,091 were excluded. Only 236 papers were spotted to have superlative quality data, which is appropriate under titles and sub-titles of the present review. The phytoconstituents having multiple research evidence along with wide number of medicinal plants sources and mechanism reported for nephroprotection have been selected and reviewed.

CONCLUSION

This review, based on pre-clinical and clinical data of NP phytoconstituents, provides scientific-basis for the rational discovery, development and utilization of these upcoming treatment practices. Further,-more clinical studies are warranted to improve the pharmacodynamic and pharmacokinetic understanding of phytoconstituents. Also, more specific evaluation for natural sources is needed.

Neurodegenerative Diseases and Flavonoids: Special Reference to Kaempferol

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

Naringenin alleviates paraquat-induced dopaminergic neuronal loss in SH-SY5Y cells and a rat model of Parkinson's disease

Parkinson's disease (PD), a common neurodegenerative disease is characterized by the progressive loss of dopaminergic neurons in the substantia nigra. The cause of dopaminergic loss in PD remains unknown for a long time, however, recent reports suggest oxidative stress plays a key role in the pathogenesis of PD. Paraquat (PQ), a widely used herbicide is an oxidative stress inducer that has been implicated as a potential risk factor for the development of PD. Flavonoids are naturally occurring polyphenolic compounds that display a variety of therapeutic properties against oxidative stress. Naringenin (NAR), a natural flavonoid, exhibits neuroprotection against PD-related pathology. However, studies on its neuroprotective role and the underlying mechanisms are scarce, therefore the present study explored the potential neuroprotective role of NAR in PQ-induced parkinsonism in SH-SY5Y cells and rat model. The effect of NAR on PQ-induced cellular toxicity was determined by measuring cell viability, oxidative stress, ATP levels and the same effect was determined by assessing behavioral, biochemical, immunohistochemical, qRT-PCR and Western blot in rat model. NAR treatment in SH-SY5Y cells resulted in increased cell viability, reduced oxidative stress, elevated mitochondrial membrane potential, and higher cellular ATP levels. In rats, NAR treatment resulted in significant neuroprotection against PQ-induced behavioral deficits, oxidative stress, mitochondrial dysfunction, and astrocytosis. NAR treatment significantly modulated PQ-induced mRNA expressions of DRD2, DAT, LRRK2, SNCA, β-catenin, caspase-3, BDNF genes. NAR treatment increased TH protein expression and modulated its immunoreactivity in rat striatum. Also, GFAP decreased in response to NAR treatment. So, in the present study, NAR exhibits neuroprotection against PQ-induced neurotoxicity and neurodegeneration indicating its novel therapeutic potential against PD.

Nephroprotective effect of naringin in methotrexate induced renal toxicity in male rats

The current work aims to study the nephroprotective potential of naringin (NG), a flavanone derived from citrus fruits, in methotrexate (MTX)-induced renal toxicity. Thirty male rats were divided into five groups; control group (IP saline), MTX group (IP single dose, 20 mg/kg), and three groups co-treated with MTX and naringin (IP daily dose; 20, 40, and 80 mg/kg, respectively). Kidney tissues were used to investigate renal function, oxidative stress, lipid peroxidation, and caspase-3 activity. Biochemical cytokine analysis was performed in addition to ultrastructural examinations of kidney tissue. When compared to the MTX-treated rats, MTX+NG significantly reduced the levels of urea, creatinine, MDA, NO, TNFα, IL-6, and caspase-3 activity. A significant increase in the levels of the antioxidant enzymes and GSH were also noted. Additionally, naringin ameliorated the apparent ultrastructural changes observed in the glomeruli and renal tubules of MTX-intoxicated rats. Noticeable structural improvements of glomerular lesions, proximal, and distal convoluted tubular epithelium were observed in MTX+NG treated animals, including podocytes with regular foot processes, perfectly organized filtration barrier, no signs of GBM thickening, organized brush border, and normal architecture of microvilli. Naringin (80 mg/kg) had the maximum amelioration effect. To the best of our knowledge, this is the first study to investigate the ultrastructural manifestations of naringin and/or MTX on the kidney of rats. Taken all, naringin has a potent therapeutic effect and can be used in adjuvant therapy to prevent MTX-induced nephrotoxicity. Nevertheless, the molecular mechanism underlying the nephroprotective capacity of naringin needs further investigation.

An Overview of the Nrf2/ARE Pathway and Its Role in Neurodegenerative Diseases

Nrf2 is a basic region leucine-zipper transcription factor that plays a pivotal role in the coordinated gene expression of antioxidant and detoxifying enzymes, promoting cell survival in adverse environmental or defective metabolic conditions. After synthesis, Nrf2 is arrested in the cytoplasm by the Kelch-like ECH-associated protein 1 suppressor (Keap1) leading Nrf2 to ubiquitin-dependent degradation. One Nrf2 activation mechanism relies on disconnection from the Keap1 homodimer through the oxidation of cysteine at specific sites of Keap1. Free Nrf2 enters the nucleus, dimerizes with small musculoaponeurotic fibrosarcoma proteins (sMafs), and binds to the antioxidant response element (ARE) sequence of the target genes. Since oxidative stress, next to neuroinflammation and mitochondrial dysfunction, is one of the hallmarks of neurodegenerative pathologies, a molecular intervention into Nrf2/ARE signaling and the enhancement of the transcriptional activity of particular genes are targets for prevention or delaying the onset of age-related and inherited neurogenerative diseases. In this study, we review evidence for the Nrf2/ARE-driven pathway dysfunctions leading to various neurological pathologies, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, as well as amyotrophic lateral sclerosis, and the beneficial role of natural and synthetic molecules that are able to interact with Nrf2 to enhance its protective efficacy.

Flavonoids, the Family of Plant-derived Antioxidants making inroads into Novel Therapeutic Design against IR-induced Oxidative Stress in Parkinson's Disease

Background:

Ionizing radiation from telluric sources is unceasingly an unprotected pitfall to humans. Thus, the foremost contributors to human exposure are global and medical radiations. Various evidences assembled during preceding years reveal the pertinent role of ionizing radiation-induced oxidative stress in the progression of neurodegenerative insults, such as Parkinson’s disease, which have been contributing to increased proliferation and generation of reactive oxygen species.

Objective:

This review delineates the role of ionizing radiation-induced oxidative stress in Parkinson’s disease and proposes novel therapeutic interventions of flavonoid family, offering effective management and slowing down the progression of Parkinson’s disease.

Methods:

Published papers were searched in MEDLINE, PubMed, etc., published to date for in-depth database collection.

Results:

The oxidative damage may harm the non-targeted cells. It can also modulate the functions of the central nervous system, such as protein misfolding, mitochondria dysfunction, increased levels of oxidized lipids, and dopaminergic cell death, which accelerate the progression of Parkinson’s disease at the molecular, cellular, or tissue levels. In Parkinson’s disease, reactive oxygen species exacerbate the production of nitric oxides and superoxides by activated microglia, rendering death of dopaminergic neuronal cell through different mechanisms.

Conclusion:

Rising interest has extensively engrossed in the clinical trial designs based on the plant-derived family of antioxidants. They are known to exert multifarious impact on neuroprotection via directly suppressing ionizing radiation-induced oxidative stress and reactive oxygen species production or indirectly increasing the dopamine levels and activating the glial cells.

Comparison of microwave-assisted techniques for the extraction of antioxidants from Citrus paradisi Macf. biowastes

Microwave-assisted extraction (MAE) and solvent-free microwave extraction and Soxhlet extraction were applied to Ray Ruby grapefruit leaves (Citrus paradisi Macf.) to compare extract efficiency. Face centered composite designs were constructed via response surface methodology. Effects of factors of MAE were investigated on total phenolic content (TPC) and naringin content (NC). The optimized conditions were established as 1.4 kWL^-1 for microwave power density, 20.00 gL^-1 for solid/solvent ratio, 218.180 s for extraction time, while responses were calculated as 14.210 mg of gallic acid equivalent per g of the dried leaf (mg GAE g^-1DL) and 13.198 mg of naringin per g of dried leaf (mg Ng^-1DL) for TPC and NC, respectively. SFME and classical Soxhlet methods were also conducted for comparison reasons.

Naringin treatment improved main clozapine-induced adverse effects in rats; emphasis on weight gain, metabolic abnormalities, and agranulocytosis

Schizophrenia is one of the major neuropsychiatric disorders affecting people worldwide. Unfortunately, currently available antipsychotic medications possess several side effects. Among them, clozapine is one of the atypical antipsychotics prescribed in schizophrenia wing to its blocking effect on dopamine (D2) and serotonin (5-HT_1c ) receptors. However, it has been recently reserved for resistant schizophrenia due to its several side effects. The current research aimed at investigating potential naringin add-on benefit to cease the main side effects of clozapine in ketamine-induced psychosis in rats. In this study, schizophrenia was induced in rats via ketamine administration that could promote neuropathological patterns of schizophrenia. Afterwards, clozapine and naringin were administered to rats in order to improve such effects induced by ketamine. Clozapine administration promoted weight gain, hyperglycemia, dyslipidemia, and agranulocytosis. However, naringin was able to reduce such adverse effects when added to clozapine treatment. Naringin increased total leukocyte count preventing agranulocytosis either when administered alone or in combination with clozapine. In addition, via its metabolic activities, naringin treatment lowered serum total cholesterol and triglycerides levels. Moreover, naringin prevented weight gain when administered. Finally, naringin reduced serum glucose level preventing hyperglycemia associated with clozapine treatment. Collectively, these findings may suggest that naringin possesses a potential add-on benefit to clozapine in treatment of schizophrenia.

Protective Effect of Natural Products against Huntington's Disease: An Overview of Scientific Evidence and Understanding Their Mechanism of Action

Huntington's disease (HD), a neurodegenerative disease, normally starts in the prime of adult life, followed by a gradual occurrence of characteristic psychiatric disturbances and cognitive and motor dysfunction. To the best of our knowledge, there is no treatment available to completely mitigate the progression of HD. Among various therapeutic approaches, exhaustive literature reports have confirmed the medicinal benefits of natural products in HD experimental models. Building on this information, this review presents a brief overview of the neuroprotective mechanism(s) of natural products against in vitro/in vivo models of HD. Relevant studies were identified from several scientific databases, including PubMed, ScienceDirect, Scopus, and Google Scholar. After screening through literature from 2005 to the present, a total of 14 medicinal plant species and 30 naturally isolated compounds investigated against HD based on either in vitro or in vivo models were included in the present review. Behavioral outcomes in the HD in vivo model showed that natural compounds significantly attenuated 3-nitropropionic acid (3-NP) induced memory loss and motor incoordination. The biochemical alteration has been markedly alleviated with reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and increased mitochondrial energy production. Interestingly, following treatment with certain natural products, 3-NP-induced damage in the striatum was ameliorated, as seen histologically. Overall, natural products afforded varying degrees of neuroprotection in preclinical studies of HD via antioxidant and anti-inflammatory properties, preservation of mitochondrial function, inhibition of apoptosis, and induction of autophagy.

BACE1 and cholinesterase inhibitory activities of compounds from Cajanus cajan and Citrus reticulata: an in silico study

Alzheimer's disease (AD) is one of the major neurodegenerative diseases whose underlying risk factors are yet to be fully understood. However, reduced cellular level of cholinesterase, as well as formation and deposition of amyloid plaques (Aβ) are thought to play critical roles in the pathogenesis of AD. Therefore, increases in cholinergic transmitter levels via cholinesterase (ChE) inhibitors as well as inhibition of amyloid plaques formation and aggregation via beta secretase-1 (BACE1) inhibitors have been proposed as treatment for this disease. This study was aimed at investigating the BACE1 and ChE inhibitory properties of compounds from Cajanus cajan and Citrus reticulata based on their traditional connection with the management of neurodegenerative diseases, coupled with their protective effects on chemical-induced cognitive impairment. Using in silico methods, one hundred and nineteen compounds from C. cajan and C. reticulata were docked with acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and BACE1 using Vina. Molecular interactions of the top-ranked compounds for the 3 protein targets were viewed with Discovery Studio, followed by characterization of their ADME properties using the Swiss online ADME web tool. Among the one hundred and ninety nine compounds screened, 3 compounds, genistin (76), naphthalen-2-yl-acetic acid, 6-hydroxy-6-methyl-cyclodecyl ester (94) and vitexin (119) have remarkable binding affinity for the three protein targets and passed the oral drugability test, while only naphthalen-2-yl-acetic acid, 6-hydroxy-6-methyl-cyclodecyl ester (94) exhibited BBB permeation property. Genistin and vitexin from C. cajan and naphthalen-2-yl-acetic acid, 6-hydroxy-6-methyl-cyclodecyl ester from C. reticulata possibly contributed, at least in part, to the neurotherapeutic potentials of these plants.

Citrus flavonoids and their antioxidant evaluation

The antioxidant ability is the link and bridge connecting a variety of biological activities. Citrus flavonoids play an essential role in regulating oxidative stress and are an important source of daily intake of antioxidant supplements. Many studies have shown that citrus flavonoids promote health through antioxidation. In this review, the biosynthesis, composition and distribution of citrus flavonoids were concluded. The detection methods of antioxidant capacity of citrus flavonoids were divided into four categories: chemical, cellular, animal and clinical antioxidant capacity evaluation systems. The modeling methods, applicable scenarios, and their relative merits were compared based on these four systems. The antioxidant functions of citrus flavonoids under different evaluation systems were also discussed, especially the regulation of the Nrf2-antioxidases pathway. Some shortcomings in the current research were pointed out, and some suggestions for progress were put forward.

Cardioprotective Effects of Natural Products via the Nrf2 Signaling Pathway

Due to its poor regenerative capacity, the heart is specifically vulnerable to xenobiotic- induced cardiotoxicity, myocardial ischaemia/reperfusion injury and other pathologies. Nuclear factor erythroid-2-related factor 2 (Nrf2) is considered as an essential factor in protecting cardiomyocytes against oxidative stress resulting from free radicals and reactive oxygen species. It also serves as a key regulator of antioxidant enzyme expression via the antioxidant response element, a cis-regulatory element, which is found in the promoter region of several genes encoding detoxification enzymes and cytoprotective proteins. It has been reported that a variety of natural products are capable of activating Nrf2 expression, and in this way, increase the antioxidant potential of cardiomyocytes. In the present review, we consider the cardioprotective activities of natural products and their possible therapeutic potential.

In silico approach of naringin as potent phosphatase and tensin homolog (PTEN) protein agonist against prostate cancer

Prostate cancer (PC) is one of the major impediments affecting men, which leads approximately 31,620 deaths in both developing and developed countries. Although some chemotherapy drugs have been reported for prostate cancer, they are not effective due to the lack of safety, efficacy and low selectivity. Hence, the novel alternative anticancer agents with remarkable effect are highly appreciable. Natural plants contain several bio-active compounds which have been traditionally used for the various medical treatments. Particularly, naringin is a natural bio-active compound commonly found in the citrus fruits, which have shown numerous biological activities. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene, which activates both lipid phosphates and protein phosphates. The PTEN gene is negative regulator of PI3K/AKT/mTOR pathways, since, this signaling pathway play an essential role in the cell survival, proliferation and migration. In the present in silico investigation, structure based virtual screening, molecular docking, molecular dynamics simulation and Adsorption, Distribution, Metabolism, Excretion (ADME) prediction were employed to determine the binding affinity, stability and drug likeness properties of top ranked screened compounds and naringin, respectively. The results revealed that the complex has good molecular interactions, binding stability (peak between 0.3 and 0.4 nm) and no violations in the Lipinski Rule of 5 in naringin, but the screened compounds violated the drug likeness properties. From the in silico analyses, it is identified that naringin compound might assist in the development of novel therapeutic candidate against prostate cancer.Communicated by Ramaswamy H. Sarma.

Naringin Confers Protection against Psychosocial Defeat Stress-Induced Neurobehavioral Deficits in Mice: Involvement of Glutamic Acid Decarboxylase Isoform-67, Oxido-Nitrergic Stress, and Neuroinflammatory Mechanisms

Psychosocial stress has been widely reported to contribute to psychiatric disturbances. Perturbations in the enzymes of GABAergic and cholinergic systems have been implicated as precursors in different stress-related neuropsychiatric diseases. Targeting glutamic acid decarboxylase-67 kDa (GAD67) and acetylcholinesterase (AChE) via oxidative, nitrergic, and neuroinflammatory mechanisms have been recognized as prospective strategies for the prevention of psychosocial stress-induced behavioral impairments. Naringin, a neuro-active flavonoid compound isolated from citrus fruits, has been shown to produce memory-enhancing, antiepileptic, antidepressant, and anti-inflammatory activities similarly to ginseng, a very potent adaptogen. In this communication, we assessed the effect of naringin on social-defeat stress (SDS)-induced behavioral, GABAergic, cholinergic, oxidative, nitrergic, and neuroinflammatory changes in mice using the resident-intruder paradigm. The intruder male mice were culled into six groups. Groups 1 and 2 (normal- and SDS-controls) received sterile saline, groups 3-5 were given naringin (25-100 mg/kg, i.p.) whereas group 6 had ginseng (50 mg/kg, i.p.) daily for 14 days, but followed by 10 min SDS (physical and psychological) exposure to groups 2-6 with aggressor-resident mice. Behavioral effects using Y-maze, elevated-plus maze, sociability, and tail-suspension tests were assessed on day 14. GAD67, AChE enzymes, and biomarkers of oxidative, nitrergic, and neuroinflammatory changes were assayed in the striatum, prefrontal cortex, and hippocampus. Naringin and ginseng reversed all SDS-induced behavioral impairments. Naringin increased the levels of GAD67 and decreased AChE activities in the striatum, prefrontal cortex, and hippocampus. Furthermore, naringin reduced pro-inflammatory cytokines (TNF-α, IL-6), malondialdehyde, nitrite concentrations, and increased glutathione levels in a region-dependent manner. Our study suggests that naringin attenuated SDS-induced behavioral endophenotypes of neuropsychiatric disease through increased GAD67 synthesis, inhibition of AChE activity, oxidative, nitrergic stress, and neuroinflammatory processes in stress-sensitive brain regions.

Supplementation with a putative calorie restriction mimetic micronutrient blend increases glutathione concentrations and improves neuroenergetics in brain of healthy middle-aged men and women

BACKGROUND

Caloric restriction (CR) without micronutrient deficiency has been shown to increase both lifespan and healthspan. In animals, CR has been demonstrated to increase glutathione (GSH), a neuroprotective antioxidant, in the brain and preserve brain mitochondrial function by altering neuroenergetics. In humans it has been associated with improvements in mood states and cognitive function. However, most CR studies have employed a 30-60% reduction in calories which is likely too stringent for most people to adhere to long-term. Thus, there is an unmet need for nutritional supplements which can mimic the biological effects of CR, without the need for calorie limitations.

AIM

The purpose of the present randomized, placebo-controlled clinical trial was to use Proton (¹H) Magnetic Resonance Spectroscopic (MRS) measurements to determine non-invasively whether a blend of micronutrients, a putative CR mimetic, positively modulates metabolites related to neuroprotection and neuroenergetics in the brain.

METHODS

Healthy middle-aged men and women (N = 63 [33 women]; age: 40-60 years) were randomized in a double-blind manner to 6 weeks supplementation with either the putative CR mimetic or placebo. At baseline and 6 weeks, subjects underwent MRS at 3 T to investigate changes in brain chemistry, including the neurometabolites: GSH, Glutamate (Glu), Glutamine (Gln) and N-Acetylaspartate (NAA).

RESULTS

GSH, a marker of antioxidant and cellular redox status, increased in the brain of participants in the supplement group. The supplement group also showed an increase in the Glu/Gln ratio, a marker of excitatory neurotransmission and bioenergetics. A trend for an increase in NAA/H₂O, a marker of neuronal integrity, was observed in females in the supplement group.

CONCLUSIONS

The present study reveals that 6-weeks daily supplementation with a micronutrient blend elicits positive changes in brain neurochemistry. This is the first study to demonstrate that a putative CR mimetic increases brain GSH concentrations and improves neuroprotection and neuroenergetics in the brain of healthy humans. This study was registered at www.clinicaltrials.gov as NCT02439983.