Antioxidant and pro-angiogenic effects of corilagin in rat cerebral ischemia via Nrf2 activation

Corilagin Alleviates Ang II-Induced Cardiac Fibrosis by Regulating the PTEN/AKT/mTOR Pathway

This research aimed to evaluate the therapeutic effect of corilagin (Cor) against angiotensin II (Ang II)-induced cardiac fibrosis and its underlying mechanisms. C57BL/6 mice (male, 8-10 weeks) received saline or Ang II (2.0 mg/kg/day) via subcutaneous infusion and intraperitoneal injection of Cor (30 mg/kg) for 28 days. Ang II induction increased the fibrotic area, whereas Cor treatment inhibited the fibrotic area significantly. Cor markedly reduced the Ang II-induced cardiac fibroblasts. Cor significantly inhibited Ang II-induced increase in expressions of smooth muscle alpha-actin (α-SMA), collagen I, collagen III, transforming growth factor beta 1 (TGF-β1), fibronectin, and connective tissue growth factor (CTGF). Cor suppressed the intracellular reactive oxygen species (ROS) production. Cor therapy reduced Ang II-induced malondialdehyde (MDA) content, whereas superoxide dismutase (SOD) and catalase (CAT) activities were increased (all, P < .001). Moreover, Ang II induction elevated the expression of phosphorylated phosphatase and tensin homolog (p-PTEN), phosphorylated protein kinase B (p-AKT) (Ser473) and phosphorylated mammalian target of rapamycin (p-mTOR) (Ser 2448), whereas Cor reduced their expressions. Cor treatment inhibited the migration ability of the cardiac fibroblast, whereas a PTEN inhibitor, VO-ohpic, increased the migration capability. Cor could have a protective effect against Ang II-induced cardiac fibrosis via inhibition of the PTEN/AKT/mTOR pathway.

UHPLC-ESI-QTOF-MS metabolite profiles of different extracts from Pelargonium endlicherianum parts and their biological properties based on network pharmacological approaches

In the present study, we aimed to investigate the chemical profiles and biological activities of different extracts (ethyl acetate, dichloromethane, ethanol, and water) of Pelargonium endlicherianum parts (aerial parts and roots). Free radical scavenging, reducing power, phosphomolybdenum, and metal chelating were assayed for antioxidant properties. To detect enzyme inhibitory properties, cholinesterase, amylase, glucosidase, and tyrosinase were chosen as target enzymes. The ethanol extract of the aerial parts contained higher amounts of total bioactive compounds (120.53 mg GAE/g-24.46 mg RE/g). The ethanol and water extracts of these parts were tentatively characterized by UHPLC-ESI-QTOF-MS and 95 compounds were annotated. In addition, the highest acetylcholiesterase (3.74 mg GALAE/g) and butyrylcholinesterase (3.92 mg GALAE/g) abilities were observed by the ethanol extract of roots. The water extract from aerial parts exhibited the most pronounced inhibitory effects on multiple cancer cell lines, especially A549 (IC50: 23.2 µg/mL) and HT-29 (IC50: 27.43 µg/mL) cells. Using network pharmacology, P. endlicherianum compounds were studied against cancer, revealing well-connected targets such as epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase (PI3K), AKT, receptor tyrosine-protein kinase erbB-2, and growth factor receptor bound protein 2 (GRB2) with significant impact on cancer-related pathways. The results could open a new path from natural treasure to functional applications with P. endlicherianum and highlight a new study on other uninvestigated Pelargonium species.

Integrated network pharmacology, molecular docking and pharmacodynamic study reveals protective effects and mechanisms of corilagin against cerebral ischemia-induced injury

BACKGROUND

Stroke is one of the leading causes of death and long-term disability worldwide. Previous studies have found that corilagin has antioxidant, anti-inflammatory, anti-atherosclerotic and other pharmacological activities and has a protective effect against cardiac and cerebrovascular injury.

OBJECTIVES

The aim of this study was to investigate the protective effects of corilagin against ischemic stroke and to elucidate the underlying molecular mechanisms using network pharmacology, molecular docking, and animal and cell experiments.

METHODS

We investigated the potential of corilagin to ameliorate cerebral ischemia-reperfusion injury using in vivo rat middle cerebral artery occlusion/reperfusion (MCAO/R) and in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) models.

RESULTS

Our results suggest that corilagin may exert its anti-ischemic stroke effect by interacting with 92 key targets, including apoptosis-associated proteins (Bcl-2, Bax, caspase-3) and PI3K/Akt signaling pathway-related proteins. In vivo and in vitro experiments showed that corilagin treatment improved neurological deficits, attenuated cerebral infarct volume, and mitigated neuronal damage in MCAO/R rats. Corilagin treatment also enhanced the survival of PC12 cells exposed to OGD/R, reduced the rate of LDH leakage, inhibited cell apoptosis, and activated the PI3K/Akt signaling pathway. Importantly, the effects of corilagin on the PI3K/Akt signaling pathway and apoptosis-associated proteins were reversed by the PI3K-specific inhibitor LY294002.

CONCLUSIONS

These results indicate that the molecular mechanism of the anti-ischemic effect of corilagin involves inhibiting neuronal apoptosis and activating the PI3K/Akt signaling pathway. These findings provide a theoretical and experimental basis for the further development and application of corilagin as a potential anti-ischemic stroke agent.

Dietary Polyphenols: Review on Chemistry/Sources, Bioavailability/Metabolism, Antioxidant Effects, and Their Role in Disease Management

Polyphenols, as secondary metabolites ubiquitous in plant sources, have emerged as pivotal bioactive compounds with far-reaching implications for human health. Plant polyphenols exhibit direct or indirect associations with biomolecules capable of modulating diverse physiological pathways. Due to their inherent abundance and structural diversity, polyphenols have garnered substantial attention from both the scientific and clinical communities. The review begins by providing an in-depth analysis of the chemical intricacies of polyphenols, shedding light on their structural diversity and the implications of such diversity on their biological activities. Subsequently, an exploration of the dietary origins of polyphenols elucidates the natural plant-based sources that contribute to their global availability. The discussion extends to the bioavailability and metabolism of polyphenols within the human body, unraveling the complex journey from ingestion to systemic effects. A central focus of the review is dedicated to unravelling the antioxidant effects of polyphenols, highlighting their role in combating oxidative stress and associated health conditions. The comprehensive analysis encompasses their impact on diverse health concerns such as hypertension, allergies, aging, and chronic diseases like heart stroke and diabetes. Insights into the global beneficial effects of polyphenols further underscore their potential as preventive and therapeutic agents. This review article critically examines the multifaceted aspects of dietary polyphenols, encompassing their chemistry, dietary origins, bioavailability/metabolism dynamics, and profound antioxidant effects. The synthesis of information presented herein aims to provide a valuable resource for researchers, clinicians, and health enthusiasts, fostering a deeper understanding of the intricate relationship between polyphenols and human health.

The cell-specific roles of Nrf2 in acute and chronic phases of ischemic stroke

Ischemic stroke refers to the sudden loss of blood flow in a specific area of the brain. It is the fifth leading cause of mortality and the leading cause of permanent disability. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) controls the production of several antioxidants and protective proteins and it has been investigated as a possible pharmaceutical target for reducing harmful oxidative events in brain ischemia. Each cell type exhibits different roles and behaviors in different phases post-stroke, which is comprehensive yet important to understand to optimize management strategies and goals for care for stroke patients. In this review, we comprehensively summarize the protective effects of Nrf2 in experimental ischemic stroke, emphasizing the role of Nrf2 in different cell types including neurons, astrocytes, oligodendrocytes, microglia, and endothelial cells during acute and chronic phases of stroke and providing insights on the neuroprotective role of Nrf2 on each cell type throughout the long term of stroke care. We also highlight the importance of targeting Nrf2 in clinical settings while considering a variety of important factors such as age, drug dosage, delivery route, and time of administration.

Role of NADPH Oxidase-Derived ROS-Mediated IL-6/STAT3 and MAPK/NF-κB Signaling Pathways in Protective Effect of Corilagin against Acetaminophen-Induced Liver Injury in Mice

Acetaminophen (APAP) overdose causes acute liver injury via oxidative stress, uncontrolled inflammatory response, and subsequent hepatocyte death. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a potent source of cellular reactive oxygen species (ROS) and may contribute to oxidative stress in many inflammatory processes. Corilagin, a component of Phyllanthus urinaria, possesses antioxidant, anti-inflammatory, and hepatoprotective effects. We evaluated the mechanisms underlying the protective effect of corilagin against acetaminophen-induced liver injury. Mice were intraperitoneally administrated 300 mg/kg APAP or equal volume of saline (control), with or without various concentrations of corilagin (0, 1, 5, or 10 mg/kg) administered after 30 min. All animals were sacrificed 16 h after APAP administration, and serum and liver tissue assays including histology, immunohistochemistry, and Western blot assay were performed. Corilagin post-treatment significantly attenuated APAP-induced liver injury (p < 0.005), inflammatory cell infiltration, hepatic proinflammatory cytokine levels, and hepatic oxidative stress. Furthermore, corilagin attenuated the protein levels of NOX1, NOX2, signal transducer and activator of transcription 3 (STAT3), and nuclear factor kappa B (NF-κB) in APAP-induced liver injury. These results indicated that the antioxidant, anti-inflammatory, and protective effects of corilagin in APAP-induced liver injury might involve the regulation of interleukin (IL)-6/STAT3 and mitogen-activated protein kinase (MAPK)/NF-κB signaling pathways through NOX-derived ROS.

Integrating network pharmacology and pharmacological evaluation to explore the protective mechanism of Ershiwuwei Zhenzhu pill in ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ershiwuwei Zhenzhu Pill (EZP), a representative and classic formula in Tibetan medicine, is commonly used in the treatment of various cerebrovascular diseases, including ischemic stroke (IS). Nevertheless, their efficacy and potential mechanism in treating IS have yet to be investigated.

AIM OF THE STUDY

This study aimed to investigate the potential mechanisms of EZP in the treatment of IS based on network pharmacology and experimental verification.

MATERIALS AND METHODS

The chemical profile of EZP was characterized using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The targets related to the compounds in EZP were predicted by the Swiss Target Prediction and Target Net platform, and targets of IS were collected from the Gene Cards and OMIM databases. Subsequently, a protein-protein interaction (PPI) network of targets was constructed and analyzed by the STRING database and Cytoscape software, version 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed, and an ingredient-target-pathway network was constructed. Ultimately, the middle cerebral artery occlusion (MCAO) model was established to evaluate the anti-IS effects of EZP by detecting the neurological deficit score, HE, Nissl and TCC staining, and inflammatory factors, and the expression of key protein targets was detected by western blotting.

RESULTS

A total of 129 components were identified in EZP. Network pharmacology revealed 3136 compound targets and 2826 disease-related targets, and 412 overlapping proteins were obtained as potential therapeutic targets. The PPI network results showed that 6 key targets (AKT1, SRC, VEGFA, TP53, TNF and EGFR) were core targets of EZP in the treatment of IS. Western blotting demonstrated that the expression levels of AKT1, VEGFA, TP53, SRC, TNF and EGFR in the brain tissue of MCAO rats were significantly changed after treatment with EZP compared to the model group.

CONCLUSIONS

EZP ameliorated IS in MCAO rats. The underlying mechanism might be associated with inhibiting inflammation and apoptosis, promoting angiogenesis and protecting neurons by regulating multiple targets and pathways.

Corilagin alleviates intestinal ischemia/reperfusion injury by relieving oxidative stress and apoptosis via AMPK/Sirt1-autophagy pathway

Intestinal ischemia/reperfusion (II/R) injury is a common pathological process with high clinical morbidity and mortality. Autophagy plays an important role in the pathological development of II/R. Corilagin (CA) is a natural ellagitannin with various pharmacological effects such as autophagy regulation, antioxidant, and antiapoptosis. However, whether CA alleviates II/R injury is still unclear. In this study, we had found that CA significantly attenuated II/R induced intestinal tissue pathological damage, oxidative stress, and cell apoptosis in rats. Further studies showed that CA significantly promoted AMPK phosphorylation and sirt1 expression, and thus activated autophagy by upregulating protein expression of autophagy-related proteins Beclin1 and LC3II and promoting SQSTM1/P62 degradation both in vivo and in vitro. Inhibition of AMPK phosphorylation by its inhibitor compound C(CC) significantly abolished CA-mediated autophagy activation and the relievable effects on oxidative stress and apoptosis in vitro, suggesting the excellent protective activity of CA against II/R injury via AMPK/Sirt1-autophagy pathway. These findings confirmed the potent effects of CA against II/R injury, and provided novel insights into the mechanisms of the compound as a potential candidate for the treatment of II/R.

Corilagin alleviates intestinal ischemia/reperfusion-induced intestinal and lung injury in mice via inhibiting NLRP3 inflammasome activation and pyroptosis

Intestinal ischemia reperfusion (II/R) is a clinical emergency that frequently occurs in a variety of clinical conditions. Severe intestinal injury results in the release of cytotoxic substances and inflammatory mediators which can activate local inflammatory response and bacterial translocation. This triggers multi-organ failure, including lung injury, which is a common complication of II/R injury and contributes to the high mortality rate. Corilagin (Cor) is a natural ellagitannin found in a variety of plants. It has many biological and pharmacological properties, including antioxidant, anti-inflammatory and anti-apoptosis activities. However, no studies have evaluated the effects and molecular mechanisms of Cor in alleviating II/R-induced intestinal and lung damage. In this study, Cor was found to significantly alleviate II/R-induced pathological damage, inflammatory response, oxidative stress, NLRP3 inflammasome activation, and pyroptosis in intestinal and lung tissues both in vivo and in vitro. Further, Cor inhibited the NLRP3 inflammasome activation and pyroptosis in RAW264.7 and MLE-12 cells induced by LPS/nigericin and that in IEC-6 cells induced by nigericin, indicating an amelioration of Cor in II/R-induced intestinal and lung injury via inhibiting NLRP3 inflammasome activation and pyroptosis. Thus, Cor might be a potential therapeutic agent for II/R-induced inflammation and tissue injury.

A Glossary for Chemical Approaches towards Unlocking the Trove of Metabolic Treasures in Actinomycetes

Actinobacterial natural products showed a critical basis for the discovery of new antibiotics as well as other lead secondary metabolites. Varied environmental and physiological signals touch the antibiotic machinery that faced a serious decline in the last decades. The reason was exposed by genomic sequencing data, which revealed that Actinomycetes harbor a large portion of silent biosynthetic gene clusters in their genomes that encrypt for secondary metabolites. These gene clusters are linked with a great reservoir of yet unknown molecules, and arranging them is considered a major challenge for biotechnology approaches. In the present paper, we discuss the recent strategies that have been taken to augment the yield of secondary metabolites via awakening these cryptic genes in Actinomycetes with emphasis on chemical signaling molecules used to induce the antibiotics biosynthesis. The rationale, types, applications and mechanisms are discussed in detail, to reveal the productive path for the unearthing of new metabolites, covering the literature until the end of 2020.

Redox-Modulating Capacity and Antineoplastic Activity of Wastewater Obtained from the Distillation of the Essential Oils of Four Bulgarian Oil-Bearing Roses

The wastewater from the distillation of rose oils is discharged directly into the soil because it has a limited potential for future applications. The aim of the present study was to determine in vitro the chromatographic profile, redox-modulating capacity, and antineoplastic activity of wastewater obtained by distillation of essential oils from the Bulgarian Rosa alba L., Rosa damascena Mill., Rosa gallica L., and Rosa centifolia L. We applied UHPLC-HRMS for chromatographic analysis of rose wastewaters, studied their metal-chelating and Fe(III)-reducing ability, and performed MTT assay for the evaluation of cytotoxic potential against three tumorigenic (HEPG2-hepatocellular adenocarcinoma, A-375-malignant melanoma, A-431-non-melanoma epidermoid squamous skin carcinoma) and one non-tumorigenic human cell lines (HaCaT-immortalized keratinocytes). The median inhibitory concentrations (IC₅₀) were calculated with nonlinear modeling using the MAPLE^® platform. The potential of the wastewaters to induce apoptosis was also examined. Mono-, di-, and acylated glycosides of quercetin and kaempferol, ellagic acid and its derivatives as main chemical components, and gallic acid and its derivatives-such as catechin and epicatechin-were identified. The redox-modulating capacity of the samples (TPTZ test) showed that all four wastewaters exhibited the properties of excellent heavy metal cleaners, but did not exert very strong cytotoxic effects. The lowest IC₅₀ rate was provided in wastewater from R. centifolia (34-35 µg/mL of gallic acid equivalents after a 72 h period for all cell lines). At 24 and 48 hours, the most resistant cell line was HEPG2, followed by HaCaT. After 72 h of exposure, the IC₅₀ values were similar for tumor and normal cells. Still, R. damascena had a selectivity index over 2.0 regarding A-431 non-melanoma skin cancer cells, showing a good toxicological safety profile in addition to moderate activity-IC₅₀ of 35 µg/mL polyphenols. The obtained results related to wastewaters acquired after the distillation of essential oils from the Bulgarian R. alba, R. damascena, R. gallica, and R. centifolia direct our attention to further studies for in-depth elucidation of their application as detoxifying agents under oxidative damage conditions in other experimental datasets.

Corilagin induces apoptosis and autophagy in NRF2‑addicted U251 glioma cell line

Corilagin, extracted from the Euphorbiaceae and Phyllanthus plants, inhibits the growth of a number of types of tumors. Compared with temozolomide, the traditional chemotherapy drug, corilagin has demonstrated stronger antitumor activity. However, the pharmaceutical mechanism of corilagin in glioma remains unclear. Nuclear factor erythroid 2 like 2 (NFE2L2 or NRF2) is positively associated with several types of tumor including glioma. In the present study, NRF2 expression was higher in glioma tissues compared with non-glioma specimens. Therefore, it was hypothesized that corilagin targets NRF2 regulation of U251 cell apoptosis. The present study used Hoechst 33258 staining to demonstrate that corilagin induced glioma cell apoptosis and observed that the expression of the apoptosis-related gene Bcl-2 was reduced. In addition, corilagin induced autophagy and promoted the conversion of light chain 3 (LC3) protein from LC3I to LC3II. NRF2 expression was downregulated by corilagin stimulation. Furthermore, the gene expression pattern following knockdown of NRF2 in U251 cells using siRNA was consistent with corilagin stimulation. Therefore, it was preliminarily concluded that corilagin induces apoptosis and autophagy by reducing NRF2 expression.

Punicalin Alleviates OGD/R-Triggered Cell Injury via TGF-β-Mediated Oxidative Stress and Cell Cycle in Neuroblastoma Cells SH-SY5Y

Purpose

The research aimed to identify the active component from Punica granatum L. to alleviate ischemia/reperfusion injury and clarify the underlying mechanism of the active component alleviating ischemia/reperfusion injury.

Materials and Methods

The SH-SY5Y cell model of oxygen-glucose deprivation/reoxygenation (OGD/R) was established to simulate the ischemia/reperfusion injury. According to the strategy of bioassay-guided isolation, the active component of punicalin from Punica granatum L. was identified. Flow cytometry and Western blotting were employed to evaluate the effects of OGD/R and/or punicalin on cell cycle arrest. Immunofluorescence assay was applied to assess the nucleus translocation. The relative content of ROS and GSH and the enzyme activities of CAT and SOD were examined using ELISA.

Results

The data of bioassay-guided isolation showed that punicalin from Punica granatum L. could alleviate OGD/R-induced cell injury in SH-SY5Y cells. Flow cytometry analysis and Western blotting for probing the expression of CDK1, p-CDK1, cyclin B1, and p21 revealed that punicalin could relieve OGD/R-induced cell cycle G0/G1 arrest. Additionally, immunofluorescence assay and Western blotting for probing the expression of TGF-β and p-Smad2/p-Smad3 showed that punicalin could relieve the OGD/R-induced TGF-β/Smad pathway. Furthermore, the TGF-β/Smad pathway inhibitor of LY2157299 was employed to confirm that the TGF-β/Smad pathway is crucial to the effect of punicalin. At last, it was indicated that punicalin could relieve OGD/R-induced oxidative stress.

Conclusion

Punicalin, an active component from Punica granatum L., was identified as a protective agent to alleviate the OGD/R-induced cell injury, which could exert the protective effect via TGF-β/Smad pathway-regulated oxidative stress and cell cycle arrest in SH-SY5Y cells.

Protective effects of natural compounds against oxidative stress in ischemic diseases and cancers via activating the Nrf2 signaling pathway: A mini review

Oxidative stress, an imbalance between reactive oxygen species and antioxidants, has been seen in the pathological states of many disorders such as ischemic diseases and cancers. Many natural compounds (NCs) have long been recognized to ameliorate oxidative stress due to their inherent antioxidant activities. The modulation of oxidative stress by NCs via activating the Nrf2 signaling pathway is summarized in the review. Three NCs, ursolic acid, betulinic acid, and curcumin, and the mechanisms of their cytoprotective effects are investigated in myocardial ischemia, cerebral ischemia, skin cancer, and prostate cancer. To promote the therapeutic performance of NCs with poor water solubility, the formulation approach, such as the nano drug delivery system, is elaborated as well in this review.

Corilagin reduces acetaminophen-induced hepatotoxicity through MAPK and NF-κB signaling pathway in a mouse model

Corilagin is a major active polyphenolic tannins extracted from Phyllanthus urinaria, an important herb used in traditional medicine. Previous reports demonstrated that corilagin possesses antioxidant and anti-inflammatory properties. Therefore, this study aimed to evaluate its hepatoprotective effects and mechanisms on acetaminophen (APAP)-induced liver injury in mice. Mice included in this study were intraperitoneally injected with a hepatotoxic APAP dose (300 mg/kg). After a 30 min of APAP administration, corilagin was injected intraperitoneally at concentrations of 0, 1, 5, 10, and 20 mg/kg. Then, after 16 h of corilagin treatment, mice were sacrificed for further analysis. APAP overdose significantly elevated the serum ALT level, hepatic myeloperoxidase (MPO) activity, cytokines (TNF-α, IL-1β, and IL-6) production, malondialdehyde (MDA) activity, and ERK/JNK MAPK and NF-κB protein expressions. Corilagin treatment significantly decreased these parameters in a dose-dependent manner (1-20 mg/kg). This study demonstrated that corilagin may be a potential therapeutic target for the prevention of APAP-induced hepatotoxicity by down-regulating the inflammatory response and by inhibiting ERK/JNK MAPK and NF-κB signaling pathways.

Corilagin suppresses RANKL-induced osteoclastogenesis and inhibits oestrogen deficiency-induced bone loss via the NF-κB and PI3K/AKT signalling pathways

Over‐activated osteoclastogenesis, which is initiated by inflammation, has been implicated in osteoporosis. Corilagin, a natural compound extracted from various medicinal herbaceous plants, such as Cinnamomum cassia, has antioxidant and anti‐inflammatory activities. We found that Corilagin suppressed osteoclast differentiation in a dose‐dependent manner, significantly decreased osteoclast‐related gene expression and impaired bone resorption by osteoclasts. Moreover, phosphorylation of members of the nuclear factor‐kappaB (NF‐κB) and PI3K/AKT signalling pathways was reduced by Corilagin. In a murine model of osteoporosis, Corilagin inhibited osteoclast functions in vivo and restored oestrogen deficiency‐induced bone loss. In conclusion, our findings suggested that Corilagin inhibited osteoclastogenesis by down‐regulating the NF‐κB and PI3K/AKT signalling pathways, thus showing its potential possibility for the treatment of osteoporosis.

Activation of Nrf2 by Natural Bioactive Compounds: A Promising Approach for Stroke?

Stroke represents one of the main causes of disability and death worldwide. The pathological subtypes of stroke are ischemic stroke, the most frequent, and hemorrhagic stroke. Nrf2 is a transcription factor that regulates redox homeostasis. In stress conditions, Nrf2 translocates inside the nucleus and induces the transcription of enzymes involved in counteracting oxidative stress, endobiotic and xenobiotic metabolism, regulators of inflammation, and others. Different natural compounds, including food and plant-derived components, were shown to be able to activate Nrf2, mediating an antioxidant response. Some of these compounds were tested in stroke experimental models showing several beneficial actions. In this review, we focused on the studies that evidenced the positive effects of natural bioactive compounds in stroke experimental models through the activation of Nrf2 pathway. Interestingly, different natural compounds can activate Nrf2 through multiple pathways, inducing a strong antioxidant response associated with the beneficial effects against stroke. According to several studies, the combination of different bioactive compounds can lead to a better neuroprotection. In conclusion, natural bioactive compounds may represent new therapeutic strategies against stroke.

Sestrin2 promotes angiogenesis to alleviate brain injury by activating Nrf2 through regulating the interaction between p62 and Keap1 following photothrombotic stroke in rats

AIMS

The lack of effective treatments for ischemic stroke is concerning. Here, we aimed to examine the protective effects of sestrin2 in ischemic stroke and determine the mechanism by which sestrin2 attenuates cerebral injuries.

MAIN METHODS

Ischemic stroke was induced in Sprague-Dawley rats using a photothrombotic ischemia (PTI) model. After sestrin2 was overexpressed or silenced, neurological deficits and brain infarction were evaluated. Cerebral angiogenesis and the expression of related proteins were examined by Western blotting and immunofluorescence. The interaction between p62 and Keap1 was measured by coimmunoprecipitation (CoIP) and an in situ proximity ligation assay (PLA).

KEY FINDINGS

The overexpression of sestrin2 was found to improve the neurological function of rats 10 days after PTI and to reduce the infarct volume and brain edema in rats 10 days after PTI. It was shown that upregulating sestrin2 enhanced the relative immunofluorescence intensity of CD34, CD31 and DCX. Sestrin2 overexpressionalso increased the number and total length of CD34 and CD31 positive vessels and the expression of nuclear and total Nrf2, HO-1, VEGF and p62. However, downregulating sestrin2 induced almost the opposite results. Furthermore, we demonstrated that sestrin2 increased the interaction between p62 and Keap1.

SIGNIFICANCE

Based on our data, sestrin2 may promote angiogenesis by activating the Nrf2 pathway through increasing the interaction between p62 and Keap1 via upregulating p62 expression.

NRF2 as a Therapeutic Target in Neurodegenerative Diseases

Increased reactive oxygen species production and oxidative stress have been implicated in the pathogenesis of numerous neurodegenerative conditions including among others Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Friedrich’s ataxia, multiple sclerosis, and stroke. The endogenous antioxidant response pathway protects cells from oxidative stress by increasing the expression of cytoprotective enzymes and is regulated by the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2). In addition to regulating the expression of antioxidant genes, NRF2 has also been shown to exert anti-inflammatory effects and modulate both mitochondrial function and biogenesis. This is because mitochondrial dysfunction and neuroinflammation are features of many neurodegenerative diseases as well NRF2 has emerged as a promising therapeutic target. Here, we review evidence for a beneficial role of NRF2 in neurodegenerative conditions and the potential of specific NRF2 activators as therapeutic agents.

Protective effects of leonurine against ischemic stroke in mice by activating nuclear factor erythroid 2-related factor 2 pathway

Aims

Leonurine has been shown to trigger antioxidant responses during ischemic stroke, and nuclear factor erythroid 2‐related factor 2 (Nrf‐2) imparts protective effects against oxidative injury. The present study has determined that leonurine prevents ischemic injury of brain tissues via Nrf‐2 pathway activation.

Methods

Male ICR mice and Nrf‐2^−/− mice were subjected to permanent middle cerebral artery occlusion (pMCAO) and received leonurine treatment at 2 hours after pMCAO by intraperitoneal injection. Neurological deficit scores as well as infarct volume were assessed to determine the neuroprotective role of leonurine. Nrf‐2 was investigated using Western blotting and real‐time polymerase chain reaction (RT‐PCR) analysis to elucidate the neuroprotective mechanism of leonurine. Commercial kits were employed to determine reactive oxygen species (ROS), superoxide (SOD), catalase (CAT), glutathione peroxidase (GSH‐Px), malonaldehyde (MDA), and glutathione (GSH). Vascular endothelial growth factor (VEGF) was evaluated by Western blotting and RT‐PCR analysis, and VEGF was localized using immunofluorescence.

Results

The application of leonurine on ICR mice resulted in an improvement in neurological deficit scores and a reduction in infarct volume. Leonurine upregulated nuclear Nrf‐2 protein and increased total Nrf‐2 protein expression and mRNA levels. Leonurine regulated SOD, MDA, CAT, GSH, and GSH‐Px, and it significantly inhibited ROS production in ICR mice. Leonurine improved VEGF expression and increased VEGF expression in neurons, astrocytes, and endothelial cells. However, leonurine had no obvious beneficial effects on Nrf‐2^−/− mice.

Conclusions

Leonurine exerted neuroprotective effects, promoted antioxidant responses, and upregulated VEGF expression by activating the Nrf‐2 pathway.

Aspirin eugenol ester attenuates oxidative injury of vascular endothelial cells by regulating NOS and Nrf2 signalling pathways

BACKGROUND AND PURPOSE

Aspirin eugenol ester (AEE) is a new drug compound synthesized by combining aspirin with eugenol. It was reported to possess anti-thrombotic, anti-atherosclerotic, and anti-oxidative effects. However, its molecular mechanism against oxidative injury is unclear. This study investigated how AEE affected the oxidative injury of vascular endothelial cells in vivo and in vitro.

EXPERIMENTAL APPROACH

A hamster model of atherosclerosis induced by a high fat diet (HFD) and an in vitro model of oxidative stress, H₂ O₂ -induced apoptosis of HUVECs, were used to investigate the anti-oxidative effects of AEE.

KEY RESULTS

AEE significantly reduced the stimulatory effect of HFD on malondialdehyde, the inhibitory effect of HFD on SOD activity and GSH/GSSG ratio, and the overexpression of inducible NOS (iNOS) in the aorta. In vitro, incubation of HUVECs with H₂ O₂ led their apoptosis, dysfunctions of the NO systems (including increased iNOS activity, decreased endothelial NOS activity, and increased production of NO), an imbalance in calcium homeostasis and energy metabolism with an increase in intracellular free calcium and decrease in ATP, and a down-regulation of Nrf2. In contrast, in the HUVECs pretreated with 1 μM AEE for 24 hr, the above adverse effects induced by H₂ O₂ were significantly ameliorated. Moreover, the decrease in NO production and activity of iNOS induced by AEE was significantly attenuated in Nrf2-inhibited HUVECs.

CONCLUSION AND IMPLICATION

AEE protects vascular endothelial cells from oxidative injury by regulating NOS and Nrf2 signalling pathways. This suggests that AEE is a novel potential agent for the prevention of atherosclerosis.

Critical Role of Nrf2 in Experimental Ischemic Stroke

Ischemic stroke is one of the leading causes of death and long-term disability worldwide; however, effective clinical approaches are still limited. The transcriptional factor Nrf2 is a master regulator in cellular and organismal defense against endogenous and exogenous stressors by coordinating basal and stress-inducible activation of multiple cytoprotective genes. The Nrf2 network not only tightly controls redox homeostasis but also regulates multiple intermediary metabolic processes. Therefore, targeting Nrf2 has emerged as an attractive therapeutic strategy for the prevention and treatment of CNS diseases including stroke. Here, the current understanding of the Nrf2 regulatory network is critically examined to present evidence for the contribution of Nrf2 pathway in rodent ischemic stroke models. This review outlines the literature for Nrf2 studies in preclinical stroke and focuses on the in vivo evidence for the role of Nrf2 in primary and secondary brain injuries. The dynamic change and functional importance of Nrf2 signaling, as well as Nrf2 targeted intervention, are revealed in permanent, transient, and global cerebral ischemia models. In addition, key considerations, pitfalls, and future potentials for Nrf2 studies in preclinical stroke investigation are discussed.

Nrf2/ARE Pathway Modulation by Dietary Energy Regulation in Neurological Disorders

Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of an array of enzymes with important detoxifying and antioxidant functions. Current findings support the role of high levels of oxidative stress in the pathogenesis of neurological disorders. Given the central role played by Nrf2 in counteracting oxidative damage, a number of studies have targeted the modulation of this transcription factor in order to confer neuroprotection. Nrf2 activity is tightly regulated by oxidative stress and energy-based stimuli. Thus, many dietary interventions based on energy intake regulation, such as dietary energy restriction (DER) or high-fat diet (HFD), modulate Nrf2 with consequences for a variety of cellular processes that affect brain health. DER, by either restricting calorie intake or meal frequency, activates Nrf2 thereby triggering its protective effects, whilst HFD inhibit this pathway, thereby exacerbating oxidative stress. Consequently, DER protocols can be valuable strategies in the management of central nervous system (CNS) disorders. Herein, we review current knowledge of the role of Nrf2 signaling in neurological diseases, namely Alzheimer’s disease, Parkinson’s disease, multiple sclerosis and cerebral ischemia, as well as the potential of energy intake regulation in the management of Nrf2 signaling.

MicroRNA-150 contributes to ischemic stroke through its effect on cerebral cortical neuron survival and function by inhibiting ERK1/2 axis via Mal

Ischemic stroke, caused by the blockage of blood supply, is a major cause of death worldwide. For identifying potential candidates, we explored the effects microRNA-150 (miR-150) has on ischemic stroke and its underlying mechanism by developing a stable middle cerebral artery occlusion (MCAO) rat model. Gene expression microarray analysis was performed to screen differentially expressed genes associated with MCAO. We evaluated the expression of miR-150 and Mal and the status of ERK1/2 axis in the brain tissues of MCAO rats. Then the cerebral cortical neurons (CCNs) were obtained and introduced with elevated or suppressed miR-150 or silenced Mal to validate regulatory mechanisms for miR-150 governing Mal in vitro. The relationship between miR-150 and Mal was verified by dual luciferase reporter gene assay. Besides, cell growth and apoptosis of CCNs were detected by means of MTT assay and flow cytometry analyses. We identified Mal as a downregulated gene in MCAO, based on the microarray data of GSE16561. MiR-150 was over-expressed and negatively targeted Mal in the brain tissues obtained from MCAO rats and their CCNs. Increasing miR-150 blocked the ERK1/2 axis, resulting in an inhibited cell growth of CNNs but an enhanced apoptosis. Furthermore, MiR-150 inhibition was observed to have effects on CNNs as opposed to those inhibited by miR-150 promotion. The key findings of this study support the notion that miR-150 under-expression-mediated direct promotion of Mal protects CNN functions through the activation of the ERK1/2 axis, and underscore the concept that miR-150 may represent a novel pharmacological target for ischemic stroke intervention.

Ultra Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry-Based Metabonomics Reveal Protective Effect of Terminalia chebula Extract on Ischemic Stroke Rats

Terminalia chebula (TC), a kind of Combretaceae, is a widely used herb in India and East Asia to treat cerebrovascular diseases. However, the potential mechanism of the neuroprotective effects of TC at the metabonomics level is still not clear. The present study focused on the effects of TC on metabonomics in a stroke model. Rats were divided randomly into sham, model, and TC groups. Rats in the TC group were intragastrically administered with TC for 7 days after a middle cerebral artery occlusion (MCAO) operation. The sham and the model groups received vehicle for the same length of time. Subsequently, the neuroprotective effects of TC were examined by evaluation of neurological defects, assessment of infarct volume, and identification of biochemical indicators for antioxidant and anti-inflammatory activities. Further, metabonomics technology was employed to evaluate the endogenous metabolites profiling systematically. Consist with the results of biochemical and histopathological assays, pattern recognition analysis showed a clear separation of the model group and the sham group, indicating the recovery impact of TC on the MCAO rats. Moreover, 12 potential biomarkers were identified in the MCAO model group, involving energy (lactic acid, succinic acid, and fumarate), amino acids (leucine, alanine, and phenylalanine), and glycerophospholipid (PC [16:0/20:4], PC [20:4/20:4], LysoPC [18:0], and LysoPC [16:0]) metabolism, as well as other types of metabolism (arachidonic acid and palmitoylcarnitine). Notably, it was found that metabolite levels of TC group were partially reversed to normal. In conclusion, TC could ameliorate MCAO in rats by affecting energy metabolism (glycolysis and the TCA cycle), amino acid metabolism, glycerophospholipid metabolism, and other types of metabolism.