Rutin, A Natural Flavonoid Protects PC12 Cells Against Sodium Nitroprusside-Induced Neurotoxicity Through Activating PI3K/Akt/mTOR and ERK1/2 Pathway

RUTIN, a widely consumed flavonoid, that commonly induces hormetic effects

Rutin is a flavonoid present in numerous fruits and vegetables and therefore widely consumed by humans. It is also a popular dietary supplement of 250-500 mg/day. There is considerable consumer interest in rutin due to numerous reports in the biomedical literature of its multi-system chemo-preventive properties. The present paper provides the first assessment of rutin-induced hormetic concentration/dose responses, their quantitative features and mechanistic basis, along with their biological, biomedical, clinical, and public health implications. The findings indicate that rutin-induced hormetic dose responses are widespread, being reported in numerous biological models and cell types for a wide range of endpoints. Of critical importance is that the optimal hormetic findings shown in in vitro systems are currently not achievable for human populations due to low gastrointestinal tract bioavailability. These findings have the potential to strengthen future experimental studies with rutin, particularly concerning study design parameters.

Polyphenols Targeting MAP Kinase Signaling Pathway in Neurological Diseases: Understanding Molecular Mechanisms and Therapeutic Targets

Polyphenols are a class of secondary metabolic products found in plants that have been extensively studied for how well they regulate biological processes, such as the proliferation of cells, autophagy, and apoptosis. The mitogen-activated protein kinase (MAPK)-mediated signaling cascade is currently identified as a crucial pro-inflammatory pathway that plays a significant role in the development of neuroinflammation. This process has been shown to contribute to the pathogenesis of several neurological conditions, such as Alzheimer's disease (AD), Parkinson's disease (PD), CNS damage, and cerebral ischemia. Getting enough polyphenols through eating habits has resulted in mitigating the effects of oxidative stress (OS) and lowering the susceptibility to associated neurodegenerative disorders, including but not limited to multiple sclerosis (MS), AD, stroke, and PD. Polyphenols possess significant promise in dealing with the root cause of neurological conditions by modulating multiple therapeutic targets simultaneously, thereby attenuating their complicated physiology. Several polyphenolic substances have demonstrated beneficial results in various studies and are presently undergoing clinical investigation to treat neurological diseases (NDs). The objective of this review is to provide a comprehensive summary of the different aspects of the MAPK pathway involved in neurological conditions, along with an appraisal of the progress made in using polyphenols to regulate the MAPK signaling system to facilitate the management of NDs.

Rutin ameliorate PFOA induced renal damage by reducing oxidative stress and improving lipid metabolism

Perfluorooctanoic acid (PFOA) is a persistent environmental pollutant that can accumulate in the kidneys and eventually cause kidney damage. Rutin (RUTIN) is a natural flavonoid with multiple biological activities, and its use in against kidney damage has been widely studied in recent years. It is not yet known whether rutin protects against kidney damage caused by PFOA. In this study, 30 ICR mice were randomly divided into three groups: CTRL group, PFOA group and PFOA+RUTIN group. The mice were fed continuously by gavage for 28 days. Renal pathological changes were assessed by HE and PASM staining, and serum renal function and lipid indicators were measured. RNA-seq and enrichment analysis using GO, KEGG and PPI to detect differential expression of genes in treatment groups. Kidney tissue protein expression was determined by Western blot. Research has shown that rutin can improve glomerular and tubular structural damage, and increase serum CREA, HDL-C levels and decrease LDH, LDL-C levels. The expression of AQP1 and ACOT1 was up-regulated after rutin treatment. Transcriptomic analysis indicated that PFOA and rutin affect the transcriptional expression of genes related to lipid metabolism and oxidative stress, and may affected by PI3K-Akt, PPAR, NRF2/KEAP1 signaling pathways. In conclusion, rutin ameliorated renal damage caused by PFOA exposure, and this protective effect may be exerted by ameliorating oxidative stress and regulating lipid metabolism.

Byrsonima sericea Ethanol Extract Protected PC12 Cells from the Oxidative Stress and Apoptosis Induced by 6-Hydroxydopamine

Parkinson's disease is characterized by the progressive loss of dopaminergic neurons in the nigrostriatal pathway and oxidative stress is one of the main mechanisms that lead to neuronal death in this disease. Previous studies have shown antioxidant activity from the leaves of Byrsonima sericea, a plant of the Malpighiaceae family. This study aimed to evaluate the cytoprotective activity of the B. sericea ethanolic extract (BSEE) against the cytotoxicity induced by 6-hydroxydopamine (6-OHDA) in PC12 cells, an in vitro model of parkinsonism. The identification of phenolic compounds in the extract by HPLC-DAD revealed the presence of geraniin, rutin, isoquercetin, kaempferol 3-O-β-rutinoside, and quercetin. The BSEE (75-300 µg/mL) protected PC12 cells from toxicity induced by 6-OHDA (25 µg/mL), protected cell membrane integrity and showed antioxidant activity. BSEE was able to decrease nitrite levels, glutathione depletion, and protect cells from 6-OHDA-induced apoptosis. Thus, we suggest that the BSEE can be explored as a possible cytoprotective agent for Parkinson's disease due to its high antioxidant capacity and anti-apoptotic action.

Hyperoside Prevents Aβ42-Induced Neurotoxicity in PC12 Cells and Caenorhabditis elegans

Traditional Chinese medicines such as hyperoside-rich Acanthopanax senticosus and Crataegus pinnatifida have been confirmed to exhibit anti-oxidative stress properties. Hyperoside, the main ingredient of numerous antioxidant herbs, may have the ability to postpone the onset of neurodegenerative diseases. This study investigates the possible therapeutic mechanism of hyperoside as a natural antioxidant against Alzheimer's disease (AD) in Caenorhabditis elegans and PC12 cells. Specifically, hyperoside reduced reactive oxygen species (ROS) level and Aβ42-induced neurotoxicity in C. elegans worms. Meanwhile, hyperoside reduced ROS production and increased mitochondrial membrane potentialin Aβ42-induced PC12 cells, which possibly due to the increase of antioxidant enzymes activity and the diminution of malondialdehyde levels. Hoechst 33,342 staining and flow cytometry analysis results suggested that hyperoside reverses cell apoptosis. Network pharmacology predicts potentially relevant hyperoside targets and pathways in AD therapy. As anticipated, hyperoside reversed Aβ42-stimulated downregulation of the PI3K/Akt/Nrf2/HO-1. The PI3K inhibitor LY294002 partially abolished the protective capability of hyperoside. The results of molecular docking further indicated that the PI3K/Akt pathways may be involved in the protection of Aβ42-induced PC12 cells by hyperoside treatment. The study provides theoretical information for research and development of hyperoside as an antioxidant dietary supplement.

Therapeutic targeting of Ras/Raf/MAPK pathway by natural products: A systematic and mechanistic approach for neurodegeneration

BACKGROUND

Multiple dysregulated pathways are behind the pathogenesis of neurodegenerative diseases (NDDs); however, the crucial targets are still unknown. Oxidative stress, apoptosis, autophagy, and inflammation are the most dominant pathways that strongly influence neurodegeneration. In this way, targeting the Ras/Raf/mitogen-activated protein kinases (MAPKs) pathway appears to be a developing strategy for combating NDDs like Parkinson's disease, Alzheimer's disease, stroke, aging, and other NDDs. Accordingly, plant secondary metabolites have shown promising potentials for the simultaneous modulation of the Ras/Raf/MAPKs pathway and play an essential role in NDDs. MAPKs include p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase (JNK), which are important molecular players in neurodegeneration. Ras/Raf, which is located the upstream of MAPK pathway influences the initiation and progression of neurodegeneration and is regulated by natural products.

PURPOSE

Thus, the present study aimed to investigate the neuroprotective roles of plant- and marine-derived secondary metabolites against several NDDs through the modulation of the Ras/Raf/MAPK signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was performed to highlight the modulatory roles of natural products on the Ras/Raf/MAPK signaling pathway in NDDs, according to the PRISMA guideline, using scholarly electronic databases, including PubMed, Scopus, and Web of Sciences. Associated reference lists were also searched for the literature review.

RESULTS

From a total of 1495 results, finally 107 articles were included in the present study. The results show that several natural compounds such as alkaloid, phenolic, terpenoids, and nanoformulation were shown to have modulatory effects on the Ras/Raf/MAPKs pathway.

CONCLUSION

Natural products are promising multi-targeted agents with on NDDs through Ras/Raf/MAPKs pathway. Nevertheless, additional and complementary studies are necessary to check its efficacy and potential side effects.

Identifying the potential transcriptional regulatory network in Hirschsprung disease by integrated analysis of microarray datasets

Objective

Hirschsprung disease (HSCR) is one of the common neurocristopathies in children, which is associated with at least 20 genes and involves a complex regulatory mechanism. Transcriptional regulatory network (TRN) has been commonly reported in regulating gene expression and enteric nervous system development but remains to be investigated in HSCR. This study aimed to identify the potential TRN implicated in the pathogenesis and diagnosis of HSCR.

Methods

Based on three microarray datasets from the Gene Expression Omnibus database, the multiMiR package was used to investigate the microRNA (miRNA)-target interactions, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Then, we collected transcription factors (TFs) from the TransmiR database to construct the TF-miRNA-mRNA regulatory network and used cytoHubba to identify the key modules. Finally, the receiver operating characteristic (ROC) curve was determined and the integrated diagnostic models were established based on machine learning by the support vector machine method.

Results

We identified 58 hub differentially expressed microRNAs (DEMis) and 16 differentially expressed mRNAs (DEMs). The robust target genes of DEMis and DEMs mainly enriched in several GO/KEGG terms, including neurogenesis, cell-substrate adhesion, PI3K-Akt, Ras/mitogen-activated protein kinase and Rho/ROCK signaling. Moreover, 2 TFs (TP53 and TWIST1), 4 miRNAs (has-miR-107, has-miR-10b-5p, has-miR-659-3p, and has-miR-371a-5p), and 4 mRNAs (PIM3, CHUK, F2RL1, and CA1) were identified to construct the TF-miRNA-mRNA regulatory network. ROC analysis revealed a strong diagnostic value of the key TRN regulons (all area under the curve values were more than 0.8).

Conclusion

This study suggests a potential role of the TF-miRNA-mRNA network that can help enrich the connotation of HSCR pathogenesis and diagnosis and provide new horizons for treatment.

Polyphenols Targeting Oxidative Stress in Spinal Cord Injury: Current Status and Future Vision

A spinal cord injury (SCI) occurs when the spinal cord is deteriorated or traumatized, leading to motor and sensory functions lost even totally or partially. An imbalance within the generation of reactive oxygen species and antioxidant defense levels results in oxidative stress (OS) and neuroinflammation. After SCI, OS and occurring pathways of inflammations are significant strenuous drivers of cross-linked dysregulated pathways. It emphasizes the significance of multitarget therapy in combating SCI consequences. Polyphenols, which are secondary metabolites originating from plants, have the promise to be used as alternative therapeutic agents to treat SCI. Secondary metabolites have activity on neuroinflammatory, neuronal OS, and extrinsic axonal dysregulated pathways during the early stages of SCI. Experimental and clinical investigations have noted the possible importance of phenolic compounds as important phytochemicals in moderating upstream dysregulated OS/inflammatory signaling mediators and axonal regeneration's extrinsic pathways after the SCI probable significance of phenolic compounds as important phytochemicals in mediating upstream dysregulated OS/inflammatory signaling mediators. Furthermore, combining polyphenols could be a way to lessen the effects of SCI.

Effect of Ethyl Acetate Fraction from Eucommia ulmoides Leaves on PM2.5-Induced Inflammation and Cognitive Dysfunction

This study aimed to evaluate the protective effect of the ethyl acetate from Eucommia ulmoides leaves (EFEL) on PM2.5-induced cognitive impairment in BALB/c mice. EFEL improved PM2.5-induced cognitive decline by improving spontaneous alternative behavioral and long-term memory ability. EFEL increased ferric reducing activity power (FRAP) in serum. In addition, EFEL increased superoxide dismutase (SOD) and reduced glutathione (GSH) contents and inhibited the production of malondialdehyde (MDA) in lung and brain tissues. EFEL also restored the mitochondrial function by regulating reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) level, and ATP level in lung and brain tissues. EFEL ameliorated the cholinergic system by regulating the acetylcholine (ACh) content and acetylcholinesterase (AChE) activity in the brain tissue and the expression of AChE and choline acetyltransferase (ChAT) in the whole brain and hippocampal tissues. EFEL reduced PM2.5-induced excessive expression of inflammatory protein related to the lung, whole brain, olfactory bulb, and hippocampus. Physiological compounds of EFEL were identified as 5-O-caffeolyquinic acid, rutin, quercetin, and quercetin glycosides. As a result, EFEL has anti-inflammation and anti-amnesic effect on PM2.5-induced cognitive impairment by regulating the inflammation and inhibiting the lung and brain tissue dysfunction, and its effect is considered to be due to the physiological compounds of EFEL.

Decoding the role of inflammation-related microRNAs in cancer cachexia: a study using HPV16-transgenic mice and in silico approaches

Cachexia is associated with poor prognosis in cancer patients, and inflammation is one of its main drive factors. MicroRNAs have recently emerged as important players in cancer cachexia and are involved in reciprocal regulation networks with pro-inflammatory signaling pathways. We hypothesize that inflammation-driven cancer cachexia is regulated by specific microRNAs. The aim of this study is to explore the expression and role of inflammation-related microRNAs in muscle wasting. HPV16-transgenic mice develop systemic inflammation and muscle wasting and are a model for cancer cachexia. We employed gastrocnemius muscle samples from these mice to study the expression of microRNAs. Bioinformatic tools were then used to explore their potential role in muscle wasting. Among the microRNAs studied, miR-223-3p (p = 0.004), let-7b-5p (p = 0.034), miR-21a-5p (p = 0.034), miR-150-5p (p = 0.027), and miR-155-5p (p = 0.011) were significantly upregulated in muscles from cachectic mice. In silico analysis showed that these microRNAs participate in several processes related to muscle wasting, including muscle structure development and regulation of the MAPK pathway. When analyzing protein-protein interactions (PPI)-networks, two major clusters and the top 10 hubs were obtained. From the top 10, Kras (p = 0.050) and Ccdn1 (p = 0.009) were downregulated in cachectic muscles, as well as Map2k3 (p = 0.007). These results show that miR-223-3p, let-7b-5p, miR-21a-5p, miR-150-5p, and miR-155-5p, play a role in muscle wasting in HPV16 transgenic mice, possible through regulating the MAPK cascades. Future experimental studies are required to validate our in silico analysis, and to explore the usefulness of these microRNAs and MAPK signaling as new potential biomarkers or therapy targets for cancer cachexia.

Foliar application of flavonoids (rutin) regulates phytoremediation efficiency of Amaranthus hypochondriacus L. by altering the permeability of cell membranes and immobilizing excess Cd in the cell wall

The gap between the current serious soil heavy metal (HM) contamination and the low efficiency of soil remediation threatens human health. The aim of this study was to propose a method to improve the efficiency of phytoremediation by exogenous rutin application and explain the potential mechanism. A series of rutin treatments were designed to evaluate the biomass, cadmium (Cd) accumulation and physiological and biochemical responses of Amaranthus hypochondriacus under different Cd stresses. The results showed a decline in cell membrane damage with rutin application, and more Cd ions were immobilized in the cell wall than in the vacuole, resulting in an increase in Cd tolerance in plants. The addition of rutin caused significant effects on the synthesis of glutathione (GSH), including the advancement of the conversion of GSH to phytochelatins (PCs). Among them, PC₂ and PC₃ in the leaves contributed the most to the high accumulation of Cd. Overall, the phytoremediation efficiency and phytoextraction amount of Amaranthus hypochondriacus with rutin application were improved maximumly by 219.48% and 260.00%, respectively. This study provides a constructive approach for improving the efficiency of phytoremediation by foliar application of flavonoids and contributes to the further development of soil remediation in Cd-contaminated fields.

Effects of Polyphenols on Oxidative Stress, Inflammation, and Interconnected Pathways during Spinal Cord Injury

Despite the progression in targeting the complex pathophysiological mechanisms of neurodegenerative diseases (NDDs) and spinal cord injury (SCI), there is a lack of effective treatments. Moreover, conventional therapies suffer from associated side effects and low efficacy, raising the need for finding potential alternative therapies. In this regard, a comprehensive review was done regarding revealing the main neurological dysregulated pathways and providing alternative therapeutic agents following SCI. From the mechanistic point, oxidative stress and inflammatory pathways are major upstream orchestras of cross-linked dysregulated pathways (e.g., apoptosis, autophagy, and extrinsic mechanisms) following SCI. It urges the need for developing multitarget therapies against SCI complications. Polyphenols, as plant-derived secondary metabolites, have the potential of being introduced as alternative therapeutic agents to pave the way for treating SCI. Such secondary metabolites presented modulatory effects on neuronal oxidative stress, neuroinflammatory, and extrinsic axonal dysregulated pathways in the onset and progression of SCI. In the present review, the potential role of phenolic compounds as critical phytochemicals has also been revealed in regulating upstream dysregulated oxidative stress/inflammatory signaling mediators and extrinsic mechanisms of axonal regeneration after SCI in preclinical and clinical studies. Additionally, the coadministration of polyphenols and stem cells has shown a promising strategy for improving post-SCI complications.

Foliar spray with rutin improves cadmium remediation efficiency excellently by enhancing antioxidation and phytochelatin detoxification of Amaranthus hypochondriacus

Rutin is a flavonoid with strong antioxidative effects on plant metabolism that facilitates resistance to environmental stress. The effect of foliar rutin on cadmium (Cd) uptake in Amaranthus hypochondriacus (K472) was studied. The results showed that a foliar spray of rutin alleviated Cd toxicity, promoted plant growth, improved Cd transfer to and storage in aerial plant parts and Cd accumulation with positive effects over time. A rutin concentration of 1.5 mg/mL showed the strongest promotion effect: the biomass and Cd content were increased at 13 days by 68.62% and 405.54% compared to 3 days, respectively, whereas a high concentration of rutin (5 mg/mL) inhibited plant growth and hindered Cd absorption. Two stages of Cd detoxification were identified in K472 after appropriate rutin application. First, an antioxidant system including an enzymatic antioxidant (superoxide dismutase [SOD]) and nonenzymatic antioxidants (glutathione [GSH] and flavonoids) was activated to enhance plant stress resistance. Quercetin and phytochelatin (PC) synthesis were then enhanced to perform detoxification synergistically with the antioxidant system to improve stress tolerance and achieve stable Cd detoxification. The results demonstrated that appropriately prolonging the application time of exogenous rutin to K472 is an effective way to improve the Cd remediation efficiency.

Rutin promotes activation and reduces apoptosis of primordial follicles by regulating Akt phosphorylation after in vitro culture of ovine ovarian tissue

The aims of this study were to analyze the effects of different concentrations of rutin on primordial follicle survival and development after in vitro culture of sheep ovarian tissue, and to verify the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) pathway in the rutin actions. Ovarian fragments were fixed for histological analysis (fresh control) or cultured in α-minimum essential medium alone (α-MEM⁺: control medium) or in α-MEM⁺supplemented with different concentrations of rutin (0.1; 1 or 10 μg/mL) for 7 days. Inhibition of the PI3K activity was performed in fragments cultured with 50 μM LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3 (apoptosis) and Akt phosphorylation (p-Akt). The results showed that 1 μg/mL rutin has a greater percentage of normal follicles (P < 0.05) than those of α-MEM⁺ and other rutin treatments. In addition, 1 μg/mL rutin maintained the follicular apoptosis similar (P > 0.05) to that of the fresh control and lower than α-MEM⁺ and 10 μg/mL rutin. All rutin concentrations increased (P < 0.05) follicular activation compared to fresh control and α-MEM⁺. Furthermore, follicular and oocyte diameters increased (P < 0.05) only after culture with 1 μg/mL rutin. After PI3K inhibition, there was a reduction (P < 0.05) of rutin follicular effects. In conclusion, rutin at 1 μg/mL reduces apoptosis, promotes activation and growth of sheep primordial follicles through the modulation of the PI3K/Akt signaling pathway after in vitro culture of ovine ovarian tissue.

Antiviral Activity of Chrysin against Influenza Virus Replication via Inhibition of Autophagy

Influenza viruses cause respiratory infections in humans and animals, which have high morbidity and mortality rates. Although several drugs that inhibit viral neuraminidase are used to treat influenza infections, the emergence of resistant viruses necessitates the urgent development of new antiviral drugs. Chrysin (5,7-dihydroxyflavone) is a natural flavonoid that exhibits antiviral activity against enterovirus 71 (EV71) by inhibiting viral 3C protease activity. In this study, we evaluated the antiviral activity of chrysin against influenza A/Puerto Rico/8/34 (A/PR/8). Chrysin significantly inhibited A/PR/8-mediated cell death and the replication of A/PR/8 at concentrations up to 2 μM. Viral hemagglutinin expression was also markedly decreased by the chrysin treatment in A/PR/8-infected cells. Through the time course experiment and time-of-addition assay, we found that chrysin inhibited viral infection at the early stages of the replication cycle. Additionally, the nucleoprotein expression of A/PR/8 in A549 cells was reduced upon treatment with chrysin. Regarding the mechanism of action, we found that chrysin inhibited autophagy activation by increasing the phosphorylation of mammalian target of rapamycin (mTOR). We also confirmed a decrease in LC3B expression and LC3-positive puncta levels in A/PR/8-infected cells. These results suggest that chrysin exhibits antiviral activity by activating mTOR and inhibiting autophagy to inhibit the replication of A/PR/8 in the early stages of infection.

Protective effects of Lavandula stoechas L. methanol extract against 6-OHDA-induced apoptosis in PC12 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a neurodegenerative disorder associated with oxidative stress-induced neuronal damage and death. In European and Persian Traditional Medicine, aerial parts (leaves, stems, and flowers) of Lavandula stoechas L. have been widely used for treating neurodegenerative disorders including PD.

AIM OF THE STUDY

Herein, the protective effects of L. stoechas methanol extract were investigated on 6-hydroxydopamine (6-OHDA)-induced cytotoxicity and oxidative damage in PC12 cells.

MATERIALS AND METHODS

The cells were pretreated with a standardized L. stoechas methanol extract (2.5-20 μg/mL) for 24 h and exposed to 6-OHDA (200 μM) thereafter. The cell viability percentage was determined by AlamarBlue test. Intracellular reactive oxygen species (ROS) production was determined by a fluorimetric method using 2',7'-dichlorodihydrofluorescein diacetate and cellular apoptosis was assessed by the fluorescent probe propidium iodide test. Finally, the expression of proteins involved in apoptosis pathway (Phospho SAPK/JNK, SAPK/JNK, p44/42 MAPK (ERK1/2) and Poly ADP ribose polymerase (PARP)) was measured via Western blot analysis.

RESULTS

Treatment of PC12 cells with 6-OHDA could significantly increase cytotoxicity, ROS level, and cell apoptosis. Pretreatment of PC12 cells with the extract could significantly decrease 6-OHDA cytotoxicity, ROS production, (2.5 and 5 μg/mL) and cell apoptosis (5 μg/mL). Western blot analysis showed that 6-OHDA exposure could increase the expression of proteins involved in apoptosis signaling, while pretreatment with L. stoechas (5 μg/mL) reduced apoptotic proteins.

CONCLUSIONS

The present study demonstrated that L. stoechas, which has been traditionally used in Persian Medicine for treating CNS diseases, is a valuable source of active compounds with neuroprotective, anti-oxidant, and anti-apoptotic activity.

Rutin improves glutamate uptake and inhibits glutamate excitotoxicity in rat brain slices

Rutin is an important flavonoid consumed in the daily diet. It is also known as vitamin P and has been extensively investigated due to its pharmacological properties. On the other hand, neuronal death induced by glutamate excitotoxicity is present in several diseases including neurodegenerative diseases. The neuroprotective properties of rutin have been under investigation, although its mechanism of action is still poorly understood. We hypothesized that the mechanisms of neuroprotection of rutin are associated with the increase in glutamate metabolism in astrocytes. This study aimed to evaluate the protective effects of rutin with a focus on the modulation of glutamate detoxification. We used brain organotypic cultures from post-natal Wistar rats (P7-P9) treated with rutin to evaluate neural cell protection and levels of proteins involved in the glutamate metabolism. Moreover, we used cerebral cortex slices from adult Wistar rats to evaluate glutamate uptake. We showed that rutin inhibited the cell death and loss of glutamine synthetase (GS) induced by glutamate that was associated with an increase in glutamate-aspartate transporter (GLAST) in brain organotypic cultures from post-natal Wistar rats. Additionally, it was observed that rutin increased the glutamate uptake in cerebral cortex slices from adult Wistar rats. We conclude that rutin is a neuroprotective agent that prevents glutamate excitotoxicity and thereof suggest that this effect involves the regulation of astrocytic metabolism.

Rutin Prevents LTA Induced Oxidative Changes in H9c2 Cells

Lipoteichoic acid (LTA), a component of Gram-positive bacteria cell walls is involved in infective endocarditis (IE), a life-threatening disease. We evaluated for the first time, whether flavonoid rutin (quercetin-3-rutinoside) can block LTA-induced pro-inflammatory response and reactive oxygen species (ROS) production, and reduction of antioxidant enzymes. We found that rutin suppresses LTA effects on the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, as well as the pro-inflammatory enzyme cyclooxygenase-2, preventing phosphorylation of the mitogen-activated protein kinases (MAPKs), p38, and c-Jun N-terminal kinase, and the increase of ROS production induced by LTA. Taken together, these findings suggest that rutin prevents oxidative damage, inflammation, and MAPKs activation induced by LTA. Rutin may exert a protective effect in IE. These data provide novel insights for future use of rutin to prevent the mechanisms of LTA-related pathogenesis, inflammatory processes, and antioxidant enzyme levels in diseases such as IE.

6'"-p-Coumaroylspinosin protects PC12 neuronal cells from acrylamide-induced oxidative stress and apoptosis

6'"-p-coumaroylspinosin (P-CS) is a flavonoid isolated from Ziziphi Spinosae Semen (ZSS), whereas, the antioxidative activity has not been reported. Oxidative stress is believed to be one of the main causes of neurodegenerative disorders. In this study, the antioxidative effect of P-CS on PC12 cells was determined. The cells were treated with acrylamide (AA) in the absence or presence of P-CS, and cell apoptosis was analyzed. Interestingly, P-CS pretreatment of the cells could significantly prevent AA-induced cell death, glutathione (GSH) contents decrease, and reactive oxygen species (ROS) overproduction. Further investigation of the molecular mechanism underlying the effect of P-CS on cell apoptosis revealed that P-CS was able to suppress the expression of Bax and Bim induced by AA and inhibit the JNKs pathway. Our findings support a role of P-CS in preventing neuronal cell apoptosis induced by AA, suggesting its therapeutic potential for the treatment of neurodegenerative disorders as a medicinal supplement. PRACTICAL APPLICATIONS: Oxidative stress is believed to cause damage in subcellular organelles, nucleic acids, and alteration in protein aggregation as well as disruption of the signaling cascades associated with aging and apoptosis. A small molecule, non-poisonous natural antioxidant is needed to protect the brain from oxidative stress. Compared with western medicine, natural products carry less risk of adverse effects and are not too expensive, especially for the third-world countries. Furthermore, ZSS could be used to produce or prepare antioxidants, such as P-CS, which has been reported significant anti-oxidative activity in this study.

Rutin promotes osteogenic differentiation of periodontal ligament stem cells through the GPR30-mediated PI3K/AKT/mTOR signaling pathway

Rutin is one of the flavonoids found in fruits and vegetables. Recent reports have revealed that rutin is a major player in proliferation and bone development. However, data on how rutin regulates the proliferation of periodontal ligament stem cells (PDLSCs), as well as the differentiation of osteogenic cells are scanty. Here, our findings showed that rutin enhanced PDLSCs proliferation, increased ALP activity, and matrix mineralization. Moreover, rutin significantly promoted the expression of osteogenic genes and elevated phosphorylated AKT and mTOR. Treatment with LY294002 reversed these effects by inhibiting PI3K. We also found that the expression levels of GPR30 were increased by rutin. Interestingly, this upregulation was not altered after the addition of LY294002. In addition, G15, a selective antagonist of GPR30, could reduce the beneficial effects induced by rutin and interfere with the modulation of PI3K/AKT/mTOR signal transduction. Collectively, our findings revealed that rutin increased proliferation and osteogenic differentiation of PDLSCs through GPR30-mediated PI3K/AKT/mTOR signal transduction. Therefore, it could be deduced that rutin as a certain flavonoid possesses therapeutic value for periodontal bone regeneration and tissue engineering.

Impact statement

In our study, the effects and mechanisms of rutin on the osteogenic differentiation and proliferation of PDLSCs were investigated. Our findings might provide basic knowledge and guidance to understand and use rutin in the bioengineering of the periodontal tissues and regeneration of bones. The following is a short description of the main findings: rutin promotes the osteogenic differentiation and proliferation of PDLSCs; PI3K/AKT/mTOR signal pathway mediates the effects of rutin on PDLSCs; rutin activates PI3K/AKT/mTOR signal pathway via GPR30.

N2L, a novel lipoic acid-niacin dimer protects HT22 cells against β-amyloid peptide-induced damage through attenuating apoptosis

β-amyloid protein (Aβ) is thought to be the primary cause of the pathogenesis of Alzheimer's disease (AD). Niacin has been reported to have beneficial effects on AD. Previously, we synthesized a novel compound lipoicacid-niacin dimer (N2L) and revealed that it had potent blood-lipid regulation and antioxidative properties without aflushing effect. Given that lipid metabolism is also associated with AD, the present study aimed to investigate the neuroprotective effects of N2L on Aβ_1-42-induced cytotoxicity in HT22 cells. We found that N2L significantly attenuated cell apoptosis, MDA level, ROS content, and the mitochondrial membrane potential corruption induced by Aβ_1-42 in HT22 cells. In addition, the activities of SOD, GSH-px and CAT that were decreased by Aβ_1-42 were also restored by N2L. Furthermore, N2L reduced proapoptotic signaling by increasing the expression of anti-apoptotic Bcl-2 and decreasing the protein expression of both pro-apoptotic Bax and cleaved Caspase-3. Together, these findings indicate that N2L holds great potential for neuroprotection against Aβ_1-42-induced cytotoxicity via inhibition of oxidative stress and cell apoptosis, suggesting that N2L may be a promising agent for AD therapy.

Pristimerin attenuates cell proliferation of uveal melanoma cells by inhibiting insulin-like growth factor-1 receptor and its downstream pathways

Uveal melanoma (UM) has a high mortality rate due to liver metastasis. The insulin‐like growth factor‐1 receptor (IGF‐1R) is highly expressed in UM and has been shown to be associated with hepatic metastases. Targeting IGF signalling may be considered as a promising approach to inhibit the process of metastatic UM cells. Pristimerin (PRI) has been demonstrated to inhibit the growth of several cancer cells, but its role and underlying mechanisms in the IGF‐1‐induced UM cell proliferation are largely unknown. The present study examined the anti‐proliferative effect of PRI on UM cells and its possible role in IGF‐1R signalling transduction. MTT and clonogenic assays were used to determine the role of PRI in the proliferation of UM cells. Flow cytometry was performed to detect the effect of PRI on the cell cycle distribution of UM cells. Western blotting was carried out to assess the effects of PRI and IGF‐1 on the IGF‐1R phosphorylation and its downstream targets. The results indicated that IGF‐1 promoted the UM cell proliferation and improved the level of IGF‐1R phosphorylation, whereas PRI attenuated the effect of IGF‐1. Interestingly, PRI could not only induce the G1 phase accumulation and reduce the G2 phase induced by IGF‐1, but also could stimulate the expression of p21 and inhibit the expression of cyclin D1. Besides, PRI could attenuate the phosphorylations of Akt, mTOR and ERK1/2 induced by IGF‐1. Furthermore, the molecular docking study also demonstrated that PRI had potential inhibitory effects on IGF‐1R. Taken together, these results indicated that PRI could inhibit the proliferation of UM cells through down‐regulation of phosphorylated IGF‐1R and its downstream signalling.

Role of GS28 in sodium nitroprusside-induced cell death in cervical carcinoma cells

Golgi S-nitro-N-acetylpenicillamine receptor complex 1 (GS28) has been implicated in Golgi vesicle transport. We examined the role of GS28 and its molecular mechanisms in sodium nitroprusside (SNP)-induced cell death using GS28 siRNA (siGS28)-transfected HeLa cells. Significant inhibition of cytotoxicity was observed in the cells treated with SNP, and photodegraded SNP showed equal cytotoxicity to SNP. Pretreatment with an ERK inhibitor or siErk1 cotransfection blocked the inhibition in cytotoxicity. Additionally, increased phosphorylation of ERK was maintained in the cells treated with SNP, and Nrf2 level was dependent on ERK phosphorylation. However, pretreatment with a pan-caspase inhibitor had no effect on cytotoxicity or procaspase-3 level. Pretreatment with an autophagy inhibitor or siATG5 cotransfection blocked the inhibition of cytotoxicity. The changes of LC3 corresponded to that in siErk1-cotransfected cells. These data suggest that GS28 has an inductive role in SNP-induced cell death via inhibition of ERK, leading to inhibition of autophagic processes in HeLa cells.

Activation of anti-oxidant of curcumin pyrazole derivatives through preservation of mitochondria function and Nrf2 signaling pathway

Oxidative stress is an important cause of neurodegenerative diseases. Antioxidant is an potential important method to treat such diseases. The aim of this study is to discover new and effective antioxidants and their mechanism. The neuroprotective effect of six curcumin pyrozole compounds were first evaluated on sodium nitroprusside (SNP) - induced PC12 cell injury by testing cell viability and LDH release. The results showed that four compounds (C1-C4) have more significant protective effects compared to curcumin and edaravone. Furthermore, compounds C1-C4 can attenuate the intracellular ROS, and compound C3 is the most effective one which can preservate the mitochondria function by inhibiting the mitochondrial membrane potential loss and enhance nuclear translocation of Nrf2 in PC12 cell. These results indicated that C3 may be a potential candidate drug for treating neurodegenerative diseases.

Crocin, a natural product attenuates lipopolysaccharide-induced anxiety and depressive-like behaviors through suppressing NF-kB and NLRP3 signaling pathway

Depression is one of the foremost psychological illness which is closely leagued with inflammation. Crocin is a natural product that exhibits both anti-inflammatory and anti-oxidant activities. However, little is known about anti-inflammatory mechanisms of crocin on LPS-induced anxiety and depressive-like behaviors. The objective of this study is emphasized on neuroprotective role of crocin against LPS-induced anxiety and depressive-like behaviors in mice. It is observed that crocin inhibited LPS-induced production of NO, TNF-α, IL-1β and ROS in BV-2 microglial cells. Moreover, crocin significantly declined the expression of iNOS, NF-κB p65 and CD16/32 (M1 marker), as well as elevated the expression of CD206 (M2 marker) in BV-2 cell line with decreased LPS-induced anxiety and depressive-like behaviors by improved locomotor activity, reduced sucrose intake, and decreased immobility time in forced swim and tail suspension test in Kunming mice. Expression of NLRP3, ASC and caspase-1 by i.p administration of LPS found to be neutralized with reduction in level of IL-1β, IL-18 and TNF-α in mouse hippocampus. In conclusion, these results suggested that crocin as a potential therapeutic candidate for neuro-inflammation and depressive-like behaviors induced by LPS. The effect was found to be due to inhibition of NLRP3 inflammasome and NF-κB and its promoted M1 to M2 phenotypic conversion of microglia.

Protective effect of rutin against brain injury induced by acrylamide or gamma radiation: role of PI3K/AKT/GSK-3β/NRF-2 signalling pathway

This study was designed to evaluate the effect of rutin on PI3K/AKT-signalling in case of acrylamide or γ-radiation-induced neurotoxicity. To induce brain damage, animals were received acrylamide (25 mg/kg b.wt./orally/day) or 5 Gy of γ-radiation exposure accompanied with an administration of rutin (200 mg/kg b.wt./orally/day). Our data revealed that, compared to acrylamide or γ-radiation, rutin activated PI3K/AKT/GSK-3β/NRF-2-pathway through increased protein levels of p-PI3K, p-AKT and p-GSK-3β and up-regulated the expression of NRF-2. This was achieved by modulating MDA, GST, IL-1β, IL-6 and reduced the interference of ROS with IGF-1 and NGF stimulating the PI3K/AKT-signaling. Furthermore, histopathological examinations of brain tissues showed that rutin has modulated tissue architecture after acrylamide or γ-radiation induced tissue damage. It could be concluded that rutin provides protection effect against acrylamide or γ-radiation-induced neurotoxicity via activation of the PI3K/AKT/GSK-3β/NRF-2-pathway by altering the phosphorylation state through its ability to scavenge free radicals generation, modulating gene expression and its anti-inflammatory effects.

Extract of Spatholobus suberctus Dunn ameliorates ischemia-induced injury by targeting miR-494

Cerebral stroke is a leading cause of death and permanent disability. The current therapeutic outcome of ischemic stroke (>85% of all strokes) is very poor, thus novel therapeutic drug is urgently needed. In vitro cell model of ischemia was established by oxygen-glucose deprivation (OGD) and in vivo animal model of ischemia was established by middle cerebral artery occlusion (MCAO). The effects of Spatholobus suberctus Dunn extract (SSCE) on OGD-induced cell injury, MCAO-induced neural injury and miR-494 level were all evaluated. The possible target genes were virtually screened utilizing bioinformatics and verified by luciferase assay. Subsequently, the effects of abnormally expressed miR-494 on OGD-induced cell injury and target gene expression were determined. Additionally, whether SSCE affected target gene expression through modulation of miR-494 was studied. Finally, the effects of aberrantly expressed Sox8 on OGD-induced injury and signaling pathways were estimated. SSCE reduced OGD-induced cell injury and ameliorated MCAO-induced neuronal injury, along with down-regulation of miR-494. Then, OGD-induced cell injury was increased by miR-494 overexpression but decreased by miR-494 silence. Sox8 was a target gene of miR-494, and SSCE could up-regulate Sox8 expression via down-regulating miR-494. Afterwards, OGD-induced cell injury was proved to be increased by Sox8 inhibition but reduced by Sox8 overexpression. Finally, OGD-induced inhibition of PI3K/AKT/mTOR and MAPK pathways was further inhibited by Sox8 silence but activated by Sox8 overexpression. SSCE ameliorates ischemia-induced injury both in vitro and in vivo by miR-494-mediated modulation of Sox8, involving activations of PI3K/AKT/mTOR and MAPK pathways.

Protective effects of flavonoids against Alzheimer's disease-related neural dysfunctions

Senile ages of human life is mostly associated with developmental of several neurological complicated conditions including decreased cognition and reasoning, increased memory loss and impaired language performance. Alzheimer's disease (AD) is the most prevalent neural disorder associated with dementia, consisting of about 70% of dementia reported cases. Failure of currently approved chemical anti-AD therapeutic agents has once again brought up the idea of administering naturally occurring compounds as effective alternative and/or complementary regimens in AD treatment. Polyphenol structured neuroprotecting agents are group of biologically active compounds abundantly found in plants with significant protecting effects against neural injuries and degeneration. As a subclass of this family, Flavonoids are potent anti-oxidant, anti-inflammatory and signalling pathways modulatory agents. Phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen activated protein kinase (MAPK) pathways are both affected by Flavonoids. Regulation of pro-survival transcription factors and induction of specific genes expression in hippocampus are other important anti AD therapeutic activities of Flavonoids. These agents are also capable of inhibiting specific enzymes involved in phosphorylation of tau proteins including β-secretases, cyclin dependent kinase 5 and glycogen synthase. Other significant anti AD effects of Flavonoids include neural rehabilitation and lost cognitive performance recovery. In this review, first we briefly describe the pathophysiology and important pathways involved in pathology of AD and then describe the most important mechanisms through which Flavonoids demonstrate their significant neuroprotective effects in AD therapy.

Amentoflavone protects dopaminergic neurons in MPTP-induced Parkinson's disease model mice through PI3K/Akt and ERK signaling pathways

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc). Mitochondrial dysfunction and cell apoptosis are suggested to be actively involved in the pathogenesis of PD. In the present study, the neuroprotective effect of amentoflavone (AF), a naturally occurring biflavonoid from Selaginella tamariscina, was examined in PD models both in vitro and in vivo. On SH-SY5Y cells, AF treatment dose-dependently reduced 1-methyl-4-phenylpyridinium (MPP⁺)-induced nuclear condensation and loss of cell viability without obvious cytotoxicity. It inhibited the activation of caspase-3 and p21 but increased the Bcl-2/Bax ratio. Further study disclosed that AF enhanced the phosphorylation of PI3K, Akt and ERK1/2 down-regulated by MPP⁺ in SH-SY5Y cells, the effect of which could be blocked by LY294002, the inhibitor of PI3K. Consistently, AF alleviated the behavioral deterioration in pole and traction tests and rescued the loss of dopaminergic neurons in SNpc and fibers in striatum in methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mice. It also could enhance the activation of PI3K and Akt as well as Bcl-2/Bax ratio in SN. Moreover, AF alleviated gliosis as well as the gene expression levels of IL-1β and iNOS in SN. Collectively, these results suggested that AF protected dopaminergic neurons against MPTP/MPP⁺-induced neurotoxicity, which might be mediated through activation of PI3K/Akt and ERK signaling pathways in dopaminergic neurons and attenuation of neuroinflammation.

L-F001, a Multifunction ROCK Inhibitor Prevents 6-OHDA Induced Cell Death Through Activating Akt/GSK-3beta and Nrf2/HO-1 Signaling Pathway in PC12 Cells and Attenuates MPTP-Induced Dopamine Neuron Toxicity in Mice

Amounting evidences demonstrated that Rho/Rho-associated kinase (ROCK) might be a novel target for the therapy of Parkinson's disease (PD). Recently, we synthesized L-F001 and revealed it was a potent ROCK inhibitor with multifunctional effects. Here we investigated the effects of L-F001 in PD models. We found that L-F001 potently attenuated 6-OHDA-induced cytotoxicity in PC12 cells and significantly decreased intracellular reactive oxygen species (ROS), prevented the 6-OHDA-induced decline of mitochondrial membrane potential and intracellular GSH levels. In addition, L-F001 increased Akt and GSK-3beta phosphorylation and induced the nuclear Nrf2 and HO-1 expression in a time- and concentration-dependent manner. Moreover, L-F001 restored the levels of p-Akt and p-GSK-3beta (Ser9) as well as HO-1 expression reduced by 6-OHDA. Those effects were blocked by the specific PI3K inhibitor, LY294002, indicating the involvement of Akt/GSK-3beta pathway in the neuroprotective effect of L-F001. In addition, L-F001 significantly attenuated the tyrosinehydroxylase immunoreactive cell loss in 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP)-induced mice PD model. Together, our findings suggest that L-F001 prevents 6-OHDA-induced cell death through activating Akt/GSK-3beta and Nrf2/HO-1 signaling pathway and attenuates MPTP-induced dopaminergic neuron toxicity in mice. L-F001 might be a promising drug candidate for PD.

Artemisinin conferred ERK mediated neuroprotection to PC12 cells and cortical neurons exposed to sodium nitroprusside-induced oxidative insult

The production of nitric oxide (NO) is one of the primary mediators of ischemic damage, glutamate neurotoxicity and neurodegeneration and therefore inhibition of NO-induced neurotoxicity may be considered a therapeutic target for reducing neuronal cell death (neuroprotection). In this study, artemisinin, a well-known anti-malaria drug was found to suppress sodium nitroprusside (SNP, a nitric oxide donor)-induced cell death in the PC12 cells and brain primary cortical neuronal cultures. Pretreatment of PC12 cells with artemisinin significantly suppressed SNP-induced cell death by decreasing the extent of oxidation, preventing the decline of mitochondrial membrane potential, restoring abnormal changes in nuclear morphology and reducing lactate dehydrogenase release and inhibiting caspase 3/7 activities. Western blotting analysis revealed that artemisinin was able to activate extracellular regulated protein kinases (ERK) pathway. Furthermore, the ERK inhibitor PD98059 blocked the neuroprotective effect of artemisinin whereas the PI3K inhibitor LY294002 had no effect. Cumulatively these findings support the notion that artemisinin confers neuroprotection from SNP-induce neuronal cell death insult, a phenomenon coincidentally related to activation of ERK phosphorylation. This SNP-induced oxidative insult in PC12 cell culture model may be useful to investigate molecular mechanisms of NO-induced neurotoxicity and drug-induced neuroprotection, and to generate novel therapeutic concepts for ischemic disease treatment.

Impact of Plant-Derived Flavonoids on Neurodegenerative Diseases

Neurodegenerative disorders have a common characteristic that is the involvement of different cell types, typically the reactivity of astrocytes and microglia, characterizing gliosis, which in turn contributes to the neuronal dysfunction and or death. Flavonoids are secondary metabolites of plant origin widely investigated at present and represent one of the most important and diversified among natural products phenolic groups. Several biological activities are attributed to this class of polyphenols, such as antitumor activity, antioxidant, antiviral, and anti-inflammatory, among others, which give significant pharmacological importance. Our group have observed that flavonoids derived from Brazilian plants Dimorphandra mollis Bent., Croton betulaster Müll. Arg., e Poincianella pyramidalis Tul., botanical synonymous Caesalpinia pyramidalis Tul. also elicit a broad spectrum of responses in astrocytes and neurons in culture as activation of astrocytes and microglia, astrocyte associated protection of neuronal progenitor cells, neuronal differentiation and neuritogenesis. It was observed the flavonoids also induced neuronal differentiation of mouse embryonic stem cells and human pluripotent stem cells. Moreover, with the objective of seeking preclinical pharmacological evidence of these molecules, in order to assess its future use in the treatment of neurodegenerative disorders, we have evaluated the effects of flavonoids in preclinical in vitro models of neuroinflammation associated with Parkinson's disease and glutamate toxicity associated with ischemia. In particular, our efforts have been directed to identify mechanisms involved in the changes in viability, morphology, and glial cell function induced by flavonoids in cultures of glial cells and neuronal cells alone or in interactions and clarify the relation with their neuroprotective and morphogetic effects.