The role of bioactive compounds on the promotion of neurite outgrowth

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.

Promotion of neurite outgrowth by 3,5,7,3',4'-pentamethoxyflavone is mediated through ERK signaling pathway in Neuro2a cells

In this study, the effects of 3,5,7,3',4'-pentamethoxyflavone (KP1), a major bioactive ingredient isolated from the Kaempferia parviflora rhizomes, on a neurite outgrowth in Neuro2a cells and its mechanism have been investigated. KP1 increased concentration-dependently the percentage of neurite-bearing cells. KP1 showed a remarkable capability to elicit neurite outgrowth in Neuro2a cells, as evidenced by morphological alterations and immunostaining using anti-class III β-tubulin and anti-NeuN antibodies. KP1 also displayed a higher neurogenic activity than retinoic acid (RA), a promoter of neurite outgrowth in Neuro2a cells. KP1 treatment caused significant elevation in phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38 MAPK) and glycogen synthase kinase-3β (GSK-3β). However, KP1-triggered neurite outgrowth was markedly inhibited by treatment with the ERK inhibitor U0126, whereas p38 MAPK inhibitor SB203580 and GSK-3β inhibitor SB216763 did not influence KP1-induced neurite outgrowth. These results demonstrate that KP1 elicits neurite outgrowth and triggers cell differentiation of Neuro2a cells through ERK signal pathway.

Current and further outlook on the protective potential of Antrodia camphorata against neurological disorders

Prevalent neurological disorders such as Alzheimer's disease, Parkinson's disease, and stroke are increasingly becoming a global burden as society ages. It is well-known that degeneration and loss of neurons are the fundamental underlying processes, but there are still no effective therapies for these neurological diseases. In recent years, plenty of studies have focused on the pharmacology and feasibility of natural products as new strategies for the development of drugs that target neurological disorders. Antrodia camphorata has become one of the most promising candidates, and the crude extracts and some active metabolites of it have been reported to play various pharmacological activities to alleviate neurological symptoms at cellular and molecular levels. This review highlights the current evidence of Antrodia camphorata against neurological disorders, including safety evaluation, metabolism, blood-brain barrier penetration, neuroprotective activities, and the potential on regulating the gut-microbiome-brain axis. Furthermore, potential strategies to resolve problematic issues identified in previous studies are also discussed. We aim to provide an overview for the ongoing development and utilization of Antrodia camphorata in cerebral neuropathology.

Amelioration of behavioral and histological impairments in somatosensory cortex injury rats by limbal mesenchymal stem cell transplantation

Introduction

Cortical lesions can cause major sensory and motor impairments, representing a significant challenge in neuroscience and clinical medicine. Limbal mesenchymal stem cells (LMSCs), renowned for their remarkable ability to proliferate and distinct characteristics within the corneal epithelium, offer a promising opportunity for regenerative treatments. This study aimed to assess whether the transplantation of LMSCs could improve tactile ability in rats with lesions of the barrel cortex.

Methods

In this experimental study, we divided 21 rats into three groups: a control group, a lesion group with cortical cold lesion induction but no stem cell treatment, and a group receiving LMSC transplantation following cold lesion induction. We conducted 3-week sensory assessments using a texture discrimination test and an open-field test. We also performed Nissl staining to assess changes on the cellular level.

Results

Rats in the LMSC transplantation group demonstrated significant improvements in their ability to discrimination textures during the second and third weeks compared to those in the lesion group. The open-field test results showed an increased exploratory behavior of rats in the LMSC transplantation group by the third week compared to the lesion group. Additionally, Nissl staining revealed cellular alterations in the damaged cortex, with a significant distinction observed between rats in the LMSCs and lesion group.

Conclusion

The findings suggest that LMSC transplantation enhances sensory recovery in rats with cortical lesions, particularly their ability to discriminate textures. LMSC transplantation benefits brain tissue reparation after a cold lesion on the somatosensory cortex.

Brazilian Green Propolis' Artepillin C and Its Acetylated Derivative Activate the NGF-Signaling Pathways and Induce Neurite Outgrowth in NGF-Deprived PC12 Cells

Artepillin C is the most studied compound in Brazilian Green Propolis and, along with its acetylated derivative, displays neurotrophic activity on PC12 cells. Specific inhibitors of the trkA receptor (K252a), PI3K/Akt (LY294002), and MAPK/ERK (U0126) signaling pathways were used to investigate the neurotrophic mechanism. The expression of proteins involved in axonal and synaptic plasticity (GAP-43 and Synapsin I) was assessed by western blotting. Additionally, physicochemical properties, pharmacokinetics, and drug-likeness were evaluated by the SwissADME web tool. Both compounds induced neurite outgrowth by activating the NGF-signaling pathways but through different neuronal proteins. Furthermore, in silico analyses showed interesting physicochemical and pharmacokinetic properties of these compounds. Therefore, these compounds could play an important role in axonal and synaptic plasticity and should be further investigated.

Intravitreal injection of Huperzine A promotes retinal ganglion cells survival and axonal regeneration after optic nerve crush

Traumatic optic neuropathy (TON) is a condition that causes massive loss of retinal ganglion cells (RGCs) and their axonal fibers, leading to visual insufficiency. Several intrinsic and external factors can limit the regenerative ability of RGC after TON, subsequently resulting in RGC death. Hence, it is important to investigate a potential drug that can protect RGC after TON and enhance its regenerative capacity. Herein, we investigated whether Huperzine A (HupA), extracted from a Chinese herb, has neuroprotective effects and may enhance neuronal regeneration following the optic nerve crush (ONC) model. We compared the three modes of drug delivery and found that intravitreal injection of HupA could promote RGC survival and axonal regeneration after ONC. Mechanistically, HupA exerted its neuroprotective and axonal regenerative effects through the mTOR pathway; these effects could be blocked by rapamycin. To sum up, our findings suggest a promising application of HupA in the clinical treatment of traumatic optic nerve.

Maitake Medicinal Mushroom, Grifola frondosa (Agaricomycetes), and Its Neurotrophic Properties: A Mini-Review

Neurodegeneration is one of the most common manifestations in an aging population. The occurrence of oxidative stress and neuroinflammation are the main contributors to the phenomenon. Neurologic conditions such as Alzheimer's disease (AD) and Parkinson's disease (PD) are challenging to treat due to their irreversible manner as well as the lack of effective treatment. Grifola frondosa (Dicks.: Fr.) S.F. Gray, or maitake mushroom, is believed to be a potential choice as a therapeutic agent for neurodegenerative diseases. G. frondosa is known to be a functional food that has a wide variety of medicinal purposes. Thus, this review emphasizes the neuroprotective effects and the chemical composition of G. frondosa. Various studies have described that G. frondosa can protect and proliferate neuronal cells through neurogenesis, antioxidative, anti-inflammatory, and anti-β-amyloid activities. The mechanism of action behind these therapeutic findings in various in vitro and in vivo models has also been intensively studied. In this mini review, we also summarized the chemical composition of G. frondosa to provide a better understanding of the presence of nutritional compounds in G. frondosa.

The healing bitterness of Gentiana lutea L., phytochemistry and biological activities: A systematic review

Over many years, natural products have been a source of healing agents and have exhibited beneficial uses for treating human diseases. The Gentiana genus is the biggest genus in the Gentianaceae, with over 400 species distributed mainly in alpine zones of temperate countries around the world. Plants in the Gentiana genus have historically been used to treat a wide range of diseases. Still, only in the last years has particular attention been paid to the biological activities of Gentiana lutea Linn., also known as yellow Gentian or bitterwort. Several in vitro/vivo investigations and human interventional trials have demonstrated the promising activity of G. lutea extracts against oxidative stress, microbial infections, inflammation, obesity, atherosclerosis, etc.. A systematic approach was performed using Pubmed and Scopus databases to update G. lutea chemistry and activity. Specifically, this systematic review synthesized the major specialized bitter metabolites and the biological activity data obtained from different cell lines, animal models, and human interventional trials. This review aims to the exaltation of G. lutea as a source of bioactive compounds that can prevent and treat several human illnesses.

Neurotrophic Factors and Dendritic Spines

Dendritic spines are highly dynamic structures that play important roles in neuronal plasticity. The morphologies and the numbers of dendritic spines are highly variable, and this diversity is correlated with the different morphological and physiological features of this neuronal compartment. Dendritic spines can change their morphology and number rapidly, allowing them to adapt to plastic changes. Neurotrophic factors play important roles in the brain during development. However, these factors are also necessary for a variety of processes in the postnatal brain. Neurotrophic factors, especially members of the neurotrophin family and the ephrin family, are involved in the modulation of long-lasting effects induced by neuronal plasticity by acting on dendritic spines, either directly or indirectly. Thereby, the neurotrophic factors play important roles in processes attributed, for example, to learning and memory.

Tea Polyphenols as Prospective Natural Attenuators of Brain Aging

No organism can avoid the process of aging, which is often accompanied by chronic disease. The process of biological aging is driven by a series of interrelated mechanisms through different signal pathways, including oxidative stress, inflammatory states, autophagy and others. In addition, the intestinal microbiota play a key role in regulating oxidative stress of microglia, maintaining homeostasis of microglia and alleviating age-related diseases. Tea polyphenols can effectively regulate the composition of the intestinal microbiota. In recent years, the potential anti-aging benefits of tea polyphenols have attracted increasing attention because they can inhibit neuroinflammation and prevent degenerative effects in the brain. The interaction between human neurological function and the gut microbiota suggests that intervention with tea polyphenols is a possible way to alleviate brain-aging. Studies have been undertaken into the possible mechanisms underpinning the preventative effect of tea polyphenols on brain-aging mediated by the intestinal microbiota. Tea polyphenols may be regarded as potential neuroprotective substances which can act with high efficiency and low toxicity.

Baccharin from Brazilian green propolis induces neurotrophic signaling pathways in PC12 cells: potential for axonal and synaptic regeneration

Neurodegenerative diseases are characterized by progressive loss of the structure and function of specific neuronal populations, and have been associated with reduced neurotrophic support. Neurotrophins, like NGF (nerve growth factor), are endogenous proteins that induce neuritogenesis and modulate axonal growth, branching, and synapsis; however, their therapeutic application is limited mainly by low stability, short half-life, and inability to cross the blood-brain barrier (BBB). Small neurotrophic molecules that have suitable pharmacokinetics and are able to cross the BBB are potential candidates for neuroprotection. Baccharin is a bioactive small molecule isolated from Brazilian green propolis. In the present study, we investigated the neurotrophic and neuroprotective potential of baccharin in the PC12 cell neuronal model. We used pharmacological inhibitors (K252a, LY294002, and U0126), and ELISA (phospho-trkA, phospho-Akt, and phospho-MEK) to investigate the involvement of trkA receptor, PI3k/Akt pathway, and MAPK/Erk pathway, respectively. Additionally, we evaluated the expression of axonal (GAP-43) and synaptic (synapsin I) proteins by western blot. The results showed that baccharin induces neuritogenesis in NGF-deprived PC12 cells, through activation of trkA receptor and the downstream signaling cascades (PI3K/Akt and MAPK/ERK), which is the same neurotrophic pathway activated by NGF in PC12 cells and neurons. Baccharin also induced the expression of GAP-43 and synapsin I, which mediate axonal and synaptic plasticity, respectively. Additionally, in silico predictions of baccharin showed favorable physicochemical properties, pharmacokinetics, drug-likeness, and medicinal chemistry friendliness. Altogether, these findings suggest that baccharin is a promising neurotrophic agent whose therapeutic application in neurodegeneration should be further investigated.

Roles of the Cannabinoid System in the Basal Ganglia in Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disease usually caused by neuroinflammation, oxidative stress and other etiologies. Recent studies have found that the cannabinoid system present in the basal ganglia has a strong influence on the progression of PD. Altering the cannabinoid receptor activation status by modulating endogenous cannabinoid (eCB) levels can exert an anti-movement disorder effect. Therefore, the development of drugs that modulate the endocannabinoid system may be a novel strategy for the treatment of PD. However, eCB regulation is complex, with diverse cannabinoid receptor functions and the presence of dopaminergic, glutamatergic, and γ-aminobutyric signals interacting with cannabinoid signaling in the basal ganglia region. Therefore, the study of eCB is challenging. Here, we have described the function of the cannabinoid system in the basal ganglia and its association with PD in three parts (eCBs, cannabinoid receptors, and factors regulating the cannabinoid metabolism) and summarized the mechanisms of action related to the cannabinoid analogs currently aimed at treating PD. The shortcomings identified from previous studies and the directions that should be explored in the future will provide insights into new approaches and ideas for the future development of cannabinoid-based drugs and the treatment of PD.

Exploring Aromatic Medicinal Compounds for the Treatment of Amyotrophic Lateral Sclerosis

Purpose: Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative condition, in which motor neurons start to degenerate due to the accumulation of protein aggregates in the neuron cytoplasm. The formation of aggregates causes neurotoxicity, facilitated by the N-terminal domain (NTD) of the transactive response DNA-binding protein-43 (TDP-43). Therapies used to treat ALS manage secondary symptoms, but do not stop the activity of the rogue NTD domain of TDP-43. Therefore, new drug candidates should be designed to deal efficiently with this disease by inhibiting the domains involved in the development of ALS. This study determined the chemical affinity of aromatic medicinal compounds with NTD. Screening of 1323 medicinal compounds was conducted with PYRX 0.9 software against NTD. Compounds obtained from this analysis were further used to predict absorption, distribution, metabolism, excretion, and toxic (ADMET) properties and their effect on major gene targets of ALS. Results: From 1300 + compounds, acetovanillone showed binding affinity for NTD and had good ADMET and drug likeness attributes. This compound reduced the expression of CXCL2, NOP56, and SOD1 genes implicated in ALS pathogenesis. Conclusion: These results concluded that acetovanillone is a candidate drug for in vitro and clinical studies into the exploitation of drugs within ALS therapeutics.

A Novel In Vitro Assay Using Human iPSC-Derived Sensory Neurons to Evaluate the Effects of External Chemicals on Neuronal Morphology: Possible Implications in the Prediction of Abnormal Skin Sensation

Neuronal morphological changes in the epidermis are considered to be one of causes of abnormal skin sensations in dry skin-based skin diseases. The present study aimed to develop an in vitro model optimised for human skin to test the external factors that lead to its exacerbation. Human-induced pluripotent stem cell-derived sensory neurons (hiPSC-SNs) were used as a model of human sensory neurons. The effects of chemical substances on these neurons were evaluated by observing the elongation of nerve fibers, incidence of blebs (bead-like swellings), and the expression of nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2). The nerve fiber length increased upon exposure to two common cosmetic preservatives-methylparaben and phenoxyethanol-but not to benzo[a]pyrene, an air pollutant at the estimated concentrations in the epidermis. Furthermore, the incidence of blebs increased upon exposure to benzo[a]pyrene. However, there was a decrease in the expression of NMNAT2 in nerve fibers, suggesting degenerative changes. No such degeneration was found after methylparaben or phenoxyethanol at the estimated concentrations in the epidermis. These findings suggest that methylparaben and phenoxyethanol promote nerve elongation in hiPSC-SNs, whereas benzo[a]pyrene induces nerve degeneration. Such alterations may be at least partly involved in the onset and progression of sensitive skin.

Regulation of Neurogenesis and Neuronal Differentiation by Natural Compounds

Neuronal damage or degeneration is the main feature of neurological diseases. Regulation of neurogenesis and neuronal differentiation is important in developing therapies to promote neuronal regeneration or synaptic network reconstruction. Neurogenesis is a multistage process in which neurons are generated and integrated into existing neuronal circuits. Neuronal differentiation is extremely complex because it can occur in different cell types and can be caused by a variety of inducers. Recently, natural compounds that induce neurogenesis and neuronal differentiation have attracted extensive attention. In this paper, the potential neural induction effects of medicinal plant-derived natural compounds on neural stem/progenitor cells (NS/PCs), the cultured neuronal cells, and mesenchymal stem cells (MSCs) are reviewed. The natural compounds that are efficacious in inducing neurogenesis and neuronal differentiation include phenolic acids, polyphenols, flavonoids, glucosides, alkaloids, terpenoids, quinones, coumarins, and others. They exert neural induction effects by regulating signal factors and cell-specific genes involved in the process of neurogenesis and neuronal differentiation, including specific proteins (β-tubulin III, MAP-2, tau, nestin, neurofilaments, GFAP, GAP-43, NSE), related genes and proteins (STAT3, Hes1, Mash1, NeuroD1, notch, cyclin D1, SIRT1, reggie-1), transcription factors (CREB, Nkx-2.5, Ngn1), neurotrophins (BDNF, NGF, NT-3) and signaling pathways (JAK/STAT, Wnt/β-catenin, MAPK, PI3K/Akt, GSK-3β/β-catenin, Ca2+/CaMKII/ATF1, Nrf2/HO-1, BMP). The natural compounds with neural induction effects are of great value for neuronal regenerative medicine and provide promising prevention and treatment strategies for neurological diseases.

Caesalpinia mimosoides Leaf Extract Promotes Neurite Outgrowth and Inhibits BACE1 Activity in Mutant APP-Overexpressing Neuronal Neuro2a Cells

Alzheimer’s disease (AD) is implicated in the imbalance of several proteins, including Amyloid-β (Aβ), amyloid precursor protein (APP), and BACE1. APP overexpression interferes with neurite outgrowth, while BACE1 plays a role in Aβ generation. Medicinal herbs with effects on neurite outgrowth stimulation and BACE1 inhibition may benefit AD. This study aimed to investigate the neurite outgrowth stimulatory effect, along with BACE1 inhibition of Caesalpinia mimosoides (CM), using wild-type (Neuro2a) and APP (Swedish mutant)-overexpressing (Neuro2a/APPSwe) neurons. The methanol extract of CM leaves stimulated neurite outgrowth in wild-type and APP-overexpressing cells. After exposure to the extract, the mRNA expression of the neurite outgrowth activation genes growth-associated protein-43 (GAP-43) and teneurin-4 (Ten-4) was increased in both Neuro2a and Neuro2a/APPSwe cells, while the mRNA expression of neurite outgrowth negative regulators Nogo receptor (NgR) and Lingo-1 was reduced. Additionally, the extract suppressed BACE1 activity in the APP-overexpressing neurons. Virtual screening demonstrated that quercetin-3′-glucuronide, quercetin-3-O-glucoside, clausarinol, and theogallin were possible inhibitors of BACE1. ADMET was analyzed to predict drug-likeness properties of CM-constituents. These results suggest that CM extract promotes neurite outgrowth and inhibits BACE1 activity in APP-overexpressing neurons. Thus, CM may serve as a source of drugs for AD treatment. Additional studies for full identification of bioactive constituents and to confirm the neuritogenesis in vivo are needed for translation into clinic of the present findings.

Gastrodiae rhizoma attenuates brain aging via promoting neuritogenesis and neurodifferentiation

BACKGROUND

Gastrodiae Rhizoma (Tianma), the dried tuber of Gastrodia elata Bl. (Orchidaceae), is listed as a top-grade herbal medicine in Shen-nong Ben-ts'ao Jing and has been used for treating headaches, dizziness, vertigo and convulsion. It has a neuroprotective effect and extends the lifespan in mouse models of Huntington's disease and Niemann-Pick type C disease. However, its effect on senescence remains unknown.

PURPOSE

This study aimed to investigate the anti-aging effects and the underlying mechanism of Gastrodiae Rhizoma.

METHODS

D-galactose (D-gal)- and BeSO₄-induced cellular senescence and senescence-associated β-galactosidase (SA-β-gal) activity were evaluated in SH-SY5Y and PC12 cells. D-gal-induced aging mice were used as an in vivo model. Animal behaviors including nesting and burrowing and Morris water maze were conducted. Neurogenesis in the hippocampus was assessed by immunohistochemistry and confocal microscopy, and the aging-related proteins were assessed by Western blot analysis. The potential neuritogenesis activity of the partially purified fraction of Gastrodiae Rhizoma (TM-2) and its major ingredients were investigated in PC12 cells.

RESULTS

TM-2 could improve D-gal-induced learning and memory impairement by inhibiting oxidative stress, increasing hippocampal neurogenesis and regulating the SH2B1-Akt pathway. Moreover, N⁶-(4-hydroxybenzyl)adenine riboside (T1-11) and parishins A and B, three constituents of TM-2, had anti-aging activity, as did T1-11 and parishin A induced neuritogenesis.

CONCLUSION

Our data suggested that TM-2 slowed down D-gal-induced cellular and mouse brain aging. These results indicate that Gastrodiae Rhizoma has a beneficial effect on senescence. It may be used for neuroprotection and promoting neurogenesis.

Synthesis and biological evaluation of phenothiazine derivative-containing hydroxamic acids as potent class II histone deacetylase inhibitors

The pathogenesis of Alzheimer's disease (AD) has been associated with dysregulation of histone deacetylases (HDACs). Previously, acridine-based HDAC inhibitors have shown potential in ameliorating HDAC activity and enhancing neurite outgrowth. In this study, the acridine ring was modified using various phenothiazine derivatives. Several resulting compounds exhibited potent enzyme-inhibiting activity towards class II HDACs when compared to the clinically approved HDAC inhibitor SAHA. Compound 4f demonstrated the highest class II HDAC inhibition (IC₅₀ = 4.6-600 nM), as well as promotion of neurite outgrowth. Importantly, compound 4f displayed no cytotoxicity against neuron cells. Compound 4f was further evaluated for cellular effects. Altogether, these findings show a potential strategy in HDAC inhibition for treatment of the neurological disease.

Box Jellyfish (Cnidaria, Cubozoa) Extract Increases Neuron's Connection: A Possible Neuroprotector Effect

Neurodegenerative diseases are one of the major causes of death worldwide, characterized by neurite atrophy, neuron apoptosis, and synapse loss. No effective treatment has been indicated for such diseases so far, and the search for new drugs is being increased in the last years. Animal venoms' secretion/venom can be an alternative for the discovery of new molecules, which could be the prototype for a new treatment. Here, we present the biochemical characterization and activity of the extract from the box jellyfish Chiropsalmus quadrumanus (Cq) on neurites. The Cq methanolic extract was obtained and incubated to human SH-SY5Y neurons, and neurite parameters were evaluated. The extract was tested in other cell types to check its cytotoxicity and was submitted to biochemical analysis by mass spectrometry in order to check its composition. We could verify that the Cq extract increased neurite outgrowth length and branching junctions, amplifying the contact between SH-SY5Y neurons, without affecting cell body and viability. The extract action was selective for neurons, as it did not cause any effects on other cell types, such as tumor line, nontumor line, and red blood cells. Moreover, mass spectrometry analysis revealed that there are no proteins but several low molecular mass compounds and peptides. Three peptides, characterized as cryptides, and 14 low molecular mass compounds were found to be related to cytoskeleton reorganization, cell membrane expansion, and antioxidant/neuroprotective activity, which act together to increase neuritogenesis. After this evaluation, we conclude that the Cq extract is a promising tool for neuronal connection recovery, an essential condition for the treatment of neurodegenerative diseases.

Molecular mechanism of nur77 gene expression and downstream target genes in the early stage of forskolin-induced differentiation in PC12 cells

Forskolin promotes neuronal differentiation of PC12 cells via the PKA-CREB-dependent signaling pathway. Activation of PKA by forskolin phosphorylates CREB, which then binds to CRE sites in numerous gene promoters. However, it is unclear which gene contains the CRE sites responsible for forskolin-induced neuronal differentiation. In this study, we investigated how an immediate early gene, nur77, which has CRE sites in the promoter region, contributes to the early stage of differentiation of forskolin-treated PC12 cells. After treatment with forskolin, expression of Nur77 was upregulated within 1 hr. In addition, knockdown of nur77 inhibited neurite outgrowth induced by forskolin. We also revealed that the specific four CRE sites near the transcriptional start site (TSS) of nur77 were strongly associated with phosphorylated CREB within 1 hr after treatment with forskolin. To analyze the roles of these four sites, reporter assays using the nur77 promoter region were performed. The results showed that nur77 expression was mediated through three of the CRE sites, -242, -222, and -78, and that -78, the nearest of the three to the TSS of nur77, was particularly important. An analysis of neuronal markers controlled by Nur77 after A-CREB-Nur77-Synapsin1 signaling pathway plays a pivotal role in differentiation of forskolin-induced PC12 cells.

Sesamin Promotes Neurite Outgrowth under Insufficient Nerve Growth Factor Condition in PC12 Cells through ERK1/2 Pathway and SIRT1 Modulation

The promotion of neurogenesis can be a promising strategy to improve and restore neuronal function in neurodegenerative diseases. Nerve growth factor (NGF) plays a key role in neurite outgrowth and synaptic formation during brain repair stage. Nowadays, there are several studies on the developing methods to enhance the endogenous NGF activity for treatment and restore the neuronal function. In this study, the potentiating effect of sesamin, a major lignan in sesame seeds (Sesamum indicum) and oil, on NGF-induced neurogenesis and its involved mechanisms were firstly reported. Sesamin effectively enhanced the PC12 neuron-like cell differentiation and neurite length under insufficient conditions of NGF. The neuronal markers including synaptophysin and growth-associated protein-43 along with the synaptic connections were significantly increased in combination treatment between sesamin and NGF. Moreover, sesamin also increased the level of phospho-ERK1/2 and SIRT1 protein, an important regulatory protein of the neurogenesis process. The neurogenesis was blocked by the specific SIRT1 inhibitor, JGB1741, suggesting that the neuritogenic effect of sesamin was associated with SIRT1 protein modulation. Taken together, the potentiating effect of sesamin on NGF-induced neurogenesis in this finding could be used for alternative treatment in neurodegenerative diseases, including Alzheimer's disease.

Synthesis of some new acylhydrazone compounds containing the 1,2,4-triazole structure and their neuritogenic activities in Neuro-2a cells

In the present study, a novel series of acylhydrazone compounds (A0–A10) with the structure of 1,2,4-triazole have been designed and synthesized.

The effect of coniferaldehyde on neurite outgrowth in neuroblastoma Neuro2a cells

Neurite outgrowth is the differentiation process by which neurons establish synapses. In the dentate gyrus of the hippocampus, new neurons are constantly produced and undergo neurite outgrowth to form synapses, and this process is involved in cognitive ability. Therefore, if an agent could modulate neurite outgrowth, it could potentially be developed as a compound for modulating cognitive ability. In this study, we examined whether coniferaldehyde, a natural compound, regulates neurite outgrowth in Neuro2a cells. We ascertained morphological changes and measured the percentage of neurite-bearing cells and neurite lengths. Coniferaldehyde significantly increased the percentage of neurite-bearing cells, and the length of neurites in a concentration-dependent manner, without inducing cell death. We then have identified that, coniferaldehyde activates the extracellular signals-regulated Kinase 1 and 2 (ERK1/2), and further noted that, U0126, an ERK1/2 inhibitor, blocks coniferaldehyde-facilitated neurite outgrowth. Moreover, Subchronic administration of CA enhanced learning and memory, and increased neurite length of newborn neurons in the hippocampus. These results suggest that coniferaldehyde induces neurite outgrowth by a process possibly mediated by ERK1/2 signaling and enhances learning and memory.

The effects of Centella asiatica (L.) Urban on neural differentiation of human mesenchymal stem cells in vitro

Background

Centella asiatica (L.) Urban, known as Indian Pennywort, is a tropical medicinal plant from Apiaceae family native to Southeast Asian countries. It has been widely used as a nerve tonic in Ayuverdic medicine since ancient times. However, whether it can substitute for neurotrophic factors to induce human mesenchymal stem cell (hMSCs) differentiation into the neural lineage remains unknown. This study aimed to investigate the effect of a raw extract of C. asiatica (L.) (RECA) on the neural differentiation of hMSCs in vitro.

Methods

The hMSCs derived from human Wharton’s jelly umbilical cord (hWJMSCs; n = 6) were treated with RECA at different concentrations; 400, 800, 1200, 1600, 2000 and 2400 μg/ml. The cytotoxicity of RECA was evaluated via the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) and cell proliferation assays. The hWJMSCs were then induced to neural lineage for 9 days either with RECA alone or RECA in combination with neurotrophic factors (NF). Cell morphological changes were observed under an inverted microscope, while the expression of the neural markers S100β, p75 NGFR, MBP, GFAP and MOG was analyzed by quantitative polymerase chain reaction and immunocytochemistry. The cell cycle profile of differentiated and undifferentiated hWJMSCs was investigated through cell cycle analysis.

Results

RECA exerted effects on both proliferation and neural differentiation of hWJMSCs in a dose-dependent manner. RECA reduced the proliferation of hWJMSCs and was cytotoxic to cells above 1600 μg/ml, with IC₅₀ value, 1875 ± 55.67 μg/ml. In parallel with the reduction in cell viability, cell enlargement was also observed at the end of the induction. Cells treated with RECA alone had more obvious protein expression of the neural markers compared to the other groups. Meanwhile, gene expression of the aforementioned markers was detected at low levels across the experimental groups. The supplementation of hWJMSCs with RECA did not change the normal life cycle of the cells.

Conclusions

Although RECA reduced the proliferation of hWJMSCs, a low dose of RECA (400 μg/ml), alone or in combination of neurotrophic factors (NF + RECA 400 μg/ml), has the potential to differentiate hWJMSCs into Schwann cells and other neural lineage cells.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2581-x) contains supplementary material, which is available to authorized users.

The Effect of Resveratrol on the Composition and State of Lipids and the Activity of Phospholipase A2 During the Excitation and Regeneration of Somatic Nerves

It has been shown that in the somatic nerve's lipids, both during excitation and transection, changes occur with the composition of individual phospholipids and in phospholipids fatty acids, which changes the phase state of the myelin and nerve fiber axolemma lipid bilayer. A main contribution in the nerve degenerative processes is dependent on the composition phospholipid's fatty acid changes during the activation of both Ca²⁺-dependent and Ca²⁺-independent phospholipase A₂ forms. At the same time, we studded changes in phosphoinisitol (PI) and diacylglycerol (DAG), which depend on the phosphoinositide cycle function during nerve excitation and degeneration processes. It was found that myelin lipids and nerve fiber axolemmas are involved not only in the functioning of the peripheral nerves, but also the pathological processes underlying deep functional and structural disorders. The effect of resveratrol on regeneration processes in the damaged rat sciatic nerve has also been investigated.

Effects of Carbazole Derivatives on Neurite Outgrowth and Hydrogen Peroxide-Induced Cytotoxicity in Neuro2a Cells

Many studies have demonstrated that oxidative stress plays an important role in several ailments including neurodegenerative diseases and cerebral ischemic injury. Previously we synthesized some carbazole compounds that have anti-oxidant ability in vitro. In this present study, we found that one of these 22 carbazole compounds, compound 13 (3-ethoxy-1-hydroxy-8- methoxy-2-methylcarbazole-5-carbaldehyde), had the ability to protect neuro2a cells from hydrogen peroxide-induced cell death. It is well known that neurite loss is one of the cardinal features of neuronal injury. Our present study revealed that compound 13 had the ability to induce neurite outgrowth through the PI3K/Akt signaling pathway in neuro2a cells. These findings suggest that compound 13 might exert a neurotrophic effect and thus be a useful therapy for the treatment of brain injury.

Distal Axonal Proteins and Their Related MiRNAs in Cultured Cortical Neurons

Proteins and microRNAs (miRNAs) within the axon locally regulate axonal development. However, protein profiles of distal axons of cortical neurons have not been fully investigated. In particular, networks of genes encoding axonal proteins and their related miRNAs in sub compartments of neurons such as axons remain unknown. Using embryonic cortical neurons cultured in a microfluidic device and proteomic approaches, we found that distal axons contain 883 proteins. Bioinformatics analysis revealed that 94 out of these 883 proteins are related to regulating axonal growth. Of the 94 genes encoding these proteins, there were 56 candidate genes that can be putatively targeted by axon-enriched 62 miRNAs with 8mer sites that exactly match these target genes. Among them, we validated 11 proteins and 11 miRNAs, by means of western blot and RT-PCR, respectively. Treatment of distal axons with chondroitin sulfate proteoglycans (CSPGs) that inhibit axonal growth elevated miR-133b, -203a, -29a, and -92a, which were associated with reduced protein level of AKT, MTOR, PI3K, DPYSL2, MAP1B, and PPP2CA. In contrast, reduction of miR-128, -15b, -195, -26b, -34b, -376b, and -381 by CSPGs was accompanied by increased EZR, KIF5A, DCX, GSK3B, and ROCK2 proteins. In silico pathway analysis revealed an interconnected network of these miRNAs and protein coding genes that is highly related to regulating axonal growth. Our data provide new insights into networks of miRNAs and their related proteins in distal axons in mediating axonal growth.

Echinocystic Acid Facilitates Neurite Outgrowth in Neuroblastoma Neuro2a Cells and Enhances Spatial Memory in Aged Mice

Aging leads to functional changes in the brain and decreases ability of learning and memory. Neurite outgrowth is important in learning and memory, therefore regulation of neurite outgrowth might be a candidate for treating aged brain. Echinocystic acid (EA), a pentacyclic triterpene, has shown to exert various neurological effects. However, the effect of EA on neurite outgrowth has not been studied. In this study, we examined if EA is effective on neurite outgrowth and memory in aged mice. The effect of EA on neurite outgrowth was observed by examining neurite processes of Neuro2a cells treated with EA. Western blot analysis was conducted to examine possible mechanisms. Morris water maze test was used to examine the effect of EA on learning and memory in aged mice. Immunohistochemistry was conducted to observe the effect of EA on neurite outgrowth in the hippocampus. EA was shown to induce neurite outgrowth in a concentration dependent manner without affecting cell viability. Moreover, EA treatment increased phosphorylation of c-jun N-terminal kinase (JNK) and JNK inhibitor, SP600125, blocked the effect of EA on neurite outgrowth. These results demonstrated that EA treatment promotes neurite outgrowth through the JNK signaling pathway. In in vivo experiments, EA treatment increased neurite outgrowth in aged mouse hippocampus. Moreover, EA treatment enhanced spatial learning and memory in aged mice. These results suggest that EA can be developed as a new, naturally occurring drug to treat ageing-related neurological diseases.

Methylene-Cycloalkylacetate (MCA) Scaffold-Based Compounds as Novel Neurotropic Agents

One of the main symptoms in degenerative diseases is death of neuronal cell followed by the loss of neuronal pathways. In neuronal cultures, neurite outgrowths are cell sprouts capable of transforming into either axons or dendrites, to further form functional neuronal synaptic connections. Such connections have an important role in brain cognition, neuronal plasticity, neuronal survival, and regeneration. Therefore, drugs that stimulate neurite outgrowth may be found beneficial in ameliorating neural degeneration. Here, we establish the existence of a unique family of methylene-cycloalkylacetate-based molecules (MCAs) that interface with neuronal cell properties and operate as acceptable pharmacophores for a novel neurotropic (neurite outgrowth inducing) lead compounds. Using an established PC12 cell bioassay, we investigated the neurotropic effect of methylene-cycloalkylacetate compounds by comparison to NGF, a known neurotropic factor. Micrographs of the cells were collected by using a light microscope camera, and digitized photographs were analyzed for compound-induced neurotropic activity using an NIH image protocol. The results indicate that the alkene element, integrated within the cycloalkylacetate core, is indispensable for neurotropic activity. The discovered lead compounds need further mechanistic investigation and may be improved toward development of a neurotropic drug.

Semisynthesis and biological evaluation of prenylated resveratrol derivatives as multi-targeted agents for Alzheimer's disease

A series of prenylated resveratrol derivatives were designed, semisynthesized and biologically evaluated for inhibition of β-secretase (BACE1) and amyloid-β (Aβ) aggregation as well as free radical scavenging and neuroprotective and neuritogenic activities, as potential novel multifunctional agents against Alzheimer's disease (AD). The results showed that compound 4b exhibited good anti-Aβ aggregation (IC₅₀ = 4.78 µM) and antioxidant activity (IC₅₀ = 41.22 µM) and moderate anti-BACE1 inhibitory activity (23.70% at 50 µM), and could be a lead compound. Moreover, this compound showed no neurotoxicity along with a greater ability to inhibit oxidative stress on P19-derived neuronal cells (50.59% cell viability at 1 nM). The neuritogenic activity presented more branching numbers (9.33) and longer neurites (109.74 µm) than the control, and was comparable to the quercetin positive control. Taken together, these results suggest compound 4b had the greatest multifunctional activities and might be a very promising lead compound for the further development of drugs for AD.

The role of chalcones: helichrysetin, xanthohumol, and flavokawin-C in promoting neurite outgrowth in PC12 Adh cells

Chalcones are a group of compounds widely distributed in plant kingdom. The aim of this study was to assess the neurite outgrowth stimulatory activity of selected chalcones, namely helichrysetin, xanthohumol and flavokawin-C. Using adherent rat pheochromocytoma (PC12 Adh) cells, the chalcones were subjected to neurite outgrowth assay and the extracellular nerve growth factor (NGF) levels were determined. Xanthohumol (10 μg/mL) displayed the highest (p < 0.05) percentage of neurite-bearing PC12 Adh cells and the highest (p < 0.05) NGF level in the culture medium of xanthohumol-treated cells. While, helichrysetin induced a moderately high numbers of neurite-bearing cells, flavokawin-C did not stimulate neurite outgrowth. This work supports the potential use of xanthohumol as a potential neuroactive compound to stimulate neurite outgrowth.

In silico insight into EGFR treatment in patients with lung carcinoma and T790M mutations

The T790M mutational basis of treatment failure, following treatment via alteration of the epidermal growth factor receptor (EGFR) pathway, is a well-known anomaly in patients with non-small cell lung cancer (NSCLC). The T790M mutation activates the kinase domain, causing tyrosine kinase inhibitors, such as gefitinib, to elicit little or no response. To overcome this acquired resistance in NSCLC cells, the present study utilized a structure-based drug designing method to identify a novel lead compound. An in-house traditional Chinese medicinal compound database was used and following initial virtual screening, pre-absorption, distribution, metabolism and excretion/Tox and automated docking analyses, nardosinon was selected as the most appropriate candidate for further analysis. Two NSCLC cell lines, PC9GR4 and H2347, were used to test nardosinon and the results were compared with gefitinib. Results from an initial cell death assay revealed that nardosinon was able to induce cell death in NSCLC cells with and without the T790M mutation. These findings suggest that nardosinon may be an effective pharmacological compound for NSCLC treatment, including T790M EGFR mutant NSCLC cells.

Equol, a Dietary Daidzein Gut Metabolite Attenuates Microglial Activation and Potentiates Neuroprotection In Vitro

Estrogen deficiency has been well characterized in inflammatory disorders including neuroinflammation. Daidzein, a dietary alternative phytoestrogen found in soy (Glycine max) as primary isoflavones, possess anti-inflammatory activity, but the effect of its active metabolite Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman) has not been well established. In this study, we investigated the anti-neuroinflammatory and neuroprotective effect of Equol in vitro. To evaluate the potential effects of Equol, three major types of central nervous system (CNS) cells, including microglia (BV-2), astrocytes (C6), and neurons (N2a), were used. Effects of Equol on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), Mitogen activated protein kinase (MAPK) signaling proteins, and apoptosis-related proteins were measured by western blot analysis. Equol inhibited the lipopolysaccharide (LPS)-induced TLR4 activation, MAPK activation, NF-kB-mediated transcription of inflammatory mediators, production of nitric oxide (NO), release of prostaglandin E2 (PGE-2), secretion of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), in Lipopolysaccharide (LPS)-activated murine microglia cells. Additionally, Equol protects neurons from neuroinflammatory injury mediated by LPS-activated microglia through downregulation of neuronal apoptosis, increased neurite outgrowth in N2a cell and neurotrophins like nerve growth factor (NGF) production through astrocytes further supporting its neuroprotective potential. These findings provide novel insight into the anti-neuroinflammatory effects of Equol on microglial cells, which may have clinical significance in cases of neurodegeneration.

Negletein as a neuroprotectant enhances the action of nerve growth factor and induces neurite outgrowth in PC12 cells

Negletein has been shown to have therapeutic potential for inflammation-associated diseases, but its effect on neurite outgrowth is still unknown. The present study showed that negletein alone did not trigger PC12 cells to differentiate and extend neurites. When compared with the cells in the untreated control, a significant (P < 0.05) induction and a higher neurite outgrowth activity was observed when the cells were cotreated with negletein (10 µM) and a low dose of nerve growth factor (NGF; 5 ng/mL). The neurite outgrowth process was blocked by the tyrosine kinase receptor (Trk) inhibitor, K252a, suggesting that the neuritogenic effect was NGF-dependent. Negletein (10 µM) together with NGF (5 ng/mL) enhanced the phosphorylation of extracellular signal-regulated kinases (ERKs), protein kinase B (Akt), and cAMP response element-binding protein (CREB). The growth associated protein-43 (GAP-43) and the NGF level were also upregulated by negletein (10 µM) and a low dose of NGF (5 ng/mL). Negletein at nanomolar concentration also was found to be sufficient to mediate the survival of serum-deprived PC12 cells up to 72 h. Taken together, negletein might be useful as an efficient bioactive compound to protect neurons from cell death and promote neuritogenesis. © 2016 BioFactors, 42(6):591-599, 2016.

Design and Synthesis of Dimeric Securinine Analogues with Neuritogenic Activities

Neurite outgrowth is crucial during neuronal development and regeneration, and strategies that aim at promoting neuritogenesis are beneficial for reconstructing synaptic connections after neuronal degeneration and injury. Using a bivalent analogue strategy as a successful approach, the current study identifies a series of novel dimeric securinine analogues as potent neurite outgrowth enhancers. Compounds 13, 14, 17-19, and 21-23, with different lengths of carbon chain of N,N-dialkyl substituting diacid amide linker between two securinine molecules at C-15 position, exhibited notable positive effects on both neuronal differentiation and neurite extension of neuronal cells. Compound 14, one of the most active compounds, was used as a representative compound for mechanistic studies. Its action on neurite outgrowth was through phosphorylation/activation of multiple signaling molecules including Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), extracellular signal-regulated kinase (ERK) and Akt. These findings collectively identify a new group of beneficial compounds for neuritogenesis, and may provide insights on drug discovery of neural repair and regeneration.

Bioactive components of Chinese herbal medicine enhance endogenous neurogenesis in animal models of ischemic stroke: A systematic analysis

BACKGROUND

Chinese herbal medicine (CHM) has been used to treat stroke for thousands of years. The objective of the study is to assess the current evidence for bioactive components of CHM as neurogenesis agent in animal models of ischemic stroke.

METHODS

We searched PubMed, China National Knowledge Infrastructure, WanFang Database, and VIP Database for Chinese Technical Periodicals published from the inception up to November 2015. The primary measured outcome was one of neurogenesis biomarker, including Bromodeoxyuridine (BrdU), Nestin, doublecortin (DCX), polysialylated form of the neural cell adhesion molecule (PSA-NCAM), neuronal nuclear antigen (NeuN), and glial fibrillary acidic protein (GFAP).

RESULTS

Thirty eligible studies were identified. The score of quality assessment ranged from 2 of 10 to 7 of 10. Compared with controls, 10 studies conducting neurobehavioral evaluation showed significant effects on bioactive components of CHM for improving neurological deficits score after ischemic insults (P < 0.01 or P < 0.05); 6 studies in Morris water-maze test showed bioactive components of CHM significantly decreased escape latency and increased residence time (P < 0.05); 5 studies demonstrated that bioactive components of CHM significantly reduced infarct volume after ischemic stroke (P < 0.05); 25 of 26 studies showed that bioactive components of CHM significantly increased the expression of BrdU and/or Nestin markers in rats/mice brain after ischemic injury (P < 0.05, or P < 0.01); 4 of 5 studies for promoting the expression of PSA-NCAM or DCX biomarker (P < 0.05); 5 studies for improving the expression of NeuN biomarker (P < 0.05); 6 of 7 studies for promoting the expression of GFAP biomarker in brain after ischemic stroke (P < 0.05).

CONCLUSION

The findings suggest that bioactive components of CHM may improve neurological function, reduce infarct volume, and promote endogenous neurogenesis, including proliferation, migration, and differentiation of neural stem cells after ischemic stroke. However, evidences are supported but limited because only a few studies were available for each descriptive analysis. Further rigor study is still needed.

Mechanism for neurotropic action of vorinostat, a pan histone deacetylase inhibitor

In this study we investigated the neurotrophic actions of vorinostat (suberoylanilide hydroxamic acid, SAHA), a class I and class II HDAC inhibitor, on the differentiation of Neuroscreen-1 (NS-1) cells. NS-1 cell is a subclone of the rat pheochromocytoma cell line (PC 12). Vorinostat independently induced neurite outgrowth in NS-1 cells. The NS-1 cells were further interrogated for the effects of vorinostat on intracellular neurotrophin signaling pathways, to understand its mechanism of neurotrophic action. Selective inhibitors of MEK1/2 (PD98059 and U0126), phosphoinositide 3-kinase (PI3K) (LY294002) and tyrosine kinase A (TrkA) (GW441756) were employed for these interrogations. Our results suggest that neurite outgrowth mediated by both nerve growth factor (NGF), an intrinsic neurotrophin, and vorinostat were blocked by the inhibitors of MEK1/2 & PI3K. Vorinostat induced phosphorylation of ERK1/2 occurs at 2h post treatment. Phosphorylation of ERK was abolished in presence of U0126, further confirming the role of ERK pathway in vorinostat-induced differentiation of NS-1 cells. Vorinostat-induced neurite outgrowth also involves the activation of upstream extracellular kinase TrkA, as both vorinostat mediated neurite outgrowth and activation of ERK were attenuated in presence of the TrkA inhibitor, GW441756. Vorinostat also stimulated hyperacetylation of α-tubulin and histones H3/H4 in NS-1 cells. The results suggest that vorinostat exerts a positive effect on the neuritogenesis via activation of MEK1/2 & PI3K pathways involving an upstream kinase, TrkA. Bioactive small molecules with neurotrophic and neuritogenic actions, like vorinostat identified in the present study, hold great promise as therapeutic agents for treatment of neurodegenerative diseases and neuronal injuries by virtue of their ability to stimulate neuritic outgrowth.

Anti-neuroinflammatory and neuroprotective effects of the Lindera neesiana fruit in vitro

BACKGROUND

Lindera neesiana Kurz (Lauraceae), popularly known as Siltimur in Nepal, is an aromatic and spicy plant with edible fruits. It is a traditional herbal medicine widely used for the treatment of diarrhea, tooth pain, headache, and gastric disorders and is also used as a stimulant.

PURPOSE

The aim of the present study was to examine in vitro cytoprotective, anti-neuroinflammatory and neuroprotective potential of an aqueous extract of L. neesiana (LNE) fruit using different central nervous system (CNS) cell lines.

METHODS

In order to study the neuroprotective potential of LNE, we used three different types of CNS cell lines: murine microglia (BV2), rat glioma (C6), and mouse neuroblastoma (N2a). Cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reagent, and prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and nerve growth factor (NGF) release in the culture media was determined using enzyme linked immunosorbent assay (ELISA) kits. Western blot analysis was performed to determine the protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), mitogen activated protein kinase (MAPK) family proteins, Bax, B cell lymphoma (BCL)-2, and cleaved caspase 3. Neurite outgrowth was determined using the IncuCyte imaging system.

RESULTS

LNE treatment not only reduced nitric oxide (NO) production in a dose-dependent manner, but also significantly reduced proinflammatory cytokines, iNOS and COX-2 production by lipopolysaccharide (LPS) stimulated BV-2 cells. LNE increased the expression of phosphorylated (p)-extracellular signal-regulated kinase (ERK), whereas p-p38 and p- janus kinase (JNK) expression was significantly decreased in activated microglia. Furthermore, LNE increased cell viability of N2a cells, which was accompanied by decreased caspase-3 expression and the ratio of Bax/Bcl2 protein expression as well as increased NGF and neurite outgrowth, suggesting its neuroprotective potential against LPS-induced effects. Additionally, LNE substantially increased nuclear factor erythroid 2-related factor 2 (Nrf2) secretion in N2a cells and inhibited lipid dehydrogenase (LDH) release in H2O2-stimulated BV2 cells demonstrating the strong anti-inflammatory and antioxidant effects of LNE in CNS cell lines.

CONCLUSION

Here we found that water the soluble extract of LNE has promising anti-neuroinflammation and anti-apoptotic properties and identify LNE as a potential natural candidate for neuroprotection.

Dimethylsulfoniopropionate Promotes Process Outgrowth in Neural Cells and Exerts Protective Effects against Tropodithietic Acid

The marine environment harbors a plethora of bioactive substances, including drug candidates of potential value in the field of neuroscience. The present study was undertaken to investigate the effects of dimethylsulfoniopropionate (DMSP), produced by several algae, corals and higher plants, on cells of the mammalian nervous system, i.e., neuronal N2a and OLN-93 cells as model system for nerve cells and glia, respectively. Additionally, the protective capabilities of DMSP were assessed in cells treated with tropodithietic acid (TDA), a marine metabolite produced by several Roseobacter clade bacteria. Both cell lines, N2a and OLN-93, have previously been shown to be a sensitive target for the action of TDA, and cytotoxic effects of TDA have been connected to the induction of oxidative stress. Our data shows that DMSP promotes process outgrowth and microtubule reorganization and bundling, accompanied by an increase in alpha-tubulin acetylation. Furthermore, DMSP was able to prevent the cytotoxic effects exerted by TDA, including the breakdown of the mitochondrial membrane potential, upregulation of heat shock protein Hsp32 and activation of the extracellular signal-regulated kinases 1/2 (ERK1/2). Our study points to the conclusion that DMSP provides an antioxidant defense, not only in algae but also in mammalian neural cells.

Disease chemopreventive effects and molecular mechanisms of hydroxylated polymethoxyflavones

Recent increasing attention in research of polymethoxyflavones (PMFs) from Citrus genus because of their wide range of biological properties has been reported in various studies. Hydroxylated PMFs are unique flavones and recognized as the methoxy group of PMFs that is substituted for hydroxyl one. Hydroxylated PMFs are naturally existed in citrus peel and other plants as well as occurred as metabolites of their PMFs counterparts. Several in vitro and in vivo studies have documented the chemopreventive effects of hydroxylated PMFs including anti-cancer, anti-inflammation, anti-atherosclerosis, and neuroprotection. They function to regulate cell death, proliferation, differentiation, repair, and metabolism through acting on modulation of signaling cascade, gene transcription, and protein function and enzyme activity. The mechanisms of action of hydroxylated PMFs in disease chemoprevention depend on their structure, the number, and position of hydroxyl group. Although the efficacy of hydroxylated PMFs in chemoprevention and the oral bioavailability requires further investigation, they still provide great promise for improving human health. This review highlights the recent published data of hydroxylated PMFs with chemopreventive potential and the underlying mechanism involved.