Esculetin improves cognitive impairments induced by transient cerebral ischaemia and reperfusion in mice via regulation of mitochondrial fragmentation and mitophagy

Research progress of traditional Chinese medicine in the treatment of ischemic stroke by regulating mitochondrial dysfunction

Ischemic stroke (IS) is a severe cerebrovascular disease with increasing incidence and mortality rates in recent years. The pathogenesis of IS is highly complex, with mitochondrial dysfunction playing a critical role in its onset and progression. Thus, preserving mitochondrial function is a pivotal aspect of treating ischemic brain injury. In response, there has been growing interest among scholars in the regulation of mitochondrial function through traditional Chinese medicine (TCM), including herb-derived compounds, individual herbs, and herbal prescriptions. This article reviews recent research on the mechanisms of mitochondrial dysfunction in IS and explores the potential of TCM in treating this condition by targeting mitochondrial dysfunction.

Antioxidant and anti‑inflammatory effects of esculin and esculetin (Review)

Fraxinus chinensis Roxb is a deciduous tree, which is distributed worldwide and has important medicinal value. In Asia, the bark of Fraxinus chinensis Roxb is a commonly used traditional Chinese medicine called Qinpi. Esculetin is a coumarin compound derived from the bark of Fraxinus chinensis Roxb and its glycoside form is called esculin. The aim of the present study was to systematically review relevant literature on the antioxidant and anti-inflammatory effects of esculetin and esculin. Esculetin and esculin can promote the expression of various endogenous antioxidant proteins, such as superoxide dismutase, glutathione peroxidase and glutathione reductase. This is associated with the activation of the nuclear factor erythroid-derived factor 2-related factor 2 signaling pathway. The anti-inflammatory effects of esculetin and esculin are associated with the inhibition of the nuclear factor κ-B and mitogen-activated protein kinase inflammatory signaling pathways. In various inflammatory models, esculetin and esculin can reduce the expression levels of various proinflammatory factors such as tumor necrosis factor-α, interleukin (IL)-1β and IL-6, thereby inhibiting the development of inflammation. In summary, esculetin and esculin may be promising candidates for the treatment of numerous diseases associated with inflammation and oxidative stress, such as ulcerative colitis, acute lung and kidney injury, lung cancer, acute kidney injury.

Plant-Derived Coumarins: A Narrative Review of Their Structural and Biomedical Diversity

Plant-derived coumarin (PDC) is a naturally occurring heterocyclic backbone that belongs to the benzopyrone family. PDC and its based products are characterized by low toxicity and high distribution in a variety of herbal treatments that have numerous therapeutic potentials. These include anticoagulants, antibacterials, anti-inflammatory agents, anticancer agents, antioxidants, and others. So, it may be appropriate to investigate the qualities and potential bioactivities of PDCs. This article provides an overview of the biomedical potentials, availability, and clinical use possibilities of PDCs, with a focus on their important modes of action, using information on various pharmacological qualities discovered. The data used in this study came from published research between 2015 and 2023. We reviewed a selection of databases, including PubMed, Scopus, Web of Science, and Google Scholar, during that period. In conclusion, because of their abundance in medicinal plants, the clinical biochemistry attributes of PDCs are currently of interest. In a variety of medical specialties, PDCs serve a useful role as therapeutic agents.

Progress of medicinal plants and their active metabolites in ischemia-reperfusion injury of stroke: a novel therapeutic strategy based on regulation of crosstalk between mitophagy and ferroptosis

The death of cells can occur through various pathways, including apoptosis, necroptosis, mitophagy, pyroptosis, endoplasmic reticulum stress, oxidative stress, ferroptosis, cuproptosis, and disulfide-driven necrosis. Increasing evidence suggests that mitophagy and ferroptosis play crucial regulatory roles in the development of stroke. In recent years, the incidence of stroke has been gradually increasing, posing a significant threat to human health. Hemorrhagic stroke accounts for only 15% of all strokes, while ischemic stroke is the predominant type, representing 85% of all stroke cases. Ischemic stroke refers to a clinical syndrome characterized by local ischemic-hypoxic necrosis of brain tissue due to various cerebrovascular disorders, leading to rapid onset of corresponding neurological deficits. Currently, specific therapeutic approaches targeting the pathophysiological mechanisms of ischemic brain tissue injury mainly include intravenous thrombolysis and endovascular intervention. Despite some clinical efficacy, these approaches inevitably lead to ischemia-reperfusion injury. Therefore, exploration of treatment options for ischemic stroke remains a challenging task. In light of this background, advancements in targeted therapy for cerebrovascular diseases through mitophagy and ferroptosis offer a new direction for the treatment of such diseases. In this review, we summarize the progress of mitophagy and ferroptosis in regulating ischemia-reperfusion injury in stroke and emphasize their potential molecular mechanisms in the pathogenesis. Importantly, we systematically elucidate the role of medicinal plants and their active metabolites in targeting mitophagy and ferroptosis in ischemia-reperfusion injury in stroke, providing new insights and perspectives for the clinical development of therapeutic drugs for these diseases.

Renoprotective effect of esculetin against ischemic acute kidney injury-diabetic comorbidity

Mitophagy maintains cellular homeostasis by eliminating damaged mitochondria. Accumulated damaged mitochondria can lead to oxidative stress and cell death. Induction of the PINK1/Parkin-mediated mitophagy is reported to be renoprotective in acute kidney injury (AKI). Esculetin, a naturally available coumarin, has shown protective action against diabetic complications. However, its effect on AKI-diabetes comorbidity has not been explored yet. Therefore, we aimed to investigate the renoprotective effect of esculetin against AKI under diabetic conditions via regulating PINK1/Parkin-mediated mitophagy. For this, type 1 diabetic male Wistar rats were treated with two doses of esculetin (50 and 100 mg/kg/day orally) for five days followed by AKI induction by bilateral ischemic-reperfusion injury (IRI). NRK-52E cells grown in high glucose were exposed to sodium azide (10 mM) for induction of hypoxia/reperfusion injury (HRI) in-vitro. Esculetin (50 µM) treatment for 24 h was given to the cells before HRI. The in-vitro samples were utilized for cell viability and ΔΨm assay, immunoblotting, and immunofluorescence. Rats' plasma, urine, and kidney samples were collected for biochemical analysis, histopathology, and western blotting. Our results showed a significant decrease in kidney injury-specific markers and increased expression of mitophagy markers (PINK1 and Parkin) with esculetin treatment. Moreover, esculetin prevented the HRI and hyperglycemia-induced decrease in ΔΨm and autophagosome marker. Also, esculetin therapy reduced oxidative stress via increased Nrf2 and Keap1 expression. Esculetin attenuated AKI under diabetic condition by preventing mitochondrial dysfunction via inducing PINK1/Parkin-mediated mitophagy, suggesting its potential as an effective therapy for preventing AKI-diabetes comorbidity.

Effect of Nrf2 on brain injury induced by hydraulic shock via regulation of mitophagy and apoptosis

The specific protective mechanism of mitophagy and Nrf2 in brain injury has not been fully clarified. This study aimed to reveal the effect of Nrf2 on hydraulic shock brain injury in mice, and explore its possible mechanism. Twenty-four Nrf2 knockout (Nrf2-/-) and wild-type mice (WT) of C57BL/6J were randomly divided into two groups: control group (C) and brain injury group (TBI). Hematoxylin-eosin staining (HE) assay was used for the histomorphological observation. The apoptotic state of brain tissue was detected by TUNEL. Mechanical damage in vitro models of glial cells were prepared. The wild-type (WT) and Nrf2 knockout (KO) mice were constructed to investigate the changes of mitophagy and apoptosis-related indicators by Western blotting. The experimental results showed that 24 h after TBI, the tissue structure was highly porous, the cells were highly edema, the neuronal space increased significantly, the neuron degeneration, and the cell vacuolation was obvious. Meanwhile, the number of apoptotic cells and the apoptosis rate of glial cells increased significantly. After injury, the relative expression of Parkin, Pink, Beclin and LC-3II proteins were significantly decreased in all mice. The protein expressions of Caspase3 and Caspase12 were significantly increased. However, in the TBI group, KO mice were more impaired than WT mice. In conclusion, Nrf2 plays a protective role by promoting mitophagy to inhibit apoptosis in the process of brain injury caused by hydraulic shock in mice, which provides a new idea for the effective treatment of brain injury.

The role of dynamin-related protein 1 in cerebral ischemia/hypoxia injury

Mitochondrial dysfunction, especially in terms of mitochondrial dynamics, has been reported to be closely associated with neuronal outcomes and neurological impairment in cerebral ischemia/hypoxia injury. Dynamin-related protein 1 (Drp1) is a cytoplasmic GTPase that mediates mitochondrial fission and participates in neuronal cell death, calcium signaling, and oxidative stress. The neuroprotective role of Drp1 inhibition has been confirmed in several central nervous system disease models, demonstrating that targeting Drp1 may shed light on novel approaches for the treatment of cerebral ischemia/hypoxia injury. In this review, we aimed to highlight the roles of Drp1 in programmed cell death, oxidative stress, mitophagy, and mitochondrial function to provide a better understanding of mitochondrial disturbances in cerebral ischemia/hypoxia injury, and we also summarize the advances in novel chemical compounds targeting Drp1 to provide new insights into potential therapies for cerebral ischemia/hypoxia injury.

Alleviation of ischemic brain injury by exercise preconditioning is associated with modulation of autophagy and mitochondrial dynamics in cerebral cortex of female aged mice

Evidence from clinical studies and preclinical studies supports that exercise preconditioning can not only reduce the risk of stroke but also improve brain tissue and functional outcome after stroke. It has been demonstrated that autophagy and mitochondrial dynamics are involved in ischemic stroke. However, it is still unclear whether exercise preconditioning-induced neuroprotection against stroke is associated with modulation of autophagy and mitochondrial dynamics. Although age and sex interactively affect ischemic stroke risk, incidence, and outcome, studies based on young male animals are most often used to explore the role of exercise preconditioning in the prevention of ischemic stroke. In the current study, we examined whether exercise preconditioning could modulate autophagy and mitochondrial dynamics in a brain ischemia and reperfusion (I/R) model of female aged mice. The results showed that exercise preconditioning reduced infarct volume and improved neurological deficits. Additionally, increased levels of autophagy-related proteins LC3-II/LC3-I, LC3-II, p62, Atg7, and mitophagy-related proteins Bnip3L and Parkin, as well as increased levels of mitochondrial fusion modulator Mfn2 and mitochondrial fission modulator Drp1 in the ischemic cortex of female aged mice at 12 h after I/R were present. Our results could contribute to a better understanding of exercise preconditioning-induced neuroprotection against ischemic stroke for the elderly.

Review of Plant Extracts and Active Components: Mechanisms of Action for the Treatment of Obesity-Induced Cognitive Impairment

Obesity has been shown to negatively impact cognitive functions, but effective treatments for obesity-induced cognitive impairment are lacking. Natural dietary and plant products, functional foods, and plant-derived compounds have gained attention as potential remedies in part due to the nootropic properties of plants and certain plant-derived agents. This review discusses plant extracts and plant-derived substances that have been shown to ameliorate obesity-induced cognitive impairment in animal models. Mechanistic evaluations of their therapeutic effects are also summarized. A literature search was conducted using PubMed and Google Scholar databases, resulting in the review of 27 English language articles meeting the inclusion criteria. The nine plants (e.g., Ashwagandha, Adzuki bean, and olive) and 18 plant-derived substances (e.g., curcumin, Huperzine A, and Roxburgh's jewel orchid polysaccharides) included in this review improved obesity-induced cognitive impairment through several mechanisms, including attenuation of neuroinflammation, improvement in both central and peripheral insulin resistance, enhancement of neuroprotection and neurogenesis, and modulation of the synthesis and release of cognition-associated neurotransmitters. Based on these findings, plants and plant-derived substances may hold promise for the prevention and treatment of obesity-induced cognitive impairment. Further research is warranted to explore the clinical potential of these plant-derived treatments and to elucidate their underlying molecular mechanisms.

Role of the HIF-1α/BNIP3 Signaling Pathway in Recurrent Hepatocellular Carcinoma and the Mechanism of Traditional Chinese Medicine

Recurrence of hepatocellular carcinoma (HCC) negatively affects the quality of life of patients and leads to death. Studies have shown that recurrent hepatocellular carcinoma (RHCC) is closely related to tissue hypoxia and autophagy. It has been shown that hypoxia-inducible factor-1α (HIF-1α) and its downstream factor BCL-2 19 kDa-interacting protein 3 (BNIP3) promote cellular autophagy under hypoxic conditions, resulting in metastasis and RHCC. In this article, the molecular structures of HIF-1α and BNIP3 are described, and the significance of the HIF-1α/BNIP3 signaling pathway in RHCC is explained. Moreover, the role and mechanism of traditional Chinese medicine (TCM) in treating RHCC by modulating the HIF-1α/BNIP3 signaling pathway is discussed. Studies have shown that the HIF-1α/BNIP3 signaling pathway is a potential target of TCM in the treatment of RHCC. The mechanism of the HIF-1α/BNIP3 signaling pathway in RHCC and the progress achieved in TCM research on targeting and regulating this pathway are also reviewed in this article. The objective was to provide a theoretical basis for the prevention and treatment of RHCC, as well as further drug development.

Natural Coumarin Derivatives Activating Nrf2 Signaling Pathway as Lead Compounds for the Design and Synthesis of Intestinal Anti-Inflammatory Drugs

Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor related to stress response and cellular homeostasis that plays a key role in maintaining the redox system. The imbalance of the redox system is a triggering factor for the initiation and progression of non-communicable diseases (NCDs), including Inflammatory Bowel Disease (IBD). Nrf2 and its inhibitor Kelch-like ECH-associated protein 1 (Keap1) are the main regulators of oxidative stress and their activation has been recognized as a promising strategy for the treatment or prevention of several acute and chronic diseases. Moreover, activation of Nrf2/keap signaling pathway promotes inhibition of NF-κB, a transcriptional factor related to pro-inflammatory cytokines expression, synchronically promoting an anti-inflammatory response. Several natural coumarins have been reported as potent antioxidant and intestinal anti-inflammatory compounds, acting by different mechanisms, mainly as a modulator of Nrf2/keap signaling pathway. Based on in vivo and in vitro studies, this review focuses on the natural coumarins obtained from both plant products and fermentative processes of food plants by gut microbiota, which activate Nrf2/keap signaling pathway and produce intestinal anti-inflammatory activity. Although gut metabolites urolithin A and urolithin B as well as other plant-derived coumarins display intestinal anti-inflammatory activity modulating Nrf2 signaling pathway, in vitro and in vivo studies are necessary for better pharmacological characterization and evaluation of their potential as lead compounds. Esculetin, 4-methylesculetin, daphnetin, osthole, and imperatorin are the most promising coumarin derivatives as lead compounds for the design and synthesis of Nrf2 activators with intestinal anti-inflammatory activity. However, further structure-activity relationships studies with coumarin derivatives in experimental models of intestinal inflammation and subsequent clinical trials in health and disease volunteers are essential to determine the efficacy and safety in IBD patients.

Therapeutic Potential of Phenolic Compounds in Medicinal Plants-Natural Health Products for Human Health

Phenolic compounds and flavonoids are potential substitutes for bioactive agents in pharmaceutical and medicinal sections to promote human health and prevent and cure different diseases. The most common flavonoids found in nature are anthocyanins, flavones, flavanones, flavonols, flavanonols, isoflavones, and other sub-classes. The impacts of plant flavonoids and other phenolics on human health promoting and diseases curing and preventing are antioxidant effects, antibacterial impacts, cardioprotective effects, anticancer impacts, immune system promoting, anti-inflammatory effects, and skin protective effects from UV radiation. This work aims to provide an overview of phenolic compounds and flavonoids as potential and important sources of pharmaceutical and medical application according to recently published studies, as well as some interesting directions for future research. The keyword searches for flavonoids, phenolics, isoflavones, tannins, coumarins, lignans, quinones, xanthones, curcuminoids, stilbenes, cucurmin, phenylethanoids, and secoiridoids medicinal plant were performed by using Web of Science, Scopus, Google scholar, and PubMed. Phenolic acids contain a carboxylic acid group in addition to the basic phenolic structure and are mainly divided into hydroxybenzoic and hydroxycinnamic acids. Hydroxybenzoic acids are based on a C6-C1 skeleton and are often found bound to small organic acids, glycosyl moieties, or cell structural components. Common hydroxybenzoic acids include gallic, syringic, protocatechuic, p-hydroxybenzoic, vanillic, gentistic, and salicylic acids. Hydroxycinnamic acids are based on a C6-C3 skeleton and are also often bound to other molecules such as quinic acid and glucose. The main hydroxycinnamic acids are caffeic, p-coumaric, ferulic, and sinapic acids.

Esculetin alleviates pentylenetetrazole-induced seizures, cognitive impairment and pro-inflammatory cytokines and suppresses penicillin-induced epileptiform activity in rats

AIMS

To investigate the effects of different doses of esculetin on epileptiform activity, behavioral seizures, memory impairment, and cortical and hippocampal NF-κB, as a mediator of pro-inflammatory gene induction, and pro-inflammatory cytokines in penicillin- and pentylenetetrazole(PTZ)-induced seizure models in rats.

MAIN METHODS

Different doses of esculetin (5, 10, and 20 mg/kg), and diazepam (5 mg/kg) as a positive control, were tested in penicillin- and pentylenetetrazole(PTZ)-induced seizure models. In the PTZ model, cognitive function, behavioral seizures, and cortical and hippocampal pro-inflammatory biomarkers and survival factor was evaluated. In the penicillin model, the frequency and amplitude of electrophysiological epileptiform activity were assessed.

KEY FINDINGS

In the PTZ model, the 10 mg/kg esculetin displayed anticonvulsant effects by extending onset-times of myoclonic-jerk and generalized tonic-clonic seizure, and by diminishing seizure severity and duration of generalized tonic-clonic seizure. It also ameliorated PTZ-induced cognitive impairment, and cortical and hippocampal activin-A, IL-1β, IL-6 and NF-κB levels. In the penicillin model, the 10 mg/kg esculetin decreased the frequency of spikes without changing the amplitude of spikes. As a positive-control, diazepam reversed all changes induced by both PTZ and penicillin.

SIGNIFICANCE

Esculetin exhibits anticonvulsant and memory-improving effects by alleviating the behavioral and electrophysiological characteristics of epileptic seizures. Additionally, esculetin exerts anti-neuroinflammatory actions in the PTZ-induced seizures model. Thus, esculetin may be a multi-targeted promising agent with anticonvulsant and anti-neuroinflammatory effects in the treatment of epilepsy.

The Role of Nrf2 in Relieving Cerebral Ischemia-Reperfusion Injury

Ischemic stroke includes two related pathological damage processes: brain injury caused by primary ischemia and secondary ischemia reperfusion (I/R) injury. I/R injury has become a worldwide health problem. Unfortunately, there is still a lack of satisfactory drugs for ameliorating cerebral I/R damage. Nrf2 is a vital endogenous antioxidant protein, which combines with Keap1 to maintain a dormant state under physiological conditions. When pathological changes such as I/R occurs, Nrf2 dissociates from Keap1 and activates the expression of downstream antioxidant proteins to exert a protective effect. Recent research have shown that the activated Nrf2 not only effectively inhibits oxidative stress, but also performs the ability to repair the function of compromised mitochondria, alleviate endoplasmic reticulum stress, eliminate inflammatory response, reduce blood-brain barrier permeability, inhibit neuronal apoptosis, enhance the neural network remolding, thereby exerting significant protective effects in alleviating the injuries caused by cell oxygen-glucose deprivation, or animal cerebral I/R. However, no definite clinical application report demonstrated the efficacy of Nrf2 activators in the treatment of cerebral I/R. Therefore, further efforts are needed to elaborate the role of Nrf2 activators in the treatment of cerebral I/R. Here, we reviewed the possible mechanisms underlying its potential pharmacological benefits in alleviating cerebral I/R injury, so as to provide a theoretical basis for studying its mechanism and developing Nrf2 activators.

The critical role of the endolysosomal system in cerebral ischemia

Cerebral ischemia is a serious disease that triggers sequential pathological mechanisms, leading to significant morbidity and mortality. Although most studies to date have typically focused on the lysosome, a single organelle, current evidence supports that the function of lysosomes cannot be separated from that of the endolysosomal system as a whole. The associated membrane fusion functions of this system play a crucial role in the biodegradation of cerebral ischemia-related products. Here, we review the regulation of and the changes that occur in the endolysosomal system after cerebral ischemia, focusing on the latest research progress on membrane fusion function. Numerous proteins, including N-ethylmaleimide-sensitive factor and lysosomal potassium channel transmembrane protein 175, regulate the function of this system. However, these proteins are abnormally expressed after cerebral ischemic injury, which disrupts the normal fusion function of membranes within the endolysosomal system and that between autophagosomes and lysosomes. This results in impaired "maturation" of the endolysosomal system and the collapse of energy metabolism balance and protein homeostasis maintained by the autophagy-lysosomal pathway. Autophagy is the final step in the endolysosomal pathway and contributes to maintaining the dynamic balance of the system. The process of autophagosome-lysosome fusion is a necessary part of autophagy and plays a crucial role in maintaining energy homeostasis and clearing aging proteins. We believe that, in cerebral ischemic injury, the endolysosomal system should be considered as a whole rather than focusing on the lysosome. Understanding how this dynamic system is regulated will provide new ideas for the treatment of cerebral ischemia.

Targeting mitochondria in the regulation of neurodegenerative diseases: A comprehensive review

Mitochondria are one of the essential cellular organelles. Apart from being considered as the powerhouse of the cell, mitochondria have been widely known to regulate redox reaction, inflammation, cell survival, cell death, metabolism, etc., and are implicated in the progression of numerous disease conditions including neurodegenerative diseases. Since brain is an energy-demanding organ, mitochondria and their functions are important for maintaining normal brain homeostasis. Alterations in mitochondrial gene expression, mutations, and epigenetic modification contribute to inflammation and neurodegeneration. Dysregulation of reactive oxygen species production by mitochondria and aggregation of proteins in neurons leads to alteration in mitochondria functions which further causes neuronal death and progression of neurodegeneration. Pharmacological studies have prioritized mitochondria as a possible drug target in the regulation of neurodegenerative diseases. Therefore, the present review article has been intended to provide a comprehensive understanding of mitochondrial role in the development and progression of neurodegenerative diseases mainly Alzheimer's, Parkinson's, multiple sclerosis, and amyotrophic lateral sclerosis followed by possible intervention and future treatment strategies to combat mitochondrial-mediated neurodegeneration.

Protective effects of Aster yomena (Kitam.) Honda from cognitive dysfunction induced by high-fat diet

In our study, we investigated whether Aster yomena (Kitam.) Honda (AY) improved cognitive impairment which results from consumption of high-fat diet (HFD). When ethyl acetate fraction from AY (EFAY) was administered to C57BL/6J mice fed with 60% HFD, EFAY significantly enhanced cognitive ability that was impaired by HFD in T-maze test and novel object recognition test. Furthermore, EFAY increased memory and learning functions that were proven during Morris water maze test. We further elucidated protective mechanisms of EFAY against cognitive decline that resulted from obesity by western blotting. In the brain, HFD increased neuronal inflammation and disturbed insulin receptor substrate-1 (IRS-1)/Akt pathway. However, EFAY significantly downregulated inflammation-related protein expressions such as nuclear factor-κB interleukin-1β, inducible nitric oxide synthase and cyclooxygenase-2, compared with the HFD-fed control group. Furthermore, the IRS-1/Akt pathway was regulated by EFAY, indicating that EFAY ameliorated insulin resistance in the brain. PRACTICAL APPLICATIONS: Obesity and its complications increase the risk for developing cognitive dysfunction such as dementia. Administration of ethyl acetate fraction from AY (EFAY)-attenuated cognitive and memory impairment by inhibitions of neuronal oxidative stress and low-grade chronic inflammation in high-fat diet (HFD)-induced cognitive impairment mouse model. In addition, EFAY-administered mice disturbed cerebral insulin receptor substrate-1 (IRS-1)/Akt pathway. These data suggest that EFAY-improved cognitive impairment induced by HFD through modulation of insulin resistance and inflammation. Therefore, we proposed that AY could be a potential agent to prevent cognitive dysfunction induced by obesity and insulin resistance.

Mitochondrial Quality and Quantity Control: Mitophagy Is a Potential Therapeutic Target for Ischemic Stroke

Ischemic stroke is a cerebrovascular disease with high mortality and disability, which seriously affects the health and lives of people around the world. Effective treatment for ischemic stroke has been limited by its complex pathological mechanisms. Increasing evidence has indicated that mitochondrial dysfunction plays an essential role in the occurrence, development, and pathological processes of ischemic stroke. Therefore, strict control of the quality and quantity of mitochondria via mitochondrial fission and fusion as well as mitophagy is beneficial to the survival and normal function maintenance of neurons. Under certain circumstances, excessive mitophagy also could induce cell death. This review discusses the dynamic changes and double-edged roles of mitochondria and related signaling pathways of mitophagy in the pathophysiology of ischemic stroke. Furthermore, we focus on the possibility of modulating mitophagy as a potential therapy for the prevention and prognosis of ischemic stroke. Notably, we reviewed recent advances in the studies of natural compounds, which could modulate mitophagy and exhibit neuroprotective effects, and discussed their potential application in the treatment of ischemic stroke.

The interplay between oxidative stress and autophagy: focus on the development of neurological diseases

Regarding the epidemiological studies, neurological dysfunctions caused by cerebral ischemia or neurodegenerative diseases (NDDs) have been considered a pointed matter. Mount-up shreds of evidence support that both autophagy and reactive oxygen species (ROS) are involved in the commencement and progression of neurological diseases. Remarkably, oxidative stress prompted by an increase of ROS threatens cerebral integrity and improves the severity of other pathogenic agents such as mitochondrial damage in neuronal disturbances. Autophagy is anticipated as a cellular defending mode to combat cytotoxic substances and damage. The recent document proposes that the interrelation of autophagy and ROS creates a crucial function in controlling neuronal homeostasis. This review aims to overview the cross-talk among autophagy and oxidative stress and its molecular mechanisms in various neurological diseases to prepare new perceptions into a new treatment for neurological disorders. Furthermore, natural/synthetic agents entailed in modulation/regulation of this ambitious cross-talk are described.

Mitochondrial quality control in stroke: From the mechanisms to therapeutic potentials

Mitochondrial damage is a critical contributor to stroke‐induced injury, and mitochondrial quality control (MQC) is the cornerstone of restoring mitochondrial homeostasis and plays an indispensable role in alleviating pathological process of stroke. Mitochondria quality control promotes neuronal survival via various adaptive responses for preserving mitochondria structure, morphology, quantity and function. The processes of mitochondrial fission and fusion allow for damaged mitochondria to be segregated and facilitate the equilibration of mitochondrial components such as DNA, proteins and metabolites. The process of mitophagy is responsible for the degradation and recycling of damaged mitochondria. This review aims to offer a synopsis of the molecular mechanisms involved in MQC for recapitulating our current understanding of the complex role that MQC plays in the progression of stroke. Speculating on the prospect that targeted manipulation of MQC mechanisms may be exploited for the rationale design of novel therapeutic interventions in the ischaemic stroke and haemorrhagic stroke. In the review, we highlight the potential of MQC as therapeutic targets for stroke treatment and provide valuable insights for clinical strategies.

Possible Engagement of Nicotinic Acetylcholine Receptors in Pathophysiology of Brain Ischemia-Induced Cognitive Impairment

Post-stroke disabilities like cognitive impairment impose are complex conditions with great economic burdens on health care systems. For these comorbidities, no effective therapies have been identified yet. Nicotinic acetylcholine receptors (nAChRs) are multifunctional receptors participating in various behavioral and neurobiological functions. During brain ischemia, the increased glutamate accumulation leads to neuronal excitotoxicity as well as mitochondrial dysfunction. These abnormalities then cause the increased levels of oxidants, which play key roles in neuronal death and apoptosis in the infarct zone. Additionally, recall of cytokines and inflammatory factors play a prominent role in the exacerbation of ischemic injury. As well, neurotrophic factors' insufficiency results in synaptic dysfunction and cognitive impairments in ischemic brain. Of note, nAChRs through various signaling pathways can participate in therapeutic approaches such as cholinergic system's stimulation, and reduction of excitotoxicity, inflammation, apoptosis, oxidative stress, mitochondrial dysfunction, and autophagy. Moreover, the possible roles of nAChRs in neurogenesis, synaptogenesis, and stimulation of neurotrophic factors expression have been reported previously. On the other hand, the majority of the above-mentioned mechanisms were found to be common in both brain ischemia pathogenesis and cognitive function tuning. Therefore, it seems that nAChRs might be known as key regulators in the control of ischemia pathology, and their modulation could be considered as a new avenue in the multi-target treatment of post-stroke cognitive impairment.

Mitochondrial Quality Control in Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is one of the leading causes of death and also a major cause of adult disability worldwide. Revascularization via reperfusion therapy is currently a standard clinical procedure for patients with ischemic stroke. Although the restoration of blood flow (reperfusion) is critical for the salvage of ischemic tissue, reperfusion can also, paradoxically, exacerbate neuronal damage through a series of cellular alterations. Among the various theories postulated for ischemia/reperfusion (I/R) injury, including the burst generation of reactive oxygen species (ROS), activation of autophagy, and release of apoptotic factors, mitochondrial dysfunction has been proposed to play an essential role in mediating these pathophysiological processes. Therefore, strict regulation of the quality and quantity of mitochondria via mitochondrial quality control is of great importance to avoid the pathological effects of impaired mitochondria on neurons. Furthermore, timely elimination of dysfunctional mitochondria via mitophagy is also crucial to maintain a healthy mitochondrial network, whereas intensive or excessive mitophagy could exacerbate cerebral I/R injury. This review will provide a comprehensive overview of the effect of mitochondrial quality control on cerebral I/R injury and introduce recent advances in the understanding of the possible signaling pathways of mitophagy and potential factors responsible for the double-edged roles of mitophagy in the pathological processes of cerebral I/R injury.

Garciesculenxanthone B induces PINK1-Parkin-mediated mitophagy and prevents ischemia-reperfusion brain injury in mice

Mitophagy is a selective form of autophagy involving the removal of damaged mitochondria via the autophagy-lysosome pathway. PINK1-Parkin-mediated mitophagy is one of the most important mechanisms in cardiovascular disease, cerebral ischemia-reperfusion (I/R) injury, and neurodegenerative diseases. In this study we conducted an image-based screening in YFP-Parkin HeLa cells to discover new mitophagy regulators from natural xanthone compounds. We found that garciesculenxanthone B (GeB), a new xanthone compound from Garcinia esculenta, induced the formation of YFP-Parkin puncta, a well known mitophagy marker. Furthermore, treatment with GeB dose-dependently promoted the degradation of mitochondrial proteins Tom20, Tim23, and MFN1 in YFP-Parkin HeLa cells and SH-SY5Y cells. We revealed that GeB stabilized PINK1 and triggered Parkin translocation to the impaired mitochondria to induce mitophagy, and these effects were abolished by knockdown of PINK1. Finally, in vivo experiments demonstrated that GeB partially rescued ischemia-reperfusion-induced brain injury in mice. Taken together, our findings demonstrate that the natural compound GeB can promote the PINK1-Parkin-mediated mitophagy pathway, which may be implicated in protection against I/R brain injury.

The protective effect of esculetin against aluminium chloride-induced reproductive toxicity in rats

One of the prominent health problems caused by Aluminium was the decrease in male fertility rates. In the study, the protective effect of Esculetin (ESC) against the reproductive toxicity induced by Aluminium chloride (AlCl₃ ) was investigated. For this purpose, AlCl₃ was administrated to Wistar Albino rats at a dose of 34 mg/kg and ESC was administrated at a dose of 50 mg/kg for 70 days. It was determined that AlCl₃ treatment reduced sperm motility and concentration, increased dead/live rate and abnormal sperm rate. It decreased serum testosterone level, and co-treatment of ESC significantly regulated these values. In the AlCl₃ -treated group, MDA level increased and GSH level, GPx and CAT activities decreased compared with those of the control group. However, co-treatment of ESC showed an amelioratory effect on the values except for CAT activity. It was observed that the expression level of NRF-2 increased in the ESC and AlCl₃  + ESC groups, and NF-κB increased in the AlCl₃ group with the control group. It was determined that Caspase-3 expression decreased, and Bcl-2 expression increased in AlCl₃  + ESC group compared to AlCl₃ group. It was also determined that AlCl₃ -induced tissue injury was significantly prevented by ESC co-treatment.

The Role of Mitophagy in Ischemic Stroke

Mitochondria are important places for eukaryotes to carry out energy metabolism and participate in the processes of cell differentiation, cell information transmission, and cell apoptosis. Autophagy is a programmed intracellular degradation process. Mitophagy, as a selective autophagy, is an evolutionarily conserved cellular process to eliminate dysfunctional or redundant mitochondria, thereby fine-tuning the number of mitochondria and maintaining energy metabolism. Many stimuli could activate mitophagy to regulate related physiological processes, which could ultimately reduce or aggravate the damage caused by stimulation. Stroke is a common disease that seriously affects the health and lives of people around the world, and ischemic stroke, which is caused by cerebral vascular stenosis or obstruction, accounts for the vast majority of stroke. Abnormal mitophagy is closely related to the occurrence, development and pathological mechanism of ischemic stroke. However, the exact mechanism of mitophagy involved in ischemic stroke has not been fully elucidated. In this review, we discuss the process and signal pathways of mitophagy, the potential role of mitophagy in ischemic stroke and the possible signal transduction pathways. It will help deepen the understanding of mitophagy and provide new ideas for the treatment of ischemic stroke.

Melatonin and regulation of autophagy: Mechanisms and therapeutic implications

Mitochondria are essential subcellular units that generate basic energy for the cell, as well as influence Ca²⁺ flux, apoptosis, and cell signaling. Mitophagy can selectively remove impaired mitochondria to preserve mitochondrial function, which is crucial for normal cellular maintenance. Mitochondrial dysfunction and mitophagy are widely reported to be linked to various pathogeneses. In addition, there is increasing evidence regarding the beneficial role of melatonin in the regulation and intervention of mitophagy progression. In this review, we focus on specific pathological conditions, including ischemia/reperfusion injury (IRI), cancer and neurodegenerative diseases, and elucidate the essential role of melatonin in the modulation of mitophagy in each of these distinct disorders.

Activation of CB1R-Dependent PGC-1α Is Involved in the Improved Mitochondrial Biogenesis Induced by Electroacupuncture Pretreatment

Electroacupuncture (EA) pretreatment induces cerebral ischemic tolerance; however, the mechanism remains poorly understood. This study aimed to determine the participation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-mediated mitochondrial biogenesis in the neuroprotection of EA and whether cannabinoid receptor 1 (CB1R) is involved in this mechanism. At 2 hours after EA pretreatment, adult male C57BL/6j mice were subjected to 60-minute right middle cerebral artery occlusion (MCAO). Mitochondrial function, the level of mitochondrial biogenesis-related proteins (nuclear transcription factor 1, NRF1; mitochondrial transcription factor A, TFAM), and mitochondrial DNA (mtDNA) were measured. A small interfering RNA (siRNA) targeting PGC-1α and the CB1R antagonists AM251 and SR141716A were given to the animals before EA pretreatment, and mitochondrial function and biogenesis were examined after MCAO. EA ameliorated the mitochondrial function, upregulated the NRF1 and TFAM expression, and increased the mtDNA levels and the volume and number of mitochondria. EA pretreatment increased the expression of PGC-1α, whereas the PGC-1α siRNA and CB1R antagonists reversed the improved neuroprotection and increased mitochondrial biogenesis induced by EA. Our results indicated that EA pretreatment protects the mitochondria and promotes mitochondrial biogenesis by activating CB1R-dependent PGC-1α, which provides a novel mechanism for EA pretreatment-induced ischemic tolerance.

Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2) and Mitochondrial Dynamics/Mitophagy in Neurological Diseases

Mitochondria play an essential role in bioenergetics and respiratory functions for cell viability through numerous biochemical processes. To maintain mitochondria quality control and homeostasis, mitochondrial morphologies change rapidly in response to external insults and changes in metabolic status through fusion and fission (so called mitochondrial dynamics). Furthermore, damaged mitochondria are removed via a selective autophagosomal process, referred to as mitophagy. Although mitochondria are one of the sources of reactive oxygen species (ROS), they are themselves vulnerable to oxidative stress. Thus, endogenous antioxidant defense systems play an important role in cell survival under physiological and pathological conditions. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a redox-sensitive transcription factor that maintains redox homeostasis by regulating antioxidant-response element (ARE)-dependent transcription and the expression of antioxidant defense enzymes. Although the Nrf2 system is positively associated with mitochondrial biogenesis and mitochondrial quality control, the relationship between Nrf2 signaling and mitochondrial dynamics/mitophagy has not been sufficiently addressed in the literature. This review article describes recent clinical and experimental observations on the relationship between Nrf2 and mitochondrial dynamics/mitophagy in various neurological diseases.

Esculetin as a Bifunctional Antioxidant Prevents and Counteracts the Oxidative Stress and Neuronal Death Induced by Amyloid Protein in SH-SY5Y Cells

Oxidative stress (OS) appears to be an important determinant during the different stages of progression of Alzheimer’s Disease (AD). In particular, impaired antioxidant defense mechanisms, such as the decrease of glutathione (GSH) and nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2), a master regulator of antioxidant genes, including those for GSH, are associated with OS in the human AD brain. Among the neuropathological hallmarks of AD, the soluble oligomers of amyloid beta (Aβ) peptides seem to promote neuronal death through mitochondrial dysfunction and OS. In this regard, bifunctional antioxidants can exert a dual neuroprotective role by scavenging reactive oxygen species (ROS) directly and concomitant induction of antioxidant genes. In this study, among natural coumarins (esculetin, scopoletin, fraxetin and daphnetin), we demonstrated the ability of esculetin (ESC) to prevent and counteract ROS formation in neuronal SH-SY5Y cells, suggesting its profile as a bifunctional antioxidant. In particular, ESC increased the resistance of the SH-SY5Y cells against OS through the activation of Nrf2 and increase of GSH. In similar experimental conditions, ESC could also protect the SH-SY5Y cells from the OS and neuronal death evoked by oligomers of Aβ_1–42 peptides. Further, the use of the inhibitors PD98059 and LY294002 also showed that Erk1/2 and Akt signaling pathways were involved in the neuroprotection mediated by ESC. These results encourage further research in AD models to explore the efficacy and safety profile of ESC as a novel neuroprotective agent.

Coumarins as Modulators of the Keap1/Nrf2/ARE Signaling Pathway

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.