Icariin attenuates cerebral ischemia-reperfusion injury through inhibition of inflammatory response mediated by NF-κB, PPARα and PPARγ in rats

Flavonoids serve as a promising therapeutic agent for ischemic stroke

Ischemic stroke (IS) continues to be a major public health concern and is characterized by significantly high mortality and disabling rates. Inhibiting nerve cells death and enhancing the repair of ischemic tissue are important treatment concepts for IS. Currently, the mainstream treatment strategies mainly focus on short-term care, which underscores the urgent need for novel therapeutic strategies for long-term care. Emerging data reveal that flavonoids have surfaced as promising candidates for IS patients' long-term care. Flavonoids can alleviate neuroinflammation and anti-apoptosis due to their characteristic pharmacological mechanisms. Clinical evidence suggests that long-term flavonoids intake improves IS patients' long-term outcomes. Though the effect of flavonoids in IS treatment has been explored for decades, the neuroprotective pharmacodynamics have not been well established. Thereby, the aim of current review is to summarize the pathways involved in neuroprotective effect of flavonoids. This review will also advance the potential of flavonoids as a viable clinical candidate for the treatment of IS.

Research progress on quercetin in improving the survival rate of random skin flap

Random skin flap transplantation is critical in wound repair, organ reconstruction and cosmetic surgery, yet skin flap necrosis remains a common and challenging issue. Quercetin, a flavonoid abundant in various plants, exhibits anti-inflammatory, antioxidant, and other beneficial pharmacological effects. Recent studies suggest quercetin can improve random skin flap survival by modulating inflammation, reducing oxidative stress, and promoting angiogenesis. This review evaluates quercetin's potential mechanisms and efficacy, proposing a foundation for its clinical use in preventing ischemic necrosis and enhancing flap viability.

Evaluating the antifibrotic potential of naringenin, asiatic acid, and icariin using murine and human precision-cut liver slices

Liver fibrosis is an exaggerated wound healing response defined by the excessive accumulation of extracellular matrix. This study investigated the antifibrotic potential of naringenin (NRG), asiatic acid (AA), and icariin (ICA) using murine and human precision-cut liver slices (PCLS). These natural products have shown promise in animal models, but human data are lacking. In this study, PCLS prepared from male mouse liver tissue (mPCLS), healthy human liver tissue (hhPCLS), and cirrhotic human liver tissue (chPCLS) were cultured for 48 h with varying concentrations of the three compounds. Our findings indicate that NRG reduced collagen type 1 (COL1A1) expression in a concentration-dependent manner in both mPCLS and chPCLS, decreased fibrosis-related gene expression, and significantly lowered pro-collagen type 1 (PCOL1A1) levels in the culture medium by 54 ± 21% (mPCLS) and 78 ± 35% (chPCLS). Furthermore, NRG effectively inhibited IL-1β and TNF-α in mPCLS and IL-1β in chPCLS on both gene and protein levels. AA specifically reduced COL1A1 and PCOL1A1 in chPCLS, while ICA selectively downregulated Col1a1 and Acta2 gene expression in mPCLS. This study suggests NRG's potential as an effective antifibrotic agent, warranting further investigation into its mechanisms and therapeutic applications in liver fibrosis.

The positive role of transforming growth factor-β1 in ischemic stroke

Ischemic stroke is one of the most disabling and fatal diseases around the world. The damaged brain tissues will undergo excessive autophagy, vascular endothelial cells injury, blood-brain barrier (BBB) impairment and neuroinflammation after ischemic stroke. However, there is no unified viewpoint on the underlying mechanism of brain damage. Transforming growth factor-β1 (TGF-β1), as a multi-functional cytokine, plays a crucial role in the intricate pathological processes and helps maintain the physiological homeostasis of brain tissues through various signaling pathways after ischemic stroke. In this review, we summarize the protective role of TGF-β1 in autophagic flux, BBB, vascular remodeling, neuroinflammation and other aspects after ischemic stroke. Based on the review, we believe that TGF-β1 could serve as a key target for treating ischemic stroke.

Icariin alleviates oxygen-induced retinopathy by targeting microglia hexokinase 2

Retinopathy of prematurity (ROP) is a retinal disease-causing retinal neovascularization that can lead to blindness. Oxygen-induced retinopathy (OIR) is a widely used ROP animal model. Icariin (ICA) has anti-oxidative and anti-inflammation properties; however, whether ICA has a regulatory effect on OIR remains unclear. In this study, ICA alleviated pathological neovascularization, microglial activation and blood-retina barrier (BRB) damage in vivo. Further results indicated that endothelial cell tube formation, migration and proliferation were restored by ICA treatment in vitro. Proteomic microarrays and molecular mimicry revealed that ICA can directly bind to hexokinase 2 (HK2) and decrease HK2 protein expression in vivo and in vitro. In addition, ICA inhibited the AKT/mTOR/HIF1α pathway activation. The effects of ICA on pathological neovascularization, microglial activation and BRB damage disappeared after HK2 overexpression in vivo. Similarly, the endothelial cell function was revised after HK2 overexpression. HK2 overexpression reversed ICA-induced AKT/mTOR/HIF1α pathway inhibition in vivo and in vitro. Therefore, ICA prevented pathological angiogenesis in OIR in an HK2-dependent manner, implicating ICA as a potential therapeutic agent for ROP.

Investigating the anti-inflammatory effects of icariin: A combined meta-analysis and machine learning study

Objective

The objectives of this study were to define the superiority of icariin and its derivatives' anti-inflammatory activities and to create a reference framework for evaluating preclinical evidence. This method combines machine learning and meta-analysis to identify underlying biological pathways.

Methods

Data came from PubMed, Embase, Web of Science, and the Cochrane Library. SYRCLE was used to evaluate the risk of bias in a subset of research. Meta-analysis and detailed subgroup analyses, categorized by species, genders, disease type, dosage, and treatment duration, were performed using R and STATA 15.0 software to derive nuanced insights. Employing R software (version 4.2.3) and the tidymodels package, the analysis focused on constructing a model and selecting features, with TNF-α as the dependent variable. This approach aims to identify significant predictors of drug efficacy. An in-depth literature facilitated the synthesis of anti-inflammatory mechanisms attributed to icariin and its constituent compounds.

Results

Following a meticulous search and selection process, 19 studies, involving 370 and 260 animals were included in the meta-analysis and machine-learning assessment, respectively. The findings revealed that icariin and its derivatives markedly reduced inflammation markers, including TNF-α and IL-1β. Additionally, machine-learning outcomes, with TNF-α as the target variable, indicated enhanced anti-inflammatory effects of icariin across respiratory, urological, neurological, and digestive disease types. These effects were more pronounced at doses exceeding 27.52 mg/kg/day and treatment durations beyond 31.22 days.

Conclusion

Strong anti-inflammatory effects are exhibited by icariiin and its derivatives, which are especially beneficial in the management of digestive, neurological, pulmonary, and urinary conditions. Effective for periods longer than 31.22 days and at dosages more than 27.52 mg/kg/day. Subsequent research will involve more targeted animal experiments and safety assessments to obtain more comprehensive preclinical evidence.

Natural herbal extract roles and mechanisms in treating cerebral ischemia: A systematic review

Background

Stroke has been the focus of medical research due to its serious consequences and sequelae. Among the tens of millions of new stroke patients every year, cerebral ischemia patients account for the vast majority. While cerebral ischemia drug research and development is still ongoing, most drugs are terminated at preclinical stages due to their unacceptable toxic side effects. In recent years, natural herbs have received considerable attention in the pharmaceutical research and development field due to their low toxicity levels. Numerous studies have shown that natural herbs exert actions that cannot be ignored when treating cerebral ischemia.

Methods

We reviewed and summarized the therapeutic effects and mechanisms of different natural herbal extracts on cerebral ischemia to promote their application in this field. We used keywords such as "natural herbal extract," "herbal medicine," "Chinese herbal medicine" and "cerebral ischemia" to comprehensively search PubMed, ScienceDirect, ScienceNet, CNKI, and Wanfang databases, after which we conducted a detailed screening and review strategy.

Results

We included 120 high-quality studies up to 10 January 2024. Natural herbal extracts had significant roles in cerebral ischemia treatments via several molecular mechanisms, such as improving regional blood flow disorders, protecting the blood-brain barrier, and inhibiting neuronal apoptosis, oxidative stress and inflammatory responses.

Conclusion

Natural herbal extracts are represented by low toxicity and high curative effects, and will become indispensable therapeutic options in the cerebral ischemia treatment field.

4'-O-methylbavachalcone alleviates ischemic stroke injury by inhibiting parthanatos and promoting SIRT3

Cerebral ischemia-reperfusion injury (CIRI) can induce massive death of ischemic penumbra neurons via oxygen burst, exacerbating brain damage. Parthanatos is a form of caspase-independent cell death involving excessive activation of PARP-1, closely associated with intense oxidative stress following CIRI. 4'-O-methylbavachalcone (MeBavaC), an isoprenylated chalcone component in Fructus Psoraleae, has potential neuroprotective effects. This study primarily investigates whether MeBavaC can act on SIRT3 to alleviate parthanatos of ischemic penumbra neurons induced by CIRI. MeBavaC was oral gavaged to the middle cerebral artery occlusion-reperfusion (MCAO/R) rats after occlusion. The effects of MeBavaC on cerebral injury were detected by the neurological deficit score and cerebral infarct volume. In vitro, PC-12 cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R), and assessed cell viability and cell injury. Also, the levels of ROS, mitochondrial membrane potential (MMP), and intracellular Ca2+ levels were detected to reflect mitochondrial function. We conducted western blotting analyses of proteins involved in parthanatos and related signaling pathways. Finally, the exact mechanism between the neuroprotection of MeBavaC and parthanatos was explored. Our results indicate that MeBavaC reduces the cerebral infarct volume and neurological deficit scores in MCAO/R rats, and inhibits the decreased viability of PC-12 cells induced by OGD/R. MeBavaC also downregulates the expression of parthanatos-related death proteins PARP-1, PAR, and AIF. However, this inhibitory effect is weakened after the use of a SIRT3 inhibitor. In conclusion, the protective effect of MeBavaC against CIRI may be achieved by inhibiting parthanatos of ischemic penumbra neurons through the SIRT3-PARP-1 axis.

Icariin alleviates renal inflammation and tubulointerstitial fibrosis via Nrf2-mediated attenuation of mitochondrial damage

Tubulointerstitial fibrosis is an inevitable consequence of all progressive chronic kidney disease (CKD) and contributes to a substantial health burden worldwide. Icariin, an active flavonoid glycoside obtained from Epimedium species, exerts potential antifibrotic effect. The study aimed to explore the protective effects of icariin against tubulointerstitial fibrosis in unilateral ureteral obstruction (UUO)-induced CKD mice and TGF-β1-treated HK-2 cells, and furthermore, to elucidate the underlying mechanisms. The results demonstrated that icariin significantly improved renal function, alleviated tubular injuries, and reduced fibrotic lesions in UUO mice. Furthermore, icariin suppressed renal inflammation, reduced oxidative stress as evidenced by elevated superoxide dismutase activity and decreased malondialdehyde level. Additionally, TOMM20 immunofluorescence staining and transmission electron microscope revealed that mitochondrial mass and morphology of tubular epithelial cells in UUO mice was restored by icariin. In HK-2 cells treated with TGF-β1, icariin markedly decreased profibrotic proteins expression, inhibited inflammatory factors, and protected mitochondria along with preserving mitochondrial morphology, reducing reactive oxygen species (ROS) and mitochondrial ROS (mtROS) overproduction, and preserving membrane potential. Further investigations demonstrated that icariin could activate nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway both in vivo and in vitro, whereas inhibition of Nrf2 by ML385 counteracted the protective effects of icariin on TGF-β1-induced HK-2 cells. In conclusion, icariin protects against renal inflammation and tubulointerstitial fibrosis at least partly through Nrf2-mediated attenuation of mitochondrial dysfunction, which suggests that icariin could be developed as a promising therapeutic candidate for the treatment of CKD.

RAGE acted as a new anti-inflammatory target for Icariin's treatment against vascular dementia based on network pharmacology-directed verification

Vascular dementia (VaD) ranks as the second most prevalent form of dementia and poses a considerable global health challenge. Icariin has been recognized for its robust neuroprotective effects in combating VaD. Nonetheless, the underlying mechanisms have not been fully elucidated. An integrated approach involving network pharmacology, molecular docking, and molecular dynamics simulations (MDS) was employed to systematically investigate the potential pharmacological actions of Icariin in counteracting VaD. The AGE/RAGE pathway was identified as a promising anti-inflammatory pathway. A chronic cerebral hypoperfusion mouse model was utilized to establish VaD. Both Icariin and FP S-ZM1 (a RAGE inhibitor) were administered through oral gavage and intraperitoneal injection, respectively. The Morris water maze (MWZ) was used to evaluate cognitive functions. Moreover, immunofluorescence, RT-qP CR, and Western blot analyses were carried out to evaluate the effects of FP S-ZM1 on neuroinflammation. Network analysis identified 14 crucial targets and highlighted the AGE-RAGE signaling cascade in diabetic complications as the foremost KEGG pathway with potential anti-neuroinflammatory property. MDS results suggested a stable binding of the RAGE-Icariin complex. Remarkably, Icariin was found to effectively mitigate cognitive deficits in VaD mice, which was correlated with the upregulation of the P I3K/AKT pathway and downregulation of the JNK/cJUN signaling cascade. Critically, co-administration of FP S-ZM1 enhanced Icariin's ameliorative effects on cognitive deficits, owing to bolstered anti-neuroinflammatory action. This study unveils the potential of Icariin in alleviating cognitive dysfunction and neuroinflammation in VaD, which may be attributed to the modulation of the AGE/RAGE pathway.Communicated by Ramaswamy H. Sarma.

Regulatory mechanisms of natural compounds from traditional Chinese herbal medicines on the microglial response in ischemic stroke

BACKGROUND

Development of clinically effective neuroprotective agents for stroke therapy is still a challenging task. Microglia play a critical role in brain injury and recovery after ischemic stroke. Traditional Chinese herbal medicines (TCHMs) are based on a unique therapeutic principle, have various formulas, and have long been widely used to treat stroke. Therefore, the active compounds in TCHMs and their underlying mechanisms of action are attracting increasing attention in the field of stroke drug development.

PURPOSE

To summarize the regulatory mechanisms of TCHM-derived natural compounds on the microglial response in animal models of ischemic stroke.

METHODS

We searched studies published until 10 April 2023 in the Web of Science, PubMed, and ScienceDirect using the following keywords: natural compounds, natural products or phytochemicals, traditional Chinese Medicine or Chinese herbal medicine, microglia, and ischemic stroke. This review was prepared according to PRISMA (Preferred Reporting Item for Systematic Reviews and Meta-Analysis) guidelines.

RESULTS

Natural compounds derived from TCHMs can attenuate the M1 phenotype of microglia, which is involved in the detrimental inflammatory response, via inhibition of NF-κB, MAPKs, JAK/STAT, Notch, TLR4, P2X7R, CX3CR1, IL-17RA, the NLRP3 inflammasome, and pro-oxidant enzymes. Additionally, the neuroprotective response of microglia with the M2 phenotype can be enhanced by activating Nrf2/HO-1, PI3K/AKT, AMPK, PPARγ, SIRT1, CB2R, TREM2, nAChR, and IL-33/ST2. Several clinical trials showed that TCHM-derived natural compounds that regulate microglial responses have significant and safe therapeutic effects, but further well-designed clinical studies are needed.

CONCLUSIONS

Further research regarding the direct targets and potential pleiotropic or synergistic effects of natural compounds would provide a more reasonable approach for regulation of the microglial response with the possibility of successful stroke drug development.

Up-regulation of PPAR-γ involved in the therapeutic effect of icariin on cigarette smoke-induced inflammation

Icariin (ICA) might be a potential anti-inflammatory medication in a variety of diseases including COPD, and previous studies showed that ICA could attenuate cigarette smoke (CS)-induced inflammation by inhibiting nuclear factor (NF)-κB. Peroxisome proliferator-activated receptor (PPAR) γ, a nuclear hormone receptor, has been reported to play a critical role in the inflammatory process in COPD. Whether PPAR-γ is involved in the anti-inflammatory effect of icariin on COPD has scarcely been explored. This study aimed at investigating the role of ICA in PPAR-γ expression in the CS-induced model, and then elucidating the therapeutic effects of ICA on COPD based on the PPARγ-NF-κB signaling pathway. The Beas-2B cells and H292 cells were induced with cigarette smoke extract (CSE) for 8 h after treatment with ICA for 16 h. The PPARγ expression and NF-κB pathway-related indicators were detected by western blotting, cellular immunofluorescence, and Real-time PCR. The PPARγ knock down or T0070907-treated Beas-2B cells were constructed to further investigate the relationship between the inhibition of NF-κB by ICA and PPARγ. A COPD model was established by CS exposure for 6 months, and ICA (40 mg/kg) was administrated by gastric perfusion. Then, the pulmonary function, lung histology, inflammatory cytokine levels, and protein expressions were detected. We found ICA up-regulated PPARγ protein expression in both Beas-2B cells and H292 cells, and it improved CSE-induced PPARγ down regulation and NF-κB activation. Furthermore, the inhibition of NF-κB pathway by ICA was partially dependent on PPARγ in the PPARγ knock down or T0070907-treated Beas-2B cells, suggesting that ICA attenuated CSE-induced inflammatory responses were associated with modulating the PPARγ-NF-κB pathway. Moreover, ICA showed similar effects on PPARγ and NF-κB expressions in the COPD model, and it effectively ameliorated the pulmonary function and lung inflammatory infiltration in the COPD rat model. Conclusively, the therapeutic effect of ICA on COPD was indirectly achieved by reducing airway inflammation, which was partially associated with modulating the PPARγ-NF-κB signaling pathway.

Regulatory mechanism of icariin in cardiovascular and neurological diseases

Cardiovascular diseases (CVDs) and neurological diseases are widespread diseases with substantial rates of morbidity and mortality around the world. For the past few years, the preventive effects of Chinese herbal medicine on CVDs and neurological diseases have attracted a great deal of attention. Icariin (ICA), the main constituent of Epimedii Herba, is a flavonoid. It has been shown to provide neuroprotection, anti-tumor, anti-osteoporosis, and cardiovascular protection. The endothelial protection, anti-inflammatory, hypolipidemic, antioxidative stress, and anti-apoptosis properties of ICA can help stop the progression of CVDs and neurological diseases. Therefore, our review summarized the known mechanisms and related studies of ICA in the prevention and treatment of cardio-cerebrovascular diseases (CCVDs), to better understand its therapeutic potential.

Therapeutic Effect of Icaritin on Cerebral Ischemia-Reperfusion-Induced Senescence and Apoptosis in an Acute Ischemic Stroke Mouse Model

An ischemic stroke is brain damage caused by interruption of blood supply to the brain that can cause death and long-term disability. New medical strategies or therapies are urgently needed for ischemic stroke. Icaritin (ICT) is a metabolite of icariin (ICA), which are two active flavonoid components extracted from Herba epimedii and considered neuroprotective agents in animal models of Alzheimer’s disease and ischemic stroke. The therapeutic effect of ICT on ischemic still remains to be clarified. The aim of this study was to investigate the therapeutic effect of ICT on cerebral ischemia-reperfusion-associated senescence and apoptosis in a middle cerebral artery occlusion (MCAO) mouse model (ischemia for 50 min and reperfusion for 24 h). Administration of ICT after ischemia significantly reduced MCAO-induced neurological damage, infarct volume, and histopathological changes in the brain of acute ischemic stroke mice. ICT treatment could also reduce neuronal apoptosis and senescence and reversed the expression of apoptosis- and senescence-related signaling proteins. These findings suggest that ICT may have therapeutic potential to ameliorate acute ischemic stroke.

Potential effects of icariin, the Epimedium-derived bioactive compound in the treatment of COVID-19: a hypothesis

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected the world's health systems for more than two years. This disease causes a high mortality rate followed by cytokine storm-induced oxidative stress and acute respiratory distress syndrome (ARDS). Therefore, many drugs have been considered with emphasis on their anti-inflammatory and antioxidant effects in controlling the consequences of SARS-CoV-2 infection. Icariin is a major bioactive pharmaceutical compound derived from Epimedium plants, which is known due to its anti-inflammatory and antioxidant effects. Additionally, the protective effects of icariin have been studied in different pathologies through modulating intracellular pathways. In addition to the potential effect of this compound on inflammation and oxidative stress caused by SARS-CoV-2 infection, it appears to interfere with intracellular pathways involved in viral entry into the cell. Therefore, this paper aims to review the molecular mechanisms of anti-inflammatory and antioxidant properties of icariin, and hypothesizes its potential to inhibit SARS-CoV-2 entry into host cells through modulating the intracellular pathways.

Anti-inflammatory and immunoregulatory effects of icariin and icaritin

Inflammation and immunity dysregulation have received widespread attention in recent years due to their occurrence in the pathophysiology of many conditions. In this regard, several pharmacological studies have been conducted aiming to evaluate the potential anti-inflammatory and immunomodulatory effects of phytochemicals. Epimedium, a traditional Chinese medicine, is often used as a tonic, aphrodisiac, and anti-rheumatic agent. Icariin (ICA) is the main active ingredient of Epimedium and is, once ingested, mainly metabolized into Icaritin (ICT). Data from in vitro and in vivo studies suggested that ICA and its metabolite (ICT) regulated the functions and activation of immune cells, modulated the release of inflammatory factors, and restored aberrant signaling pathways. ICA and ICT were also involved in anti-inflammatory and immune responses in several diseases, including multiple sclerosis, asthma, atherosclerosis, lupus nephritis, inflammatory bowel diseases, rheumatoid arthritis, and cancer. Yet, data showed that ICA and ICT exhibited similar but not identical pharmacokinetic properties. Therefore, based on their higher solubility and bioavailability, as well as trends indicating that single-ingredient compounds offer broader and safer therapeutic capabilities, ICA and ICT delivery systems and treatment represent interesting avenues with promising clinical applications. In this study, we reviewed the anti-inflammatory and immunomodulatory mechanisms, as well as the pharmacokinetic properties of ICA and its metabolite ICT.

Anti-Inflammatory Effects of Natural Products on Cerebral Ischemia

Cerebral ischemia with high mortality and morbidity still requires the effectiveness of medical treatments. A growing number of investigations have shown strong links between inflammation and cerebral ischemia. Natural medicine’s treatment methods of cerebral ischemic illness have amassed a wealth of treatment experience and theoretical knowledge. This review summarized recent progress on the disease inflammatory pathways as well as 26 representative natural products that have been routinely utilized to treat cerebral ischemic injury. These natural products have exerted anti-inflammatory effects in cerebral ischemia based on their inflammatory mechanisms, including their inflammatory gene expression patterns and their related different cell types, and the roles of inflammatory mediators in ischemic injury. Overall, the combination of the potential therapeutic interventions of natural products with the inflammatory mechanisms will make them be applicable for cerebral ischemic patients in the future.

The Signaling Pathways and Targets of Natural Compounds from Traditional Chinese Medicine in Treating Ischemic Stroke

Ischemic stroke (IS) is a common neurological disorder associated with high disability rates and mortality rates. At present, recombinant tissue plasminogen activator (r-tPA) is the only US(FDA)-approved drug for IS. However, due to the narrow therapeutic window and risk of intracerebral hemorrhage, r-tPA is currently used in less than 5% of stroke patients. Natural compounds have been widely used in the treatment of IS in China and have a wide range of therapeutic effects on IS by regulating multiple targets and signaling pathways. The keywords "ischemia stroke, traditional Chinese Medicine, Chinese herbal medicine, natural compounds" were used to search the relevant literature in PubMed and other databases over the past five years. The results showed that JAK/STAT, NF-κB, MAPK, Notch, Nrf2, and PI3K/Akt are the key pathways, and SIRT1, MMP9, TLR4, HIF-α are the key targets for the natural compounds from traditional Chinese medicine in treating IS. This study aims to update and summarize the signaling pathways and targets of natural compounds in the treatment of IS, and provide a base of information for the future development of effective treatments for IS.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

Role of Phytoconstituents as PPAR Agonists: Implications for Neurodegenerative Disorders

Peroxisome proliferator-activated receptors (PPAR-γ, PPAR-α, and PPAR-β/δ) are ligand-dependent nuclear receptors that play a critical role in the regulation of hundreds of genes through their activation. Their expression and targeted activation play an important role in the treatment of a variety of diseases, including neurodegenerative, cardiovascular, diabetes, and cancer. In recent years, several reviews have been published describing the therapeutic potential of PPAR agonists (natural or synthetic) in the disorders listed above; however, no comprehensive report defining the role of naturally derived phytoconstituents as PPAR agonists targeting neurodegenerative diseases has been published. This review will focus on the role of phytoconstituents as PPAR agonists and the relevant preclinical studies and mechanistic insights into their neuroprotective effects. Exemplary research includes flavonoids, fatty acids, cannabinoids, curcumin, genistein, capsaicin, and piperine, all of which have been shown to be PPAR agonists either directly or indirectly. Additionally, a few studies have demonstrated the use of clinical samples in in vitro investigations. The role of the fruit fly Drosophila melanogaster as a potential model for studying neurodegenerative diseases has also been highlighted.

Icariin inhibits the expression of IL-1β, IL-6 and TNF-α induced by OGD/R through the IRE1/XBP1s pathway in microglia

CONTEXT

Icariin (ICA), a flavonol glycoside extracted from Epimedium brevicornum Maxim (Berberidaceae), has been proven to inhibit inflammatory response in ischaemic rats in our laboratory's previous work. However, its underlying mechanism is still unclear.

OBJECTIVE

This study investigates the effects of ICA on endoplasmic reticulum (ER) stress mediated inflammation induced by cerebral ischaemia-reperfusion (I/R) injury in vitro.

MATERIALS AND METHODS

The primary cultured microglia were treated with oxygen-glucose deprivation (OGD) for 2 h followed by a 24 h reoxygenation. ICA (0.37, 0.74 and 1.48 μmol/L) administration was performed 1 h prior OGD and acting through 2 h OGD. The control group was cultured in normal conditions. At 24 h after reoxygenation, the expression of IRE1α, XBP1u, XBP1s, NLRP3 and caspase-1 was detected by western blotting (WB) and quantitative real-time (qRT) PCR; the expression of p-IRE1α was examined by WB; the expression of IL-1β, IL-6 and TNF-α was measured by WB and enzyme-linked immunosorbent assay (ELISA).

RESULTS

ICA (0.37, 0.74 and 1.48 μmol/L) reduced the ratio of p-IRE1α/IRE1α, the mRNA level of IRE1α, the expression of XBP1u, XBP1s, NLRP3, caspase-1 at both the mRNA and protein level expression of IL-1β, IL-6 and TNF-α in OGD/R injured microglia. Overexpression of IRE1 significantly reversed the effects of ICA.

DISCUSSION AND CONCLUSIONS

These results suggested that ICA might decrease the expression of IL-1β, IL-6 and TNF-α by inhibiting IRE1/XBP1s pathway. The anti-inflammatory effect of ICA may provide a potential therapeutic strategy for the treatment of brain injury after stroke.

Bioactive Flavonoids Icaritin and Icariin Protect against Cerebral Ischemia-Reperfusion-Associated Apoptosis and Extracellular Matrix Accumulation in an Ischemic Stroke Mouse Model

Stroke, which is the second leading cause of mortality in the world, is urgently needed to explore the medical strategies for ischemic stroke treatment. Both icariin (ICA) and icaritin (ICT) are the major active flavonoids extracted from Herba epimedii that have been regarded as the neuroprotective agents in disease models. In this study, we aimed to investigate and compare the neuroprotective effects of ICA and ICT in a middle cerebral artery occlusion (MCAO) mouse model. Male ICR mice were pretreated with both ICA and ICT, which ameliorated body weight loss, neurological injury, infarct volume, and pathological change in acute ischemic stroke mice. Furthermore, administration of both ICA and ICT could also protect against neuronal cell apoptotic death, oxidative and nitrosative stress, lipid peroxidation, and extracellular matrix (ECM) accumulation in the brains. The neuroprotective effects of ICT are slightly better than that of ICA in acute cerebral ischemic stroke mice. These results suggest that pretreatment with both ICA and ICT improves the neuronal cell apoptosis and responses of oxidative/nitrosative stress and counteracts the ECM accumulation in the brains of acute cerebral ischemic stroke mice. Both ICA and ICT treatment may serve as a useful therapeutic strategy for acute ischemic stroke.

Nuclear Receptors in Myocardial and Cerebral Ischemia-Mechanisms of Action and Therapeutic Strategies

Nearly 18 million people died from cardiovascular diseases in 2019, of these 85% were due to heart attack and stroke. The available therapies although efficacious, have narrow therapeutic window and long list of contraindications. Therefore, there is still an urgent need to find novel molecular targets that could protect the brain and heart against ischemia without evoking major side effects. Nuclear receptors are one of the promising targets for anti-ischemic drugs. Modulation of estrogen receptors (ERs) and peroxisome proliferator-activated receptors (PPARs) by their ligands is known to exert neuro-, and cardioprotective effects through anti-apoptotic, anti-inflammatory or anti-oxidant action. Recently, it has been shown that the expression of aryl hydrocarbon receptor (AhR) is strongly increased after brain or heart ischemia and evokes an activation of apoptosis or inflammation in injury site. We hypothesize that activation of ERs and PPARs and inhibition of AhR signaling pathways could be a promising strategy to protect the heart and the brain against ischemia. In this Review, we will discuss currently available knowledge on the mechanisms of action of ERs, PPARs and AhR in experimental models of stroke and myocardial infarction and future perspectives to use them as novel targets in cardiovascular diseases.

Flavonoids modulate AMPK/PGC-1α and interconnected pathways toward potential neuroprotective activities

As progressive, chronic, incurable and common reasons for disability and death, neurodegenerative diseases (NDDs) are significant threats to human health. Besides, the increasing prevalence of neuronal gradual degeneration and death during NDDs has made them a global concern. Since yet, no effective treatment has been developed to combat multiple dysregulated pathways/mediators and related complications in NDDs. Therefore, there is an urgent need to create influential and multi-target factors to combat neuronal damages. Accordingly, the plant kingdom has drawn a bright future. Among natural entities, flavonoids are considered a rich source of drug discovery and development with potential biological and medicinal activities. Growing studies have reported multiple dysregulated pathways in NDDs, which among those mediator AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) play critical roles. In this line, critical role of flavonoids in the upregulation of AMPK/PGC-1α pathway seems to pave the road in the treatment of Alzheimer's disease (AD), Parkinson's disease (PD), aging, central nervous system (brain/spinal cord) damages, stroke, and other NDDs. In the present study, the regulatory role of flavonoids in managing various NDDs has been shown to pass through AMPK/PGC-1α signaling pathway.

Icariin enhance mild hypothermia-induced neuroprotection via inhibiting the activation of NF-κB in experimental ischemic stroke

Therapeutic hypothermia (TH) is a promising neuroprotective agent for treating stroke. However, its clinical application was limited by the impractical duration. Icariin (ICA) were reported to have therapeutic effect on cerebral ischemia. In this research, our aim was to investigate whether the combination of TH and ICA had better neuroprotective effects on ischemic stroke. An ischemia-reperfusion rat model was established and treated with mild hypothermia, ICA or JSH-23 (inhibitor of NF-κB). Thermistor probe, 2'3'5'-triphenyl tetrazolium chloride (TTC), 5/12-score system, and ELISA were used to detect temperature (rectum, cortex, striatum), infarct volume, neurological deficit, and cerebral cell death of these rats. The expressions of tumor necrosis factor (TNF)-α, Interleukin- 6 (IL-6), nuclear factor-kappa B (NF-κB), nuclear factor erythroid2-related factor (Nrf2), peroxisome proliferator activated receptor gamma (PPARα), PPARγ, Janus kinase 2 (JAK2), p-JAK2, signal transducers and activators of transduction-3 (STAT3), and p-STAT3 were detected by Western blot or q-PCR. Mild hypothermia, ICA, and JSH-23 reduced the cerebral infarct volume, neurological deficit, cerebral cell death of rats, downregulated the expressions of TNF-α, IL-6, C-Caspase 3 and Bax, and the activation of PPARs/Nrf2/NF-κB and JAK2/STAT3 pathways, but elevated the expression of Bcl-2. ICA promoted the effect of mild hypothermia on infarct volume, neurological deficit, and cerebral cell death. Moreover, ICA also enhanced the regulatory effect of mild hypothermia on apoptosis/inflammation factors expressions and activation of PPARs/Nrf2/NF-κB and JAK2/STAT3 pathways. ICA could promote mild hypothermia-induced neuroprotection by inhibiting the activation of NF-κB through the PPARs/Nrf2/NF-κB and JAK2/STAT3/NF-κB pathways in experimental stroke.

Berberine exerts neuroprotective activities against cerebral ischemia/reperfusion injury through up-regulating PPAR-γ to suppress NF-κB-mediated pyroptosis

OBJECTIVE

Berberine (BBR) is an anti-inflammatory alkaloid compound extracted from herbs. The purpose of this study is to probe the possible effect and the mechanism of BBR against cerebral ischemia/reperfusion (I/R) injury.

METHODS

In vitro oxygen and glucose deprivation (OGD) model was established on neurons from rat hippocampus, which was then subjected to BBR, IVA337 (PPAR-γ agonist), or GW9662 (PPAR-γ antagonist) treatment, to identify their effects on neuronal pyroptosis. MTT assay was utilized to determine cell survival rates, TUNEL staining for observation of β-tubulin and MAP2 expressions, qRT-PCR for detection of mRNA expression of PPAR-γ, Western blot for assessment of protein expressions of PPAR-γ and pyroptosis-related proteins (AIM2, NLPR3, ASC, cleaved-Caspase-1, GSDMD, and GSDMD-N), and ELISA for examination of IL-18 and IL-1β expressions.

RESULTS

OGD modeling induced neuron pyroptosis, as evidenced by increased expression levels of pyroptosis-related proteins as well as IL-1β and IL-18, and elevated cell apoptosis rate. In addition, OGD exposure led to PPAR-γ up-regulation and NF-κB activation. Overexpression of PPAR-γ ameliorated cell pyroptosis, while knockdown of PPAR-γ intensified neuron pyroptosis that could be reversed by BBR. Furthermore, either BBR could block the activation of NF-κB signaling pathway through PPAR-γ.

CONCLUSION

BBR protects rats from cerebral I/R injury by up-regulating PPAR-γ to restrain NF-κB-mediated pyroptosis.

Icariin, an Up-and-Coming Bioactive Compound Against Neurological Diseases: Network Pharmacology-Based Study and Literature Review

Icariin is a biologically active substance in Epimedii herba that is used for the treatment of neurologic disorders. However, a comprehensive analysis of the molecular mechanisms of icariin is lacking. In this review, we present a brief history of the use of icariin for medicinal purposes; describe the active chemical components of Epimedii herba; and examine the evidence from experimental studies that have uncovered molecular targets of icariin in different diseases. We also constructed a protein–protein interaction network and carried out Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses to predict the therapeutic actions of icariin in nervous system diseases including Alzheimer disease, Parkinson disease, ischemic stroke, depressive disorder, multiple sclerosis, glioblastoma, and hereditary spastic paraplegias. The results of our analyses can guide future studies on the application of icariin to the treatment of neurologic disorders.

Selenium attenuates ischemia/reperfusion injury‑induced damage to the blood‑brain barrier in hyperglycemia through PI3K/AKT/mTOR pathway‑mediated autophagy inhibition

Ischemic stroke is a leading cause of mortality and disability. Diabetes mellitus, characterized by hyperglycemia, is a common concomitant disease of ischemic stroke, which is associated with autophagy dysfunction and blood‑brain barrier (BBB) damage following cerebral ischemia/reperfusion (I/R) injury. At present, there is no effective treatment strategy for the disease. The purpose of the present study was to explore the molecular mechanisms underlying the protective effects of selenium on the BBB following I/R injury in hyperglycemic rats. Middle cerebral artery occlusion was performed in diabetic Sprague‑Dawley rats. Treatment with selenium and the autophagy inhibitor 3‑methyladenine significantly reduced cerebral infarct volume, brain water content and Evans blue leakage, while increasing the expression of tight junction (TJ) proteins and decreasing that of autophagy‑related proteins (P<0.05). In addition, selenium increased the phosphorylation levels of PI3K, AKT and mTOR (P<0.05). A mouse bEnd.3 brain microvascular endothelial cell line was co‑cultured in vitro with an MA‑h mouse astrocyte‑hippocampal cell line to simulate the BBB. The cells were then subjected to hyperglycemia, followed by oxygen‑glucose deprivation for 1 h and reoxygenation for 24 h. It was revealed that selenium increased TJ protein levels, reduced BBB permeability, decreased autophagy levels and enhanced the expression of phosphorylated (p)‑AKT/AKT and p‑mTOR/mTOR proteins (P<0.05). Treatment with wortmannin (an inhibitor of PI3K) significantly prevented the beneficial effects of selenium on the BBB, whereas insulin‑like growth factor 1 (a PI3K activator) mimicked the effects of selenium. In conclusion, the present findings indicated that selenium can inhibit autophagy by regulating the PI3K/AKT/mTOR signaling pathway, significantly preventing BBB damage following cerebral I/R injury in hyperglycemic conditions.

Peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ): Molecular Effects and Its Importance as a Novel Therapeutic Target for Cerebral Ischemic Injury

Cerebral ischemic injury is a leading cause of death and long-term disability throughout the world. Peroxisome proliferator-activated receptor gamma (PPAR-ɣ) is a ligand-activated nuclear transcription factor that is a member of the PPAR family. PPAR-ɣ has been shown in several in vitro and in vivo models to prevent post-ischemic inflammation and neuronal damage by negatively controlling the expression of genes modulated by cerebral ischemic injury, indicating a neuroprotective effect during cerebral ischemic injury. A extensive literature review of PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out to understand the nature of the extensive work done on the mechanistic role of Peroxisome proliferator activated receptor gamma and its modulation in Cerebral ischemic injury. PPAR-ɣ can interact with specific DNA response elements to control gene transcription and expression when triggered by its ligand. It regulates lipid metabolism, improves insulin sensitivity, modulates antitumor mechanisms, reduces oxidative stress, and inhibits inflammation. This review article provides insights on the current state of research into the neuroprotective effects of PPAR-ɣ in cerebral ischemic injury, as well as the cellular and molecular mechanisms by which these effects are modulated, such as inhibition of inflammation, reduction of oxidative stress, suppression of pro-apoptotic production, modulation of transcription factors, and restoration of injured tissue through neurogenesis and angiogenesis.

Rapid classification and identification of chemical constituents in Epimedium koreanum Nakai by UPLC-Q-TOF-MS combined with data post-processing techniques

INTRODUCTION

Epimedium koreanum Nakai (EKN), is a well-known Chinese herbal medicine for the treatment of osteoporosis, immunosuppression, tumours and cardiovascular diseases. Comprehensive component identification is essential for elucidation of its pharmacological mechanism and quality control. However, its complex chemical composition has caused certain difficulties in the analysis of this traditional Chinese medicine (TCM). Therefore, there is an urgent need to establish a method for rapid classification and identification of EKN chemical components.

OBJECTIVE

To establish a method for rapid classification and identification of the main components of flavonoids, organic acids and alkaloids in EKN.

METHODS

The samples were analysed by ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and data post-processing techniques. The UPLC system used a BEH C₁₈ column to separate the total extract of EKN. The mobile phase consisted of 0.1% formic acid in water and acetonitrile, and the EKN extract was analysed by gradient elution at a flow rate of 0.4 mL/min. In both the positive and negative ion modes, the fragment information was obtained and compared with those of the characteristic fragmentations and neutral losses described in the literature to quickly identify the target compounds.

RESULTS

Finally, we successfully screened out 51 chemical components, including 40 flavonoids, nine organic acids, and two alkaloids.

CONCLUSION

The established method not only comprehensively analysed the chemical compositions of EKN, solved the difficult problems of analysis and identification of the complex chemical compositions of the TCM, but also further promoted the development of the application of chemical compositions of TCM.

Curcumin ameliorates ischemic stroke injury in rats by protecting the integrity of the blood-brain barrier

The blood-brain barrier (BBB) is critical for proper cerebral homeostasis and its dysfunction during ischemic stroke can result in significant neurological injury. The major goal of the present study was to identify whether curcumin pretreatment possessed protective effects on BBB integrity during the 24 h of acute ischemic brain injury. To investigate the protective effects of curcumin, male Sprague-Dawley rats were divided into multiple groups, including sham, middle cerebral artery occlusion/reperfusion (MCAO/R) vehicle and curcumin pretreated MCAO/R groups. The effects of curcumin were measured by analyzing neurological deficits, infarct size, BBB permeability and expression levels of permeability-related proteins in the brain. It was found that curcumin pretreatment significantly improved neurological scores, decreased infarct size, and protected synaptic remodeling of hippocampal neurons and upregulated the protein expression level of tight junction proteins, ZO-1, occludin and claudin-5 in ischemic rat brains. Furthermore, curcumin pretreatment before stroke was shown to downregulate the phosphorylation of NF-κB and MMP-9, which are central mediators of inflammation. The results from the present study indicated that curcumin pretreatment ameliorated ischemic stroke injury by protecting BBB integrity and synaptic remodeling, as well as inhibiting inflammatory responses.

PPARγ in Ischemia-Reperfusion Injury: Overview of the Biology and Therapy

Ischemia-reperfusion injury (IRI) is a complex pathophysiological process that is often characterized as a blood circulation disorder caused due to various factors (such as traumatic shock, surgery, organ transplantation, burn, and thrombus). Severe metabolic dysregulation and tissue structure destruction are observed upon restoration of blood flow to the ischemic tissue. Theoretically, IRI can occur in various tissues and organs, including the kidney, liver, myocardium, and brain, among others. The advances made in research regarding restoring tissue perfusion in ischemic areas have been inadequate with regard to decreasing the mortality and infarct size associated with IRI. Hence, the clinical treatment of patients with severe IRI remains a thorny issue. Peroxisome proliferator-activated receptor γ (PPARγ) is a member of a superfamily of nuclear transcription factors activated by agonists and is a promising therapeutic target for ameliorating IRI. Therefore, this review focuses on the role of PPARγ in IRI. The protective effects of PPARγ, such as attenuating oxidative stress, inhibiting inflammatory responses, and antagonizing apoptosis, are described, envisaging certain therapeutic perspectives.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Nutraceuticals in the Prevention of Neonatal Hypoxia-Ischemia: A Comprehensive Review of their Neuroprotective Properties, Mechanisms of Action and Future Directions

Neonatal hypoxia-ischemia (HI) is a brain injury caused by oxygen deprivation to the brain due to birth asphyxia or reduced cerebral blood perfusion, and it often leads to lifelong limiting sequelae such as cerebral palsy, seizures, or mental retardation. HI remains one of the leading causes of neonatal mortality and morbidity worldwide, and current therapies are limited. Hypothermia has been successful in reducing mortality and some disabilities, but it is only applied to a subset of newborns that meet strict inclusion criteria. Given the unpredictable nature of the obstetric complications that contribute to neonatal HI, prophylactic treatments that prevent, rather than rescue, HI brain injury are emerging as a therapeutic alternative. Nutraceuticals are natural compounds present in the diet or used as dietary supplements that have antioxidant, anti-inflammatory, or antiapoptotic properties. This review summarizes the preclinical in vivo studies, mostly conducted on rodent models, that have investigated the neuroprotective properties of nutraceuticals in preventing and reducing HI-induced brain damage and cognitive impairments. The natural products reviewed include polyphenols, omega-3 fatty acids, vitamins, plant-derived compounds (tanshinones, sulforaphane, and capsaicin), and endogenous compounds (melatonin, carnitine, creatine, and lactate). These nutraceuticals were administered before the damage occurred, either to the mothers as a dietary supplement during pregnancy and/or lactation or to the pups prior to HI induction. To date, very few of these nutritional interventions have been investigated in humans, but we refer to those that have been successful in reducing ischemic stroke in adults. Overall, there is a robust body of preclinical evidence that supports the neuroprotective properties of nutraceuticals, and these may represent a safe and inexpensive nutritional strategy for the prevention of neonatal HI encephalopathy.

Traditional Chinese Medicine Monomers: Novel Strategy for Endogenous Neural Stem Cells Activation After Stroke

Stem cell therapy, which has become a potential regenerative medical treatment and a promising approach for treating brain injuries induced by different types of cerebrovascular disease, has various application methods. Activation of endogenous neural stem cells (NSCs) can enable infarcted neuron replacement and promote neural networks’ regeneration without the technical and ethical issues associated with the transplantation of exogenous stem cells. Thus, NSC activation can be a feasible strategy to treat central nervous system (CNS) injury. The potential molecular mechanisms of drug therapy for the activation of endogenous NSCs have gradually been revealed by researchers. Traditional Chinese medicine monomers (TCMs) are active components extracted from Chinese herbs, and some of them have demonstrated the potential to activate proliferation and neurogenesis of NSCs in CNS diseases. Ginsenoside Rg1, astragaloside IV (AST), icariin (ICA), salvianolic acid B (Sal B), resveratrol (RES), curcumin, artesunate (ART), and ginkgolide B (GB) have positive effects on NSCs via different signaling pathways and molecules, such as the Wingless/integrated/β-catenin (Wnt/β-catenin) signaling pathway, the sonic hedgehog (Shh) signaling pathway, brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase 1 (HO-1). This article may provide further motivation for researchers to take advantage of TCMs in studies on CNS injury and stem cell therapy.

Tectorigenin attenuates the OGD/R-induced HT-22 cell damage through regulation of the PI3K/AKT and the PPARγ/NF-κB pathways

Tectorigenin (TEC) is an effective compound that derived from many plants, such as Iris unguicularis, Belamcanda chinensis and Pueraria thunbergiana Benth. Evidence suggested that TEC has anti-tumor, anti-oxidant activity, anti-bacterial and anti-inflammatory effects. In addition, there has some evidence indicated that TEC is a potential anti-stroke compound; however, its specific roles and associated mechanism have not yet been elucidated. In the present study, we aimed to investigate the anti-inflammatory, anti-oxidant activity and anti-apoptosis effects of TEC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced HT-22 cells, and clarified the relevant mechanisms. Here, we observed that TEC significantly promoted cell survival, impeded cell apoptosis, inhibited ROS and inflammatory cytokines IL-1β, IL-6, TNF-α production in OGD/R-induced HT-22 cells. Moreover, TEC activated PI3K/AKT signal pathway, increased PPARγ expression and inhibited NF-κB pathway activation in OGD/R-induced HT-22 cells. Further studies indicated that PPARγ inhibitor GW9662 activated NF-κB pathway after TEC treatment in OGD/R-induced HT-22 cells. Also, PI3K/AKT inhibitor LY294002, PPARγ inhibitor GW9662 and NF-κB activator LPS both reversed the effects of TEC on OGD/R-induced HT-22 cell biology. Taken together, this research confirmed that TEC benefit to HT-22 cell survival and against OGD/R damage through the PI3K/AKT and PPARγ/NF-κB pathways. These results indicated that TEC might be an effective compound in the treatment for ischemic brain injury.

Neuroprotective effects of icariin in neonatal hypoxia-ischemic brain damage via its anti-apoptotic property

INTRODUCTION

Neonatal hypoxic-ischemic brain damage (HIBD) is a brain disease that is caused by perinatal asphyxia. Icariin (ICA), which is an active component of Epimedii (a Chinese medicinal herb), has been verified to demonstrate a wide range of therapeutic effects, such as alleviating various kinds of brain injury.

OBJECTIVE

The current study aims to examine the neuroprotective effects of ICA on neonatal HIBD in mice.

MATERIALS AND METHODS

A modified version of the Rice-Vannucci method was performed to establish neonatal HIBD in 7-day-old mouse pups that were pretreated with ICA or vehicle. The infarct volume was measured, and behavioral tests were conducted to assess the protective effects of ICA on the neonatal brain and to evaluate functional recovery after injury. TUNEL staining was used to detect cell apoptosis, and the levels of cleaved caspase-3 and phosphorylated protein kinase B (Akt) were determined by using Western blot.

RESULTS

We showed that pretreatment with ICA could significantly reduce brain damage, improve neurobehavioral outcomes, and suppress apoptotic cell death following HI injury. ICA reversed the HI-induced reduction in phosphorylated Akt and activation of cleaved caspase-3.

CONCLUSION

The results demonstrate that ICA exerts potential neuroprotective effects on neonatal HIBD, which may be mediated by its anti-apoptotic activity.

Recent Research on Flavonoids and their Biomedical Applications

Flavonoids, commonly found in various plants, are a class of polyphenolic compounds having a basic structural unit of 2-phenylchromone. Flavonoid compounds have attracted much attention due to their wide biological applications. In order to facilitate further research on the biomedical application of flavonoids, we surveyed the literature published on the use of flavonoids in medicine during the past decade, documented the commonly found structures in natural flavonoids, and summarized their pharmacological activities as well as associated mechanisms of action against a variety of health disorders including chronic inflammation, cancer, cardiovascular complications and hypoglycemia. In this mini-review, we provide suggestions for further research on the biomedical applications of flavonoids.

Natural Products for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are a heterogeneous group of disorders characterized by the progressive degeneration of the structure and function of the central nervous system or peripheral nervous system. Alzheimer's Disease (AD), Parkinson's Disease (PD) and Spinal Cord Injury (SCI) are the common neurodegenerative diseases, which typically occur in people over the age of 60. With the rapid development of an aged society, over 60 million people worldwide are suffering from these uncurable diseases. Therefore, the search for new drugs and therapeutic methods has become an increasingly important research topic. Natural products especially those from the Traditional Chinese Medicines (TCMs), are the most important sources of drugs, and have received extensive interest among pharmacist. In this review, in order to facilitate further chemical modification of those useful natural products by pharmacists, we will bring together recent studies in single natural compound from TCMs with neuroprotective effect.

A Network Pharmacological Approach to Investigate the Mechanism of Action of Active Ingredients of Epimedii Herba and Their Potential Targets in Treatment of Alzheimer's Disease

Background

Epimedii Herba is a traditional Chinese herbal medicine used to treat central nervous system diseases such as Alzheimer’s disease in China. However, the pharmacological mechanism is unclear. To investigate the mechanisms of Epimedii Herba in the treatment of Alzheimer’s disease, we assessed effective compounds, corresponding targets, and related pathways of Epimedii Herba in the treatment of Alzheimer’s disease based on network pharmacology.

Material/Methods

The active components and targets of Epimedii Herba were obtained through the TCMSP database and the DrugBank database. The DisGeNET database and GeneCards database were used to search for Alzheimer’s disease targets. The common targets of components and disease were obtained by Wayne diagram. Gene ontology (GO) analysis and enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed using the DAVID database. The component-target-pathway interaction network model was constructed using Cytoscape software. Auto Duck Vina software was used for molecular docking to analyze the affinity of the key ingredients and the main targets.

Results

We screened 17 active ingredients and 27 key targets of Epimedii Herba in the treatment of Alzheimer’s disease, which were related to the HIF-1 signaling pathway, TNF signaling pathway, PI3K-Akt signaling pathway, NF-κB signaling pathway, VEGF signaling pathway, and sphingolipid signaling pathway.

Conclusions

Based on network pharmacology, the multi-component, multi-target, and multi-pathway characteristics of Epimedii Herba in the treatment of Alzheimer’s disease were explored. Our results provide new ideas for future pharmacological and experimental research on Epimedii Herba in the treatment of Alzheimer’s disease.

Molecular Mechanisms of Action of Emodin: As an Anti-Cardiovascular Disease Drug

Emodin is a natural occurring anthraquinone derivative isolated from roots and barks of numerous plants, molds, and lichens. It is found to be an active ingredient in different Chinese herbs including Rheum palmatum and Polygonam multiflorum, and it is a pleiotropic molecule with diuretic, vasorelaxant, anti-bacterial, anti-viral, anti-ulcerogenic, anti-inflammatory, and anti-cancer effects. Moreover, emodin has also been shown to have a wide activity of anti-cardiovascular diseases. It is mainly involved in multiple molecular targets such as inflammatory, anti-apoptosis, anti-hypertrophy, anti-fibrosis, anti-oxidative damage, abnormal, and excessive proliferation of smooth muscle cells in cardiovascular diseases. As a new type of cardiovascular disease treatment drug, emodin has broad application prospects. However, a large amount of evidences detailing the effect of emodin on many signaling pathways and cellular functions in cardiovascular disease, the overall understanding of its mechanisms of action remains elusive. In addition, by describing the evidence of the effects of emodin in detail, the toxicity and poor oral bioavailability of mice have been continuously discovered. This review aims to describe a timely overview of emodin related to the treatment of cardiovascular disease. The emphasis is to summarize the pharmacological effects of emodin as an anti-cardiovascular drug, as well as the targets and its potential mechanisms. Furthermore, the treatment of emodin compared with conventional cardiovascular drugs or target inhibitors, the toxicity, pharmacokinetics and derivatives of emodin were discussed.

The circadian nuclear receptor RORα negatively regulates cerebral ischemia-reperfusion injury and mediates the neuroprotective effects of melatonin

Disruptions of the circadian rhythm and reduced circulating levels of the circadian hormone melatonin predispose to ischemic stroke. Although the nuclear receptor RORα is considered as a circadian rhythm regulator and a mediator of certain melatonin effects, its potential role in cerebral ischemia-reperfusion (CI/R) injury and in the neuroprotective effects of melatonin remain undefined. Here, we observed that CI/R injury in RORα-deficient mice was associated with greater cerebral infarct size, brain edema, and cerebral apoptosis compared with wild-type model. In contrast, transgenic mice with brain-specific overexpression of RORα versus non-transgenic controls exerted significantly reduced infarct volume, brain edema and apoptotic response induced by CI/R. Mechanistically, RORα deficiency was found to exacerbate apoptosis pathways mediated by endoplasmic-reticulum stress and mitochondria and aggravate oxidative/nitrative stress after CI/R. Further studies revealed that RORα deficiency intensified the activation of nuclear factor-κB signaling induced by CI/R. Given the emerging evidence of RORα as an essential melatonin activity mediator, we further investigated the RORα roles in melatonin-exerted neuroprotection against acute ischemic stroke. Melatonin treatment significantly decreased infarct volume and cerebral apoptosis; mitigated endoplasmic reticulum stress and mitochondrial dysfunction; and inhibited CI/R injury-induced oxidative/nitrative stress and nuclear factor-κB activation, which was eradicated in RORα-deficient mice. Collectively, current findings suggest that RORα is a novel endogenous neuroprotective receptor, and a pivotal mediator of melatonin's suppressive effects against CI/R injury.

Icariin protects neurons from endoplasmic reticulum stress-induced apoptosis after OGD/R injury via suppressing IRE1α-XBP1 signaling pathway

Icariin (ICA), a flavonol glycoside isolated from Epimedium, has been considered as a potential alternative therapy for ischemic stroke. However, the protective mechanisms of ICA on cerebral ischemia-reperfusion (I/R) are not fully illuminated yet. The effects of ICA on ER stress and inflammatory response which were involved in the pathological process of cerebral I/R were investigated in vitro. Microglia and neurons were subjected to OGD/R. ICA was administrated to microglia 1 h before OGD and maintained 2 h throughout OGD. At 24 h after reoxygenation, the protein expression of IL-1 β, IL-6, TNF-α in the supernatant of microglia was measured using ELISA assay; neuronal apoptosis was assessed by TUNEL staining; and cell viability was detected using CKK-8 assay; the expression of IRE1α, XBP1u, XBP1s, and cleaved caspase-3 in neurons was examined by western blotting and qRT-PCR; the expression of p-IRE1α in neurons was detected by western blotting. We found that OGD/R induced the expression of IL-1 β, IL-6, TNF-α in the supernatant of microglia; OGD/R and these proinflammatory cytokines promoted the mRNA as well as protein expression of XBP1u, XBP1s and cleaved caspase-3, increased the ratio of p-IRE1α/IRE1α, as well as apoptosis, and decreased cell viability in primary cortical neurons, while ICA reversed the levels of the above factors. IRE1 overexpression enhanced ER stress as well as apoptosis, and impaired the protective effects of ICA. These results suggested that ICA can inhibit apoptosis in neurons after OGD/R through IRE1/XBP1 signaling pathway beside its anti-inflammatory effect.

Icariin protects against sodium azide-induced neurotoxicity by activating the PI3K/Akt/GSK-3β signaling pathway

Background

Icariin (ICA) is one of the major active flavonoids extracted from the traditional Chinese herb Epimedium brevicornum Maxim and has been shown to have neuroprotective effects. This study was designed to investigate the effect of ICA on sodium azide (NaN₃)-induced rat adrenal pheochromocytoma (PC12) cell damage and to further examine the underlying mechanisms.

Methods

To explore its possible mechanism, we used NaN₃ (50 mM)-induced neuronal PC12 cell damage. Cell viability was evaluated by CCK-8 and lactate dehydrogenase (LDH) assays. Mitochondrial membrane potential (MMP) was detected by JC-1. Glucose concentration was assessed by the glucose oxidase method. The role of ICA in the PI3K/Akt/GSK-3β signaling pathway was explored by Western blotting.

Results

The results indicate that pretreatment with ICA reduced NaN₃-induced cell damage and significantly reduced the leakage rate of LDH in PC12 cells. ICA pretreatment increased the MMP and a decrease in glucose concentration indicate increased glucose consumption. Furthermore, the protein levels of p-PI3K (p85), PI3K-110α, p-Ser473-Akt and p-Ser9-GSK-3β were markedly decreased in PC12 cells after NaN₃ treatment for 24 h, whereas these effects were reverted after pretreatment with ICA. Tau phosphorylation at the Ser396/404 and Thr217 sites was significantly decreased by pretreatment with ICA.

Conclusions

These results suggest that ICA protects against NaN₃-induced neurotoxicity in PC12 cells by activating the PI3K/Akt/GSK-3β signaling pathway.

Icariside II, a phosphodiesterase 5 inhibitor, attenuates cerebral ischaemia/reperfusion injury by inhibiting glycogen synthase kinase-3β-mediated activation of autophagy

Background and Purpose

Cerebral ischaemia/reperfusion causes exacerbated neuronal damage involving excessive autophagy and neuronal loss. The present study was designed to investigate the effect of icariside II, one of main active ingredients of Herba Epimedii on this loss and whether this is related to its PDE 5 inhibitory action.

Experimental Approach

Focal cerebral ischaemia was induced in the rat by transient middle cerebral artery occlusion over 2 hr, followed by reperfusion with icariside II, 3‐methylamphetamine or rapamycin. The effect of icariside II was determined measuring behaviour changes and the size of the infarction. The expressions of PDE 5, autophagy‐related proteins and the level of phosphorylation of glycogen synthase kinase‐3β (GSK‐3β) were determined. Cultured primary cortical neurons were subjected to oxygen and glucose deprivation followed by reoxygenation in the presence and absence of icariside II. A surface plasmon resonance assay and molecular docking were used to explore the interactions of icariside II with PDE 5 or GSK‐3β.

Key Results

Icariside II not only protected against induced ischaemic reperfusion injury in rats but also attenuated such injury in primary cortical neurons. The neuroprotective effects of icariside II on such injury were attributed to interfering with the PKG/GSK‐3β/autophagy axis by directly bounding to PDE 5 and GSK‐3β.

Conclusions and Implications

These findings indicate that icariside II attenuates cerebral I/R‐induced injury via interfering with PKG/GSK‐3β/autophagy axis. This study raises the possibility that icariside II and other PDE 5 inhibitors maybe effective in the treatment ischaemia stroke.

Knockdown of IL-32 protects PC12 cells against oxygen-glucose deprivation/reoxygenation-induced injury via activation of Nrf2/NF-κB pathway

Cerebral ischemia/reperfusion injury (IRI) is one of major causes of ischemic organ damage. It is well established that inflammatory cytokines serve as regulatory factors in cerebral oxygen glucose deprivation/reoxygenation (OGD/R). However, the involving mechanism is not clear enough. OGD/R PC12 cells were used as a hypoxia/reoxygenation model. IL-32 expression and cell viability were detected by qRT-PCR and CCK-8 assay, respectively. Cell apoptosis were determined by flow cytometry and western blotting. Protein levels of inflammatory factors, and the activity of MPO, MDA and SOD were analyzed. Furthermore, western blot assay was carried out to assess protein levels of Nrf2, keap1, NQO-1, p-p65, p-IκBα, p65 and IκBα. The results revealed that IL-32 expression was significantly upregulated in PC12 cells induced by OGD/R. Nrf2, keap1 and NQO-1 level was reduced while phosphorylation level of p65 and IκBα was up-regulated in OGD/R-induced PC12 cells. Mechanism investigations found that IL-32 silence elevated the level of Nrf2, Keap1 and NQO-1, reduced p-p65 and p-IκBα level, and regulated the contents of TNF-a, IL-1β, IL-6 and MCP-1 in OGD/R PC12 cells. In addition, knockdown of IL-32 suppressed production of intracellular ROS, elevated SOD activity, reduced MPO and MDA content, and enhanced cell viability. Furthermore, cell apoptosis was induced in OGD/R PC12 cells with IL-32 silence. However, Nrf2 inhibitor reversed the effects of IL-32 knockdown on OGD/R PC12 cells. This research suggests that IL-32 silence may alleviate OGD/R and Nrf2 plays an important role in the protection by IL-32 silence on PC12 cells induced by OGD/R.