Quercetin attenuates ischemia reperfusion injury by protecting the blood-brain barrier through Sirt1 in MCAO rats

Neuroprotective potential for mitigating ischemia-reperfusion-induced damage

Reperfusion following cerebral ischemia causes both structural and functional damage to brain tissue and could aggravate a patient's condition; this phenomenon is known as cerebral ischemia-reperfusion injury. Current studies have elucidated the neuroprotective role of the sirtuin protein family (Sirtuins) in modulating cerebral ischemia-reperfusion injury. However, the potential of utilizing it as a novel intervention target to influence the prognosis of cerebral ischemia-reperfusion injury requires additional exploration. In this review, the origin and research progress of Sirtuins are summarized, suggesting the involvement of Sirtuins in diverse mechanisms that affect cerebral ischemia-reperfusion injury, including inflammation, oxidative stress, blood-brain barrier damage, apoptosis, pyroptosis, and autophagy. The therapeutic avenues related to Sirtuins that may improve the prognosis of cerebral ischemia-reperfusion injury were also investigated by modulating Sirtuins expression and affecting representative pathways, such as nuclear factor-kappa B signaling, oxidative stress mediated by adenosine monophosphate-activated protein kinase, and the forkhead box O. This review also summarizes the potential of endogenous substances, such as RNA and hormones, drugs, dietary supplements, and emerging therapies that regulate Sirtuins expression. This review also reveals that regulating Sirtuins mitigates cerebral ischemia-reperfusion injury when combined with other risk factors. While Sirtuins show promise as a potential target for the treatment of cerebral ischemia-reperfusion injury, most recent studies are based on rodent models with circadian rhythms that are distinct from those of humans, potentially influencing the efficacy of Sirtuins-targeting drug therapies. Overall, this review provides new insights into the role of Sirtuins in the pathology and treatment of cerebral ischemia-reperfusion injury.

Traditional Chinese Medicine for Inhibiting Ferroptosis in Ischemic-Related Diseases

Ischemic-related diseases, such as myocardial infarction and stroke, are primarily driven by a deficit in oxygen supply leading to cellular damage and death. Ferroptosis has emerged as an important mechanism contributing to the progression of ischemic injury, characterized by iron-dependent lipid peroxidation. This review aims to provide a comprehensive overview of the significant mechanisms underlying ferroptosis in ischemic conditions and explores the potential effects of traditional Chinese medicines (TCMs) and their extracts. Numerous compounds extracted from TCMs, including flavonoids, polyphenols and terpenes, exhibit potent antiferroptotic effects by activating nuclear factor erythroid 2-related factor 2, upregulating glutathione peroxidase 4, inhibiting lipid peroxidation and so on. These properties render TCMs a promising candidate for developing novel ferroptosis therapeutic strategies. This review underscores the importance of investigating the interactions between ferroptosis and TCMs within the context of ischemic diseases. These findings provide valuable insights for future research to identify targets associated with ferroptosis regulation, thereby expanding the pharmacological perspective of TCMs in treating ischemic diseases and revealing the potential of novel therapeutic strategies. Additionally, this highlights the relevance of integrating traditional and modern medical approaches in addressing complex health issues.

Role of histone deacetylases and sirtuins in the ischaemic stroke: a systematic review and meta-analysis of animal studies

BACKGROUND

Treatment of ischaemic stroke requires exploration of novel neuroprotective strategies owing to the constraints of thrombolytic therapy. Recent research implies that modulation of histone deacetylases (HDAC) or sirtuins (SIRT) could be beneficial in achieving this goal.

METHODS

This systematic review and meta-analysis evaluates the effectiveness of HDAC/SIRT enzyme modulation in treating acute ischaemic stroke. It includes relevant studies but excludes human and in vitro research and non-primary studies. An electronic search was conducted across databases PubMed, Web of Science and Scopus until 20 March 2025. The methodological quality was assessed using a modified SYRCLE risk of bias tool. Infarct volume and neurological responses were extracted as key outcomes, and a random-effects meta-analysis of infarct volume was conducted for studies directly targeting HDAC/SIRT enzymes.

RESULTS

A review of 71 studies involving over 1600 animals focused on ischaemic stroke treatments, predominantly using male rodents in a transient middle cerebral artery occlusion model. Most treatments were administered intraperitoneally, starting from the inception of ischaemia until 5 days afterwards. Non-selective HDAC inhibitors and SIRT1 modulators were targeted most frequently. The meta-analysis on infarct volume with 95% CI showed an overall effect estimate of -1.529 and suggested that non-selective HDAC inhibitors exhibit the most promise in reducing infarct size. Additionally, agonists of SIRT3/7, SIRT6, SIRT1 and HDAC1, along with inhibitors of SIRT5, HDAC6 and HDAC3, may play a significant role in the treatment of ischaemic stroke. Importantly, neuroprotective treatments have been found to be most effective in reducing infarct volume when administered within 24 hours following ischaemia.

DISCUSSION

This study highlights the most promising neuroprotective trials for ischaemic stroke by focusing on infarct volume as a key outcome. However, relying exclusively on infarct volume may not fully capture the effectiveness of these treatments.

Role of sirtuins in cerebral ischemia-reperfusion injury: Mechanisms and therapeutic potential

The high incidence and mortality rate of cardiac arrest (CA) establishes it as a critical clinical challenge in emergency medicine globally. Despite continuous advances in advanced life support (ALS) technology, the prognosis for patients experiencing cardiac arrest remains poor, with cerebral ischemia and reperfusion injury (CIRI) being a significant determinant of adverse neurological outcomes and increased mortality. Sirtuins (SIRTs) are a class of highly evolutionarily conserved NAD+-dependent histone deacylenzymes capable of regulating the expression of various cytoprotective genes to play a neuroprotective role in CIRI. SIRTs mainly regulate the levels of downstream proteins such as PGC 1-α, Nrf 2, NLRP 3, FoxOs, and PINK 1 to inhibit inflammatory response, attenuate oxidative stress, improve mitochondrial dysfunction, promote angiogenesis, and inhibit apoptosis while reducing CIRI. Natural active ingredients are widely used in regulating the protein level of SIRTs in the body because of their multi-components, multi-pathway, multi-target, and minimal toxic side effects. However, these naturally active ingredients still face many challenges related to drug targeting, pharmacokinetic properties, and drug delivery. The emergence and vigorous development of new drug delivery systems, such as nanoparticles, micromilk, and exosomes, provide strong support for solving the above problems. In the context of the rapid development of molecular biology technology, non-coding RNA (NcRNA), represented by miRNA and LncRNA, offers great potential for achieving gene-level precision medicine. In the context of multidisciplinary integration, combining SIRTs proteins with biotechnology, omics technologies, artificial intelligence, and material science will strongly promote the deepening of their basic research and expand their clinical application. This review describes the major signaling pathways of targeting SIRTs to mitigate CIRI, as well as the current research status of Chinese and Western medicine and medical means for the intervention level of SIRTs. Meanwhile, the challenges and possible solutions in the clinical application of targeted drugs are summarized. In the context of medical and industrial crossover, the development direction of SIRTs in the future is discussed to provide valuable reference for basic medical researchers and clinicians to improve the clinical diagnosis and treatment effects of CIRI.

Potential therapeutic targets for ischemic stroke in pre-clinical studies: Epigenetic-modifying enzymes DNMT/TET and HAT/HDAC

Ischemic stroke (IS) remains a leading cause of mortality and disability worldwide, driven by genetic predispositions and environmental interactions, with epigenetics playing a pivotal role in mediating these processes. Specific modifying enzymes that regulate epigenetic changes have emerged as promising targets for IS treatment. DNA methyltransferases (DNMTs), ten-eleven translocation (TET) dioxygenases, histone acetyltransferases (HATs), and histone deacetylases (HDACs) are central to epigenetic regulation. These enzymes maintain a dynamic balance between DNA methylation/demethylation and histone acetylation/deacetylation, which critically influences gene expression and neuronal survival in IS. This review is based on both in vivo and in vitro experimental studies, exploring the roles of DNMT/TET and HAT/HDAC in IS, evaluating their potential as therapeutic targets, and discussing the use of natural compounds as modulators of these enzymes to develop novel treatment strategies.

Quercetin alleviates cerebral ischemia and reperfusion injury in hyperglycemic animals by reducing endoplasmic reticulum stress through activating SIRT1

Hyperglycemia aggravates cerebral ischemic reperfusion injury (CIRI). Neuroprotective drugs that are effective in reducing CIRI in animals with normoglycemic condition are ineffective in ameliorating CIRI under hyperglycemic condition. This study investigated whether quercetin alleviates hyperglycemic CIRI by inhibiting endoplasmic reticulum stress (ERS) through modulating the SIRT1 signaling pathway. A middle cerebral artery occlusion/reperfusion (MCAO/R) model was induced in STZ-injected hyperglycemic rats. High glucose and oxygen glucose deprivation/reoxygenation (OGD/R) models were established in HT22 cells. The results demonstrated that hyperglycemia exacerbated CIRI, and quercetin pretreatment decreased the neurological deficit score and cerebral infarct volume, and alleviated neuron damage in the cortex of the penumbra in hyperglycemic MCAO/R rats, indicating that quercetin could be a candidate for treating hyperglycemic CIRI. Moreover, quercetin pretreatment reduced apoptosis, inhibited the expression of the ERS marker proteins GRP78 and ATF6, and mitigated the expression of the ERS-mediated proapoptotic protein CHOP in hyperglycemic MCAO/R rats, suggesting that quercetin alleviated hyperglycemic CIRI by inhibiting ERS and ERS-mediated apoptosis. Furthermore, quercetin upregulated Sirt1 expression in HG+OGD/R treated HT22 cells and inhibited PERK, p-eIF2α, ATF4, and CHOP expression. In contrast, the SIRT1 selective inhibitor EX-527 blocked the effect of quercetin on protein expression in the SIRT1/PERK pathway and aggravated HT22 cell injury. These findings indicate that quercetin inhibits ERS-mediated apoptosis through modulating the SIRT1 and PERK pathway. In conclusion, quercetin alleviates hyperglycemic CIRI by inhibiting ERS-mediated apoptosis through activating SIRT1 that consequently suppressed ERS signaling.

Exploring the mechanism of Polygonum Cuspidatum in the treatment of ischemic stroke by network pharmacology analysis and experimental validation

Polygonum cuspidatum (PC), a traditional Chinese medicine, has been employed in the treatment of ischemic stroke (IS), yet its precise mechanisms of action remain to be elucidated. This study integrates network pharmacology with in vitro and in vivo experiments to investigate the underlying mechanisms of PC in the treatment of IS. The active components of PC in rat serum samples were identified using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). The active ingredients and mechanism of PC were predicted by network pharmacology. Interactions between key active compounds and major targets were validated through molecular docking. Finally, the efficacy and mechanism of PC in the treatment of IS were verified through in vivo and in vitro experiments. A total of 43 active components of PC were identified, along with 142 targets associated with IS. KEGG analysis suggested that the PI3K/Akt signaling pathway may play a key role in PC's regulation of IS-related injury. Molecular docking confirmed that quercetin, resveratrol, apigenin, luteolin, and torachrysone, may potentially interact with core targets including AKT1, IL6, TNF, TP53 and EGFR. Additionally, we confirmed that PC significantly inhibited the release of inflammatory cytokines and upregulated the phosphorylation of the PI3K/Akt signaling pathway in vitro. In vivo experiments further validated its protective effects. We speculate that this protective effect is mediated by the modulation of the PI3K/Akt signaling pathway.

Quercetin, a natural flavonoid, protects against hepatic ischemia-reperfusion injury via inhibiting Caspase-8/ASC dependent macrophage pyroptosis

INTRODUCTION

Hepatic ischemia-reperfusion injury (IRI) is an inevitable adverse event following liver surgery, leading to liver damage and potential organ failure. Despite advancements, effective interventions for hepatic IRI remain elusive, posing a significant clinical challenge. The innate immune response significantly contributes to the pathogenesis of hepatic IRI by promoting an inflammatory cytotoxic cycle. We have reported that blocking GSDMD-induced pyroptosis in innate immunity cells protected hepatic IRI from inflammatory injury. However, the search for effective pyroptosis inhibitors continues.

OBJECTIVES

This study aims to evaluate whether quercetin, a natural flavonoid, can inhibit GSDMD-induced pyroptosis and mitigate hepatic IRI.

METHODS

We established the hepatic IRI murine model and cellular pyroptosis model to evaluate the efficacy of quercetin.

RESULTS

Quercetin effectively alleviated hepatic IRI-induced tissue necrosis and inflammation. We found that during hepatic IRI, the cleavage of GSDMD occurred in hepatic macrophages, but not in other non-parenchymal cells. Quercetin inhibited the cleavage of GSDMD in macrophages. Moreover, we found that quercetin blocked the ASC assembly to inhibit the formation of NLRP3 inflammasomes and AIM2 inflammasomes, suppressing macrophage pyroptosis. Co-immunoprecipitation experiments confirmed that quercetin inhibited the interaction between ASC and Caspase-8, which is the mechanism of ASC complex and inflammasome formation. Overexpression of Caspase-8 abolished the anti-pyroptosis effect of quercetin in NLRP3 and AIM2 inflammasome signaling. Furthermore, we found that the hepatoprotective activity of quercetin was reduced in myelocytic GSDMD-deficient mice.

CONCLUSION

Our findings suggest that quercetin has beneficial effects on hepatic IRI. Quercetin could attenuate hepatic IRI and target inhibition of macrophage pyroptosis via blocking Caspase-8/ASC interaction. We recommend that quercetin might serve as a targeted approach for the prevention and personalized treatment of hepatic IRI in perioperative patients.

Targeting sirtuins in neurological disorders: A comprehensive review

The sirtuin (SIRT) family is a group of seven conserved nicotinamide adenine dinucleotide-dependent histone deacetylases (SIRT1-SIRT7), which play crucial roles in various fundamental biological processes, including metabolism, aging, stress responses, inflammation, and cell survival. The role of SIRTs in neuro-pathophysiology has recently attracted significant attention. Notably, SIRT1-SIRT3 have been identified as key players in neuroprotection as they reduce neuroinflammation and regulate mitochondrial function. This review summarizes the latest research advancements in the role of the SIRT family in neurological diseases, mainly including neurodegenerative diseases, ischemia-related diseases, bleeding-related diseases, nervous system injury and other nervous system diseases, emphasizing their critical functions and associated signaling pathways, (e.g., AMPK/SIRT1/PGC-1α, AMPK/SIRT1/IL-1β/NF-κB, STAT2-SIRT4-mTOR, SIRT3/FOXO3α, and other signaling pathways in disease progression, particularly their protective roles in neurodegenerative diseases, ischemic injuries, and neural damage. Additionally, this review discusses progress in clinical studies targeting SIRT-specific small-molecule agonists and inhibitors. Further research on SIRTs may provide new insights into potential therapeutic strategies for the prevention and treatment of neurological disorders.

Therapeutic potential of flavonoids in neuroprotection: brain and spinal cord injury focus

Flavonoids in fruits, vegetables, and plant-based drinks have potential neuroprotective properties, with clinical research focusing on their role in reducing oxidative stress, controlling inflammation, and preventing apoptosis. Some flavonoids, such as quercetin, kaempferol, fisetin, apigenin, luteolin, chrysin, baicalein, catechin, epigallocatechin gallate, naringenin, naringin, hesperetin, genistein, rutin, silymarin, and daidzein, have been presented to help heal damage to the central nervous system by affecting key signaling pathways including PI3K/Akt and NF-κB. This review systematically analyzed articles on flavonoids, neuroprotection, and brain and spinal cord injury from primary medical databases like Scopus, PubMed, and Web of Science. Flavonoids enhance antioxidant defenses, reduce pro-inflammatory cytokine production, and aid cell survival and repair by focusing on specific molecular pathways. Clinical trials are also exploring the application of preclinical results to therapeutic approaches for patients with spinal cord injury and traumatic brain injury. Flavonoids can enhance injury healing, reduce lesion size, and enhance synaptic plasticity and neurogenesis. The full potential of flavonoids lies in their bioavailability, dose, and administration methods, but there are still challenges to overcome. This review explores flavonoid-induced neuroprotection, its clinical implications, future research opportunities, and molecular mechanisms, highlighting the potential for innovative CNS injury therapies and improved patient health outcomes.

Much More than Nutrients: The Protective Effects of Nutraceuticals on the Blood-Brain Barrier in Diseases

The dysfunction of the blood-brain barrier (BBB) is well described in several diseases, and is considered a pathological factor in many neurological disorders. This review summarizes the most important groups of natural compounds, including alkaloids, flavonoids, anthocyanidines, carotenoids, lipids, and vitamins that were investigated for their potential protective effects on brain endothelium. The brain penetration of these compounds and their interaction with BBB efflux transporters and solute carriers are discussed. The cerebrovascular endothelium is considered a therapeutic target for natural compounds in diseases. In preclinical studies modeling systemic and central nervous system diseases, nutraceuticals exerted beneficial effects on the BBB. In vivo, they decreased BBB permeability, brain edema, astrocyte swelling, and morphological changes in the vessel structure and basal lamina. At the level of brain endothelial cells, nutraceuticals increased cell survival and decreased apoptosis. From the general endothelial functions, decreased angiogenesis and increased levels of vasodilating agents were demonstrated. From the BBB functions, elevated barrier integrity by tightened intercellular junctions, and increased expression and activity of BBB transporters, such as efflux pumps, solute carriers, and metabolic enzymes, were shown. Nutraceuticals enhanced the antioxidative defense and exerted anti-inflammatory effects at the BBB. The most important signaling changes mediating the increased cell survival and BBB stability were the activation of the WNT, PI3K-AKT, and NRF2 pathways, and inhibition of the MAPK, JNK, ERK, and NF-κB pathways. Nutraceuticals represent a valuable source of new potentially therapeutic molecules to treat brain diseases by protecting the BBB.

Zhongfeng Xingnao Liquid ameliorates post-stroke cognitive impairment through sirtuin1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway

The activation of the sirtuin1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway has been shown to mitigate oxidative stress-induced apoptosis and mitochondrial damage by reducing reactive oxygen species (ROS) levels. Clinical trials have demonstrated that Zhongfeng Xingnao Liquid (ZFXN) ameliorates post-stroke cognitive impairment (PSCI). However, the underlying mechanism, particularly whether it involves protecting mitochondria and inhibiting apoptosis through the SIRT1/Nrf2/HO-1 pathway, remains unclear. This study employed an oxygen-glucose deprivation (OGD) cell model using SH-SY5Y cells and induced PSCI in rats through modified bilateral carotid artery ligation (2VO). The effects of ZFXN on learning and memory, neuroprotective activity, mitochondrial function, oxidative stress, and the SIRT1/Nrf2/HO-1 pathway were evaluated both in vivo and in vitro. Results indicated that ZFXN significantly increased the B-cell lymphoma 2 (Bcl2)/Bcl2-associated X (Bax) ratio, reduced terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL)+ cells, and markedly improved cognition, synaptic plasticity, and neuronal function in the hippocampus and cortex. Furthermore, ZFXN exhibited potent antioxidant activity, evidenced by decreased ROS and malondialdehyde (MDA) content and increased superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels. ZFXN also demonstrated considerable enhancement of mitochondrial membrane potential (MMP), Tom20 fluorescence intensity, adenosine triphosphate (ATP) and energy charge (EC) levels, and mitochondrial complex I and III activity, thereby inhibiting mitochondrial damage. Additionally, ZFXN significantly increased SIRT1 activity and elevated SIRT1, nuclear Nrf2, and HO-1 levels. Notably, these effects were substantially counteracted when SIRT1 was suppressed by the inhibitor EX-527 in vitro. In conclusion, ZFXN alleviates PSCI by activating the SIRT1/Nrf2/HO-1 pathway and preventing mitochondrial damage.

Unlocking the neuroprotective potential of Ziziphora clinopodioides flavonoids in combating neurodegenerative diseases and other brain injuries

Ziziphora clinopodioides Lam. (Z. clinopodioides) is a traditional Chinese and ethnic medicine in Xinjiang, China with various therapeutic effects. It is primarily used for conditions such as heart disease, fever with chills, palpitations, and insomnia. Flavonoids are the main medicinal components of Z. clinopodioides, Interestingly, current research has increasingly focused on its neuroprotective effects. This study provides a comprehensive overview of the potential therapeutic applications of Z. clinopodioides and its constituents in central nervous system disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and cerebral ischemia-reperfusion injury. At present, about 25 flavonoids have been isolated and identified from various organs of Z. clinopodioides, including linarin, acacetin, hyperoside, quercetin, apigenin, luteolin, chrysin, kaempferol, baicalein, rutin and others. Modern pharmacological studies have revealed that Z. clinopodioides and its constituents exhibits neuroprotective effects in vitro and in vivo, and the mechanism of action is related to anti-apoptosis, anti-inflammatory, antioxidant, autophagy, endoplasmic reticulum stress and so on. Currently, there is limited research on the extracts of Z. clinopodioides and their potential mechanisms of action in these neurological disorders. It is also important to prioritize research on biosynthetic pathways and chemical modification approaches to fully explore and improve the neuroprotective potential of Z. clinopodioides and its flavonoids and establish a strong foundation for its clinical applications.

Substance basis and pharmacological mechanism of heat-clearing herbs in the treatment of ischaemic encephalopathy: a systematic review and network pharmacology

BACKGROUND AND OBJECTIVE

Ischaemic encephalopathy is a common cerebrovascular disease caused by insufficient blood supply to the cerebral vessels. The ischaemic encephalopathy is closely associated with the development of many chronic diseases such as obesity, hypertension and diabetes. Neurotrophic therapy has become the main therapeutic strategy for ischaemic encephalopathy. However, neurotrophic drugs only slightly recover the neurological function of patients, and their long-term efficacy is uncertain. Previous reports revealed that the active ingredients of natural medicines play important roles in the treatment of cerebral ischemia. In this study, we reviewed clearing herbs with anti-ischaemic encephalopathy functions using the data from quantitative statistical and network pharmacological exploration methods. We also discussed the different bioactive components and pharmacological effects of these herbs.

METHODS

First, we collected Chinese herbal prescriptions against ischaemic encephalopathy in four databases. Then, we statistically analysed the frequency of application of heat-clearing herbs to obtain the commonly used heat-clearing herbs against ischaemic encephalopathy, and classified them according to their efficacy according to the statistical results, to summarize the mechanism of anti-ischaemic effects of different bioactive components; Second, the network database was used to obtain the above components of heat-clearing Chinese medicines and their corresponding targets of action, disease targets of ischaemic stroke; Venny 2.1.0 was used to obtain component-disease target intersections; Cytoscape was used to construct the 'Drug-Active Ingredient-Target Network Graph '; DAVID was used for GO and KEGG enrichment analysis.

RESULTS

Literature and database screening involved 149 prescriptions, with a total of 269 flavours of Chinese medicines and 20 flavours of single-flavour heat-clearing Chinese medicines; The top nine in terms of frequency of use were Radix Paeoniae Rubra、Rehmanniae Radix Praeparata、Figwort Root、Cortex Moutan、Scutellariae Radix、Coptidis Rhizoma、Gardeniae Fructus、Cassiae Semen、Lonicerae Japonicae Flos. The common components obtained from network pharmacology were beta-sitosterol, quercetin, and stigmasterol, which mainly act on key targets such as RELA, AKT1, JUN, PRKACA, PTGS2, RAF1 and CHUK; and their active ingredients are mainly involved in signalling pathways such as Calcium, PI3K-Ak, MAPK, cAMP, IL-17, HIF-1, TNF, T-cell receptor, NF-kappa B and JAK-STAT.

CONCLUSIONS

Heat-clearing herbs are useful and promising for the protection against and prevention of ischemic encephalopathy. The results of the network pharmacological studies are similar to the mechanisms of anti-ischemic encephalopathy of the active ingredients of the purgative herbs we have listed; Thin either directly protects cerebrovascular tissues by improving vascular permeability and reducing the area of infarcted tissues, or produces protective effects through molecular signaling pathways. It can be seen that the components of heat-clearing Chinese medicines can exert cerebroprotective effects through multiple pathways, which provides us with a reference for further development and study of heat-clearing Chinese medicines in the treatment of ischemic cerebrovascular diseases.

Endothelial Dysfunctions in Blood-Brain Barrier Breakdown in Alzheimer's Disease: From Mechanisms to Potential Therapies

Recent research has shown the presence of blood-brain barrier (BBB) breakdown in Alzheimer's disease (AD). BBB is a dynamic interface consisting of a continuous monolayer of brain endothelial cells (BECs) enveloped by pericytes and astrocytes. The restricted permeability of BBB strictly controls the exchange of substances between blood and brain parenchyma, which is crucial for brain homeostasis by excluding blood-derived detrimental factors and pumping out brain-derived toxic molecules. BBB breakdown in AD is featured as a series of BEC pathologies such as increased paracellular permeability, abnormal levels and functions of transporters, and inflammatory or oxidative profile, which may disturb the substance transportation across BBB, thereafter induce CNS disorders such as hypometabolism, Aβ accumulation, and neuroinflammation, eventually aggravate cognitive decline. Therefore, it seems important to protect BEC properties for BBB maintenance and neuroprotection. In this review, we thoroughly summarized the pathological alterations of BEC properties reported in AD patients and numerous AD models, including paracellular permeability, influx and efflux transporters, and inflammatory and oxidative profiles, and probably associated underlying mechanisms. Then we reviewed current therapeutic agents that are effective in ameliorating a series of BEC pathologies, and ultimately protecting BBB integrity and cognitive functions. Regarding the current drug development for AD proceeds extremely hard, this review aims to discuss the therapeutic potentials of targeting BEC pathologies and BBB maintenance for AD treatment, therefore expecting to shed a light on the future AD drug development by targeting BEC pathologies and BBB protection.

Targeting ferroptosis in treating traumatic brain injury: Harnessing the power of traditional Chinese medicine

Traumatic brain injury (TBI) exhibits high prevalence and mortality, but current treatments remain suboptimal. Traditional Chinese medicine (TCM) has long been effectively used for TBI intervention. Moreover, the recently discovered iron-dependent cell death pathway, known as ferroptosis, characterized by lipid peroxidation, as a key target in TCM-based treatments for TBI. This review provides a comprehensive overview of the latest advancements in TCM strategies targeting ferroptosis in TBI therapy, covering natural product monomers, classic formulas, and acupuncture/moxibustion. The review also addresses current challenges and outlines future research directions to further advance the development and application of TBI management strategies.

Nrf2/Keap1/ARE regulation by plant secondary metabolites: a new horizon in brain tumor management

Brain cancer is regarded as one of the most life-threatening forms of cancer worldwide. Oxidative stress acts to derange normal brain homeostasis, thus is involved in carcinogenesis in brain. The Nrf2/Keap1/ARE pathway is an important signaling cascade responsible for the maintenance of redox homeostasis, and regulation of anti-inflammatory and anticancer activities by multiple downstream pathways. Interestingly, Nrf2 plays a somewhat, contradictory role in cancers, including brain cancer. Nrf2 has traditionally been regarded as a tumor suppressor since its cytoprotective functions are considered to be the principle cellular defense mechanism against exogenous and endogenous insults, such as xenobiotics and oxidative stress. However, hyperactivation of the Nrf2 pathway supports the survival of normal as well as malignant cells, protecting them against oxidative stress, and therapeutic agents. Plants possess a pool of secondary metabolites with potential chemotherapeutic/chemopreventive actions. Modulation of Nrf2/ARE and downstream activities in a Keap1-dependant manner, with the aid of plant-derived secondary metabolites exhibits promise in the management of brain tumors. Current article highlights the effects of Nrf2/Keap1/ARE cascade on brain tumors, and the potential role of secondary metabolites regarding the management of the same.

Flavonoids Derived from Chinese Medicine: Potential Neuroprotective Agents

Due to their complex pathological mechanisms, neurodegenerative diseases have brought great challenges to drug development and clinical treatment. Studies have shown that many traditional Chinese medicines have neuroprotective pharmacological activities such as anti-inflammatory and anti-oxidation properties and have certain effects on improving the symptoms of neurodegenerative diseases and delaying disease progression. Flavonoids are the main active components of many traditional Chinese medicines for the treatment of neurodegenerative diseases. These compounds have a wide range of biological activities, including anti-inflammatory, anti-oxidative stress, regulation of autophagy balance, inhibition of apoptosis, and promotion of neuronal regeneration. This paper focuses on the neuroprotective effects of six common flavonoids: quercetin, rutin, luteolin, kaempferol, baicalein, and puerarin. It then systematically reviews their characteristics, mechanisms, and key signaling pathways, summarizes the common characteristics and laws of their neuroprotective effects, and discusses the significance of strengthening the research on the neuroprotective effects of these compounds, aiming to provide reference for more research and drug development of these substances as neuroprotective drugs.

Ferroptosis in Ischemic Stroke and Related Traditional Chinese Medicines

Stroke is a severe neurological disorder resulting from the rupture or blockage of blood vessels, leading to significant mortality and disability worldwide. Among the different types of stroke, ischemic stroke (IS) is the most prevalent, accounting for 70-80% of cases. Cell death following IS occurs through various mechanisms, including apoptosis, necrosis, and ferroptosis. Ferroptosis, a recently identified form of regulated cell death characterized by iron overload and lipid peroxidation, was first described by Dixon in 2012. Currently, the only approved pharmacological treatment for IS is recombinant tissue plasminogen activator (rt-PA), which is limited by a narrow therapeutic window and often results in suboptimal outcomes. Recent research has identified several traditional Chinese medicines (TCMs) that can inhibit ferroptosis, thereby mitigating the damage caused by IS. This review provides an overview of stroke, the role of ferroptosis in IS, and the potential of certain TCMs to inhibit ferroptosis and contribute to stroke treatment.

Targeting Nrf2 signaling pathway: new therapeutic strategy for cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally, with oxidative stress (OS) identified as a primary contributor to their onset and progression. Given the elevated incidence and mortality rates associated with CVDs, there is an imperative need to investigate novel therapeutic strategies. Nuclear factor erythroid 2-related factor 2 (Nrf2), ubiquitously expressed in the cardiovascular system, has emerged as a promising therapeutic target for CVDs due to its role in regulating OS and inflammation. This review aims to delve into the mechanisms and actions of the Nrf2 pathway, highlighting its potential in mitigating the pathogenesis of CVDs.

A comprehensive and systematic review of the potential neuroprotective effect of quercetin in rat models of spinal cord injury

CONTEXT

Spinal cord injury (SCI) is a potentially fatal neurological disease with severe complications and a high disability rate. An increasing number of animal experimental studies support the therapeutic effect of quercetin, which is a natural anti-inflammatory and antioxidant bioflavonoid.

OBJECTIVE

This paper reviewed the therapeutic effect of quercetin on a rat SCI model and summarized the relevant mechanistic research.

DATA SOURCES

PubMed, EMBASE, Web of Science, Science Direct, WanFang Data, SinoMed databases, the China National Knowledge Infrastructure, and the Vip Journal Integration Platform were searched from their inception to April 2023 for animal experiments applying quercetin to treat SCI.

STUDY SELECTION

Based on the PICOS criteria, a total of 18 eligible studies were included, of which 14 were high quality.

RESULTS

In this study, there was a gradual increase in effect based on the Basso, Beattie, and Bresnahan (BBB) score after three days (p < 0.0001). Furthermore, gender differences also appeared in the efficacy of quercetin; males performed better than females (p = 0.008). Quercetin was also associated with improved inclined plane test score (p = 0.008). In terms of biochemical indicators, meta-analysis showed that MDA (p < 0.0001) and MPO (p = 0.0002) were significantly reduced after quercetin administration compared with the control group, and SOD levels were increased (p = 0.004). Mechanistically, quercetin facilitates the inhibition of oxidative stress, inflammation, autophagy and apoptosis that occur after SCI.

CONCLUSIONS

Generally, this systematic review suggests that quercetin has a neuroprotective effect on SCI.

Quercetin Modulates Ferroptosis via the SIRT1/Nrf-2/HO-1 Pathway and Attenuates Cartilage Destruction in an Osteoarthritis Rat Model

Osteoarthritis (OA) is the most common joint disease, causing symptoms such as joint pain, swelling, and deformity, which severely affect patients' quality of life. Despite advances in medical treatment, OA management remains challenging, necessitating the development of safe and effective drugs. Quercetin (QUE), a natural flavonoid widely found in fruits and vegetables, shows promise due to its broad range of pharmacological effects, particularly in various degenerative diseases. However, its role in preventing OA progression and its underlying mechanisms remain unclear. In this study, we demonstrated that QUE has a protective effect against OA development both in vivo and in vitro, and we elucidated the underlying molecular mechanisms. In vitro, QUE inhibited the expression of IL-1β-induced chondrocyte matrix metalloproteinases (MMP3 and MMP13) and inflammatory mediators such as INOS and COX-2. It also promoted the expression of collagen II, thereby preventing the extracellular matrix (ECM). Mechanistically, QUE exerts its protective effect on chondrocytes by activating the SIRT1/Nrf-2/HO-1 and inhibiting chondrocyte ferroptosis. Similarly, in an OA rat model induced by anterior cruciate ligament transection (ACLT), QUE treatment improved articular cartilage damage, reduced joint pain, and normalized abnormal subchondral bone remodeling. QUE also reduced serum IL-1β, TNF-α, MMP3, CTX-II, and COMP, thereby slowing the progression of OA. QUE exerts chondroprotective effects by inhibiting chondrocyte oxidative damage and ferroptosis through the SIRT1/Nrf-2/HO-1 pathway, effectively alleviating OA progression in rats.

Amplification of Cardioprotective Response of Remote Ischemic Preconditioning in Rats by Quercetin: Potential Role of Activation of mTOR-dependent Autophagy and Nrf2

OBJECTIVES

Noninvasive remote ischemic preconditioning (RIPC) is a practical, acceptable, and feasible conditioning technique reported to provide cardioprotection in myocardial ischemia-reperfusion injury (MIRI). It has been well-reported that quercetin possesses antioxidant and anti-inflammatory properties. This study investigates the modification of the cardioprotective response of RIPC by quercetin.

METHODS

Adult Wistar rats were randomized into 12 groups of six animals each. MIRI was induced by subjecting the isolated hearts of Wistar rats to global ischemia for 30 min, succeeded by reperfusion of 120 min after mounting on the Langendorff PowerLab apparatus. Hind limb RIPC was applied in four alternate cycles of ischemia and reperfusion of 5 min each by tying the pressure cuff before isolation of hearts.

RESULTS

MIRI was reflected by significantly increased infarct size, LDH-1, and CK-MB, TNF-α, TBARS, and decreased GSH, catalase, and hemodynamic index, and modulated Nrf2. Pretreatment of quercetin (25 and 50 mg/kg; i.p.) significantly attenuated the MIRI-induced cardiac damage and potentiated the cardioprotective response of RIPC at the low dose. Pretreatment of ketamine (10 mg/kg; i.p.), an mTOR-dependent autophagy inhibitor, significantly abolished the cardioprotective effects of quercetin and RIPC.

CONCLUSIONS

The findings highlight the modification of the cardioprotective effect of RIPC by quercetin and that quercetin protects the heart against MIRI through multiple mechanisms, including mTOR-dependent activation of autophagy and Nrf-2 activation.

New perspectives on the therapeutic potential of quercetin in non-communicable diseases: Targeting Nrf2 to counteract oxidative stress and inflammation

Non-communicable diseases (NCDs), including cardiovascular diseases, cancer, metabolic diseases, and skeletal diseases, pose significant challenges to public health worldwide. The complex pathogenesis of these diseases is closely linked to oxidative stress and inflammatory damage. Nuclear factor erythroid 2-related factor 2 (Nrf2), a critical transcription factor, plays an important role in regulating antioxidant and anti-inflammatory responses to protect the cells from oxidative damage and inflammation-mediated injury. Therefore, Nrf2-targeting therapies hold promise for preventing and treating NCDs. Quercetin (Que) is a widely available flavonoid that has significant antioxidant and anti-inflammatory properties. It modulates the Nrf2 signaling pathway to ameliorate oxidative stress and inflammation. Que modulates mitochondrial function, apoptosis, autophagy, and cell damage biomarkers to regulate oxidative stress and inflammation, highlighting its efficacy as a therapeutic agent against NCDs. Here, we discussed, for the first time, the close association between NCD pathogenesis and the Nrf2 signaling pathway, involved in neurodegenerative diseases (NDDs), cardiovascular disease, cancers, organ damage, and bone damage. Furthermore, we reviewed the availability, pharmacokinetics, pharmaceutics, and therapeutic applications of Que in treating NCDs. In addition, we focused on the challenges and prospects for its clinical use. Que represents a promising candidate for the treatment of NCDs due to its Nrf2-targeting properties.

Quercetin improves the protection of hydroxysafflor yellow a against cerebral ischemic injury by modulating of blood-brain barrier and src-p-gp-mmp-9 signalling

Protection of the structural and functional integrity of the blood-brain barrier (BBB) is crucial for treating ischemic stroke (IS). Hydroxysafflor yellow A (HSYA) and quercetin (Quer), two main active components in the edible and medicinal plant Carthamus tinctorius L., have been reported to exhibit neuroprotective effects. We investigated the anti-IS and BBB-protective properties of HSYA and Quer and the underlying mechanisms. They decreased neurological deficits in middle cerebral artery occlusion (MCAO) mice, while their combination showed better effects. Importantly, HSYA and Quer ameliorated BBB permeability. Their effects on reduction of both EB leakage and infarct volume were similar, which may contribute to improved locomotor activities. Moreover, HSYA and Quer showed protective effects for hCMEC/D3 monolayer against oxygen-glucose deprivation. Src, p-Src, MMP-9, and P-gp were associated with ingredients treatments. Furthermore, molecular docking and molecular dynamics simulations revealed stable and tight binding modes of ingredients with Src and P-gp. The current study supports the potential role of HSYA, Quer, and their combination in the treatment of IS by regulating BBB integrity.

Exploring the therapeutic potential of quercetin: A focus on its sirtuin-mediated benefits

As the global population ages, preventing lifestyle- and aging-related diseases is increasing, necessitating the search for safe and affordable therapeutic interventions. Among nutraceuticals, quercetin, a flavonoid ubiquitously present in various plants, has garnered considerable interest. This review aimed to collate and analyze existing literature on the therapeutic potentials of quercetin, especially its interactions with SIRTs and its clinical applicability based on its bioavailability and safety. This narrative review was based on a literature survey spanning from 2015 to 2023 using PUBMED. The keywords and MeSH terms used were: "quercetin" AND "bioavailability" OR "metabolism" OR "metabolites" as well as "quercetin" AND "SIRTuin" OR "SIRT*" AND "cellular effects" OR "pathway" OR "signaling" OR "neuroprotective" OR "cardioprotective" OR "nephroprotective" OR "antiatherosclerosis" OR "diabetes" OR "antidiabetic" OR "dyslipidemia" AND "mice" OR "rats". Quercetin demonstrates multiple therapeutic activities, including neuroprotective, cardioprotective, and anti-atherosclerotic effects. Its antioxidant, anti-inflammatory, antiviral, and immunomodulatory properties are well-established. At a molecular level, it majorly interacts with SIRTs, particularly SIRT1 and SIRT6, and modulates numerous signaling pathways, contributing to its therapeutic effects. These pathways play roles in reducing oxidative stress, inflammation, autophagy regulation, mitochondrial biogenesis, glucose utilization, fatty acid oxidation, and genome stability. However, clinical trials on quercetin's effectiveness in humans are scarce. Quercetin exhibits a wide range of SIRT-mediated therapeutic effects. Despite the compelling preclinical data, more standardized clinical trials are needed to fully understand its therapeutic potential. Future research should focus on addressing its bioavailability and safety concerns.

Novel insight into the therapeutical potential of flavonoids from traditional Chinese medicine against cerebral ischemia/reperfusion injury

Cerebral ischemia/reperfusion injury (CIRI) is a major contributor to poor prognosis of ischemic stroke. Flavonoids are a broad family of plant polyphenols which are abundant in traditional Chinese medicine (TCM) and have beneficial effects on several diseases including ischemic stroke. Accumulating studies have indicated that flavonoids derived from herbal TCM are effective in alleviating CIRI after ischemic stroke in vitro or in vivo, and exhibit favourable therapeutical potential. Herein, we systematically review the classification, metabolic absorption, neuroprotective efficacy, and mechanisms of TCM flavonoids against CIRI. The literature suggest that flavonoids exert potential medicinal functions including suppressing excitotoxicity, Ca2+ overloading, oxidative stress, inflammation, thrombin's cellular toxicity, different types of programmed cell deaths, and protecting the blood-brain barrier, as well as promoting neurogenesis in the recovery stage following ischemic stroke. Furthermore, we identified certain matters that should be taken into account in future research, as well as proposed difficulties and opportunities in transforming TCM-derived flavonoids into medications or functional foods for the treatment or prevention of CIRI. Overall, in this review we aim to provide novel ideas for the identification of new prospective medication candidates for the therapeutic strategy against ischemic stroke.

Progress in discovery and development of natural inhibitors of histone deacetylases (HDACs) as anti-cancer agents

The study of epigenetic translational modifications had drawn great interest for the last few decades. These processes play a vital role in many diseases and cancer is one of them. Histone acetyltransferase (HAT) and histone deacetylases (HDACs) are key enzymes involved in the acetylation and deacetylation of histones and ultimately in post-translational modifications. Cancer frequently exhibits epigenetic changes, particularly disruption in the expression and activity of HDACs. It includes the capacity to regulate proliferative signalling, circumvent growth inhibitors, escape cell death, enable replicative immortality, promote angiogenesis, stimulate invasion and metastasis, prevent immunological destruction, and genomic instability. The majority of tumours develop and spread as a result of HDAC dysregulation. As a result, HDAC inhibitors (HDACis) were developed, and they today stand as a very promising therapeutic approach. One of the most well-known and efficient therapies for practically all cancer types is chemotherapy. However, the efficiency and safety of treatment are constrained by higher toxicity. The same has been observed with the synthetic HDACi. Natural products, owing to many advantages over synthetic compounds for cancer treatment have always been a choice for therapy. Hence, naturally available molecules are of particular interest for HDAC inhibition and HDAC has drawn the attention of the research fraternity due to their potential to offer a diverse array of chemical structures and bioactive compounds. This diversity opens up new avenues for exploring less toxic HDAC inhibitors to reduce side effects associated with conventional synthetic inhibitors. The review presents comprehensive details on natural product HDACi, their mechanism of action and their biological effects. Moreover, this review provides a brief discussion on the structure activity relationship of selected natural HDAC inhibitors and their analogues which can guide future research to discover selective, more potent HDACi with minimal toxicity.

Quercetin attenuates cerebral ischemic injury by inhibiting ferroptosis via Nrf2/HO-1 signaling pathway

AIMS

Ischemic stroke is a severe cerebrovascular disease in which neuronal death continually occurs through multiple forms, including apoptosis, autophagy, pyroptosis and ferroptosis. Quercetin (QRC), as a natural flavonoid compound, has been reported to have pharmacological effects on ischemic injury accompanied by unclear anti-ferroptotic mechanisms. This study is designed to investigate the therapeutic effects of QRC against ferroptosis in ischemic stroke.

MATERIALS AND METHODS

In vivo, the model of MCAO rats were used to assess the protective effect of QRC on cerebral ischemic. Additionally, we constructed oxidative stressed and ferroptotic cell models to explore the effects and mechanisms of QRC on ferroptosis. The related proteins were analysed by western blotting, immunohistochemical and immunofluorescence techniques.

RESULTS

The experiments demonstrated that QRC improves neurological deficits, infarct volume, and pathological features in MCAO rats, also increased the viability of HT-22 cells exposed to H2O2 and erastin. These results, including MDA, SOD, GSH, ROS levels and iron accumulation, indicated that QRC suppresses the generation of lipid peroxides and may involve in the regulatory of ferroptosis. Both in vitro and in vivo, QRC was found to inhibit ferroptosis by up-regulating GPX4 and FTH1, as well as down-regulating ACSL4. Furthermore, we observed that QRC enhances the nuclear translocation of Nrf2 and activates the downstream antioxidative proteins. Importantly, the effect of QRC on ferroptosis can be reversed by the Nrf2 inhibitor ML385.

CONCLUSIONS

This study provides evidence that QRC has a neuroprotective effect by inhibiting ferroptosis, demonstrating the therapeutic potential for cerebral ischemic stroke.

Lycopene alleviates oxidative stress-induced cell injury in human vascular endothelial cells by encouraging the SIRT1/Nrf2/HO-1 pathway

BACKGROUND AND OBJECTIVE

Epidemiological research have displayed that dietary intake rich in lycopene, an antioxidant, is negatively correlated with the risk of cardiovascular disease (CVD). This study aimed to investigate whether the intervention with different concentrations of lycopene could attenuate H₂O₂-induced oxidative stress injury in human vascular endothelial cells (VECs).

METHODS

The human VECs HMEC-1 and ECV-304 were incubated with a final concentration of 300 µmol/L H₂O₂, followed by they were incubated with lycopene at doses of 0.5, 1, or 2 µm. Subsequently, cell proliferation, cytotoxicity, cell adhesion, reactive oxygen species (ROS) contents, adhesion molecule expression, oxidative stress levels, pro-inflammatory factor production, the apoptosis protein levels, and the silent information regulator-1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway protein levels were tested by CCK-8 kit, lactate dehydrogenase (LDH) kit, immunofluorescence labeling, cell surface enzyme immunoassays (EIA), enzyme-linked immunosorbent assay (ELISA), as well as Western blot assays, respectively.

RESULTS

Under H₂O₂ stimulation, HMEC-1 and ECV-304 cell proliferation and the SIRT1/Nrf2/HO-1 pathway protein expression were significantly reduced, whereas cytotoxicity, apoptosis, cell adhesion molecule expression, pro-inflammatory and oxidative stress factors production were apparently encouraged, which were partially countered by lycopene intervention in a dose-dependent manner.

CONCLUSION

Lycopene alleviates H₂O₂-induced oxidative damage in human VECs by reducing intracellular ROS levels, inflammatory factor production, cell adhesiveness, and apoptosis rate under oxidative stress conditions through activation of the SIRT1/Nrf2/HO-1 pathway.

Quercetin improves cerebral ischemia/reperfusion injury by promoting microglia/macrophages M2 polarization via regulating PI3K/Akt/NF-κB signaling pathway

The modulation of microglial polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype shows promise as a therapeutic strategy for ischemic stroke. Quercetin, a natural flavonoid abundant in various plants, possesses anti-inflammatory, anti-apoptotic, and antioxidant properties. Nevertheless, its effect and underlying mechanism on microglia/macrophages M1/M2 polarization in the treatment of cerebral ischemia/reperfusion injury (CI/RI) remain poorly explored. In the current study, we observed that quercetin ameliorated neurological deficits, reduced infarct volume, decreased the number of M1 microglia/macrophages (CD16/32+/Iba1+), and enhanced the number of M2 microglia/macrophages (CD206+/Iba1+) after establishing the CI/RI model in rats. Subsequent in vivo and in vitro experiments indicated that quercetin downregulated M1 markers (CD86, iNOS, TNF-α, IL-1β, and IL-6) and upregulated M2 markers (CD206, Arg-1, IL-10, and TGF-β). Network pharmacology analysis and molecular docking revealed that the PI3K/Akt/NF-κB signaling pathway emerged as the core pathway. Western blot confirmed that quercetin upregulated the phosphorylation of PI3K and Akt, while alleviating the phosphorylation of IκBα and NF-κB both in vivo and in vitro. However, the PI3K inhibitor LY294002 reversed the effects of quercetin on M2 polarization and the expression of key proteins in the PI3K/Akt/NF-κB pathway in primary microglia after oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. Collectively, our findings demonstrate that quercetin facilitates microglia/macrophages M2 polarization by modulating the PI3K/Akt/NF-κB signaling pathway in the treatment of CI/RI. These findings provide novel insights into the therapeutic mechanisms of quercetin in ischemic stroke.

Targeting Nrf2 signaling pathway by quercetin in the prevention and treatment of neurological disorders: An overview and update on new developments

BACKGROUND

Neurological disorders (NLDs) are widely acknowledged as a significant public health concern worldwide. Stroke, Alzheimer's disease (AD), and traumatic brain injury (TBI) are three of these disorders that have sparked major study attention. Neurological dysfunction, protein buildup, oxidation and neuronal injury, and aberrant mitochondria are all prevalent neuropathological hallmarks of these disorders. The signaling cascade of nuclear factor erythroid 2 related factor 2 (Nrf2) shares all of them as a common target. Several studies have found that overexpression of Nrf2 is a promising treatment method in NLDs. Effective treatment of these disorders continues to be a universal concern regardless of various medicines. In order to treat a variety of neurological problems, organic remedies may provide an alternative treatment. It has been demonstrated that polyphenols like quercetin (Que) offer considerable capabilities for treating NLDs. One of Que's greatest key targets, Nrf2, has the capacity to control the production of a number of cytoprotective enzymes that exhibit neuroprotective, detoxifying, and antioxidative effects. Additionally, Que enhanced the expression of Nrf2 and inhibited alterations in the shape and death of neurons in the hippocampus.

OBJECTIVE

In this review, we have focused on Que's medicinal prospects as a neuroprotective drug.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar were used to search articles for this study.

RESULTS

The findings of this research demonstrate that (1) Que protected the blood-brain barrier via stimulating Nrf2 in animal stroke, which alleviated ischemic reperfusion and motor dysfunction. (2) By triggering the Nrf2 pathway, Que reduced the neuroinflammation and oxidative damage brought on by TBI in the cortex. (3) In an experimental model of AD, Que enhanced cognitive function by decreasing A1-4, antioxidant activity, and Nrf2 levels in the brain.

CONCLUSION

We discuss recent research on Que-mediated Nrf2 expression in the management of several NLDs in this paper.

Astragaloside IV promotes angiogenesis by targeting SIRT7/VEGFA signaling pathway to improve brain injury after cerebral infarction in rats

Cerebral infarction (CI) has become one of the leading causes of death and acquired disability worldwide. Astragaloside IV (AST IV), one of the basic components of Astragalus membranaceus, has a protective effect on CI. However, the underlying mechanism has not been conclusively elucidated. Therefore, this study aims to explore the underlying mechanism of AST IV improving brain injury after CI. Middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R) were used to simulate cerebral infarction injury in SD rats and HUVECs cells. Neurologic score, Evans blue, TTC and HE staining were used to observe brain injury in rats. Cell viability and migration were measured in vitro. Angiogenesis was detected by immunofluorescence and tube formation assay, and cell cycle was detected by flow cytometry. Western blot was used to find the expression of related proteins. Molecular docking, virtual mutation, site-directed mutagenesis, MST, and lentivirus silencing were used for target validation. The results showed that AST IV alleviated neurological impairment and promoted angiogenesis after CI. Moreover, AST IV greatly increased the transcription levels of SIRT6 and SIRT7, but had no effect on SIRT1-SIRT5, and promoted cell viability, migration, angiogenesis and S phase ratio in OGD/R-induced HUVECs. Furthermore, AST IV up-regulated the protein expressions of CDK4, cyclin D1, VEGFA and VEGF2R. Interestingly, AST IV not only bound to SIRT7, but also increased the expression of SIRT7. Silencing SIRT7 by lentivirus neutralizes the positive effects of AST IV. Taken together, the present study revealed that AST IV may improve brain tissue damage after CI by targeting SIRT7/VEGFA signaling pathway to promote angiogenesis.

Potential Role of Natural Antioxidants in Countering Reperfusion Injury in Acute Myocardial Infarction and Ischemic Stroke

Stroke and acute myocardial infarction are leading causes of mortality worldwide. The latter accounts for approximately 9 million deaths annually. In turn, ischemic stroke is a significant contributor to adult physical disability globally. While reperfusion is crucial for tissue recovery, it can paradoxically exacerbate damage through oxidative stress (OS), inflammation, and cell death. Therefore, it is imperative to explore diverse approaches aimed at minimizing ischemia/reperfusion injury to enhance clinical outcomes. OS primarily arises from an excessive generation of reactive oxygen species (ROS) and/or decreased endogenous antioxidant potential. Natural antioxidant compounds can counteract the injury mechanisms linked to ROS. While promising preclinical results, based on monotherapies, account for protective effects against tissue injury by ROS, translating these models into human applications has yielded controversial evidence. However, since the wide spectrum of antioxidants having diverse chemical characteristics offers varied biological actions on cell signaling pathways, multitherapy has emerged as a valuable therapeutic resource. Moreover, the combination of antioxidants in multitherapy holds significant potential for synergistic effects. This study was designed with the aim of providing an updated overview of natural antioxidants suitable for preventing myocardial and cerebral ischemia/reperfusion injuries.

Role of traditional Chinese medicine monomers in cerebral ischemia/reperfusion injury:a review of the mechanism

Ischemia/reperfusion (I/R) injury is a pathological process wherein reperfusion of an ischemic organ or tissue exacerbates the injury, posing a significant health threat and economic burden to patients and their families. I/R triggers a multitude of physiological and pathological events, such as inflammatory responses, oxidative stress, neuronal cell death, and disruption of the blood-brain barrier (BBB). Hence, the development of effective therapeutic strategies targeting the pathological processes resulting from I/R is crucial for the rehabilitation and long-term enhancement of the quality of life in patients with cerebral ischemia/reperfusion injury (CIRI). Traditional Chinese medicine (TCM) monomers refer to bioactive compounds extracted from Chinese herbal medicine, possessing anti-inflammatory and antioxidative effects, and the ability to modulate programmed cell death (PCD). TCM monomers have emerged as promising candidates for the treatment of CIRI and its subsequent complications. Preclinical studies have demonstrated that TCM monomers can enhance the recovery of neurological function following CIRI by mitigating oxidative stress, suppressing inflammatory responses, reducing neuronal cell death and functional impairment, as well as minimizing cerebral infarction volume. The neuroprotective effects of TCM monomers on CIRI have been extensively investigated, and a comprehensive understanding of their mechanisms can pave the way for novel approaches to I/R treatment. This review aims to update and summarize evidence of the protective effects of TCMs in CIRI, with a focus on their role in modulating oxidative stress, inflammation, PCD, glutamate excitotoxicity, Ca2+ overload, as well as promoting blood-brain barrier repairment and angiogenesis. The main objective is to underscore the significant contribution of TCM monomers in alleviating CIRI.

Natural Phytochemicals as SIRT Activators-Focus on Potential Biochemical Mechanisms

Sirtuins are a family of proteins with enzymatic activity. There are seven mammalian sirtuins (SIRT1-SIRT7) that are found in different cellular compartments. They are a part of crucial cellular pathways and are regulated by many factors, such as chemicals, environmental stress, and phytochemicals. Several in vitro and in vivo studies have presented their involvement in anti-inflammatory, antioxidant, and antiapoptotic processes. Recent findings imply that phytochemicals such as resveratrol, curcumin, quercetin, fisetin, berberine, and kaempferol may regulate the activity of sirtuins. Resveratrol mainly activates SIRT1 and indirectly activates AMPK. Curcumin influences mainly SIRT1 and SIRT3, but its activity is broad, and many pathways in different cells are affected. Quercetin mainly modulates SIRT1, which triggers antioxidant and antiapoptotic responses. Fisetin, through SIRT1 regulation, modifies lipid metabolism and anti-inflammatory processes. Berberine has a wide spectrum of effects and a significant impact on SIRT1 signaling pathways. Finally, kaempferol triggers anti-inflammatory and antioxidant effects through SIRT1 induction. This review aims to summarize recent findings on the properties of phytochemicals in the modulation of sirtuin activity, with a particular focus on biochemical aspects.

New insights into Sirt1: potential therapeutic targets for the treatment of cerebral ischemic stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, the majority of patients are currently unable to benefit from intravenous thrombolysis or intravascular mechanical thrombectomy due to the limited treatment windows and serious complications. Silent mating type information regulation 2 homolog 1 (Sirt1), a nicotine adenine dinucleotide-dependent enzyme, has emerged as a potential therapeutic target for ischemic stroke due to its ability to maintain brain homeostasis and possess neuroprotective properties in a variety of pathological conditions for the central nervous system. Animal and clinical studies have shown that activation of Sirt1 can lessen neurological deficits and reduce the infarcted volume, offering promise for the treatment of ischemic stroke. In this review, we summarized the direct evidence and related mechanisms of Sirt1 providing neuroprotection against cerebral ischemic stroke. Firstly, we introduced the protein structure, catalytic mechanism and specific location of Sirt1 in the central nervous system. Secondly, we list the activators and inhibitors of Sirt1, which are primarily divided into three categories: natural, synthetic and physiological. Finally, we reviewed the neuroprotective effects of Sirt1 in ischemic stroke and discussed the specific mechanisms, including reducing neurological deficits by inhibiting various programmed cell death such as pyroptosis, necroptosis, ferroptosis, and cuproptosis in the acute phase, as well as enhancing neurological repair by promoting angiogenesis and neurogenesis in the later stage. Our review aims to contribute to a deeper understanding of the critical role of Sirt1 in cerebral ischemic stroke and to offer novel therapeutic strategies for this condition.

Apitherapy in Post-Ischemic Brain Neurodegeneration of Alzheimer's Disease Proteinopathy: Focus on Honey and Its Flavonoids and Phenolic Acids

Neurodegeneration of the brain after ischemia is a major cause of severe, long-term disability, dementia, and mortality, which is a global problem. These phenomena are attributed to excitotoxicity, changes in the blood-brain barrier, neuroinflammation, oxidative stress, vasoconstriction, cerebral amyloid angiopathy, amyloid plaques, neurofibrillary tangles, and ultimately neuronal death. In addition, genetic factors such as post-ischemic changes in genetic programming in the expression of amyloid protein precursor, β-secretase, presenilin-1 and -2, and tau protein play an important role in the irreversible progression of post-ischemic neurodegeneration. Since current treatment is aimed at preventing symptoms such as dementia and disability, the search for causative therapy that would be helpful in preventing and treating post-ischemic neurodegeneration of Alzheimer's disease proteinopathy is ongoing. Numerous studies have shown that the high contents of flavonoids and phenolic acids in honey have antioxidant, anti-inflammatory, anti-apoptotic, anti-amyloid, anti-tau protein, anticholinesterase, serotonergic, and AMPAK activities, influencing signal transmission and neuroprotective effects. Notably, in many preclinical studies, flavonoids and phenolic acids, the main components of honey, were also effective when administered after ischemia, suggesting their possible use in promoting recovery in stroke patients. This review provides new insight into honey's potential to prevent brain ischemia as well as to ameliorate damage in advanced post-ischemic brain neurodegeneration.

Exploitation of Quercetin's Antioxidative Properties in Potential Alternative Therapeutic Options for Neurodegenerative Diseases

Oxidative stress (OS) is a condition in which there is an excess of reactive oxygen species (ROS) in the body, which can lead to cell and tissue damage. This occurs when there is an overproduction of ROS or when the body's antioxidant defense systems are overwhelmed. Quercetin (Que) is part of a group of compounds called flavonoids. It is found in high concentrations in vegetables, fruits, and other foods. Over the past decade, a growing number of studies have highlighted the therapeutic potential of flavonoids to modulate neuronal function and prevent age-related neurodegeneration. Therefore, Que has been shown to have antioxidant, anticancer, and anti-inflammatory properties, both in vitro and in vivo. Due to its antioxidant character, Que alleviates oxidative stress, thus improving cognitive function, reducing the risk of neurodegenerative diseases. On the other hand, Que can also help support the body's natural antioxidant defense systems, thus being a potentially practical supplement for managing OS. This review focuses on experimental studies supporting the neuroprotective effects of Que in Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and epilepsy.

A Mango Leaf Extract (Zynamite®) Combined with Quercetin Has Exercise-Mimetic Properties in Human Skeletal Muscle

Zynamite PX^®, a mango leaf extract combined with quercetin, enhances exercise performance by unknown molecular mechanisms. Twenty-five volunteers were assigned to a control (17 males) or supplementation group (8 males, receiving 140 mg of Zynamite^® + 140 mg quercetin/8 h for 2 days). Then, they performed incremental exercise to exhaustion (IE) followed by occlusion of the circulation in one leg for 60 s. Afterwards, the cuff was released, and a 30 s sprint was performed, followed by 90 s circulatory occlusion (same leg). Vastus lateralis muscle biopsies were obtained at baseline, 20 s after IE (occluded leg) and 10 s after Wingate (occluded leg), and bilaterally at 90 s and 30 min post exercise. Compared to the controls, the Zynamite PX^® group showed increased basal protein expression of Thr²⁸⁷-CaMKIIδ_D (2-fold, p = 0.007) and Ser⁹-GSK3β (1.3-fold, p = 0.005) and a non-significant increase of total NRF2 (1.7-fold, p = 0.099) and Ser⁴⁰-NRF2 (1.2-fold, p = 0.061). In the controls, there was upregulation with exercise and recovery of total NRF2, catalase, glutathione reductase, and Thr²⁸⁷-CaMKIIδ_D (1.2-2.9-fold, all p < 0.05), which was not observed in the Zynamite PX^® group. In conclusion, Zynamite PX^® elicits muscle signaling changes in resting skeletal muscle resembling those described for exercise training and partly abrogates the stress kinases responses to exercise as observed in trained muscles.

Phenylboronic Ester-Bridged Chitosan/Myricetin Nanomicelle for Penetrating the Endothelial Barrier and Regulating Macrophage Polarization and Inflammation against Ischemic Diseases

The brain and liver are more susceptible to ischemia and reperfusion (IR) injury (IRI), which triggers the reactive oxygen species (ROS) burst and inflammatory cascade and results in severe neuronal damage or hepatic injury. Moreover, the damaged endothelial barrier contributes to proinflammatory activity and limits the delivery of therapeutic agents such as some macromolecules and nanomedicine despite the integrity being disrupted after IRI. Herein, we constructed a phenylboronic-decorated chitosan-based nanoplatform to deliver myricetin, a multifunctional polyphenol molecule for the treatment of cerebral and hepatic ischemia. The chitosan-based nanostructures are widely studied cationic carriers for endothelium penetration such as the blood-brain barrier (BBB) and sinusoidal endothelial barrier (SEB). The phenylboronic ester was chosen as the ROS-responsive bridging segment for conjugation and selective release of myricetin molecules, which meanwhile scavenged the overexpressed ROS in the inflammatory environment. The released myricetin molecules fulfill a variety of roles including antioxidation through multiple phenolic hydroxyl groups, inhibition of the inflammatory cascade by regulation of the macrophage polarization from M1 to M2, and endothelial injury repairment. Taken together, our present study provides valuable insight into the development of efficient antioxidant and anti-inflammatory platforms for potential application against ischemic disease.

Targeting Oxidative Stress with Polyphenols to Fight Liver Diseases

Reactive oxygen species (ROS) are important second messengers in many metabolic processes and signaling pathways. Disruption of the balance between ROS generation and antioxidant defenses results in the overproduction of ROS and subsequent oxidative damage to biomolecules and cellular components that disturb cellular function. Oxidative stress contributes to the initiation and progression of many liver pathologies such as ischemia-reperfusion injury (LIRI), non-alcoholic fatty liver disease (NAFLD), and hepatocellular carcinoma (HCC). Therefore, controlling ROS production is an attractive therapeutic strategy in relation to their treatment. In recent years, increasing evidence has supported the therapeutic effects of polyphenols on liver injury via the regulation of ROS levels. In the current review, we summarize the effects of polyphenols, such as quercetin, resveratrol, and curcumin, on oxidative damage during conditions that induce liver injury, such as LIRI, NAFLD, and HCC.

Sirt1 Overexpression Inhibits Fibrous Scar Formation and Improves Functional Recovery After Cerebral Ischemic Injury Through the Deacetylation of 14-3-3ζ

Cerebral ischemic stroke is one of the leading causes of human death. The fibrous scar is one of major factors influencing repair in central nervous system (CNS) injury. Silencing information regulator 2-related enzyme 1 (Sirt1) can regulate peripheral tissue and organ fibrosis. However, it is unclear how the fibrous scar forms and is regulated and it is unknown whether and how Sirt1 regulates the formation of the fibrous scar after cerebral ischemic stroke. Therefore, in the present study, we examined the effects of Sirt1 on the formation of the fibrotic scar after middle cerebral artery occlusion/reperfusion (MCAO/R) injury in vivo and on the transforming growth factor β1 (TGF-β1)-induced meningeal fibroblast fibrotic response in vitro, and we explored the molecular mechanisms underlying the Sirt1-regulated fibrosis process in vitro. We found that MCAO/R injury induced fibrotic scar formation in the ischemic area, which was accompanied by the downregulation of Sirt1 expression. The overexpression of Sirt1 reduced the infarct volume, improved Nissl body structure and reduced neurons injury, attenuated formation of fibrotic scar, upregulated growth associated protein43 (GAP43) and synaptophysin (SYP) expression, and promoted neurological function recovery. Similarly, Sirt1 expression was also downregulated in the TGF-β1-induced fibrosis model. Sirt1 overexpression inhibited fibroblast migration, proliferation, transdifferentiation into myofibroblasts, and secretion of extracellular matrix(ECM) by regulating the deacetylation of lysine at K49 and K120 sites of 14-3-3ζ in vitro. Therefore, we believe that Sirt1 could regulate fibrous scar formation and improve neurological function after cerebral ischemic stroke through regulating deacetylation of 14-3-3ζ.

Quercetin alleviates subarachnoid hemorrhage-induced early brain injury via inhibiting ferroptosis in the rat model

Early brain injury (EBI) refers to a series of pathophysiological brain lesions that occur within 72 hr after subarachnoid hemorrhage (SAH), which is an extremely crucial factor in the poor prognosis of patients. In EBI, ferroptosis has been proven to cause neuronal death. Quercetin (QCT) is effective in deactivating reactive oxygen species (ROS), inhibiting lipid peroxidation, and even chelating iron, but its role in SAH remains unclear. In this study, the mortality rate, severity grade of SAH, brain water content (BWC), blood-brain barrier permeability, and neurological function of the rats were detected. Moreover, mitochondrial morphology in cortical neurons were observed and their sizes were subsequently quantified. The levels of lipid peroxidation on glutathione and malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) were determined, whereas the protein expressions of glutathione peroxidase 4 (GPX4), SLC7A11 (xCT), transferrin receptor 1 (TfR1), and ferroportin-1 (FPN1) were analyzed by western immunoblotting. The neurodegeneration involved in EBI was investigated by fluoro-Jade C staining, while iron staining was utilized to measure iron content. Our results showed that inhibition of ferroptosis by QCT could suppress EBI and improve neurological function in SAH rats. QCT increased the expression levels of GPX4, xCT, and FPN1, while downregulated TfR1, and exerted protective effects on neurons as well as alleviated iron accumulation and lipid peroxidation in the cortex of SAH rats. In conclusion, our study revealed that QCT might alleviate the EBI by inhibiting ferroptosis in SAH rats.

Natural Products as Modulators of Nrf2 Signaling Pathway in Neuroprotection

Neurodegenerative diseases (NDs) affect the West due to the increase in life expectancy. Nervous cells accumulate oxidative damage, which is one of the factors that triggers and accelerates neurodegeneration. However, cells have mechanisms that scavenge reactive oxygen species (ROS) and alleviate oxidative stress (OS). Many of these endogenous antioxidant systems are regulated at the gene expression level by the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In the presence of prooxidant conditions, Nrf2 translocates to the nucleus and induces the transcription of genes containing ARE (antioxidant response element). In recent years, there has been an increase in the study of the Nrf2 pathway and the natural products that positively regulate it to reduce oxidative damage to the nervous system, both in in vitro models with neurons and microglia subjected to stress factors and in vivo models using mainly murine models. Quercetin, curcumin, anthocyanins, tea polyphenols, and other less studied phenolic compounds such as kaempferol, hesperetin, and icariin can also modulate Nrf2 by regulating several Nrf2 upstream activators. Another group of phytochemical compounds that upregulate this pathway are terpenoids, including monoterpenes (aucubin, catapol), diterpenes (ginkgolides), triterpenes (ginsenosides), and carotenoids (astaxanthin, lycopene). This review aims to update the knowledge on the influence of secondary metabolites of health interest on the activation of the Nrf2 pathway and their potential as treatments for NDs.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.

Stroke: Molecular mechanisms and therapies: Update on recent developments

Stroke, a neurological disease, is one of the leading causes of death worldwide, resulting in long-term disability in most survivors. Annual stroke costs in the United States alone were estimated at $46 billion recently. Stroke pathophysiology is complex, involving multiple causal factors, among which atherosclerosis, thrombus, and embolus are prevalent. The molecular mechanisms involved in the pathophysiology are essential to understanding targeted drug development. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress, and neuroinflammation. In addition, various modifiable and non-modifiable risk factors increase the chances of stroke manifolds. Once a patient encounters a stroke, complete restoration of motor ability and cognitive skills is often rare. Therefore, shaping therapeutic strategies is paramount for finding a viable therapeutic agent. Apart from tPA, an FDA-approved therapy that is applied in most stroke cases, many other therapeutic strategies have been met with limited success. Stroke therapies often involve a combination of multiple strategies to restore the patient's normal function. Certain drugs like Gamma-aminobutyric receptor agonists (GABA), Glutamate Receptor inhibitors, Sodium, and Calcium channel blockers, and fibrinogen-depleting agents have shown promise in stroke treatment. Recently, a drug, DM199, a recombinant (synthetic) form of a naturally occurring protein called human tissue kallikrein-1 (KLK1), has shown great potential in treating stroke with fewer side effects. Furthermore, DM199 has been found to overcome the limitations presented when using tPA and/or mechanical thrombectomy. Cell-based therapies like Neural Stem Cells, Hematopoietic stem cells (HSCs), and Human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) are also being explored as a treatment of choice for stroke. These therapeutic agents come with merits and demerits, but continuous research and efforts are being made to develop the best therapeutic strategies to minimize the damage post-stroke and restore complete neurological function in stroke patients.

Targeted Mitochondrial Drugs for Treatment of Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is a complex hemodynamic pathology that is a leading cause of death worldwide and occurs in many body organs. Numerous studies have shown that mitochondria play an important role in the occurrence mechanism of ischemia-reperfusion injury and that mitochondrial structural abnormalities and dysfunction lead to the disruption of the homeostasis of the whole mitochondria. At this time, mitochondria are not just sub-organelles to produce ATP but also important targets for regulating ischemia-reperfusion injury; therefore, drugs targeting mitochondria can serve as a new strategy to treat ischemia-reperfusion injury. Based on this view, in this review, we discuss potential therapeutic agents for both mitochondrial structural abnormalities and mitochondrial dysfunction, highlighting the application and prospects of targeted mitochondrial drugs in the treatment of ischemia-reperfusion injury, and try to provide new ideas for the clinical treatment of the ischemia-reperfusion injury.

Quercetin's Effects on Glutamate Cytotoxicity

The potentially therapeutic effects of the naturally abundant plant flavonoid quercetin have been extensively studied. An extensive body of literature suggests that quercetin's powerful antioxidant effects may relate to its ability to treat disease. Glutamate excitotoxicity occurs when a neuron is overstimulated by the neurotransmitter glutamate and causes dysregulation of intracellular calcium concentrations. Quercetin has been shown to be preventative against many forms of neuronal cell death resulting from glutamate excitotoxicity, such as oncosis, intrinsic apoptosis, mitochondrial permeability transition, ferroptosis, phagoptosis, lysosomal cell death, parthanatos, and death by reactive oxygen species (ROS)/reactive nitrogen species (RNS) generation. The clinical importance for the attenuation of glutamate excitotoxicity arises from the need to deter the continuous formation of tissue infarction caused by various neurological diseases, such as ischemic stroke, seizures, neurodegenerative diseases, and trauma. This review aims to summarize what is known concerning glutamate physiology and glutamate excitotoxic pathophysiology and provide further insight into quercetin's potential to hinder neuronal death caused by cell death pathways activated by glutamate excitotoxicity. Quercetin's bioavailability may limit its use clinically, however. Thus, future research into ways to increase its bioavailability are warranted.

Natural Compounds for SIRT1-Mediated Oxidative Stress and Neuroinflammation in Stroke: A Potential Therapeutic Target in the Future

Stroke is a fatal cerebral vascular disease with a high mortality rate and substantial economic and social costs. ROS production and neuroinflammation have been implicated in both hemorrhagic and ischemic stroke and have the most critical effects on subsequent brain injury. SIRT1, a member of the sirtuin family, plays a crucial role in modulating a wide range of physiological processes, including apoptosis, DNA repair, inflammatory response, and oxidative stress. Targeting SIRT1 to reduce ROS and neuroinflammation might represent an emerging therapeutic target for stroke. Therefore, we conducted the present review to summarize the mechanisms of SIRT1-mediated oxidative stress and neuroinflammation in stroke. In addition, we provide a comprehensive introduction to the effect of compounds and natural drugs on SIRT1 signaling related to oxidative stress and neuroinflammation in stroke. We believe that our work will be helpful to further understand the critical role of the SIRT1 signaling pathway and will provide novel therapeutic potential for stroke treatment.