Phytochemicals that regulate neurodegenerative disease by targeting neurotrophins: a comprehensive review

Biotechnological approaches for the production of neuroactive huperzine A

Huperzine A (HupA), a natural Lycopodium alkaloid primarily derived from Huperzia serrata, has gained attention for its potent neuroprotective properties, particularly its ability to inhibit acetylcholinesterase and modulate key neurological pathways. This review highlights HupA's therapeutic potential in managing neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, epilepsy, and myasthenia gravis drawing on a comprehensive literature survey of in vitro, in vivo, and clinical investigation data. Given the limited yield from natural sources, this review also focuses on biotechnological strategies to enhance HupA production. These include chemical synthesis, microbial fermentation using endophytic fungi, plant tissue culture, and emerging synthetic biology approaches. Key biosynthetic intermediates and enzymes, such as lysine decarboxylase, copper amine oxidase, and cytochrome P450s, are discussed in the context of metabolic pathway elucidation and engineering. The review emphasizes the need to bridge current knowledge gaps in HupA biosynthesis to develop cost-effective, sustainable production methods. Advances in metabolic pathway elucidation and engineering hold immense potential for scalable biosynthetic production. Ultimately, the integration of HupA into neurotherapeutic regimens, coupled with innovations in its production, could revolutionize the management of neurodegenerative disorders and position it as a cornerstone of future multi-targeted treatment strategies.

The role of Panax ginseng in neurodegenerative disorders: mechanisms, benefits, and future directions

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), Multiple sclerosis (MS), and Huntington's disease (HD) represent a growing global health challenge, especially with aging populations. Characterized by progressive neuronal loss, these diseases lead to cognitive, motor, and behavioral impairments, significantly impacting patients' quality of life. Current therapies largely address symptoms without halting disease progression, underscoring the need for innovative, disease-modifying treatments. Ginseng, a traditional herbal medicine with well-known adaptogenic and neuroprotective properties, has gained attention as a potential therapeutic agent for neurodegeneration. Rich in bioactive compounds called ginsenosides, ginseng exhibits antioxidant, anti-inflammatory, and anti-apoptotic effects, making it a promising candidate for addressing the complex pathology of neurodegenerative diseases. Recent studies demonstrate that ginsenosides modulate disease-related processes such as oxidative stress, protein aggregation, mitochondrial dysfunction, and inflammation. In AD models, ginsenosides have been shown to reduce amyloid-beta accumulation and tau hyperphosphorylation, while in PD, they help protect dopaminergic neurons and mitigate motor symptoms. Ginseng's effects in ALS, MS, and HD models include improving motor function, extending neuronal survival, and reducing cellular toxicity. This review provides a comprehensive overview of the neuroprotective mechanisms of ginseng, emphasizing its therapeutic potential across various neurodegenerative diseases and discussing future research directions for its integration into clinical practice.

Interaction of some phytochemical compounds with Er2O3 nanoparticle: First principle study

CONTEXT

The interaction between phytochemicals and nanoparticles plays a crucial role in nanotechnology and biomedical applications. This study investigates the binding behavior and stability of six phytochemicals-Catechin, Limonene, Sabinene, Sinapic Acid, Vanillic Acid, and Luteolin 7-O-ß-glucuronide-with Er₂O₃ nanoparticles using Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations. The findings indicate that Luteolin, Catechin, and Sinapic Acid exhibit the strongest binding affinities and highest structural stability with Er2O3, attributed to their balanced hydrophilicity-lipophilicity and favorable electronic properties. These insights contribute to the design and functionalization of phytochemical-based nanomaterials, with potential applications in drug delivery, bioimaging, and photodynamic therapy.

METHODS

DFT calculations were conducted using Gaussian 09 at the B3LYP/6-311 +  + G(d,p) level to determine HOMO-LUMO energy gaps, dipole moments, and polarizability of the phytochemicals. MD simulations, performed using GROMACS 2019 with the CHARMM36 force field and TIP3P water model, analyzed the dynamics of phytochemical adsorption on a 5 nm Er2O3 nanoparticle over 50 ns. Key parameters such as interaction energies, root mean square deviations (RMSD), radial distribution functions (RDF), and water solubility (logS) were evaluated using ALOPGPS 2.1 software.

The effect of curcumin, catechin and resveratrol on viability, proliferation and cytotoxicity of human umbilical cord Wharton's jelly derived mesenchymal stem cells

INTRODUCTION

Mesenchymal stem cells possess the capability to proliferate and differentiate into diverse lineages. Their beneficial properties have been explored widely to treat various disorders. Phytochemicals like curcumin, catechin and resveratrol have been evaluated for their medicinal values and have promising potential in treating numerous diseases. In this study, we have elucidated the in vitro survival, proliferative and cytotoxic effects of these phytochemicals at selected range of concentrations on human umbilical cord derived Wharton's jelly mesenchymal stem cells (WJ-MSCs).

METHODS

The human WJ-MSCs were extracted using explant culture method and characterized as per International Society for Cellular Therapy (ISCT) guidelines. To analyse the effect of different phytochemicals, the WJ-MSCs were treated with various concentrations ranging from 0.1 to 1000 µM and the viability, proliferative and toxicity effects were assayed using (3-(4,5-dimethylthioazolyl-2,5-diphenyltetrozolium bromide) MTT.

RESULTS

Curcumin and catechin elicited no cytotoxic effect on WJ-MSCs after 48 hours of treatment between the concentrations ranging from 0.1 to 10 µM and the viability was maintained above 80 %. For both the phytochemicals, there was a significant decrease in the viability of WJ-MSCs after 50 µM. Resveratrol was well tolerated at higher doses till 100 µM with a viability above 90 % and cytotoxic effect was observed above 250 µM.

CONCLUSION

Curcumin, catechin and resveratrol, affect the viability and proliferation of WJ-MSCs differently at varying concentrations. This data will be useful in deciding the dose of phytochemicals when employed concomitantly with stem cells to increase their efficiency.

Phytochemicals Modulate Biosynthesis and Function of Serotonin, Dopamine, and Norepinephrine for Treatment of Monoamine Neurotransmission-Related Psychiatric Diseases

Serotonin (5-HT), dopamine (DA), and norepinephrine (NE) are key monoamine neurotransmitters regulating behaviors, mood, and cognition. 5-HT affects early brain development, and its dysfunction induces brain vulnerability to stress, raising the risk of depression, anxiety, and autism in adulthood. These neurotransmitters are synthesized from tryptophan and tyrosine via hydroxylation and decarboxylation, and are metabolized by monoamine oxidase (MAO). This review aims to summarize the current findings on the role of dietary phytochemicals in modulating monoamine neurotransmitter biosynthesis, metabolism, and function, with an emphasis on their potential therapeutic applications in neuropsychiatric disorders. Phytochemicals exert antioxidant, neurotrophic, and neurohormonal activities, regulate gene expression, and induce epigenetic modifications. Phytoestrogens activate the estrogen receptors or estrogen-responsive elements of the promoter of target genes, enhance transcription of tryptophan hydroxylase and tyrosine hydroxylase, while inhibiting that of MAO. These compounds also influence the interaction between genetic and environmental factors, potentially reversing dysregulated neurotransmission and the brain architecture associated with neuropsychiatric conditions. Despite promising preclinical findings, clinical applications of phytochemicals remain challenging. Advances in nanotechnology and targeted delivery systems offer potential solutions to enhance clinical efficacy. This review discusses mechanisms, challenges, and strategies, underscoring the need for further research to advance phytochemical-based interventions for neuropsychiatric diseases.

Synaptic plasticity and neuroprotection: The molecular impact of flavonoids on neurodegenerative disease progression

Flavonoids are a broad family of polyphenolic chemicals that are present in a wide variety of fruits, vegetables, and medicinal plants. Because of their neuroprotective qualities, flavonoids have attracted a lot of interest. The potential of flavonoids to control synaptic plasticity-a crucial process underlying memory, learning, and cognitive function-is becoming more and more clear. Dysregulation of synaptic plasticity is a feature of neurodegenerative diseases such as amyotrophic lateral sclerosis (0.4 %), Parkinson's (1-2 %), Alzheimer's (5-7 %), and Huntington's ((0.2 %)). This review discusses the molecular mechanisms via which flavonoids influence synaptic plasticity as well as their therapeutic potential in neurodegenerative diseases. Flavonoids modulate key signaling pathways such as MAPK/ERK and PI3K/Akt/mTOR to support neuroprotection, synaptic plasticity, and neuronal health, while also influencing neurotrophic factors (BDNF, NGF) and their receptors (TrkB, TrkA). They regulate neurotransmitter receptors like GABA, AMPA, and NMDA to balance excitatory and inhibitory transmission, and exert antioxidant effects via the Nrf2-ARE pathway and anti-inflammatory actions by inhibiting NF-κB signaling, highlighting their potential for treating neurodegenerative diseases. These varied reactions support the preservation of synapse function and neuronal integrity in the face of neurodegenerative insults. Flavonoids can reduce the symptoms of neurodegeneration, prevent synaptic loss, and enhance cognitive function, according to experimental studies. However, there are still obstacles to using these findings in clinical settings, such as limited bioavailability and the need for consistent dose. The focus of future research should be on improving flavonoid delivery systems and combining them with conventional medications.

Multi-Targeting Phytochemicals for Alzheimer's Disease

Alzheimer's disease (AD) is a type of neurodegenerative illness in which β-amyloid (Aβ) and tau protein accumulate in neurons in the form of tangles. The pathophysiological pathway of AD consists of Aβ-amyloid peptides, tau proteins, and oxidative stress in neurons and increased neuro-inflammatory response. Food and Drug Administration in the United States has authorized various drugs for the effective treatment of AD, which include galantamine, rivastigmine, donepezil, memantine, sodium oligomannate, lecanemab, and aducanumab. The major disadvantage of these drugs is that they only provide "symptomatic" relief. They are most effective in the early stages or for mild to moderate cases of the disease, but are not suitable for long-term use. Besides conventional therapies, phytochemicals have the potential to stop the progression of AD. According to research, the use of potential phytochemicals against AD has gained attention due to their potent anti-inflammatory, antioxidant, anti-hyperphosphorylation of the tau protein, metal chelation, and anti-amyloid properties. This study seeks to provide an up-to-date compilation of the most current and promising breakthroughs in AD therapy using phytochemicals. It could be concluded that phytochemicals light serve as an effective therapy for AD. However, more mechanistic investigations are needed to determine the clinical implications of phytochemicals in AD treatment.

Phytochemicals Targeting BDNF Signaling for Treating Neurological Disorders

Neurological disorders are defined by a deterioration or disruption of the nervous system's structure and function. These diseases, which include multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and schizophrenia, are caused by intricate pathological processes that include excitotoxicity, neuroinflammation, oxidative stress, genetic mutations, and compromised neurotrophic signaling. Although current pharmaceutical treatments relieve symptoms, their long-term efficacy is limited due to adverse side effects and weak neuroprotective properties. However, when combined with other neuroprotective drugs or adjunct therapy, they may offer additional benefits and improve treatment outcomes. Phytochemicals have emerged as attractive therapeutic agents due to their ability to regulate essential neurotrophic pathways, especially the brain-derived neurotrophic factor (BDNF) signaling cascade. BDNF is an important target for neurodegenerative disease (ND) treatment since it regulates neuronal survival, synaptic plasticity, neurogenesis, and neuroprotection. This review emphasizes the molecular pathways through which various phytochemicals-such as flavonoids, terpenoids, alkaloids, and phenolic compounds-stimulate BDNF expression and modulate its downstream signaling pathways, including GSK-3β, MAPK/ERK, PI3K/Akt/mTOR, CREB, and Wnt/β-catenin. This paper also highlights how phytochemical combinations may interact to enhance BDNF activity, offering new therapeutic options for ND treatment. Despite their potential for neuroprotection, phytochemicals face challenges related to pharmacokinetics, blood-brain barrier (BBB) permeability, and absorption, highlighting the need for further research into combination therapies and improved formulations. Clinical assessment and mechanistic understanding of BDNF-targeted phytotherapy should be the main goals of future studies. The therapeutic efficacy of natural compounds in regulating neurotrophic signaling is highlighted in this review, providing a viable approach to the prevention and treatment of NDs.

Polyphenols, Alkaloids, and Terpenoids Against Neurodegeneration: Evaluating the Neuroprotective Effects of Phytocompounds Through a Comprehensive Review of the Current Evidence

Neurodegenerative diseases comprise a group of chronic, usually age-related, disorders characterized by progressive neuronal loss, deformation of neuronal structure, or loss of neuronal function, leading to a substantially reduced quality of life. They remain a significant focus of scientific and clinical interest due to their increasing medical and social importance. Most neurodegenerative diseases present intracellular protein aggregation or their extracellular deposition (plaques), such as α-synuclein in Parkinson's disease and amyloid beta (Aβ)/tau aggregates in Alzheimer's. Conventional treatments for neurodegenerative conditions incur high costs and are related to the development of several adverse effects. In addition, many patients are irresponsive to them. For these reasons, there is a growing tendency to find new therapeutic approaches to help patients. This review intends to investigate some phytocompounds' effects on neurodegenerative diseases. These conditions are generally related to increased oxidative stress and inflammation, so phytocompounds can help prevent or treat neurodegenerative diseases. To achieve our aim to provide a critical assessment of the current literature about phytochemicals targeting neurodegeneration, we reviewed reputable databases, including PubMed, EMBASE, and COCHRANE, seeking clinical trials that utilized phytochemicals against neurodegenerative conditions. A few clinical trials investigated the effects of phytocompounds in humans, and after screening, 13 clinical trials were ultimately included following PRISMA guidelines. These compounds include polyphenols (flavonoids such as luteolin and quercetin, phenolic acids such as rosmarinic acid, ferulic acid, and caffeic acid, and other polyphenols like resveratrol), alkaloids (such as berberine, huperzine A, and caffeine), and terpenoids (such as ginkgolides and limonene). The gathered evidence underscores that quercetin, caffeine, ginkgolides, and other phytochemicals are primarily anti-inflammatory, antioxidant, and neuroprotective, counteracting neuroinflammation, neuronal oxidation, and synaptic dysfunctions, which are crucial aspects of neurodegenerative disease intervention in various included conditions, such as Alzheimer's and other dementias, depression, and neuropsychiatric disorders. In summary, they show that the use of these compounds is related to significant improvements in cognition, memory, disinhibition, irritability/lability, aberrant behavior, hallucinations, and mood disorders.

Neuroprotective Efficacy of Phytoconstituents of Methanolic Shoots Extract of Calligonum polygonoides L. in Hypercholesterolemia-associated Neurodegenerations

BACKGROUND

Small molecule phytocompounds can potentially ameliorate degenerative changes in cerebral tissues. Thus, the current study aimed to evaluate the neuroprotective efficacy of phytocompounds of methanolic shoots extract of Calligonum polygonoides L. (MSECP) in hypercholesterolemia-associated neurodegenerations.

METHODS

Phytochemical screening of the extract was made by LCMS/MS and validated by a repository of the chemical library. The hypercholesterolemia was induced through the intraperitoneal administration of poloxamer-407 with a high-fat diet. The in silico assessments were accomplished by following the molecular docking, ADME and molecular dynamics. MMPBSA and PCA (Principal Component Analysis) analyzed the molecular dynamics simulations. Consequently, in-vivo studies were examined by lipid metabolism, free radical scavenging capabilities and histopathology of brain tissues (cortex and hippocampus).

RESULTS

22 leading phytocompounds were exhibited in the test extract, as revealed by LCMS/ MS scrutiny. Molecular docking evaluated significant interactions of apigenin triacetate with target proteins (HMGCR (HMG-CoA reductase), (AChE-Acetylcholinesterase) and (BuChE- Butyrylcholinesterase). Molecular dynamics examined the interactions through assessments of the radius of gyration, RSMD, RSMF and SASA at 100 ns, which were further analyzed by MMPBSA (Molecular Mechanics Poisson-Boltzmann) and PCA (Principal Component Analysis). Accordingly, the treatment of test extract caused significant alterations in lipid profile, dyslipidemia indices, antioxidant levels and histopathology of brain tissues.

CONCLUSION

It can be concluded that apigenin triacetate is a potent phytoconstituent of MSEPC and can interact with HMGCR, AChE, and BuChE, which resulted in improved hypercholesterolemia along with neuroprotective ameliorations in the cortex and hippocampus.

Short Peptides Protect Fibroblast-Derived Induced Neurons from Age-Related Changes

Neurons become more vulnerable to stress factors with age, which leads to increased oxidative DNA damage, decreased activity of mitochondria and lysosomes, increased levels of p16, decreased LaminB1 proteins, and the depletion of the dendritic tree. These changes are exacerbated in vulnerable neuronal populations during the development of neurodegenerative diseases. Glu-Asp-Arg (EDR) and Lys-Glu-Asp (KED), and Ala-Glu-Asp-Gly (AEDG) peptides have previously demonstrated neuroprotective effects in various models of Alzheimer's disease. In this study, we investigated the influence of EDR, KED, and AEDG peptides on the aging of fibroblast-derived induced neurons. We used a new in vitro cellular model of human neuronal aging based on the transdifferentiation of aged dermal fibroblasts from elderly donors into induced cortical neurons. All peptides promote the arborization of the dendritic tree, increasing both the number of primary processes and the total length of dendrites. Tripeptides have no effect on the activity of mitochondria and lysosomes and the level of p16 protein in induced neurons. EDR peptide reduces oxidative DNA damage in induced neurons derived from elderly donor fibroblasts. Short peptides partially protect induced neurons from age-related changes and stimulate dendritogenesis in neurons. They can be recommended for use as neuroprotective agents.

Protective Effect of Arzanol against H2O2-Induced Oxidative Stress Damage in Differentiated and Undifferentiated SH-SY5Y Cells

Oxidative stress can damage neuronal cells, greatly contributing to neurodegenerative diseases (NDs). In this study, the protective activity of arzanol, a natural prenylated α-pyrone-phloroglucinol heterodimer, was evaluated against the H2O2-induced oxidative damage in trans-retinoic acid-differentiated (neuron-like) human SH-SY5Y cells, widely used as a neuronal cell model of neurological disorders. The pre-incubation (for 2 and 24 h) with arzanol (5, 10, and 25 μM) significantly preserved differentiated SH-SY5Y cells from cytotoxicity (MTT assay) and morphological changes induced by 0.25 and 0.5 mM H2O2. Arzanol reduced the generation of reactive oxygen species (ROS) induced by 2 h oxidation with H2O2 0.5 mM, established by 2',7'-dichlorodihydrofluorescein diacetate assay. The 2 h incubation of differentiated SH-SY5Y cells with H2O2 determined a significant increase in the number of apoptotic cells versus control cells, evaluated by propidium iodide fluorescence assay (red fluorescence) and NucView® 488 assay (green fluorescence). Arzanol pre-treatment (2 h) exerted a noteworthy significant protective effect against apoptosis. In addition, arzanol was tested, for comparison, in undifferentiated SH-SY5Y cells for cytotoxicity and its ability to protect against H2O2-induced oxidative stress. Furthermore, the PubChem database and freely accessible web tools SwissADME and pkCSM-pharmacokinetics were used to assess the physicochemical and pharmacokinetic properties of arzanol. Our results qualify arzanol as an antioxidant agent with potential neuroprotective effects against neuronal oxidative stress implicated in NDs.

Fraction of C. d. collilineatus venom containing crotapotin protects PC12 cells against MPP + toxicity by activating the NGF-signaling pathway

Background

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. There is no effective treatment for neurodegenerative diseases. Snake venoms are a cocktail of proteins and peptides with great therapeutic potential and might be useful in the treatment of neurodegenerative diseases. Crotapotin is the acid chain of crotoxin, the major component of Crotalus durissus collilineatus venom. PD is characterized by low levels of neurotrophins, and synaptic and axonal degeneration; therefore, neurotrophic compounds might delay the progression of PD. The neurotrophic potential of crotapotin has not been studied yet.

Methods

We evaluated the neurotrophic potential of crotapotin in untreated PC12 cells, by assessing the induction of neurite outgrowth. The activation of the NGF signaling pathway was investigated through pharmacological inhibition of its main modulators. Additionally, its neuroprotective and neurorestorative effects were evaluated by assessing neurite outgrowth and cell viability in PC12 cells treated with the dopaminergic neurotoxin MPP+ (1-methyl-4-phenylpyridinium), known to induce Parkinsonism in humans and animal models.

Results

Crotapotin induced neuritogenesis in PC12 cells through the NGF-signaling pathway, more specifically, by activating the NGF-selective receptor trkA, and the PI3K/Akt and the MAPK/ERK cascades, which are involved in neuronal survival and differentiation. In addition, crotapotin had no cytotoxic effect and protected PC12 cells against the inhibitory effects of MPP+ on cell viability and differentiation.

Conclusion

These findings show, for the first time, that crotapotin has neurotrophic/neuroprotective/neurorestorative potential and might be beneficial in Parkinson's disease. Additional studies are necessary to evaluate the toxicity of crotapotin in other cell models.

Comprehensive Strategies for Metabolic Syndrome: How Nutrition, Dietary Polyphenols, Physical Activity, and Lifestyle Modifications Address Diabesity, Cardiovascular Diseases, and Neurodegenerative Conditions

Several hallmarks of metabolic syndrome, such as dysregulation in the glucose and lipid metabolism, endothelial dysfunction, insulin resistance, low-to-medium systemic inflammation, and intestinal microbiota dysbiosis, represent a pathological bridge between metabolic syndrome and diabesity, cardiovascular, and neurodegenerative disorders. This review aims to highlight some therapeutic strategies against metabolic syndrome involving integrative approaches to improve lifestyle and daily diet. The beneficial effects of foods containing antioxidant polyphenols, intestinal microbiota control, and physical activity were also considered. We comprehensively examined a large body of published articles involving basic, animal, and human studie, as well as recent guidelines. As a result, dietary polyphenols from natural plant-based antioxidants and adherence to the Mediterranean diet, along with physical exercise, are promising complementary therapies to delay or prevent the onset of metabolic syndrome and counteract diabesity and cardiovascular diseases, as well as to protect against neurodegenerative disorders and cognitive decline. Modulation of the intestinal microbiota reduces the risks associated with MS, improves diabetes and cardiovascular diseases (CVD), and exerts neuroprotective action. Despite several studies, the estimation of dietary polyphenol intake is inconclusive and requires further evidence. Lifestyle interventions involving physical activity and reduced calorie intake can improve metabolic outcomes.

Molecular dynamic investigation for Roco4 kinase inhibitor as treatment options for parkinsonism

CONTEXT

Parkinson's disease is a neurodegenerative condition characterized by the degeneration of dopaminergic neurons, resulting in motor disabilities such as rigidity, bradykinesia, postural instability, and resting tremors. While the exact cause of Parkinson's remains uncertain, both familial and sporadic forms are often associated with the G2019S mutation found in the kinase domain of LRRK2. Roco4 is an analogue of LRRK2 protein in Dictyostelium discoideum which is an established model organism to investigate LRRK2 inhibitors. In this study, the potential treatment of Parkinson's was explored by inhibiting the activity of the mutated LRRK2 protein using Roco4 as the base protein structure. Mongolicain-A and Bacoside-A exhibited significant selectivity towards the G2019S mutation, displaying a binding affinity of - 12.3 Kcal/mol and - 11.4 Kcal/mol respectively. Mongolicain-A demonstrated increased specificity towards Roco4, while Bacoside-A demonstrated significant binding affinity to all 34 kinases proteins alike. The Molecular Dynamics Studies (MDS) results strongly suggests that Mongolicain-A is a significant inhibitor of Roco4 kinase. ADMET and drugability analysis also suggests that among the two best ligands, Mongolicain-A demonstrates significant physicochemical properties to be suitable for best drug like molecule. Based on the in-silico molecular docking, molecular dynamic simulation, ADMET and drugability analyses, it is strongly suggested that, Mongolicain-A could be a potential candidate for treatment and management of Parkinson's disease via inhibition of LRRK2 protein. Further in-vitro and in-vivo investigations are in demand to validate these findings.

METHODS

To identify potential inhibitors, 3069 phytochemicals were screened using molecular docking via AutoDock Vina. Molecular Dynamics Simulation was carried out using GROMACS 2022.2 for a duration of 100ns per complex to study the stability and inhibition potential of the protein ligand complexes. ADMET analysis was carriedout using Molinspiration and preADMET web tool.

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.

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.

Neurotrophic phenolic glycosides from the roots of Armoracia rusticana

Armoracia rusticana P. G. Gaertner. belongs to the Brassicaceae family and has aroused scientific interest for its anti-inflammatory and anticancer activities. In a continuing investigation to discover bioactive constituents from A. rusticana, we isolated 19 phenolic glycosides including three undescribed flavonol glycosides and one undescribed neolignan glycoside from MeOH extract of this plant. Their structures were elucidated based on NMR spectroscopic analysis (1H, 13C, 1H-1H COSY, HSQC, and HMBC), HRESIMS, and chemical methods. The determination of their absolute configuration was accomplished by ECD and LC-MS analysis. All the compounds were assessed for their potential neurotrophic activity through induction of nerve growth factor in C6 glioma cell lines and for their anti-neuroinflammatory activity based on the measurement of inhibition levels of nitric oxide production and pro-inflammatory cytokines (i.e., IL-1β, IL-6, and TNF-α) in lipopolysaccharide-activated microglia BV-2 cells.

Natural compounds as lactate dehydrogenase inhibitors: potential therapeutics for lactate dehydrogenase inhibitors-related diseases

Lactate dehydrogenase (LDH) is a crucial enzyme involved in energy metabolism and present in various cells throughout the body. Its diverse physiological functions encompass glycolysis, and its abnormal activity is associated with numerous diseases. Targeting LDH has emerged as a vital approach in drug discovery, leading to the identification of LDH inhibitors among natural compounds, such as polyphenols, alkaloids, and terpenoids. These compounds demonstrate therapeutic potential against LDH-related diseases, including anti-cancer effects. However, challenges concerning limited bioavailability, poor solubility, and potential toxicity must be addressed. Combining natural compounds with LDH inhibitors has led to promising outcomes in preclinical studies. This review highlights the promise of natural compounds as LDH inhibitors for treating cancer, cardiovascular, and neurodegenerative diseases.

Recent Advancements in Nanocarrier-assisted Brain Delivery of Phytochemicals Against Neurological Diseases

Despite ongoing advancements in research, the inability of therapeutics to cross the blood-brain barrier (BBB) makes the treatment of neurological disorders (NDs) a challenging task, offering only partial symptomatic relief. Various adverse effects associated with existing approaches are another significant barrier that prompts the usage of structurally diverse phytochemicals as preventive/therapeutic lead against NDs in preclinical and clinical settings. Despite numerous beneficial properties, phytochemicals suffer from poor pharmacokinetic profile which limits their pharmacological activity and necessitates the utility of nanotechnology for efficient drug delivery. Nanocarriers have been shown to be proficient carriers that can enhance drug delivery, bioavailability, biocompatibility, and stability of phytochemicals. We, thus, conducted a meticulous literature survey using several electronic databases to gather relevant studies in order to provide a comprehensive summary about the use of nanocarriers in delivering phytochemicals as a treatment approach for NDs. Additionally, the review highlights the mechanisms of drug transport of nanocarriers across the BBB and explores their potential future applications in this emerging field.

Neuroprotective Effect of Nosustrophine in a 3xTg Mouse Model of Alzheimer's Disease

Neurodegeneration, characterized by the progressive deterioration of neurons and glial cells, is a feature of Alzheimer's disease (AD). The present study aims to demonstrate that the onset and early progression of neurodegenerative processes in transgenic mice models of AD can be delayed by a cocktail of neurotrophic factors and derived peptides named Nosustrophine, a nootropic supplement made by a peptide complex extracted from the young porcine brain, ensuring neuroprotection and improving neuro-functional recovery. Experimental 3xTg-APP/Bin1/COPS5 transgenic mice models of AD were treated with Nosustrophine at two different early ages, and their neuropathological hallmark and behavior response were analyzed. Results showed that Nosustrophine increased the activity of the immune system and reduced pathological changes in the hippocampus and cortex by halting the development of amyloid plaques, mainly seen in mice of 3-4 months of age, indicating that its effect is more preventive than therapeutic. Taken together, the results indicate the potent neuroprotective activity of Nosustrophine and its stimulating effects on neuronal plasticity. This study shows for the first time an effective therapy using nootropic supplements against degenerative diseases, although further investigation is needed to understand their molecular pathways.

Vitamin E and Its Molecular Effects in Experimental Models of Neurodegenerative Diseases

With the advancement of in vivo studies and clinical trials, the pathogenesis of neurodegenerative diseases has been better understood. However, gaps still need to be better elucidated, which justifies the publication of reviews that explore the mechanisms related to the development of these diseases. Studies show that vitamin E supplementation can protect neurons from the damage caused by oxidative stress, with a positive impact on the prevention and progression of neurodegenerative diseases. Thus, this review aims to summarize the scientific evidence of the effects of vitamin E supplementation on neuroprotection and on neurodegeneration markers in experimental models. A search for studies published between 2000 and 2023 was carried out in the PubMed, Web of Science, Virtual Health Library (BVS), and Embase databases, in which the effects of vitamin E in experimental models of neurodegeneration were investigated. A total of 5669 potentially eligible studies were identified. After excluding the duplicates, 5373 remained, of which 5253 were excluded after checking the titles, 90 articles after reading the abstracts, and 11 after fully reviewing the manuscripts, leaving 19 publications to be included in this review. Experiments with in vivo models of neurodegenerative diseases demonstrated that vitamin E supplementation significantly improved memory, cognition, learning, motor function, and brain markers associated with neuroregeneration and neuroprotection. Vitamin E supplementation reduced beta-amyloid (Aβ) deposition and toxicity in experimental models of Alzheimer's disease. In addition, it decreased tau-protein hyperphosphorylation and increased superoxide dismutase and brain-derived neurotrophic factor (BDNF) levels in rodents, which seems to indicate the potential use of vitamin E in preventing and delaying the progress of degenerative lesions in the central nervous system.

Insights into the promising prospect of medicinal chemistry studies against neurodegenerative disorders

Medicinal chemistry is an interdisciplinary field that incorporates organic chemistry, biochemistry, physical chemistry, pharmacology, informatics, molecular biology, structural biology, cell biology, and other disciplines. Additionally, it considers molecular factors such as the mode of action of the drugs, their chemical structure-activity relationship (SAR), and pharmacokinetic aspects like absorption, distribution, metabolism, elimination, and toxicity. Neurodegenerative disorders (NDs), which are defined by the breakdown of neurons over time, are affecting an increasing number of people. Oxidative stress, particularly the increased production of Reactive Oxygen Species (ROS), plays a crucial role in the growth of various disorders, as indicated by the identification of protein, lipid, and Deoxyribonucleic acid (DNA) oxidation products in vivo. Because of their inherent nature, most biological molecules are vulnerable to ROS, even if they play a role in metabolic parameters and cell signaling. Due to their high polyunsaturated fatty acid content, low antioxidant barrier, and high oxygen uptake, neurons are particularly vulnerable to oxidation by nature. As a result, excessive ROS generation in neurons looks especially harmful, and the mechanisms associated with biomolecule oxidative destruction are several and complex. This review focuses on the formation and management of ROS, as well as their chemical characteristics (both thermodynamic and kinetic), interactions, and implications in NDs.

Current Advances of Plant-Based Vaccines for Neurodegenerative Diseases

Neurodegenerative diseases (NDDs) are characterized by the progressive degeneration and/or loss of neurons belonging to the central nervous system, and represent one of the major global health issues. Therefore, a number of immunotherapeutic approaches targeting the non-functional or toxic proteins that induce neurodegeneration in NDDs have been designed in the last decades. In this context, due to unprecedented advances in genetic engineering techniques and molecular farming technology, pioneering plant-based immunogenic antigen expression systems have been developed aiming to offer reliable alternatives to deal with important NDDs, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Diverse reports have evidenced that plant-made vaccines trigger significant immune responses in model animals, supported by the production of antibodies against the aberrant proteins expressed in the aforementioned NDDs. Moreover, these immunogenic tools have various advantages that make them a viable alternative for preventing and treating NDDs, such as high scalability, no risk of contamination with human pathogens, cold chain free production, and lower production costs. Hence, this article presents an overview of the current progress on plant-manufactured vaccines for NDDs and discusses its future prospects.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

Perspectives on the Molecular Mediators of Oxidative Stress and Antioxidant Strategies in the Context of Neuroprotection and Neurolongevity: An Extensive Review

Molecules with at least one unpaired electron in their outermost shell are known as free radicals. Free radical molecules are produced either within our bodies or by external sources such as ozone, cigarette smoking, X-rays, industrial chemicals, and air pollution. Disruption of normal cellular homeostasis by redox signaling may result in cardiovascular, neurodegenerative diseases and cancer. Although ROS (reactive oxygen species) are formed in the GI tract, little is known about how they contribute to pathophysiology and disease etiology. When reactive oxygen species and antioxidants are in imbalance in our bodies, they can cause cell structure damage, neurodegenerative diseases, diabetes, hypercholesterolemia, atherosclerosis, cancer, cardiovascular diseases, metabolic disorders, and other obesity-related disorders, as well as protein misfolding, mitochondrial dysfunction, glial cell activation, and subsequent cellular apoptosis. Neuron cells are gradually destroyed in neurodegenerative diseases. The production of inappropriately aggregated proteins is strongly linked to oxidative stress. This review's goal is to provide as much information as possible about the numerous neurodegenerative illnesses linked to oxidative stress. The possibilities of multimodal and neuroprotective therapy in human illness, using already accessible medications and demonstrating neuroprotective promise in animal models, are highlighted. Neuroprotection and neurolongevity may improve from the use of bioactive substances from medicinal herbs like Allium stadium, Celastrus paniculatus, and Centella asiatica. Many neuroprotective drugs' possible role has been addressed. Preventing neuroinflammation has been demonstrated in several animal models.

Diabetes Exacerbates Sepsis-Induced Neuroinflammation and Brain Mitochondrial Dysfunction

Sepsis is a life-threatening organ dysfunction, which demands notable attention for its treatment, especially in view of the involvement of immunodepressed patients, as the case of patients with diabetes mellitus (DM), who constitute a population susceptible to develop infections. Thus, considering this endocrine pathology as an implicatory role on the immune system, the aim of this study was to show the relationship between this disease and sepsis on neuroinflammatory and neurochemical parameters. Levels of IL-6, IL-10, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and mitochondrial respiratory chain complexes were evaluated in the hippocampus and prefrontal cortex 24 h after sepsis by cecal ligation and perforation (CLP) in Wistar rats induced to type 1 diabetes by alloxan (150 mg/kg). It was verified that diabetes implied immune function after 24 h of sepsis, since it contributed to the increase of the inflammatory process with higher production of IL-6 and decreased levels of IL-10 only in the hippocampus. In the same brain area, a several decrease in NGF level and activity of complexes I and II of the mitochondrial respiratory chain were observed. Thus, diabetes exacerbates neuroinflammation and results in mitochondrial impairment and downregulation of NGF level in the hippocampus after sepsis.

Therapeutic Potential of Polyscias fruticosa (L.) Harms Leaf Extract for Parkinson's Disease Treatment by Drosophila melanogaster Model

Parkinson's disease (PD) is characterized by progressive locomotive defects and loss of dopaminergic neurons. Polyscias fruticosa leaves are used by Vietnamese as herbal medicines to support the treatment of some diseases related to neurodegeneration such as Parkinson's and Alzheimer's diseases. However, recent scientific data have not provided sufficient evidence for the use of P. fruticosa leaves to treat PD or decelerate PD progression. In the present study, the capacity of P. fruticosa leaf extract for PD treatment on the dietary supplementation was investigated using dUCH-knockdown Drosophila model. The results indicated that P. fruticosa leaf extract decelerated dopaminergic neuron degeneration induced by dUCH knockdown in not only the larval stage but also the adult stage, which might result in the amelioration in locomotor ability of dUCH-knockdown larvae and flies. Furthermore, antioxidant activities and some key phytochemicals such as saponins, polyphenols, and flavonoids that might contribute to the effects of the P. fruticosa leaf extract were identified.

Semisynthesis and neurotrophic activity studies of novel neomajucin/majucin derivatives as neurotrophin small molecule mimetics

Majucin-type Illicium sesquiterpenes with potent neurotrophic activity are considered to be promising candidates for the treatment of various neurodegenerative disease. Owing to the low-abundance metabolites in Illicium genus, there are few studies on their structural modifications, structure-activity relationships, and pharmacophoric motif. Herein, structural modifications were conducted on the hydroxyl groups at C-3 and C-6 positions of two majucin-type compounds neomajucin (1) and majucin (2), and 39 neomajucin/majucin based esters were synthesized and evaluated for their neurite outgrowth-promoting activities. Among all the target derivatives, compounds 1a, 1j, 1r, 2b, 2d, 3a, 3b, 3d and 3h displayed more potent neurite outgrowth-promoting activity than their precursors. Some interesting structure-activity relationships (SARs) were also observed. Moreover, compound 1a showed good neuroprotective effect on MPP⁺-induced PC12 cell damage. Finally, compounds 1a and 3a exhibited relatively no cytotoxicity to normal human H9C2 cardiac cells. This work will shed light on the development of neomajucin/majucin derivatives as potential neurotrophic agents.

Dietary biomolecules as promising regenerative agents for peripheral nerve injury: An emerging nutraceutical-based therapeutic approach

Peripheral nerve damage is a debilitating condition that can result in partial or complete functional loss as a result of axonal degeneration, as well as lifelong dependence. Many therapies have been imbued with a plethora of positive features while posing little risks. It is worth noting that these biomolecules work by activating several intrinsic pathways that are known to be important in peripheral nerve regeneration. Although the underlying mechanism is used for accurate and speedy functional recovery, none of them are without side effects. As a result, it is believed that effective therapy is currently lacking. The dietary biomolecules-based intervention, among other ways, is appealing, safe, and effective. Upregulation of transcription factors, neurotrophic factors, and growth factors such as NGF, GDNF, BDNF, and CTNF may occur as a result of these substances' dietary intake. Upregulation of the signaling pathways ERK, JNK, p38, and PKA has also been seen, which aids in axonal regeneration. Although several mechanistic approaches to understanding their involvement have been suggested, more work is needed to reveal the amazing properties of these biomolecules. We have discussed in this article that how different dietary biomolecules can help with functional recovery and regeneration after an injury. PRACTICAL APPLICATIONS: Based on the information known to date, we may conclude that treatment techniques for peripheral nerve injury have downsides, such as complications, donor shortages, adverse effects, unaffordability, and a lack of precision in efficacy. These difficulties cast doubt on their efficacy and raise severe concerns about the prescription. In this situation, the need for safe and effective therapeutic techniques is unavoidable, and dietary biomolecules appear to be a safe, cost-efficient, and effective way to promote nerve regeneration following an injury. The information on these biomolecules has been summarized here. Upregulation of transcription factors, neurotrophic factors, and growth factors, such as NGF, GDNF, BDNF, and CTNF, as well as the ERK, JNK, p38, and PKA, signaling pathways, may stimulate axonal regeneration.

Demethyleneberberine: A possible treatment for Huntington's disease

Huntington disease (HD) is a type of neurodegenerative disease that is characterized by presence of multiple repeats (more than 36) of cytosine-adenine-guanine (CAG) trinucleotides and mutated huntingtin (mHtt). This can further lead to oxidative stress, enhancement in level of ROS/RNS, mitochondrial dysfunction and neuroinflammations. Many clinical and preclinical trials have been conducted so far for the effective treatment of HD however, none of the drugs has shown complete relief. The regeneration of neurons is a very complicated process and associated with multiple pathological pathways. Hence, finding a unique solution using single drug that could act on multiple pathological pathways is really cumbersome. In the proposed hypothesis the use of demethyleneberberine (DMB) as a potential anti-HD agent has been explained. It is a metabolite of berberine and reported to act on multiple mechanistic pathways that are responsible for HD. Present article highlights new mechanistic insights through which DMB inhibits ROS/RNS, oxidative stress, mitochondrial dysfunctions and neuroinflammation such as NFκB, TNF-α, IL-6 and IL-8, cytokinin. Further its action on cellular apoptosis and neuronal cell death are also reported.

Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Ameliorative Role of Nutraceuticals on Neurodegenerative Diseases Using the Drosophila melanogaster as a Discovery Model to Define Bioefficacy

Neurodegeneration is the destruction of neurons, and once the neurons degenerate they can't revive. This is one of the most concerned health conditions among aged population, more than ∼70% of the elderly people are suffering from neurodegeneration. Among all of the neurodegenerative diseases, Alzheimer's disease (AD), Parkinson's disease (PD) and Poly-glutamine disease (Poly-Q) are the major one and affecting most of the people around the world and posing excessive burden on the society. In order to understand this disease in non-human animal models it is pertinent to examine in model organism and various animal model are being used for such diseases like rat, mice and non-vertebrate model like Drosophila. Drosophila melanogaster is one of the best animal proven by several eminent scientist and had received several Nobel prizes for uncovering mechanism of human related genes and highly efficient model for studying neurodegenerative diseases due to its great affinity with human disease-related genes. Another factor is also employed to act as therapeutic or preventive method that is nutraceuticals. Nutraceuticals are functional natural compounds with antioxidant properties and had extensively showed the neuroprotective effect in different organisms. These nutraceuticals having antioxidant properties act through scavenging free radicals or by increasing endogenous cellular antioxidant defense molecules. For the best benefit, we are trying to utilize these nutraceuticals, which will have no or negligible side effects. In this review, we are dealing with various types of such nutraceuticals which have potent value in the prevention and curing of the diseases related to neurodegeneration.HighlightsNeurodegeneration is the silently progressing disease which shows its symptoms when it is well rooted.Many chemical drugs (almost all) have only symptomatic relief with side effects.Potent mechanism of neurodegeneration and improvement effect by nutraceuticals is proposed.Based on the Indian Cuisine scientists are trying to find the medicine from the food or food components having antioxidant properties.The best model to study the neurodegenerative diseases is Drosophila melanogaster.Many nutraceuticals having antioxidant properties have been studied and attenuated various diseases are discussed.

Neuroprotective Natural Products for Alzheimer's Disease

Alzheimer's disease (AD) is the number one neurovegetative disease, but its treatment options are relatively few and ineffective. In efforts to discover new strategies for AD therapy, natural products have aroused interest in the research community and in the pharmaceutical industry for their neuroprotective activity, targeting different pathological mechanisms associated with AD. A wide variety of natural products from different origins have been evaluated preclinically and clinically for their neuroprotective mechanisms in preventing and attenuating the multifactorial pathologies of AD. This review mainly focuses on the possible neuroprotective mechanisms from natural products that may be beneficial in AD treatment and the natural product mixtures or extracts from different sources that have demonstrated neuroprotective activity in preclinical and/or clinical studies. It is believed that natural product mixtures or extracts containing multiple bioactive compounds that can work additively or synergistically to exhibit multiple neuroprotective mechanisms might be an effective approach in AD drug discovery.

Natural Phytochemicals as Novel Therapeutic Strategies to Prevent and Treat Parkinson's Disease: Current Knowledge and Future Perspectives

Parkinson's disease (PD) is the second-most common neurodegenerative chronic disease affecting both cognitive performance and motor functions in aged people. Yet despite the prevalence of this disease, the current therapeutic options for the management of PD can only alleviate motor symptoms. Research has explored novel substances for naturally derived antioxidant phytochemicals with potential therapeutic benefits for PD patients through their neuroprotective mechanism, targeting oxidative stress, neuroinflammation, abnormal protein accumulation, mitochondrial dysfunction, endoplasmic reticulum stress, neurotrophic factor deficit, and apoptosis. The aim of the present study is to perform a comprehensive evaluation of naturally derived antioxidant phytochemicals with neuroprotective or therapeutic activities in PD, focusing on their neuropharmacological mechanisms, including modulation of antioxidant and anti-inflammatory activity, growth factor induction, neurotransmitter activity, direct regulation of mitochondrial apoptotic machinery, prevention of protein aggregation via modulation of protein folding, modification of cell signaling pathways, enhanced systemic immunity, autophagy, and proteasome activity. In addition, we provide data showing the relationship between nuclear factor E2-related factor 2 (Nrf2) and PD is supported by studies demonstrating that antiparkinsonian phytochemicals can activate the Nrf2/antioxidant response element (ARE) signaling pathway and Nrf2-dependent protein expression, preventing cellular oxidative damage and PD. Furthermore, we explore several experimental models that evaluated the potential neuroprotective efficacy of antioxidant phytochemical derivatives for their inhibitory effects on oxidative stress and neuroinflammation in the brain. Finally, we highlight recent developments in the nanodelivery of antioxidant phytochemicals and its neuroprotective application against pathological conditions associated with oxidative stress. In conclusion, naturally derived antioxidant phytochemicals can be considered as future pharmaceutical drug candidates to potentially alleviate symptoms or slow the progression of PD. However, further well-designed clinical studies are required to evaluate the protective and therapeutic benefits of phytochemicals as promising drugs in the management of PD.

Conifers Phytochemicals: A Valuable Forest with Therapeutic Potential

Conifers have long been recognized for their therapeutic potential in different disorders. Alkaloids, terpenes and polyphenols are the most abundant naturally occurring phytochemicals in these plants. Here, we provide an overview of the phytochemistry and related commercial products obtained from conifers. The pharmacological actions of different phytochemicals present in conifers against bacterial and fungal infections, cancer, diabetes and cardiovascular diseases are also reviewed. Data obtained from experimental and clinical studies performed to date clearly underline that such compounds exert promising antioxidant effects, being able to inhibit cell damage, cancer growth, inflammation and the onset of neurodegenerative diseases. Therefore, an attempt has been made with the intent to highlight the importance of conifer-derived extracts for pharmacological purposes, with the support of relevant in vitro and in vivo experimental data. In short, this review comprehends the information published to date related to conifers' phytochemicals and illustrates their potential role as drugs.

Neuroprotective effects of allocryptopine-rich alkaloid extracts against oxidative stress-induced neuronal damage

BACKGROUND

Oxidative stress is a significant feature in the pathomechanism of neurodegenerative diseases. Thus, the search for an effective and safe novel antioxidant agent with neuroprotective properties has increased the interest in medicinal plant products as a bioactive phytochemical source. However, little is known about the potential effects of the medically important Glaucium corniculatum as a natural antioxidant.

OBJECTIVE

In the present study, it was aimed to investigate the anti-oxidative, anti-apoptotic, and cell cycle regulatory mechanisms underlying the neuroprotective effects of alkaloid extracts (chloroform, methanol, and water) from G. corniculatum, which was profiled for major alkaloid/alkaloids, against H₂O₂-induced neuronal damage in differentiated PC12 cells.

MATERIALS AND METHODS

The profiles of the alkaloid extracts were analyzed by GC-MS. The effects of the alkaloid extracts on intracellular ROS production, level of apoptotic cells, and cell cycle dysregulation were analyzed by flow cytometry; the effects on mRNA expression of apoptosis-related genes were also analyzed by qRT-PCR.

RESULTS

The same alkaloid components, allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide were obtained in all three solvents, but the ratios of the components differed according to the solvents. Allocryptopine was determined to be the major alkaloid ingredient in the alkaloid extracts, with the highest amount of allocryptopine (497 μg/mg) being found in the chloroform alkaloid extract (CAE) (*p < 0.05). The best results were obtained from CAE, which has the highest amount of allocryptopine among alkaloid extracts in all studies. CAE suppressed intracellular ROS production (5.7-fold), percentage of apoptotic cells (3.0-fold), and cells in the sub G1 phase (6.8-fold); additionally, it increased cells in the G1 phase (1.5-fold) (**p < 0.01). CAE remarkably reduced the expressions of Bax, Caspase-9/-3 mRNA (2.4-3.5-fold) while increasing the expression of Bcl-2 mRNA (3.0-fold) (*p < 0.05).

CONCLUSIONS

Our results demonstrated that alkaloid extracts from G. corniculatum, which contain allocryptopine, tetrahydropalmatine, and tetrahydroberberine N-oxide suppressed oxidative stress-induced neuronal apoptosis, possibly by suppressing the mitochondrial apoptotic pathway and regulating the cell cycle. These results are the first report that related alkaloids have played a neuroprotective role by regulating multiple mechanisms. Thus, our study indicated that these alkaloids especially allocryptopine could offer an efficient and novel strategy to explore novel drugs for neuroprotection and cognitive improvement.

Endogenous modulators of neurotrophin signaling: Landscape of the transient ATP-NGF interactions

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High-resolution solution NMR structure of rhNGF has been determined.

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Quinary interactions characterize ATP binding to rhNGF.

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SPR, ITC and STD-NMR reveal ATP binding to rhNGF with mM affinity.

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NMR and MD analysis pinpoint to the presence of two binding sites of ATP on rhNGF.

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Stoichiometry of ATP-Mg²⁺ or Zn²⁺-rhNGF mixtures affects K_D affinity to TrkA/p75^NTR.

The Nerve Growth Factor (NGF) neurotrophin acts in the maintenance and growth of neuronal populations. Despite the detailed knowledge of NGF’s role in neuron physiology, the structural and mechanistic determinants of NGF bioactivity modulated by essential endogenous ligands are still lacking. We present the results of an integrated structural and advanced computational approach to characterize the extracellular ATP-NGF interaction. We mapped by NMR the interacting surface and ATP orientation on NGF and revealed the functional role of this interaction in the binding to TrkA and p75^NTR receptors by SPR. The role of divalent ions was explored in conjunction with ATP. Our results pinpoint ATP as a likely transient molecular modulator of NGF signaling, in health and disease states.

Phenolic Constituents of Chinese Quince Twigs (Chaenomeles sinensis Koehne) and Their Anti-Neuroinflammatory, Neurotrophic, and Cytotoxic Activities

Chaenomeles sinensis has been used as a food and traditional medicines. However, most of research on discovering bioactive constituents from this plant have been focused on its yellow fruit, Chinese quince, due to its wide usage. Here, we isolated and characterized three new phenolic compounds (1, 9, and 11) and 21 known compounds (2−8, 10, and 12−24) from the twigs of C. sinensis. Their chemical structures were established by spectroscopic and spectrometric data analysis including 1D and 2D NMR, high-resolution mass spectrometry (HRMS), electronic circular dichroism (ECD), and LC-MS analysis. Some of the isolated compounds (1−24) showed anti-neuroinflammatory effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells, neurotrophic activity in C6 cells through the secretion of nerve growth factor (NGF) and/or cytotoxicity against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, MKN-1).

The Neurotrophic-Like Effect of Carvacrol: Perspective for Axonal and Synaptic Regeneration

Carvacrol (CARV) is a phytochemical widely used as flavoring, preservative, and fragrance in food and cosmetic industries. CARV is able to cross the blood-brain barrier (BBB) and has demonstrated protective potential against neurodegenerative diseases by several mechanisms, including antioxidant, anti-inflammatory, anticholinesterase, and antiapoptotic effects. However, it is not known whether CARV is able to modulate axonal and synaptic plasticity, crucial events in cognition, memory, and learning. Abnormalities in axonal and synaptic plasticity, low levels of neurotrophins, and bioenergetic failure have been associated with the pathogenesis of neurodegenerative diseases, including Parkinson's (PD) and Alzheimer's diseases (ADs). Small lipophilic molecules with neurotrophic activity might be able to restore the axonal and synaptic networks that are lost in neurodegenerative processes. Therefore, this study investigated the neurotrophic potential of CARV in PC12 cell-based neuronal model. Carvacrol induced neurite outgrowth by activating the NGF high-affinity trkA receptor and the downstream PI3K-AKT and MAPK-ERK pathways, without depending on NGF. In addition, CARV increased the expression of proteins involved in neuronal plasticity (β-tubulin III, F-actin, 200-kDa neurofilament, GAP-43 and synapsin-I) and improved bioenergetics (AMPKα, p-AMPKα, and ATP). Our study showed, for the first time, a promising neurotrophic mechanism of CARV that could be beneficial in neurodegenerative and neurological diseases.

Role of medicinal plants against neurodegenerative diseases

Diseases with a significant loss of neurons, structurally and functionally are termed as neurodegenerative diseases. Due to the present therapeutic interventions and progressive nature of diseases, a variety of side effects have risen up, thus leading the patients to go for an alternative medication. The role of medicinal plants in such cases has been beneficial because of their exhibition via different cellular and molecular mechanisms. Alleviation in inflammatory responses, suppression of the functionary aspect of pro-inflammatory cytokines like a tumor, improvement in antioxidative properties is among few neuroprotective mechanisms of traditional plants. Variation in transcription and transduction pathways play a vital role in the preventive measures of plants in such diseases. Neurodegenerative diseases are generally caused by depletion of proteins, oxidative and inflammatory stress, environmental changes and so on, with aging being the most important cause. Natural compounds can be used in order to treat neurodegenerative diseases Medicinal plants such as Ginseng, Withania somnifera, Bacopa monnieri, Ginkgo biloba, etc. are some of the medicinal plants for prevention of neurological symptoms. This review deals with the use of different medicinal plants for the prevention of neurodegenerative diseases.

Effect of citrus peels-supplemented diet on longevity, memory index, redox status, cholinergic and monoaminergic enzymes in Drosophila melanogaster model

This study sought to determine the life span promoting effecof orange (Citrus sinensis), tangerine (Citrus maxima) and grapefruit (Citrus paradisi) peels in Drosophila melanogaster model. Flies (both gender, 3 to 5 days old) were divided into seven (7) groups (n = 5) containing 40 flies each; group I (control) flies were fed with basal diet, II-VII were flies were fed with basal diet containing 0.1 and 1.0% of tangerine peel (TP), orange peel (CP), and grapefruit peel (GP) respectively, for 14 days. Locomotor performance and memory index were assessed via negative geotaxis and aversive phototaxis suppression assays, respectively. Thereafter, the fly homogenates were assayed for activities of acetylcholinesterase (AChE), monoamine oxidase (MAO) and antioxidant enzymes as well as other indices of their redox. The results revealed that the citrus peels significantly improved longevity, locomotor performance, memory index, antioxidant status, and modulate cholinesterase and monoamine oxidase enzyme activities in treated flies when compared to the control. The results obtained suggest that the citrus peels offer potentials as dietary supplement with life span promoting properties in D. melanogaster model which could as well serve as a functional food additives. PRACTICAL APPLICATIONS: Citrus peels, although often considered agro-wastes, are used as food supplements and food ingredents especially in production of candies, jams and custards. This study suggests the use of orange (Citrus sinensis), tangerine (Citrus maxima), and grapefruit (Citrus paradisi) peels as dietary supplements which offers potential life span promoting properties.

Apitherapy for Parkinson's Disease: A Focus on the Effects of Propolis and Royal Jelly

The vast increase of world's aging populations is associated with increased risk of age-related neurodegenerative diseases such as Parkinson's disease (PD). PD is a widespread disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra, which encompasses a wide range of debilitating motor, emotional, cognitive, and physical symptoms. PD threatens the quality of life of millions of patients and their families. Additionally, public welfare and healthcare systems are burdened with its high cost of care. Available treatments provide only a symptomatic relief and produce a trail of noxious side effects, which increase noncompliance. Hence, researchers have recently focused on the use of nutraceuticals as safe adjunctive treatments of PD to limit its progress and associated damages in affected groups. Propolis is a common product of the beehive, which possesses a large number of therapeutic properties. Royal jelly (RJ) is a bee product that is fed to bee queens during their entire life, and it contributes to their high physical fitness, fertility, and long lifespan. Evidence suggests that propolis and RJ can promote health by preventing the occurrence of age-related debilitating diseases. Therefore, they have been used to treat various serious disorders such as diabetes mellitus, cardiovascular diseases, and cancer. Some evolving studies used these bee products to treat PD in animal models. However, a clear understanding of the collective effect of propolis and RJ as well as their mechanism of action in PD is lacking. This review evaluates the available literature for the effects of propolis and RJ on PD. Whenever possible, it elaborates on the underlying mechanisms through which they function in this disorder and offers insights for fruitful use of bee products in future clinical trials.