Fucoxanthin Mitigates Subarachnoid Hemorrhage-Induced Oxidative Damage via Sirtuin 1-Dependent Pathway

Antioxidant and Neuroprotective Effects of Fucoxanthin and Its Metabolite Fucoxanthinol: A Comparative In Vitro Study

Fucoxanthin is the most abundant carotenoid found in marine brown algae that exhibits several healthy properties. Dietary fucoxanthin is metabolized in the intestine, plasma, and other tissues to various metabolites, including fucoxanthinol. In this regard, the contribution of fucoxanthinol to the healthy properties of its precursor, fucoxanthin, against pathogenetic events associated with neurodegenerative diseases remains unexplored. Here, we evaluated and compared the antioxidant and neuroprotective effects of the carotenoids fucoxanthin and fucoxanthinol in in vitro models of Alzheimer's (AD) and Parkinson's (PD) disease. Neuronal SH-SY5Y cells were used to evaluate the antioxidant properties of the carotenoids against ABTS radical in the membrane and cytoplasm and oxidative stress elicited by tert-butyl hydroperoxide using the 2',7'-dichlorodihydrofluorescein diacetate probe. We also assessed the ability of the carotenoids to increase the glutathione (GSH) and activate the Nrf2/Keap1/ARE pathway using the monochlorobimane probe and western blotting method, respectively. The neuroprotective effects of the carotenoids against the neurotoxicity generated by oligomers of Beta-Amyloid (1-42) peptide (OAβ) and 6-hydroxydopamine (6-OHDA), which are neurotoxins of AD and PD, respectively, were finally evaluated in the same neuronal cells using the thiazolyl blue tetrazolium bromide assay. Both carotenoids could reach the cytoplasm, which explains the mainly free radical scavenging activity at this level. Notably, fucoxanthinol had higher and lower antioxidant activity than fucoxanthin at extracellular and cellular levels. Although studied carotenoids exerted the ability to activate the Nrf2/Keap1/ARE pathway, leading to an increase of intracellular GSH, our results suggested that the antioxidant activity of the carotenoids could be mainly attributed to their radical scavenging activity in neuronal membrane and cytoplasm, where they accumulate. Fucoxanthinol also shared similar neuroprotective effects as fucoxanthin against the neurotoxicity generated by OAβ and 6-OHDA, suggesting a potential neuroprotective contribution to the action of fucoxanthin administered as a food supplement in in vivo experimental models. These results encourage further research to evaluate the bioavailability of fucoxanthinol and other metabolites of fucoxanthin at the brain level to elucidate the dietary neuroprotective potential of fucoxanthin.

Therapeutic Potential of Natural Compounds in Subarachnoid Haemorrhage

Subarachnoid hemorrhage (SAH) is a common and fatal cerebrovascular disease with high morbidity, mortality and very poor prognosis worldwide. SAH can induce a complex series of pathophysiological processes, and the main factors affecting its prognosis are early brain injury (EBI) and delayed cerebral ischemia (DCI). The pathophysiological features of EBI mainly include intense neuroinflammation, oxidative stress, neuronal cell death, mitochondrial dysfunction and brain edema, while DCI is characterized by delayed onset ischemic neurological deficits and cerebral vasospasm (CVS). Despite much exploration in people to improve the prognostic outcome of SAH, effective treatment strategies are still lacking. In recent years, numerous studies have shown that natural compounds of plant origin have unique neuro- and vascular protective effects in EBI and DCI after SAH and long-term neurological deficits, which mainly include inhibition of inflammatory response, reduction of oxidative stress, anti-apoptosis, and improvement of blood-brain barrier and cerebral vasospasm. The aim of this paper is to systematically explore the processes of neuroinflammation, oxidative stress, and apoptosis in SAH, and to summarize natural compounds as potential targets for improving the prognosis of SAH and their related mechanisms of action for future therapies.

Exploring the Role of Ferroptosis-Related Circular RNAs in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular event associated with high mortality and significant morbidity. Recent studies have highlighted the emerging role of ferroptosis, a novel form of regulated cell death, in the pathogenesis of SAH. Circular RNAs (circRNAs), have been found to play essential roles in various cellular processes, including gene regulation and disease pathogenesis. The expression profile of circRNAs in neural tissues, particularly in the brain, suggests their critical role in synaptic function and neurogenesis. Moreover, the interplay between circRNAs and ferroptosis-related pathways, such as iron metabolism and lipid peroxidation, is explored in the context of SAH. Understanding the functional roles of specific circRNAs in the context of SAH may provide potential therapeutic targets to attenuate ferroptosis-associated brain injury. Furthermore, the potential of circRNAs as diagnostic biomarkers for SAH severity, prognosis, and treatment response is discussed. Overall, this review highlights the significance of studying the intricate interplay between circRNAs and ferroptosis in the context of SAH. Unraveling the mechanisms by which circRNAs modulate ferroptotic cell death may pave the way for the development of novel therapeutic strategies and diagnostic approaches for SAH management, ultimately improving patient outcomes and quality of life.

Fucoxanthin ameliorates traumatic brain injury by suppressing the blood-brain barrier disruption

Fucoxanthin is the most abundant marine carotenoid extracted from seaweed. Our previous study has shown that fucoxanthin inhibited oxidative stress after traumatic brain injury (TBI). However, the effects of fucoxanthin on TBI-induced blood-brain barrier (BBB) destruction have not been well understood. In the present study, we found that fucoxanthin improved neurological dysfunction, reduced brain edema, attenuated cortical lesion volume, and decreased dendrites loss after TBI in vivo. Moreover, fucoxanthin suppressed BBB leakage, preserved tight junction (TJ) and adherens junction (AJ) proteins, and inhibited MMP-9 expression. Furthermore, fucoxanthin alleviated apoptosis and ferroptosis, and activated mitophagy in endothelial cells (ECs) after TBI. However, the protection of fucoxanthin on BBB was attenuated when mitophagy was inhibited. Importantly, fucoxanthin also provided protective effects in bEnd.3 cells after TBI. Taken together, our results suggested that fucoxanthin played a key role in the protection of BBB after TBI through mitophagy.

Fucoxanthin, a marine derived carotenoid, attenuates surgery-induced cognitive impairments via activating Akt and ERK pathways in aged mice

BACKGROUND

Fucoxanthin is the most abundant marine carotenoid derived from brown seaweeds, possesses antioxidant, anti-inflammatory, and neuroprotective properties, and might be benefit for the treatment of neurological disorders. Post-operative cognitive dysfunction (POCD) is a neurological symptom with learning and memory impairments, mainly affecting the elderly after surgery. However, there is no effective treatments for this symptom.

PURPOSES

In this study, we evaluated the neuroprotective effects of fucoxanthin against POCD in aged mice after surgery.

STUDY DESIGN AND METHODS

The animal model of POCD was established in 12 - 14 month aged mice with a laparotomy. Curcumin was used as a positive control. The beneficial effects of fucoxanthin on POCD was analyzed by behavioral tests. Pro-inflammatory cytokines were measured by Enzyme-linked Immunosorbent Assay (ELISA). And the expressions of key proteins in the Akt and ERK signaling pathways were analyzed by Western blotting analysis. The morphology of microglial cells and astrocytes was explored by immunohistochemical staining. The activity of antioxidant superoxide dismutase (SOD) and catalase (CAT) were measured by anti-oxidative enzyme activity assays.

RESULTS

Fucoxanthin at 100 - 200 mg/kg significantly attenuated cognitive dysfunction, with a similar potency as curcumin, in aged mice after surgery. In addition, fucoxanthin and curcumin significantly increased the expression of pAkt, prevented the activation of microglial cells and astrocytes, and inhibited the secretion of pro-inflammatory interleukin-1β (IL - 1β) and tumor necrosis factor-α (TNF-α). Furthermore, fucoxanthin and curcumin elevated the ERK pathway and potently increased the activity of antioxidant enzymes. Most importantly, U0126, an inhibitor of the ERK pathway, and wortmannin, an inhibitor of the Akt pathway, significantly abolished the cognitive-enhancing effects, as well as the inhibition of neuroinflammation and the reduction of oxidative stress, induced by fucoxanthin in aged mice after surgery.

CONCLUSION

Fucoxanthin might be developed as a functional food or drug for the treatment of POCD by inhibiting neuroinflammation and enhancing antioxidant capacity via the activation of the Akt and ERK signaling pathways.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Dihydromyricetin confers cerebroprotection against subarachnoid hemorrhage via the Nrf2-dependent Prx2 signaling cascade

BACKGROUND

Several clinical and experimental studies have shown that therapeutic strategies targeting oxidative damage are beneficial for subarachnoid hemorrhage (SAH). A brain-permeable flavonoid, dihydromyricetin (DHM), can modulate redox/oxidative stress and has cerebroprotective effects in several neurological disorders. The effects of DHM on post-SAH early brain injury (EBI) and the underlying mechanism have yet to be clarified.

PURPOSE

This work investigated a potential role for DHM in SAH, together with the underlying mechanisms.

METHODS

Cerebroprotection by DHM was studied using a SAH rat model and primary cortical neurons. Atorvastatin (Ato) was a positive control drug in this investigation. The effects of DHM on behavior after SAH were evaluated by performing the neurological rotarod and Morris water maze tests, as well as by examining its effects on brain morphology and on the molecular and functional phenotypes of primary cortical neurons using dichlorodihydrofluorescein diacetate (DCFH-DA), immunofluorescent staining, biochemical analysis, and Western blot.

RESULTS

DHM was found to significantly reduce the amount of reactive oxygen species (ROS), suppress mitochondrial disruption, and increase intrinsic antioxidant enzymatic activity following SAH. DHM also significantly reduced neuronal apoptosis in SAH rats and improved short- and long-term neurological functions. DHM induced significant increases in peroxiredoxin 2 (Prx2) and nuclear factor erythroid 2-related factor 2 (Nrf2) expression, while decreasing phosphorylation of p38 and apoptotic signal-regulated kinase 1 (ASK1). In contrast, reduction of Prx2 expression using small interfering ribonucleic acid or by inhibiting Nrf2 with ML385 attenuated the neuroprotective effect of DHM against SAH. Moreover, DHM dose-dependently inhibited oxidative damage, decreased neuronal apoptosis, and increased the viability of primary cultured neurons in vitro. These positive effects were associated with Nrf2 activation and stimulation of Prx2 signaling, whereas ML385 attenuated the beneficial effects.

CONCLUSION

These results reveal that DHM protects against SAH primarily by modulating the Prx2 signaling cascade through the Nrf2-dependent pathway. Hence, DHM could be a valuable therapeutic candidate for SAH treatment.

Xanthophyll-Rich Extract of Phaeodactylum tricornutum Bohlin as New Photoprotective Cosmeceutical Agent: Safety and Efficacy Assessment on In Vitro Reconstructed Human Epidermis Model

The nutritional and health properties of algae make them perfect functional ingredients for nutraceutical and cosmeceutical applications. In this study, the Phaeodactylum tricornutum Bohlin (Phaeodactylaceae), a pleiomorphic diatom commonly found in marine ecosystems, was investigated. The in vitro culture conditions used favoured the fusiform morphotype, characterized by a high accumulation of neutral lipids, as detected by fluorescence microscopy after BODIPY staining. These data were confirmed by HPLC-DAD-APCI-MS/MS analyses carried out on the ethanolic extract (PTE), which showed a high content of xanthophylls (98.99%), and in particular of fucoxanthin (Fx, 6.67 g/100 g PTE). The antioxidant activity (ORAC, FRAP, TEAC and β-carotene bleaching) and photostability of PTE and Fx against UVA and UVB rays were firstly evaluated by in vitro cell-free assays. After this, phototoxicity and photoprotective studies were carried out on in vitro reconstructed human epidermidis models. Results demonstrated that PTE (0.1% Fx) and 0.1% Fx, both photostable, significantly (p < 0.05) reduce oxidative and inflammatory stress markers (ROS, NO and IL-1α), as well as cytotoxicity and sunburn cells induced by UVA and UVB doses simulating the solar radiation, with an excellent safety profile. However, PTE proved to be more effective than Fx, suggesting its effective and safe use in broad-spectrum sunscreens.

The Critical Role of Sirt1 in Subarachnoid Hemorrhages: Mechanism and Therapeutic Considerations

The subarachnoid hemorrhage (SAH) is an important cause of death and long-term disability worldwide. As a nicotinamide adenine dinucleotide-dependent deacetylase, silent information regulator 1 (Sirt1) is a multipotent molecule involved in many pathophysiological processes. A growing number of studies have demonstrated that Sirt1 activation may exert positive effects on SAHs by regulating inflammation, oxidative stress, apoptosis, autophagy, and ferroptosis. Thus, Sirt1 agonists may serve as potential therapeutic drugs for SAHs. In this review, we summarized the current state of our knowledge on the relationship between Sirt1 and SAHs and provided an updated overview of the downstream molecules of Sirt1 in SAHs.

Dietary Protective Potential of Fucoxanthin as an Active Food Component on Neurological Disorders

The prevalence of neurodegenerative, cerebrovascular, and psychiatric diseases and other neurological disorders has increased dramatically worldwide. Fucoxanthin is an algal pigment with many biological functions, and there is rising evidence that fucoxanthin plays a preventive and therapeutic role in neurological disorders. This review focuses on the metabolism, bioavailability, and blood-brain barrier penetration of fucoxanthin. Furthermore, the neuroprotective potential of fucoxanthin in neurodegenerative diseases, cerebrovascular diseases, and psychiatric diseases as well as other neurological disorders such as epilepsy, neuropathic pain, and brain tumors by acting on multiple targets will be summarized. The multiple targets include regulating apoptosis, reducing oxidative stress, activating the autophagy pathway, inhibiting Aβ aggregation, improving dopamine secretion, reducing α-synuclein aggregation, attenuating neuroinflammation, modulating gut microbiota, and activating brain-derived neurotrophic factor, etc. Additionally, we look forward to brain-targeted oral transport systems due to the low bioavailability and blood-brain barrier permeability of fucoxanthin. We also propose exploring the systemic mechanisms of fucoxanthin metabolism and transport through the gut-brain process and envision new therapeutic targets for fucoxanthin to act on the central nervous system. Finally, we propose dietary fucoxanthin delivery interventions to achieve preventive effects on neurological disorders. This review provides a reference for the application of fucoxanthin in the neural field.

Oxidative Stress and Intracranial Hypertension after Aneurysmal Subarachnoid Hemorrhage

Intracranial hypertension is a common phenomenon in patients with aneurysmal subarachnoid hemorrhage (aSAH). Elevated intracranial pressure (ICP) plays an important role in early brain injuries and is associated with unfavorable outcomes. Despite advances in the management of aSAH, there is no consensus about the mechanisms involved in ICP increases after aSAH. Recently, a growing body of evidence suggests that oxidative stress (OS) may play a crucial role in physio-pathological changes following aSAH, which may also contribute to increased ICP. Herein, we discuss a potential relation between increased ICP and OS, and resultantly propose antioxidant mechanisms as a potential therapeutic strategy for the treatment of ICP elevation following aSAH.

Activation of Sirtuin-1 by Pinocembrin Treatment Contributes to Reduced Early Brain Injury after Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) as a devastating neurological disorder is closely related to heightened oxidative insults and neuroinflammatory injury. Pinocembrin, a bioflavonoid, exhibits different biological functions, such as immunomodulatory, anti-inflammatory, antioxidative, and cerebroprotective activities. Herein, we examined the protective effects and molecular mechanisms of pinocembrin in a murine model of SAH. Using an endovascular perforation model in rats, pinocembrin significantly mitigated SAH-induced neuronal tissue damage, including inflammatory injury and free-radical insults. Meanwhile, pinocembrin improved behavior function and reduced neuronal apoptosis. We also revealed that sirtuin-1 (SIRT1) activation was significantly enhanced by pinocembrin. In addition, pinocembrin treatment evidently enhanced peroxisome proliferator-activated receptor-γ coactivator expression and suppressed ac-nuclear factor-kappa B levels. In contrast, EX-527, a selective SIRT1 inhibitor, blunted the protective effects of pinocembrin against SAH by suppressing SIRT1-mediated signaling. These results suggested that the cerebroprotective actions of pinocembrin after SAH were through SIRT1-dependent pathway, suggesting the potential application of pinocembrin for the treatment of SAH.

Advances in fucoxanthin chemistry and management of neurodegenerative diseases

BACKGROUND

Neurodegenerative diseases are chronic, currently incurable, diseases of the elderly, which are characterized by protein misfolding and neuronal damage. Fucoxanthin, derived from marine brown algae, presents a promising candidate for the development of effective therapeutic strategies.

HYPOTHESIS AND PURPOSE

The relationship between neurodegenerative disease management and fucoxanthin has not yet been clarified. This study focuses on the fundamental mechanisms and targets of fucoxanthin in Alzheimer's and Parkinson's disease management, showing that communication between the brain and the gut contributes to neurodegenerative diseases and early diagnosis of ophthalmic diseases. This paper also presents, new insights for future therapeutic directions based on the integrated application of artificial intelligence.

CONCLUSION

Fucoxanthin primarily binds to amyloid fibrils with spreading properties such as Aβ, tau, and α-synuclein to reduce their accumulation levels, alleviate inflammatory factors, and restore mitochondrial membranes to prevent oxidative stress via Nrf2 and Akt signaling pathways, involving reduction of specific secretases. In addition, fucoxanthin may serve as a preventive diagnosis for neurodegenerative diseases through ophthalmic disorders. It can modulate gut microbes and has potential for the alleviation and treatment of neurodegenerative diseases.

Isoliquiritigenin mitigates oxidative damage after subarachnoid hemorrhage in vivo and in vitro by regulating Nrf2-dependent Signaling Pathway via Targeting of SIRT1

BACKGROUND

Oxidative stress is a crucial factor leading to subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). Isoliquiritigenin has been verified as a powerful anti-oxidant in a variety of diseases models and can activate sirtuin 1 and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. However, the effects of isoliquiritigenin against EBI after SAH and the underlying mechanisms remain elusive.

PURPOSE

The primary goal of this study is to verify the therapeutic effects of isoliquiritigenin on EBI after SAH and the possible molecular mechanisms.

STUDY DESIGN

A prechiasmatic cistern SAH model in rats and a hemoglobin incubation SAH model in primary neurons were established. Isoliquiritigenin was administered after SAH induction. EX527 was employed to inhibit sirtuin 1 activation and ML385 was used to suppress Nrf2 signaling.

METHODS

In our study, neurological scores, brain edema, biochemical estimation, western blotting, and histopathological study were performed to explore the therapeutic action of isoliquiritigenin against SAH.

RESULTS

Our data revealed that isoliquiritigenin significantly mitigated oxidative damage after SAH as evidenced by decreased reactive oxygen species overproduction and enhanced intrinsic anti-oxidative system. Concomitant with the reduced oxidative insults, isoliquiritigenin improved neurological function and reduced neuronal death in the early period after SAH. Additionally, isoliquiritigenin administration significantly enhanced Nrf2 and sirtuin 1 expressions. Inhibition of Nrf2 by ML385 reversed the anti-oxidative and neuroprotective effects of isoliquiritigenin against SAH. Moreover, inhibiting sirtuin 1 by EX527 pretreatment suppressed isoliquiritigenin-induced Nrf2-dependent pathway and abated the cerebroprotective effects of isoliquiritigenin. In primary cortical neurons, isoliquiritigenin treatment also ameliorated oxidative insults and repressed neuronal degeneration. The beneficial aspects of isoliquiritigenin were attributed to the promotion of sirtuin 1 and Nrf2 signaling pathways and were counteracted by EX527.

CONCLUSION

Our findings suggest that isoliquiritigenin exerts cerebroprotective effects against SAH-induced oxidative insults by modulating the Nrf2-mediated anti-oxidant signaling in part through sirtuin 1 activation. Isoliquiritigenin might be a new potential drug candidate for SAH.

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.

Brown Algae as Functional Food Source of Fucoxanthin: A Review

Fucoxanthin is an algae-specific xanthophyll of aquatic carotenoid. It is prevalent in brown seaweed because it functions as a light-harvesting complex for algal photosynthesis and photoprotection. Its exceptional chemical structure exhibits numerous biological activities that benefit human health. Due to these valuable properties, fucoxanthin's potential as a potent source for functional food, feed, and medicine is being explored extensively today. This article has thoroughly reviewed the availability and biosynthesis of fucoxanthin in the brown seaweed, as well as the mechanism behind it. We included the literature findings concerning the beneficial bioactivities of fucoxanthin such as antioxidant, anti-inflammatory, anti-obesity, antidiabetic, anticancer, and other potential activities. Last, an additional view on its potential as a functional food ingredient has been discussed to facilitate a broader application of fucoxanthin as a promising bioactive compound.

Activation of SIRT1 Alleviates Ferroptosis in the Early Brain Injury after Subarachnoid Hemorrhage

Ferroptosis is a regulated cell death that characterizes the lethal lipid peroxidation and iron overload, which may contribute to early brain injury (EBI) pathogenesis after subarachnoid hemorrhage (SAH). Although Sirtuin 1 (SIRT1), a class III histone deacetylase, has been proved to have endogenous neuroprotective effects on the EBI following SAH, the role of SIRT1 in ferroptosis has not been studied. Hence, we designed the current study to determine the role of ferroptosis in the EBI and explore the correlation between SIRT1 and ferroptosis after SAH. The pathways of ferroptosis were examined after experimental SAH in vivo (prechiasmatic cistern injection mouse model) and in HT-22 cells stimulated by oxyhemoglobin (oxyHb) in vitro. Then, ferrostatin-1 (Fer-1) was used further to determine the role of ferroptosis in EBI. Finally, we explored the correlation between SIRT1 and ferroptosis via regulating the expression of SIRT1 by resveratrol (RSV) and selisistat (SEL). Our results showed that ferroptosis was involved in the pathogenesis of EBI after SAH through multiple pathways, including acyl-CoA synthetase long-chain family member 4 (ACSL4) activation, iron metabolism disturbance, and the downregulation of glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1). Inhibition of ferroptosis by Fer-1 significantly alleviated oxidative stress-mediated brain injury. SIRT1 activation could suppress SAH-induced ferroptosis by upregulating the expression of GPX4 and FSP1. Therefore, ferroptosis could be a potential therapeutic target for SAH, and SIRT1 activation is a promising method to inhibit ferroptosis.

Cycloastragenol Confers Cerebral Protection after Subarachnoid Hemorrhage by Suppressing Oxidative Insults and Neuroinflammation via the SIRT1 Signaling Pathway

Subarachnoid hemorrhage (SAH) is an acute cerebral vascular disease featured by oxidative insults and neuroinflammation. Cycloastragenol (CAG), the major active component of Astragalus radix, has a wide range of biological functions. However, the potential beneficial effects and the underlying molecular mechanisms of CAG on SAH remain obscure. In the current study, the cerebroprotective effects and mechanism of CAG on SAH were evaluated both in vivo and in vitro. Our results indicated that CAG significantly suppressed SAH-triggered oxidative insults, inflammatory mediators production, microglia activation, and the neutrophil infiltration in the brain. In addition, CAG improved neurological function and ameliorated neuronal apoptosis and degeneration after SAH. In vitro results also revealed the therapeutic effects of CAG on neurons and microglia co-culture system. Mechanistically, CAG treatment upregulated sirtuin 1 (SIRT1) expression, inhibited the levels of FoxO1, nuclear factor-kappa B, and p53 acetylation, and suppressed the subsequent oxidative, inflammatory, and apoptotic pathways. In contrast, inhibiting SIRT1 by pretreatment with Ex527 abrogated the protective actions of CAG both in vivo and in vitro models of SAH. Collectively, our findings indicated that CAG could be a promising and effective drug candidate for SAH.

Fucoxanthin Attenuates Oxidative Damage by Activating the Sirt1/Nrf2/HO-1 Signaling Pathway to Protect the Kidney from Ischemia-Reperfusion Injury

Oxidative stress is a key component of renal ischemia/reperfusion (I/R) injury. Fucoxanthin (Fx), a marine carotenoid with enhanced antioxidant capacity, acts as a ROS inhibitor in diseases such as ischemic stroke and acute lung injury. We hypothesized that fucoxanthin could attenuate renal I/R-induced oxidative damage. C57BL/6 mice ( $n=30$ ) were randomly assigned to sham, IR, $\text{IR}+\text{DMSO}$ , and $\text{IR}+\text{Fx}$ (25, 50, and 100 mg/kg) groups. The renal I/R injury was induced by clamping the left kidney nephron tip in mice. Fucoxanthin was injected intraperitoneally 24 hours before surgery. Compared with the IR group, pretreatment with fucoxanthin significantly improved renal dysfunction and tissue structural damage and inhibited ROS levels and apoptosis. Consistent results were observed in HK-2 cells. Besides, we found that renal I/R resulted in decreased expression of Sirt1, Nrf2, and HO-1, while fucoxanthin upregulated the expression of Sirt1, Nrf2, and HO-1. The protective effects of fucoxanthin were significantly reversed by EX527 (a selective inhibitor of Sirt1) or si-Sirt1. In conclusion, our study investigated the protective effect of fucoxanthin against renal I/R injury, and the underlying mechanism may be related to the activation of the Sirt1/Nrf2/HO-1 signaling pathway by fucoxanthin to attenuate oxidative stress-induced apoptosis.

An Update on Antioxidative Stress Therapy Research for Early Brain Injury After Subarachnoid Hemorrhage

The main reasons for disability and death in aneurysmal subarachnoid hemorrhage (aSAH) may be early brain injury (EBI) and delayed cerebral ischemia (DCI). Despite studies reporting and progressing when DCI is well-treated clinically, the prognosis is not well-improved. According to the present situation, we regard EBI as the main target of future studies, and one of the key phenotype-oxidative stresses may be called for attention in EBI after laboratory subarachnoid hemorrhage (SAH). We summarized the research progress and updated the literature that has been published about the relationship between experimental and clinical SAH-induced EBI and oxidative stress (OS) in PubMed from January 2016 to June 2021. Many signaling pathways are related to the mechanism of OS in EBI after SAH. Several antioxidative stress drugs were studied and showed a protective response against EBI after SAH. The systematical study of antioxidative stress in EBI after laboratory and clinical SAH may supply us with new therapies about SAH.

SIRT1 Promotes M2 Microglia Polarization via Reducing ROS-Mediated NLRP3 Inflammasome Signaling After Subarachnoid Hemorrhage

Mounting evidence has suggested that modulating microglia polarization from pro-inflammatory M1 phenotype to anti-inflammatory M2 state might be a potential therapeutic approach in the treatment of subarachnoid hemorrhage (SAH) injury. Our previous study has indicated that sirtuin 1 (SIRT1) could ameliorate early brain injury (EBI) in SAH by reducing oxidative damage and neuroinflammation. However, the effects of SIRT1 on microglial polarization and the underlying molecular mechanisms after SAH have not been fully illustrated. In the present study, we first observed that EX527, a potent selective SIRT1 inhibitor, enhanced microglial M1 polarization and nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation in microglia after SAH. Administration of SRT1720, an agonist of SIRT1, significantly enhanced SIRT1 expression, improved functional recovery, and ameliorated brain edema and neuronal death after SAH. Moreover, SRT1720 modulated the microglia polarization shift from the M1 phenotype and skewed toward the M2 phenotype. Additionally, SRT1720 significantly decreased acetylation of forkhead box protein O1, inhibited the overproduction of reactive oxygen species (ROS) and suppressed NLRP3 inflammasome signaling. In contrast, EX527 abated the upregulation of SIRT1 and reversed the inhibitory effects of SRT1720 on ROS-NLRP3 inflammasome activation and EBI. Similarly, in vitro, SRT1720 suppressed inflammatory response, oxidative damage, and neuronal degeneration, and improved cell viability in neurons and microglia co-culture system. These effects were associated with the suppression of ROS-NLRP3 inflammasome and stimulation of SIRT1 signaling, which could be abated by EX527. Altogether, these findings indicate that SRT1720, an SIRT1 agonist, can ameliorate EBI after SAH by shifting the microglial phenotype toward M2 via modulation of ROS-mediated NLRP3 inflammasome signaling.

Luteolin Confers Cerebroprotection after Subarachnoid Hemorrhage by Suppression of NLPR3 Inflammasome Activation through Nrf2-Dependent Pathway

Luteolin (LUT) possesses multiple biologic functions and has beneficial effects for cardiovascular and cerebral vascular diseases. Here, we investigated the protective effects of LUT against subarachnoid hemorrhage (SAH) and the involvement of underlying molecular mechanisms. In a rat model of SAH, LUT significantly inhibited SAH-induced neuroinflammation as evidenced by reduced microglia activation, decreased neutrophil infiltration, and suppressed proinflammatory cytokine release. In addition, LUT markedly ameliorated SAH-induced oxidative damage and restored the endogenous antioxidant systems. Concomitant with the suppressed oxidative stress and neuroinflammation, LUT significantly improved neurologic function and reduced neuronal cell death after SAH. Mechanistically, LUT treatment significantly enhanced the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), while it downregulated nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation. Inhibition of Nrf2 by ML385 dramatically abrogated LUT-induced Nrf2 activation and NLRP3 suppression and reversed the beneficial effects of LUT against SAH. In neurons and microglia coculture system, LUT also mitigated oxidative stress, inflammatory response, and neuronal degeneration. These beneficial effects were associated with activation of the Nrf2 and inhibitory effects on NLRP3 inflammasome and were reversed by ML385 treatment. Taken together, this present study reveals that LUT confers protection against SAH by inhibiting NLRP3 inflammasome signaling pathway, which may be modulated by Nrf2 activation.

Cerebroprotection by dioscin after experimental subarachnoid haemorrhage via inhibiting NLRP3 inflammasome through SIRT1-dependent pathway

BACKGROUND AND PURPOSE

Dioscin has multiple biological activities and is beneficial for cardiovascular and cerebral vascular diseases. Here, we investigated the protective effects of dioscin against subarachnoid haemorrhage and the molecular mechanisms involved.

EXPERIMENTAL APPROACH

Dioscin was administered after subarachnoid haemorrhage induced in rats. MCC950, a potent selective nod-like receptor pyrin domain-containing 3 (NLRP3) inhibitor, was used to suppress NLRP3 and EX527 (selisistat) was used to inhibit sirtuin 1 (SIRT1).

KEY RESULTS

In vivo, dioscin inhibited acute inflammatory response, oxidative damage, neurological impairment and neural cell degeneration after subarachnoid haemorrhage along with dramatically suppressing NLRP3 inflammasome activation. While pretreatment with MCC950 reduced the inflammatory response and improved neurological outcomes it did not lessen ROS production. However, giving dioscin after MCC950 reduced acute brain damage and ROS production. Dioscin increased SIRT1 expression after subarachnoid haemorrhage, whereas EX527 abolished the up-regulation of SIRT1 induced by dioscin and offset the inhibitory effects of dioscin on NLRP3 inflammasome activation. EX527 pretreatment also reversed the neuroprotective effects of dioscin against subarachnoid haemorrhage. Similarly, in vitro, dioscin dose-dependently suppressed inflammatory response, oxidative damage and neuronal degeneration and improved cell viability in neurons and microglia co-culture system. These effects were associated with inhibition of the NLRP3 inflammasome and stimulation of SIRT1 signalling, which could be inhibited by EX527 pretreatment.

CONCLUSION AND IMPLICATIONS

Dioscin provides protection against subarachnoid haemorrhage via the suppression of NLRP3 inflammasome activation through SIRT1-dependent pathway. Dioscin may be a new candidate to ameliorate early brain injury after subarachnoid haemorrhage.

Fucoxanthin rescues dexamethasone induced C2C12 myotubes atrophy

Muscle atrophy and weakness are the adverse effects of long-term or high dose usage of glucocorticoids. In the present study, we explored the effects of fucoxanthin (10 μM) on dexamethasone (10 μM)-induced atrophy in C2C12 myotubes and investigated its underlying mechanisms. The diameter of myotubes was observed under a light microscope, and the expression of myosin heavy chain (MyHC), proteolysis-related, autophagy-related, apoptosis-related, and mitochondria-related proteins was analyzed by western blots or immunoprecipitation. Fucoxanthin alleviates dexamethasone-induced muscle atrophy in C2C12 myotubes, indicated by increased myotubes diameter and expression of MyHC, decreased expression of muscle atrophy F-box (Atrogin-1) and muscle ring finger 1 (MuRF1). Through activating SIRT1, fucoxanthin inhibits forkhead box O (FoxO) transcriptional activity to reduce protein degradation, induces autophagy to enhance degraded protein clearance, promotes mitochondrial function and diminishes apoptosis. In conclusion, we identified fucoxanthin ameliorates dexamethasone induced C2C12 myotubes atrophy through SIRT1 activation.

Fucoxanthin Suppresses Osteoclastogenesis via Modulation of MAP Kinase and Nrf2 Signaling

Fucoxanthin (FX), a natural carotenoid present in edible brown seaweed, is known for its therapeutic potential in various diseases, including bone disease. However, its underlying regulatory mechanisms in osteoclastogenesis remain unclear. In this study, we investigated the effect of FX on osteoclast differentiation and its regulatory signaling pathway. In vitro studies were performed using osteoclast-like RAW264.7 cells stimulated with the soluble receptor activator of nuclear factor-κB ligand or tumor necrosis factor-alpha/interleukin-6. FX treatment significantly inhibited osteoclast differentiation and bone resorption ability, and downregulated the expression of osteoclast-specific markers such as nuclear factor of activated T cells 1, dendritic cell-specific seven transmembrane protein, and matrix metallopeptidase 9. Intracellular signaling pathway analysis revealed that FX specifically decreased the activation of the extracellular signal-regulated kinase and p38 kinase, and increased the nuclear translocation of phosphonuclear factor erythroid 2-related factor 2 (Nrf2). Our results suggest that FX regulates the expression of mitogen-activated protein kinases and Nrf2. Therefore, FX is a potential therapeutic agent for osteoclast-related skeletal disorders including osteoporosis and rheumatoid arthritis.

Fucoxanthin induced apoptotic cell death in oral squamous carcinoma (KB) cells

Fucoxanthin (Fx) is an active compound commonly found in the many types of seaweed with numerous biological activities. The main goal of this investigation is to explore the effect of Fx against the cell proliferation, apoptotic induction and oxidative stress in the oral squamous (KB) cell line. Cytotoxicity of Fx was determined by MTT assay. The intracellular ROS production, mitochondrial membrane potential (MMP) and apoptosis induction in KB cells were examined through DCFH-DA, Rhodamine-123 and DAPI, and dual staining techniques. Effect of Fx on the antioxidant enzymes and lipid peroxidation in the KB cells was studied through the standard procedures. Fx treated KB cells showed morphological changes and reduced cell survival, which is exhibited by the cytotoxic activity of 50 µM/ml (IC50) Fx against the KB cells. The Fx treatment considerably induced the apoptotosis cells (EB/AO) and decreased the MMP (Rh-123) in KB cells. Further, it was pointed out that there was an increased lipid peroxidation (LPO) with decreased antioxidants (CAT, SOD and GSH). These results concluded that Fx has the cytotoxic effect against KB cells and has the potential to induce the apoptosis via increased oxidative stress. Hence, the Fx can be a promising agent for the treatment of oral cancer and it may lead to the development of cancer therapeutics.

Astaxanthin ameliorates oxidative stress and neuronal apoptosis via SIRT1/NRF2/Prx2/ASK1/p38 after traumatic brain injury in mice

BACKGROUND AND PURPOSE

Oxidative stress and neuronal apoptosis play key roles in traumatic brain injury. We investigated the protective effects of astaxanthin against traumatic brain injury and its underlying mechanisms of action.

EXPERIMENTAL APPROACH

A weight-drop model of traumatic brain injury in vivo and hydrogen peroxide exposure in vitro model were established. Brain oedema, behaviour tests, western blot, biochemical analysis, lesion volume, histopathological study and cell viability were performed.

KEY RESULTS

Astaxanthin significantly reduced oxidative insults on Days 1, 3 and 7 after traumatic brain injury. Neuronal apoptosis was also ameliorated on Day 3. Additionally, astaxanthin improved neurological functions up to 3 weeks after traumatic brain injury. Astaxanthin treatment dramatically enhanced the expression of peroxiredoxin 2 (Prx2), nuclear factor-erythroid 2-related factor 2 (NRF2/Nrf2) and sirtuin 1 (SIRT1), while it down-regulated the phosphorylation of apoptosis signal-regulating kinase 1 (ASK1) and p38. Inhibition of Prx2 by siRNA injection reversed the beneficial effects of astaxanthin against traumatic brain injury. Additionally, Nrf2 knockout prevented the neuroprotective effects of astaxanthin in traumatic brain injury. In contrast, overexpression of Prx2 in Nrf2 knockout mice attenuated the secondary brain injury after traumatic brain injury. Moreover, inhibiting SIRT1 by EX527 dramatically inhibited the neuroprotective effects of astaxanthin and suppressed SIRT1/Nrf2/Prx2/ASK1/p38 pathway both in vivo and in vitro.

CONCLUSION AND IMPLICATIONS

Astaxanthin improved the neurological functions and protected the brain from injury after traumatic brain injury, primarily by reducing oxidative stress and neuronal death via SIRT1/Nrf2/Prx2/ASK1/p38 signalling pathway and might be a new candidate to ameliorate traumatic brain injury.