Echinatin mitigates sevoflurane-induced hippocampal neurotoxicity and cognitive deficits through mitigation of iron overload and oxidative stress

Echinatin suppresses cutaneous squamous cell carcinoma by targeting GSTM3-mediated ferroptosis

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin cancers for which effective drugs are urgently needed. Echinatin, a natural compound extracted from Glycyrrhiza plants, has shown promising antitumour effects. However, the efficacy and the direct target of echinatin in cSCC remain unclear.

PURPOSE

This study conducted a systematic investigation of the antitumour effects of echinatin on cSCC and the underlying mechanisms involved.

STUDY DESIGN AND METHODS

Three cSCC cell lines, a xenograft model, and a UV-induced cSCC mouse model were used to investigate the potential protective effects of echinatin. The interactions between echinatin and glutathione S-transferase mu3 (GSTM3) and between echinatin and peroxiredoxin-2 (PRDX2) were evaluated by a proteome microarray assay, pull-down LC‒MS/MS analysis, surface plasmon resonance, and molecular docking. The potential mechanisms of GSTM3-mediated echinatin activity were analysed by using western blotting, lentivirus infection and small interfering RNA (siRNA) transfection.

RESULTS

In this study, we found that echinatin inhibited the proliferation and migration of cSCC cells but had no cytotoxic effect on primary human keratinocytes. Furthermore, echinatin significantly inhibited tumour growth in vivo. Mechanistically, our data showed that echinatin could directly bind to GSTM3 and PRDX2. Notably, echinatin inhibited GSTM3 and PRDX2 levels by promoting their proteasomal degradation, which led to the disruption of ROS production. We then revealed that echinatin increased mitochondrial ROS production by inhibiting GSTM3. Moreover, echinatin triggered ferroptosis by inhibiting GSTM3-mediated ferroptosis negative regulation (FNR) proteins. In addition, echinatin regulated GSTM3-mediated ROS/MAPK signalling.

CONCLUSION

Echinatin has good antitumour effects both in vitro and in vivo. Moreover, our findings indicate that GSTM3 and PRDX2 could function as viable targets of echinatin in cSCC. Consequently, echinatin represents a novel treatment for cSCC through the targeting of GSTM3-mediated ferroptosis.

Echinatin alleviates inflammation and pyroptosis in hypoxic-ischemic brain damage by inhibiting TLR4/ NF-κB pathway

Hypoxic ischemic encephalopathy (HIE) is a primary cause of neonatal death and disabilities. The pathogenetic process of HIE is closely associated with neuroinflammation. Therefore, targeting and suppressing inflammatory pathways presents a promising therapeutic strategy for the treatment of HIE. Echinatin is an active component of glycyrrhiza, with anti-inflammatory and anti-oxidative properties. It is commonly combined with other traditional Chinese herbs to exert heat-clearing and detoxifying effects. This study aimed to investigate the anti-inflammatory and neuroprotective effects of Echinatin in neonatal rats with hypoxic-ischemic brain damage, as well as in PC12 cells exposed to oxygen-glucose deprivation (OGD). In vivo, Echinatin effectively reduced cerebral edema and infarct volume, protected brain tissue morphology, improved long-term behavioral functions, and inhibited microglia activation. These effects were accompanied by the downregulation of inflammatory factors and pyroptosis markers. The RNA sequencing analysis revealed an enrichment of inflammatory genes in rats with hypoxic-ischemic brain damage, and Protein-protein interaction (PPI) network analysis identified TLR4, MyD88, and NF-κB as the key regulators. In vitro, Echinatin reduced the levels of TLR4 relevant proteins, inhibited nuclear translocation of NF-κB, reduced the expression of downstreams inflammatory cytokines and pyroptosis proteins, and prevented cell membrane destructions. These findings demonstrated that Echinatin could inhibit the TLR4/NF-κB pathway, thereby alleviating neuroinflammation and pyroptosis. This suggests that Echinatin could be a potential candidate for the treatment of HIE.

Ferroptosis implication in environmental-induced neurotoxicity

Neurotoxicity, stemming from exposure to various chemical, biological, and physical agents, poses a substantial threat to the intricate network of the human nervous system. This article explores the implications of ferroptosis, a regulated form of programmed cell death characterized by iron-dependent lipid peroxidation, in environmental-induced neurotoxicity. While apoptosis has historically been recognized as a primary mechanism in neurotoxic events, recent evidence suggests the involvement of additional pathways, including ferroptosis. The study aims to conduct a comprehensive review of the existing literature on ferroptosis induced by environmental neurotoxicity across diverse agents such as natural toxins, insecticides, particulate matter, acrylamide, nanoparticles, plastic materials, metal overload, viral infections, anesthetics, chemotherapy, and radiation. The primary objective is to elucidate the diverse mechanisms through which these agents trigger ferroptosis, leading to neuronal cell death. Furthermore, the article explores potential preventive or therapeutic strategies that could mitigate ferroptosis, offering insights into protective measures against neurological damage induced by environmental stressors. This comprehensive review contributes to our evolving understanding of neurotoxicological processes, highlighting ferroptosis as a significant contributor to neuronal cell demise induced by environmental exposures. The insights gained from this study may pave the way for the development of targeted interventions to protect against ferroptosis-mediated neurotoxicity and ultimately safeguard public health.

Sevoflurane causes neurotoxicity and cognitive impairment by regulating Hippo signaling pathway-mediated ferroptosis via upregulating PRKCD

BACKGROUND

Sevoflurane (SEV) has been found to induce neurotoxicity and cognitive impairment, leading to the development of degenerative diseases. Protein kinase C delta (PRKCD) is upregulated in the hippocampus of SEV-treated mice and may be related to SEV-related neurotoxicity. However, the underlying molecular mechanisms by which SEV mediates neurotoxicity via PRKCD remain unclear.

METHODS

Normal mice and PRKCD knockout (KO) mice were exposed to SEV. Hippocampal neurons were isolated from mice hippocampal tissues. H&E staining was used for pathological morphology of hippocampal tissues, and NISSL staining was used to analyze the number of hippocampal neurons. The mRNA and protein levels were determined using quantitative real-time PCR, western blot, immunofluorescence staining and immunohistochemical staining. The mitochondrial microstructure was observed by transmission electron microscopy. Cell viability was detected by cell counting kit 8 assay, and ferroptosis was assessed by detecting related marker levels. The cognitive ability of mice was assessed by morris water maze test. And the protein levels of PRKCD, ferroptosis-related markers and Hippo pathway-related markers were examined by western bolt.

RESULTS

SEV increased PRKCD expression and ferroptosis in hippocampal tissues of mice. Also, SEV promoted mouse hippocampal neuron injury by inducing ferroptosis via upregulating PRKCD expression. Knockout of PRKCD alleviated SEV-induced neurotoxicity and cognitive impairment in mice, and relieved SEV-induced ferroptosis in hippocampal neurons. PRKCD could inhibit the activity of Hippo pathway, and its knockdown also overturned SEV-mediated ferroptosis by activating Hippo pathway.

CONCLUSION

SEV could induce neurotoxicity and cognitive impairment by promoting ferroptosis via inactivating Hippo pathway through increasing PRKCD expression.

Fer-1 Protects against Isoflurane-Induced Ferroptosis in Astrocytes and Cognitive Impairment in Neonatal Mice

Early and prolonged exposure to anesthetic agents could cause neurodevelopmental disorders in children. Astrocytes, heavily outnumber neurons in the brain, are crucial regulators of synaptic formation and function during development. However, how general anesthetics act on astrocytes and the impact on cognition are still unclear. In this study, we investigated the role of ferroptosis and GPX4, a major hydroperoxide scavenger playing a pivotal role in suppressing the process of ferroptosis, and their underlying mechanism in isoflurane-induced cytotoxicity in astrocytes and cognitive impairment. Our results showed that early 6 h isoflurane anesthesia induced cognitive impairment in mice. Ferroptosis-relative genes and metabolic changes were involved in the pathological process of isoflurane-induced cytotoxicity in astrocytes. The level of GPX4 was decreased while the expression of 4-HNE and generation of ROS were elevated after isoflurane exposure. Selectively blocking ferroptosis with Fer-1 attenuated the abovementioned cytotoxicity in astrocytes, paralleling with the reverse of the changes in GPX4, ROS and 4-HNE secondary to isoflurane anesthesia. Fer-1 attenuated the cognitive impairment induced by prolonged isoflurane exposure. Thus, ferroptosis conduced towards isoflurane-induced cytotoxicity in astrocytes via suppressing GPX4 and promoting lipid peroxidation. Fer-1 was expected to be an underlying intervention for the neurotoxicity induced by isoflurane in the developing brain, and to alleviate cognitive impairment in neonates.

Electroacupuncture suppresses neuronal ferroptosis to relieve chronic neuropathic pain

Growing evidence supports the analgesic efficacy of electroacupuncture (EA) in managing chronic neuropathic pain (NP) in both patients and NP models induced by peripheral nerve injury. However, the underlying mechanisms remain incompletely understood. Ferroptosis, a novel form of programmed cell death, has been found to be activated during NP development, while EA has shown potential in promoting neurological recovery following acute cerebral injury by targeting ferroptosis. In this study, to investigate the detailed mechanism underlying EA intervention on NP, male Sprague-Dawley rats with chronic constriction injury (CCI)-induced NP model received EA treatment at acupoints ST36 and GV20 for 14 days. Results demonstrated that EA effectively attenuated CCI-induced pain hypersensitivity and mitigated neuron damage and loss in the spinal cord of NP rats. Moreover, EA reversed the oxidative stress-mediated spinal ferroptosis phenotype by upregulating reduced expression of xCT, glutathione peroxidase 4 (GPX4), ferritin heavy chain (FTH1) and superoxide dismutase (SOD) levels, and downregulating increased expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), malondialdehyde levels and iron overload. Furthermore, EA increased the immunofluorescence co-staining of GPX4 in neurons cells of the spinal cord of CCI rats. Mechanistic analysis unveiled that the inhibition of antioxidant pathway of Nrf2 signalling via its specific inhibitor, ML385, significantly countered EA's protective effect against neuronal ferroptosis in NP rats while marginally diminishing its analgesic effect. These findings suggest that EA treatment at acupoints ST36 and GV20 may protect against NP by inhibiting neuronal ferroptosis in the spinal cord, partially through the activation of Nrf2 signalling.

Natural product-derived ferroptosis mediators

It has been 11 years since ferroptosis, a new mode of programmed cell death, was first proposed. Natural products are an important source of drug discovery. In the past five years, natural product-derived ferroptosis regulators have been discovered in an endless stream. Herein, 178 natural products discovered so far to trigger or resist ferroptosis are classified into 6 structural classes based on skeleton type, and the mechanisms of action that have been reported are elaborated upon. If pharmacodynamic data are sufficient, the structure and bioactivity relationship is also presented. This review will provide medicinal chemists with some effective ferroptosis regulators, which will promote the research of natural product-based treatment of ferroptosis-related diseases in the future.

Synthesis and Antitumor Activity Evaluation of Novel Echinatin Derivatives with a 1,3,4-Oxadiazole Moiety

A series of novel echinatin derivatives with 1,3,4-oxadiazole moieties were designed and synthesized. Most of the newly synthesized compounds exhibited moderate antiproliferative activity against the four cancer cell lines. Notably, Compound T4 demonstrated the most potent activity, with IC50 values ranging from 1.71 µM to 8.60 µM against the four cancer cell lines. Cell colony formation and wound healing assays demonstrated that T4 significantly inhibited cell proliferation and inhibited migration. We discovered that T4 exhibited moderate binding affinity with the c-KIT protein through reverse docking. The results were effectively validated through subsequent molecular docking and c-KIT enzyme activity assays. In addition, Western blot analysis revealed that T4 inhibits the phosphorylation of downstream proteins of c-KIT. The results provide valuable inspiration for exploring novel insights into the design of echinatin-related hybrids as well as their potential application as c-KIT inhibitors to enhance the efficacy of candidates.

20(S)-Ginsenoside Rh1 alleviates sevoflurane-induced ototoxicity by reducing oxidative stress levels

CONTEXT

Sevoflurane is an inhalational anesthetic widely used in pediatric surgery. However, animal studies have shown that multiple sevoflurane exposures during the neonatal period led to ototoxicity. 20(S)-Ginsenoside Rh1, a ginsenoside extract, protects against cisplatin-induced ototoxicity by scavenging free radicals.

OBJECTIVE

This study aimed to assess the effects of Rh1 on sevoflurane-induced ototoxicity.

MATERIALS AND METHODS

Neonatal cochlear explants and House Ear Institute-Organ of Corti 1 (HEI-OC1) cells were cultured and randomly divided into three groups: the control group, the sevoflurane group and the Rh1 pretreatment group. We pretreated cochlear explants or HEI-OC1 cells with 100 μM Rh1 2 hours before performing sevoflurane exposure. Immunofluorescence was used to detect hair cells and spiral ganglion neurons. Cell Counting Kit-8 assay was used to determine cell viability. Annexin V-fluorescein isothiocyanate and propidium iodide were used to evaluate apoptosis. CellROX-Green and MitoSOX-Red probes were used to measure the amount of reactive oxygen species (ROS). Tetramethylrhodamine methyl ester labeling was used to examine mitochondrial membrane potential.

RESULTS

Rh1 attenuated spiral ganglion neuron nerve fibers and synapses degeneration in cochlear explants after sevoflurane exposure. Rh1 significantly increased the viability of HEI-OC1 cells, reduced reactive oxygen species accumulation in HEI-OC1 cells, and prevented mitochondrial damage in HEI-OC1 cells after sevoflurane exposure.

DISCUSSION AND CONCLUSION

These findings suggest that Rh1 is a promising drug for preventing sevoflurane-induced ototoxicity.

Dysregulation of iron homeostasis and ferroptosis in sevoflurane and isoflurane associated perioperative neurocognitive disorders

In recent years, sevoflurane and isoflurane are the most popular anesthetics in general anesthesia for their safe, rapid onset, and well tolerant. Nevertheless, many studies reported their neurotoxicity among pediatric and aged populations. This effect is usually manifested as cognitive impairment such as perioperative neurocognitive disorders. The wide application of sevoflurane and isoflurane during general anesthesia makes their safety a major health concern. Evidence indicates that iron dyshomeostasis and ferroptosis may establish a role in neurotoxicity of sevoflurane and isoflurane. However, the mechanisms of sevoflurane- and isoflurane-induced neuronal injury were not fully understood, which poses a barrier to the treatment of its neurotoxicity. We, therefore, reviewed the current knowledge on mechanisms of iron dyshomeostasis and ferroptosis and aimed to promote a better understanding of their roles in sevoflurane- and isoflurane-induced neurotoxicity.

Liproxstatin-1 alleviates ferroptosis in sevoflurane anesthesia-induced cognitive deficits of aged mice: The role oxidative stress

In this study, we aimed to validate the hypothesis that the interplay between sevoflurane, oxidative stress and ferroptosis is crucial for the pathogenesis of sevoflurane-induced cognitive impairment in aged individuals. The mice with sevoflurane-induced cognitive impairment were used to explore the effects of sevoflurane on oxidative stress, iron homeostasis, and cognitive function in aged mice. Iron content and oxidative stress markers were analyzed in hippocampal tissue homogenates using specific assays. Additionally, the levels of iron death-related markers (Fth1 and Gpx4) were assessed by real-time PCR and Western blotting. Morris Water Maze and novel object recognition (NOR) tests were conducted to evaluate cognitive function. Sevoflurane exposure in aged mice resulted in a significant increase in iron overloading in the hippocampus, followed by a subsequent stabilization. Oxidative stress levels were elevated in the hippocampal tissue of sevoflurane-exposed mice, and a significant correlation was observed between iron death and oxidative stress. Liproxstatin-1, a ferroptosis inhibitor, effectively ameliorated the decline in memory and learning abilities induced by sevoflurane anesthesia. Liproxstatin-1 treatment reduced iron overload and oxidative stress in the hippocampal tissue of aged mice. The expression of Fth1 and Gpx4, iron death-related markers, was downregulated following Liproxstatin-1 intervention. Our findings suggest that sevoflurane anesthesia disrupts iron homeostasis, leading to increased oxidative stress and cognitive impairment in aged mice. These results highlight the potential of targeting iron-mediated processes to mitigate sevoflurane-induced cognitive impairment in the aging population.

Metformin attenuates sevoflurane-induced neurogenesis damage and cognitive impairment: involvement of the Nrf2/G6PD pathway

Anesthetics such as sevoflurane are commonly administered to infants and children. However, the possible neurotoxicity caused by prolonged or repetitive exposure to it should be a concern. The neuroprotective effects of metformin are observed in many models of neurological disorders. In this study, we investigated whether metformin could reduce the developmental neurotoxicity induced by sevoflurane exposure in neonatal rats and the potential mechanism. Postnatal day 7 (PND 7) Sprague-Dawley rats and neural stem cells (NSCs) were treated with normal saline or metformin before sevoflurane exposure. The Morris water maze (MWM) was used to observe spatial memory and learning at PND 35-42. Immunofluorescence staining was used to detect neurogenesis in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus at PND 14. MTT assays, immunofluorescence staining, and TUNEL staining were used to assess the viability, proliferation, differentiation, and apoptosis of NSCs. Western blotting and ELISA were used to assess the protein expression of cleaved caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and glucose-6-phosphate dehydrogenase (G6PD) pathway-related molecules. Exposure to sevoflurane resulted in late cognitive defects, impaired neurogenesis in both the SVZ and SGZ, reduced NSC viability and proliferation, increased NSC apoptosis, and decreased protein expression of G6PD in vitro. Metformin pretreatment attenuated sevoflurane-induced cognitive functional decline and neurogenesis inhibition. Metformin pretreatment also increased the protein expression of Nrf2 and G6PD. However, treatment with the Nrf2 inhibitor, ML385 or the G6PD inhibitor, dehydroepiandrosterone (DHEA) reversed the protective effect of metformin on sevoflurane-induced NSC damage in vitro. Our findings suggested that metformin could reduce sevoflurane-induced neurogenesis damage and neurocognitive defects in the developing rat brain by influencing the Nrf2/G6PD signaling pathways.

The effects of general anesthetics on mitochondrial structure and function in the developing brain

The use of general anesthetics in modern clinical practice is commonly regarded as safe for healthy individuals, but exposures at the extreme ends of the age spectrum have been linked to chronic cognitive impairments and persistent functional and structural alterations to the nervous system. The accumulation of evidence at both the epidemiological and experimental level prompted the addition of a warning label to inhaled anesthetics by the Food and Drug Administration cautioning their use in children under 3  years of age. Though the mechanism by which anesthetics may induce these detrimental changes remains to be fully elucidated, increasing evidence implicates mitochondria as a potential primary target of anesthetic damage, meditating many of the associated neurotoxic effects. Along with their commonly cited role in energy production via oxidative phosphorylation, mitochondria also play a central role in other critical cellular processes including calcium buffering, cell death pathways, and metabolite synthesis. In addition to meeting their immense energy demands, neurons are particularly dependent on the proper function and spatial organization of mitochondria to mediate specialized functions including neurotransmitter trafficking and release. Mitochondrial dependence is further highlighted in the developing brain, requiring spatiotemporally complex and metabolically expensive processes such as neurogenesis, synaptogenesis, and synaptic pruning, making the consequence of functional alterations potentially impactful. To this end, we explore and summarize the current mechanistic understanding of the effects of anesthetic exposure on mitochondria in the developing nervous system. We will specifically focus on the impact of anesthetic agents on mitochondrial dynamics, apoptosis, bioenergetics, stress pathways, and redox homeostasis. In addition, we will highlight critical knowledge gaps, pertinent challenges, and potential therapeutic targets warranting future exploration to guide mechanistic and outcomes research.

Natural Flavonoids and Ferroptosis: Potential Therapeutic Opportunities for Human Diseases

Flavonoids are a class of bioactive phytochemicals containing a core 2-phenylchromone skeleton and are widely found in fruits, vegetables, and herbs. Such natural compounds have gained significant attention due to their various health benefits. Ferroptosis is a recently discovered unique iron-dependent mode of cell death. Unlike traditional regulated cell death (RCD), ferroptosis is associated with excessive lipid peroxidation on cellular membranes. Accumulating evidence suggests that this form of RCD is involved in a variety of physiological and pathological processes. Notably, multiple flavonoids have been shown to be effective in preventing and treating diverse human diseases by regulating ferroptosis. In this review, we introduce the key molecular mechanisms of ferroptosis, including iron metabolism, lipid metabolism, and several major antioxidant systems. Additionally, we summarize the promising flavonoids targeting ferroptosis, which provides novel ideas for the management of diseases such as cancer, acute liver injury, neurodegenerative diseases, and ischemia/reperfusion (I/R) injury.

Role of ferroptosis in pregnancy related diseases and its therapeutic potential

Ferroptosis is a form of regulated cell death characterized by iron overload, overwhelming lipid peroxidation, and disruption of antioxidant systems. Emerging evidence suggests that ferroptosis is associated with pregnancy related diseases, such as spontaneous abortion, pre-eclampsia, gestational diabetes mellitus, intrahepatic cholestasis of pregnancy, and spontaneous preterm birth. According to these findings, inhibiting ferroptosis might be a potential option to treat pregnancy related diseases. This review summarizes the mechanisms and advances of ferroptosis, the pathogenic role of ferroptosis in pregnancy related diseases and the potential medicines for its treatment.