Antioxidant activity of 3-methyl-1-phenyl-2-pyrazolin-5-one

Discovery of selective ROCK2 inhibitors with free radical scavenging ability for the treatment of gouty arthritis

ROCK inhibitors can inhibit IL-1β and NLRP3, and their therapeutic potential for osteoarthritis and rheumatoid arthritis has been confirmed, but their impact on gouty arthritis has not been reported yet. By hybridization the structure of Edaravone, a series of ROCK inhibitors with pyrazolone scaffold were designed and synthesized. RM-04 has acceptable selective ROCK2 inhibitory activity with an IC50 of 4.62 µM, and its IC50 values for scavenging DPPH• and ABTS•+ are 16.72 µM and 23.15 µM, respectively, which is equivalent to that of Edaravone. Furthermore, RM-04 exhibits good pharmacokinetic properties and good safety in vivo. Meanwhile, in sodium urate-induced acute gout model, RM-04 at a dose of 5 mg/kg exhibited the alleviating effect approximately equivalent to that of Celecoxib, indicating that ROCKs inhibitors with antioxidation activity could reduce the damage caused by gouty arthritis.

Assessing the efficacy of amyotrophic lateral sclerosis drugs in slowing disease progression: A literature review

Amyotrophic lateral sclerosis (ALS) is a fatal and intricate neurodegenerative disease that impacts upper and lower motor neurons within the central nervous system, leading to their progressive destruction. Despite extensive research, the pathogenesis of this multifaceted disease remains elusive. The United States Food and Drug Administration (FDA) has granted approval for seven medications designed to address ALS and mitigate its associated symptoms. These FDA-sanctioned treatments are Qalsody, Relyvrio, Radicava, Rilutek, Tiglutik, Exservan, and Nuedexta. In this review, the effects of these seven drugs on ALS based on their mechanism of action, dosing, and clinical presentations are comprehensively summarized. Each medication offers a distinct approach to manage ALS, aiming to alleviate the burdensome symptoms and slow the disease's progression, thereby improving the quality of life for individuals affected by this neurological condition. However, despite these advancements in pharmaceutical interventions, finding a definitive cure for ALS remains a significant challenge. Continuous investigation into ALS pathophysiology and therapeutic avenues remains imperative, necessitating further research collaborations and innovative approaches to unravel the complex mechanisms underlying this debilitating condition.

Current perspectives on neuromodulation in ALS patients: A systematic review and meta-analysis

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons, resulting in muscle weakness, paralysis, and eventually patient mortality. In recent years, neuromodulation techniques have emerged as promising potential therapeutic approaches to slow disease progression and improve the quality of life of ALS patients. A systematic review was conducted until August 8, 2023, to evaluate the neuromodulation methods used and their potential in the treatment of ALS. The search strategy was applied in the Cochrane Central database, incorporating results from other databases such as PubMed, Embase, CTgov, CINAHL, and ICTRP. Following the exclusion of papers that did not fulfil the inclusion criteria, a total of 2090 records were found, leaving a total of 10 studies. R software was used to conduct meta-analyses based on the effect sizes between the experimental and control groups. This revealed differences in muscle stretch measures with manual muscle testing (p = 0.012) and resting motor threshold (p = 0.0457), but not with voluntary isometric contraction (p = 0.1883). The functionality of ALS was also different (p = 0.007), but not the quality of life. Although intracortical facilitation was not seen in motor cortex 1 (M1) (p = 0.1338), short-interval intracortical inhibition of M1 was significant (p = 0.0001). BDNF showed no differences that were statistically significant (p = 0.2297). Neuromodulation-based treatments are proposed as a promising therapeutic approach for ALS that can produce effects on muscle function, spasticity, and intracortical connections through electrical, magnetic, and photonic stimulation. Photobiomodulation stands out as an innovative approach that uses specific wavelengths to influence mitochondria, with the aim of improving mitochondrial function and reducing excitotoxicity. The lack of reliable placebo controls and the variation in stimulation frequency are some of the drawbacks of neuromodulation.

Update on Antioxidant Therapy with Edaravone: Expanding Applications in Neurodegenerative Diseases

The brain is susceptible to oxidative stress, which is associated with various neurological diseases. Edaravone (MCI-186, 3-methyl-1 pheny-2-pyrazolin-5-one), a free radical scavenger, has promising effects by quenching hydroxyl radicals (∙OH) and inhibiting both ∙OH-dependent and ∙OH-independent lipid peroxidation. Edaravone was initially developed in Japan as a neuroprotective agent for acute cerebral infarction and was later applied clinically to treat amyotrophic lateral sclerosis (ALS), a neurodegenerative disease. There is accumulating evidence for the therapeutic effects of edaravone in a wide range of diseases related to oxidative stress, including ischemic stroke, ALS, Alzheimer's disease, and placental ischemia. These neuroprotective effects have expanded the potential applications of edaravone. Data from experimental animal models support its safety for long-term use, implying broader applications in various neurodegenerative diseases. In this review, we explain the unique characteristics of edaravone, summarize recent findings for specific diseases, and discuss its prospects for future therapeutic applications.

Development of a Semi-Dry Method for Measuring Drug Permeation into Skin Using an Electric Facial Care Device and Iontophoresis

INTRODUCTION

Percutaneous drug delivery systems are attractive not only as a therapeutic strategy but also for cosmetic treatment. Iontophoresis is a well-recognized method for promoting transdermal absorption of ionized compounds. Franz cells are generally used to estimate drug permeation of skin by iontophoresis. However, methods using Franz cells are less versatile; for instance, the method is unsuited for use with a portable electric facial care device having a working probe of a certain size and weight. In this study, we constructed a semi-dry apparatus for use with an electric facial care device.

METHODS

The apparatus has a multilayer structure consisting of mouse skin and 3 filter papers, modeled after the Franz cell. The skin permeation of the drug edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) was then measured using this apparatus.

RESULTS

Edaravone permeation depended on working time, drug concentration, and ionization ratio of edaravone when iontophoresis was carried out with an electric facial care device. Furthermore, glycyrrhizic acid, α-tocopheryl phosphate, retinoic acid, and ascorbyl palmitate, which are recognized as functional cosmetic materials, also permeated the skin by applying iontophoresis with the device.

CONCLUSION

These results suggest that the developed measuring apparatus is applicable for use with a portable electric facial care device and that iontophoresis using a portable electric facial care device is potentially useful in the cosmetic field.

Edaravone: A Novel Possible Drug for Cancer Treatment?

Despite significant advancements in understanding the causes and progression of tumors, cancer remains one of the leading causes of death worldwide. In light of advances in cancer therapy, there has been a growing interest in drug repurposing, which involves exploring new uses for medications that are already approved for clinical use. One such medication is edaravone, which is currently used to manage patients with cerebral infarction and amyotrophic lateral sclerosis. Due to its antioxidant and anti-inflammatory properties, edaravone has also been investigated for its potential activities in treating cancer, notably as an anti-proliferative and cytoprotective drug against side effects induced by traditional cancer therapies. This comprehensive review aims to provide updates on the various applications of edaravone in cancer therapy. It explores its potential as a standalone antitumor drug, either used alone or in combination with other medications, as well as its role as an adjuvant to mitigate the side effects of conventional anticancer treatments.

High altitude hypoxia and oxidative stress: The new hope brought by free radical scavengers

Various strategies can be employed to prevent and manage altitude illnesses, including habituation, oxygenation, nutritional support, and medication. Nevertheless, the utilization of drugs for the prevention and treatment of hypoxia is accompanied by certain adverse effects. Consequently, the quest for medications that exhibit minimal side effects while demonstrating high efficacy remains a prominent area of research. In this context, it is noteworthy that free radical scavengers exhibit remarkable anti-hypoxia activity. These scavengers effectively eliminate excessive free radicals and mitigate the production of reactive oxygen species (ROS), thereby safeguarding the body against oxidative damage induced by plateau hypoxia. In this review, we aim to elucidate the pathogenesis of plateau diseases that are triggered by hypoxia-induced oxidative stress at high altitudes. Additionally, we present a range of free radical scavengers as potential therapeutic and preventive approaches to mitigate the occurrence of common diseases associated with hypoxia at high altitudes.

Encapsulation of an Antioxidant in Redox-Sensitive Self-Assembled Albumin Nanoparticles for the Treatment of Hepatitis

Hepatitis is an inflammation of the liver caused by the inadequate elimination of reactive oxygen species (ROS) derived from Kupffer cells. Edaravone is clinically used as an antioxidant but shows poor liver distribution. Herein, we report on the design of a Kupffer cell-oriented nanoantioxidant based on a disulfide cross-linked albumin nanoparticle containing encapsulated edaravone (EeNA) as a therapeutic for the treatment of hepatitis. Since the edaravone is bound to albumin, this results in a soluble and stable form of edaravone in water. Exchanging the intramolecular disulfide bonds to intermolecular disulfide bridges of albumin molecules allowed the preparation of a redox responsive albumin nanoparticle that is stable in the blood circulation but can release drugs into cells. Consequently, EeNA was fabricated by the nanoscale self-assembly of edaravone and albumin nanoparticles without the additives that are contained in commercially available edaravone preparations. EeNA retained its nanostructure under serum conditions, but the encapsulated edaravone was released efficiently under intracellular reducing conditions in macrophages. The EeNA was largely distributed in the liver and subsequently internalized into Kupffer cells within 60 min after injection in a concanavalin-A-induced hepatitis mouse. The survival rate of the hepatitis mice was significantly improved by EeNA due to the suppression of liver necrosis and oxidative stress by scavenging excessive ROS. Moreover, even through the postadministration, EeNA showed an excellent hepatoprotective action as well. In conclusion, EeNA has the potential for use as a nanotherapeutic against various types of hepatitis because of its Kupffer cell targeting ability and redox characteristics.

Cure of Alzheimer's Dementia in Many Patients by Using Intranasal Insulin to Augment an Inadequate Counter-Reaction, Edaravone to Scavenge ROS, and 1 or 2 Other Drugs to Address Affected Brain Cells

The goal of treatment for Alzheimer's dementia (AD) is the restoration of normal cognition. No drug regimen has ever achieved this. This article suggests that curing AD may be achieved by combination therapy as follows. First, with intranasal insulin to augment the body's natural counter-reaction to the changes in brain cell-types that produced the dementia. Second, with edaravone to decrease free radicals, which are increased and causal in AD. Third, as described elsewhere, with one or two drugs from among pioglitazone, fluoxetine, and lithium, which address the brain cell-types whose changed functions cause the dementia. Insulin restores cerebral glucose, which is the main nutrient for brain neurons whose depletion is responsible for the dementia; and edaravone decreases ROS, which are intrinsic causes of neuropathology in AD. This combination of drugs is a potential cure for many patients with AD, and should be tested in a clinical trial.

Network Pharmacology Prediction and Experimental Verification for Anti-Ferroptosis of Edaravone After Experimental Intracerebral Hemorrhage

Neuronal ferroptosis plays an important role in secondary brain injuries after intracerebral hemorrhage (ICH). Edaravone (Eda) is a promising free radical scavenger that inhibits ferroptosis in neurological diseases. However, its protective effects and underlying mechanisms in ameliorating post-ICH ferroptosis remain unclear. We employed a network pharmacology approach to determine the core targets of Eda against ICH. Forty-two rats were subjected to successful striatal autologous whole blood injection (n=28) or sham operation (n=14). The 28 blood-injected rats were randomly assigned to either the Eda or vehicle group (n=14) for immediate administration and then for 3 consecutive days. Hemin-induced HT22 cells were used for in vitro studies. The effects of Eda in ICH on ferroptosis and the MEK/ERK pathway were investigated in vivo and in vitro. Network pharmacology-based analysis revealed that candidate targets of Eda-treated ICH might be related to ferroptosis; among which prostaglandin G/H synthase 2 (PTGS2) was a ferroptosis marker. In vivo experiments showed that Eda alleviated sensorimotor deficits and decreased PTGS2 expression (all p<0.05) after ICH. Eda rescued neuron pathological changes after ICH (increased NeuN⁺ cells and decreased FJC⁺ cells, all p<0.01). In vitro experiments showed that Eda reduced intracellular reactive oxygen species and reversed mitochondria damage. Eda repressed ferroptosis by decreasing malondialdehyde and iron deposition and by influencing ferroptosis-related protein expression (all p<0.05) in ICH rats and hemin-induced HT22 cells. Mechanically, Eda significantly suppressed phosphorylated-MEK and phosphorylated-ERK1/2 expression. These results indicate that Eda has protective effects on ICH injury through ferroptosis and MEK/ERK pathway suppression.

Application of regulation of reactive oxygen species and lipid peroxidation to disease treatment

Although many diseases in which reactive oxygen species (ROS) and free radicals are involved in their pathogenesis are known, and antioxidants that effectively capture ROS have been identified and developed, there are only a few diseases for which antioxidants have been used for treatment. Here, we discuss on the following four concepts regarding the development of applications for disease treatment by regulating ROS, free radicals, and lipid oxidation with the findings of our research and previous reports. Concept 1) Utilization of antioxidants for disease treatment. In particular, the importance of the timing of starting antioxidant will be discussed. Concept 2) Therapeutic strategies using ROS and free radicals. Methods of inducing ferroptosis, which has been advocated as an iron-dependent cell death, are mentioned. Concept 3) Treatment with drugs that inhibit the synthesis of lipid mediators. In addition to the reduction of inflammatory lipid mediators by inhibiting cyclooxygenase and leukotriene synthesis, we will introduce the possibility of disease treatment with lipoxygenase inhibitors. Concept 4) Disease treatment by inducing the production of useful lipid mediators for disease control. We describe the treatment of inflammatory diseases utilizing pro-resolving mediators and propose potential compounds that activate lipoxygenase to produce these beneficial mediators.

Synthesis of 4-Aminopyrazol-5-ols as Edaravone Analogs and Their Antioxidant Activity

One of the powerful antioxidants used clinically is Edaravone (EDA). We synthesized a series of new EDA analogs, 4-aminopyrazol-5-ol hydrochlorides, including polyfluoroalkyl derivatives, via the reduction of 4-hydroxyiminopyrazol-5-ones. The primary antioxidant activity of the compounds in comparison with EDA was investigated in vitro using ABTS, FRAP, and ORAC tests. In all tests, 4-Amino-3-pyrazol-5-ols were effective. The lead compound, 4-amino-3-methyl-1-phenylpyrazol-5-ol hydrochloride (APH), showed the following activities: ABTS, 0.93 TEAC; FRAP, 0.98 TE; and ORAC, 4.39 TE. APH and its NH-analog were not cytotoxic against cultured normal human fibroblasts even at 100 μM, in contrast to EDA. According to QM calculations, 4-aminopyrazolols were characterized by lower gaps, IP, and η compared to 4-hydroxyiminopyrazol-5-ones, consistent with their higher antioxidant activities in ABTS and FRAP tests, realized by the SET mechanism. The radical-scavenging action evaluated in the ORAC test occurred by the HAT mechanism through OH bond breaking in all compounds, directly dependent on the dissociation energy of the OH bond. All the studied compounds demonstrated the absence of anticholinesterase activity and moderate inhibition of CES by some 4-aminopyrazolols. Thus, the lead compound APH was found to be a good antioxidant with the potential to be developed as a novel therapeutic drug candidate in the treatment of diseases associated with oxidative stress.

The design and synthesis of benzylpiperazine-based edaravone derivatives and their neuroprotective activities

New edaravone derivatives containing a benzylpiperazine moiety are designed and synthesized. The structures are characterized by 1H NMR, 13C NMR, and high-resolution mass spectrometry. The potential neuroprotective activities of the target compounds are evaluated in differentiated rat pheochromocytoma cells (PC12 cells) and in mice subjected to acute cerebral ischemia. Most of the target compounds showed neuroprotective activities both in vivo and in vitro, especially 1-(4-(4-fluorobenzyl) piperazin-1-yl)-2-(4-(5-hydroxy-3-methyl-1 H-pyrazol-1-yl)phenoxy)ethanone and 1-(4-(4-nitrobenzyl)piperazin-1-yl)-2-(4-(5-hydroxy-3-methyl-1 H-pyrazol-1-yl)phenoxy)ethanone, which displayed significant protective effects on cell viability against damage caused by H2O2, and remarkably prolonged the survival time of mice subjected to acute cerebral ischemia and decreased the mortality rate at all doses. These compounds represent lead compounds for the further discovery of neuroprotective agents for treating cerebral ischemic stroke. Molecular docking studies and basic structure–activity relationships are also presented.

Edaravone Attenuated Angiotensin II-Induced Atherosclerosis and Abdominal Aortic Aneurysms in Apolipoprotein E-Deficient Mice

Background: The aim of the study was to define whether edaravone, a free-radical scavenger, influenced angiotensin II (AngII)-induced atherosclerosis and abdominal aortic aneurysms (AAAs) formation. Methods: Male apolipoprotein E-deficient mice (8–12 weeks old) were fed with a normal diet for 5 weeks. Either edaravone (10 mg/kg/day) or vehicle was injected intraperitoneally for 5 weeks. After 1 week of injections, mice were infused subcutaneously with either AngII (1000 ng/kg/min, n = 16–17 per group) or saline (n = 5 per group) by osmotic minipumps for 4 weeks. Results: AngII increased systolic blood pressure equivalently in mice administered with either edaravone or saline. Edaravone had no effect on plasma total cholesterol concentrations and body weights. AngII infusion significantly increased ex vivo maximal diameters of abdominal aortas and en face atherosclerosis but was significantly attenuated by edaravone administration. Edaravone also reduced the incidence of AngII-induced AAAs. In addition, edaravone diminished AngII-induced aortic MMP-2 activation. Quantitative RT-PCR revealed that edaravone ameliorated mRNA abundance of aortic MCP-1 and IL-1β. Immunostaining demonstrated that edaravone attenuated oxidative stress and macrophage accumulation in the aorta. Furthermore, edaravone administration suppressed thioglycolate-induced mice peritoneal macrophages (MPMs) accumulation and mRNA abundance of MCP-1 in MPMs in male apolipoprotein E-deficient mice. In vitro, edaravone reduced LPS-induced mRNA abundance of MCP-1 in MPMs. Conclusions: Edaravone attenuated AngII-induced AAAs and atherosclerosis in male apolipoprotein E-deficient mice via anti-oxidative action and anti-inflammatory effect.

Edaravone Modulates Neuronal GPX4/ACSL4/5-LOX to Promote Recovery After Spinal Cord Injury

The FDA-approved drug edaravone has a neuroprotective effect on spinal cord injury (SCI) and many other central nervous system diseases. However, its molecular mechanism remains unclear. Since edaravone is a lipid peroxidation scavenger, we hypothesize that edaravone exerts its neuroprotective effect by inhibiting ferroptosis in SCI. Edaravone treatment after SCI upregulates glutathione peroxidase 4 (GPX4) and system Xc-light chain (xCT), which are anti-ferroptosis proteins. It downregulates pro-ferroptosis proteins Acyl-CoA synthetase long-chain family member 4 (ACSL4) and 5-lipoxygenase (5-LOX). The most significant changes in edaravone treatment occur in the acute phase, two days post injury. Edaravone modulates neuronal GPX4/ACSL4/5-LOX in the spinal segment below the lesion, which is critical for maintaining locomotion. Moreover, the GPX4/ACSL4/5-LOX in motor neuron is also modulated by edaravone in the spinal cord. Therefore, secondary injury below the lesion site is reversed by edaravone via ferroptosis inhibition. The cytokine array revealed that edaravone upregulated some anti-inflammatory cytokines such as IL-10, IL-13, and adiponectin. Edaravone reduced microgliosis and astrogliosis, indicating reduced neuroinflammation. Edaravone has a long-term effect on neuronal survival, spinal cord tissue sparing, and motor function recovery. In summary, we revealed a novel mechanism of edaravone in inhibiting neuronal ferroptosis in SCI. This mechanism may be generalizable to other neurological diseases.

Edaravone Inhibits the Production of Reactive Oxygen Species in Phagocytosis- and PKC-Stimulated Granulocytes from Multiple Sclerosis Patients Edaravone Modulate Oxidative Stress in Multiple Sclerosis

Background

Oxidative stress is associated with the pathogenesis of MS. Edaravone (EDV) has been proposed as a therapeutic resource for central nervous system diseases, and it was effective in reducing oxidative stress. However, the antioxidant mechanisms of EDV are poorly studied.

Objective

This study aimed to evaluate the effects of EDV on resting, phagocytosis, and PKC-activated granulocytes derived from MS patients and a healthy control group.

Methods

The effects of EDV on ROS production in phagocytosis (ROS production in the presence of opsonized particles) and PKC-stimulated granulocytes were evaluated in a luminol-dependent chemiluminescence method. Calphostin C was used in some experiments to compare with those of EDV.

Results

EDV inhibited ROS production in phagocytosis of opsonized particles and PKC-stimulated granulocytes from MS patients and healthy control group. In the presence of calphostin C, the inhibition of ROS production was similar to that observed with EDV.

Conclusion

These findings suggest the involvement of EDV on the ROS-PKC-NOX signaling pathways modulating oxidative stress in MS. EDV represents a promising treatment option to control oxidative innate immune response for MS.

Novel oral edaravone attenuates diastolic dysfunction of diabetic cardiomyopathy by activating the Nrf2 signaling pathway

Oxidative stress plays a crucial role in the pathophysiology of diastolic dysfunction associated with diabetic cardiomyopathy. Novel oral edaravone (OED) alleviates oxidative stress by scavenging free radicals and may be suitable for the treatment of chronic diseases such as diabetic cardiomyopathy. Oral administration of OED to type 2 diabetic rats (induced by high-sugar/high-fat diet and intraperitoneal injection of streptozotocin) for 4 w decreased malondialdehyde and increased superoxide dismutase. Moreover, it significantly improved ratios of early to late diastolic peak velocity, myocardium hypertrophy accompanied by decreased cross-sectional areas of cardiomyocytes, the proportion of apoptotic cells, collagen volume fractions, and deposition of collagen I/III. In H9c2 cells, OED reduced reactive oxygen species, cell surface area, and numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling-positive cells induced by glucolipotoxicity. OED remarkably upregulated expression of the nuclear factor E2-related factor (Nrf2) signaling pathway both in vivo and in vitro. In addition, OED promoted Nrf2 nuclear translocation and upregulated nicotinamide adenine dinucleotide phosphate quinone oxidoreductase and heme oxygenase. Silencing of Nrf2 abolished the protective effect of OED in H9c2 cells. Our findings demonstrate that OED has the therapeutic potential to ameliorate diastolic dysfunction associated with diabetic cardiomyopathy. Its effect was mainly achieved by attenuating hyperglycemia and hyperlipidemia-induced cardiomyocyte hypertrophy, apoptosis, and fibrosis by activating the Nrf2 signaling pathway.

Matrin3: Disorder and ALS Pathogenesis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of both upper and lower motor neurons in the brain and spinal cord. ALS is associated with protein misfolding and inclusion formation involving RNA-binding proteins, including TAR DNA-binding protein (TDP-43) and fused in sarcoma (FUS). The 125-kDa Matrin3 is a highly conserved nuclear DNA/RNA-binding protein that is implicated in many cellular processes, including binding and stabilizing mRNA, regulating mRNA nuclear export, modulating alternative splicing, and managing chromosomal distribution. Mutations in MATR3, the gene encoding Matrin3, have been identified as causal in familial ALS (fALS). Matrin3 lacks a prion-like domain that characterizes many other ALS-associated RNA-binding proteins, including TDP-43 and FUS, however, our bioinformatics analyses and preliminary studies document that Matrin3 contains long intrinsically disordered regions that may facilitate promiscuous interactions with many proteins and may contribute to its misfolding. In addition, these disordered regions in Matrin3 undergo numerous post-translational modifications, including phosphorylation, ubiquitination and acetylation that modulate the function and misfolding of the protein. Here we discuss the disordered nature of Matrin3 and review the factors that may promote its misfolding and aggregation, two elements that might explain its role in ALS pathogenesis.

Edaravone, a scavenger for multiple reactive oxygen species, reacts with singlet oxygen to yield 2-oxo-3-(phenylhydrazono)-butanoic acid

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a synthetic antioxidant used as a drug to treat acute ischemic stroke in Japan and amyotrophic lateral sclerosis in Japan and the USA. Its pharmacological mechanism is thought to be scavenging of reactive oxygen species, which are intimately related with these diseases. Recently, the singlet oxygen (‍¹O₂) has attracted attention among reactive oxygen species. In this study, we investigated the reactivity of edaravone toward ¹O₂ and identified its reaction products. Edaravone showed a reactivity toward ¹O₂ greater than those of uric acid, histidine, and tryptophan, which are believed to be ‍¹O₂ scavengers in vivo. And we confirmed that 2-oxo-3-(phenylhydrazono)-butanoic acid was formed as an oxidation product. We propose a plausible mechanism for 2-oxo-3-(phenylhydrazono)-butanoic acid production by ‍¹O₂-induced edaravone oxidation. Since 2-oxo-3-(phenylhydrazono)-butanoic acid has already been identified as a radical-initiated oxidation product, free radical-induced oxidation should be seriously reconsidered. We also found that edaravone can react with not only hypochlorous anions but also ‍¹O₂ that are formed from myeloperoxidase. This result suggests that edaravone treatment can be beneficial against myeloperoxidase-related injuries such as inflammation.

An Edaravone-Guided Design of a Rhodamine-Based Turn-on Fluorescent Probe for Detecting Hydroxyl Radicals in Living Systems

The hydroxyl radical (·OH), one of the reactive oxygen species (ROS) in biosystems, is found to be involved in many physiological and pathological processes. However, specifically detecting endogenous ·OH remains an outstanding challenge owing to the high reactivity and short lifetime of this radical. Herein, inspired by the scavenging mechanism of a neuroprotective drug edaravone toward ·OH, we developed a new ·OH-specific fluorescent probe RH-EDA. RH-EDA is a hybrid of rhodamine and edaravone and exploits a ·OH-specific 3-methyl-pyrazolone moiety to control its fluorescence behavior. RH-EDA itself is almost nonfluorescent in physiological conditions, which was attributed to the formation of a twisted intramolecular charge transfer (TICT) state upon photoexcitation and the acylation of its rhodamine nitrogen at the 3' position. However, upon a treatment with ·OH, its edaravone subunit was converted to the corresponding 2-oxo-3-(phenylhydrazono)-butanoic acid (OPB) derivative (to afford RH-OPB), thus leading to a significant fluorescence increase (ca. 195-fold). RH-EDA shows a high sensitivity and selectivity to ·OH without interference from other ROS. RH-EDA has been utilized for imaging endogenous ·OH production in living cells and zebrafishes under different stimuli. Moreover, RH-EDA allows a high-contrast discrimination of cancer cells from normal ones by monitoring their different ·OH levels upon stimulation with β-Lapachone (β-Lap), an effective ROS-generating anticancer therapeutic agent. The present study provides a promising methodology for the construction of probes through a drug-guided approach.

Preclinical validation of a novel oral Edaravone formulation for treatment of frontotemporal dementia

Oxidative stress is a key factor in the pathogenesis of several neurodegenerative disorders and is involved in the accumulation of amyloid beta plaques and Tau inclusions. Edaravone (EDR) is a free radical scavenger that is approved for motor neuron disease and acute ischemic stroke. EDR alleviates pathologies and cognitive impairment of AD via targeting multiple key pathways in transgenic mice. Herein, we aimed to study the effect of EDR on Tau pathology in P301L mice; an animal model of frontotemporal dementia (FTD), at two age time points representing the early and late stages of the disease. A novel EDR formulation was utilized in the study and the drug was delivered orally in drinking water for 3 months. Then, behavioral tests were conducted followed by animal sacrifice and brain dissection. Treatment with EDR improved the reference memory and accuracy in the probe trial as evaluated in Morris water maze, as well as novel object recognition and significantly alleviated motor deficits in these mice. EDR also reduced the levels of 4-hydroxy-2-nonenal and 3-nitrotyrosine adducts. In addition, immunohistochemistry showed that EDR reduced tau phosphorylation and neuroinflammation and partially rescued neurons against oxidative neurotoxicity. Moreover, EDR attenuated downstream pathologies involved in Tau hyperphosphorylation. These results suggest that EDR may be a potential therapeutic agent for the treatment of FTD.

Clinical effects and safety of edaravone in treatment of acute ischaemic stroke: A meta-analysis of randomized controlled trials

WHAT IS KNOWN AND OBJECTIVE

Edaravone is a new antioxidant and hydroxyl radical scavenger. Although there is evidence that it improves clinical outcomes of patients with acute ischaemic stroke (AIS), it is not yet widely accepted for treatment of AIS in Western countries. We further investigated the efficacy and safety of edaravone through this meta-analysis of randomized controlled clinical trials (RCTs).

METHOD

Pubmed, Embase, Web of Science and Cochrane Library were screened up to December 2020 for original articles from SCI journals that published in English. RCTs that compared edaravone versus placebo or no intervention in adult patients and reported the efficacy or safety of edaravone were regarded as eligible. Mortality was regarded as the primary outcome and the improvement of neurological impairment was regarded as the secondary outcome. Safety evaluation was conducted according to the incidence of adverse events. Review Manager 5.3 was employed to perform the assessment of the risk of bias and data synthesis. The Cochrane risk of bias tool for randomized controlled trials was employed to assess the risk of bias.

RESULTS AND DISCUSSION

Seven randomized controlled trials with 2069 patients were included. For the incidence of mortality, the pooled RR for studies that evaluated edaravone after three-month follow-up was 0.55 (95% Cl, 0.43-0.7, I²  = 0, P < 0.01). The pooled RR for improvement of neurological impairment at the three months follow-up was 1.54 (95% CI, 1.27-1.87, I²  = 0, P < 0.01) in four RCTs. On subgroup analysis of studies that were conducted in Asia, the RR was 1.56 (95% CI, 1.27-1.90, I²  = 0%; P < 0.01); the pooled RR for studies that conducted in Europe was 1.32 (95% CI, 0.64-2.72; P = 0.45); the pooled RR for studies that used edaravone for two weeks was 1.42 (95% CI, 1.10 to 1.83, I²  = 0%; P < 0.01); the pooled RR for studies that used edaravone for one week was 1.64 (95% CI, 1.24-2.16, I²  = 0%; P < 0.01); the pooled RR for studies that conducted in patients with mean age equal to or over 60 years was 1.52 (95% CI, 1.24-1.87, I²  = 0%; P < 0.01); and the pooled RR for studies that conducted in patients with mean age less than 60 was 1.80 (95% CI, 1.05-3.08, I²  = 0%; P = 0.03). For the incidence of any treatment-related adverse events, the pooled RR for studies that evaluated edaravone during treatment was 0.83 (95% CI, 0.51-1.34, I²  = 0, P = 0.43). The difference of the incidence of any treatment-related adverse events between two groups was not statistically significant.

WHAT IS NEW AND CONCLUSION

The limited studies indicate that edaravone can improve neurological impairment with a survival benefit at three-month follow-up, regardless of the mean age and course of treatment. It is worthy of promotion in the clinical treatment of AIS in Asian countries. More well-designed RCTs with larger sample sizes are needed to determine the benefits of edaravone in patients from Western countries.

Edaravone May Prevent Ferroptosis in ALS

Radicava™ (Edaravone) was approved the Food and Drug Administration (FDA) as a new treatment for amyotrophic lateral sclerosis (ALS). Edaravone is a synthetic antioxidant that specifically targets oxidative damage interacting with lipid radicals in the cell. In ALS disease the multiple cell types are involved in devastating loss of motor neurons. Mutations and biochemical changes in various cell types jointly contribute to motor neuron death, disease onset, and disease progression. The overall mechanism of neurodegeneration in ALS is still not completely understood. Dying motor neurons have been reported to exhibit features of apoptosis. However, non-apoptotic features of dying motor neurons have also been reported such as ferroptosis. The role of Edaravone in the prevention of ferroptosis in parallel with other therapeutic approaches to ALS therapy is discussed.

Small-Molecule Inhibitors of Reactive Oxygen Species Production

Reactive oxygen species (ROS) are involved in physiological cellular processes including differentiation, proliferation, and apoptosis by acting as signaling molecules or regulators of transcription factors. The maintenance of appropriate cellular ROS levels is termed redox homeostasis, a balance between their production and neutralization. High concentrations of ROS may contribute to severe pathological events including cancer, neurodegenerative, and cardiovascular diseases. In recent years, approaches to target the sources of ROS production directly in order to develop tool compounds or potential therapeutics have been explored. Herein, we briefly outline the major sources of cellular ROS production and comprehensively review the targeting of these by small-molecule inhibitors. We critically assess the value of ROS inhibitors with different mechanisms-of-action, including their potency, mode-of-action, known off-target effects, and clinical or preclinical status, while suggesting future avenues of research in the field.

Method to Improve Azo-Compound (AAPH)-Induced Hemolysis of Erythrocytes for Assessing Antioxidant Activity of Lipophilic Compounds

We examined the method of oxidative hemolysis for assessment of antioxidant activity of various compounds, especially lipophilic compounds. 2,2'-Azobis(amidinopropane) dihydrochloride (AAPH) was used as the source of free radicals for the oxidative hemolysis of horse erythrocytes. We found that absorbance at 540 nm is not appropriate for monitoring AAPH-induced hemolysis. Instead, we should use absorbance at 523 nm (an isosbestic point), because AAPH oxidizes the oxygenated hemoglobin to methemoglobin and absorbance at 540 nm does not correctly reflect the amount of released hemoglobin by AAPH-induced hemolysis. The corrected method of AAPH-induced hemolysis was applicable to assess the antioxidant activity of various hydrophilic compounds such as ascorbic acid, (-)-epicatechin, and edaravone. For the assessment of antioxidant activity of lipophilic compounds, we need appropriate dispersing agents for these lipophilic compounds. Among several agents tested, 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC) liposome at a concentration of 0.34 mM was found to be useful. Exogenous α-tocopherol incorporated using DMPC liposome as a dispersing agent was shown to protect erythrocytes from AAPH-induced hemolysis in a concentration-dependent manner.

Defective biosynthesis of ascorbic acid in Sod1-deficient mice results in lethal damage to lung tissue

Superoxide dismutase 1 (Sod1) plays pivotal roles in antioxidation via accelerating the conversion of superoxide anion radicals into hydrogen peroxide, thus inhibiting the subsequent radical chain reactions. While Sod1 deficient cells inevitably undergo death in culture conditions, Sod1-knockout (KO) mice show relatively mild phenotypes and live approximately two years. We hypothesized that the presence of abundant levels of ascorbic acid (AsA), which is naturally produced in mice, contributes to the elimination of reactive oxygen species (ROS) in Sod1-KO mice. To verify this hypothesis, we employed mice with a genetic ablation of aldehyde reductase (Akr1a), an enzyme that is involved in the biosynthesis of AsA, and established double knockout (DKO) mice that lack both Sod1 and Akr1a. Supplementation of AsA (1.5 mg/ml in drinking water) was required for the DKO mice to breed, and, upon terminating the AsA supplementation, they died within approximately two weeks regardless of age or gender. We explored the etiology of the death from pathophysiological standpoints in principal organs of the mice. Marked changes were observed in the lungs in the form of macroscopic damage after the AsA withdrawal. Histological and immunological analyses of the lungs indicated oxidative damage of tissue and activated immune responses. Thus, preferential oxidative injury that occurred in pulmonary tissues appeared to be primary cause of the death in the mice. These collective results suggest that the pivotal function of AsA in coping with ROS in vivo, is largely in pulmonary tissues that are exposed to a hyperoxygenic microenvironment.

Leading individual features of antioxidant systematically classified by the ORAC assay and its single electron transfer and hydrogen atom transfer reactivities; analyzing ALS therapeutic drug Edaravone

Many natural compounds mop up radicals and limit radical reactions and may prove useful in reducing or preventing oxidative stress-related diseases in vivo. Several assays have been developed to measure antioxidant or anti-radical activity. Here, we measured the anti-radical activities of representative antioxidants using different assays. The oxygen radical absorption capacity (ORAC) assay has two mechanistic stages. We classified antioxidant behavior using two characteristic values thought to be related to the two stages - peroxyl radical formation time (lag time) and fluorescein annihilation rate (k _obs) - by applying Voronoi polyhedral division. We focused on four class-representative antioxidants, Trolox ®, vitamin C, l-cysteine, and 2,6-di‑tert‑butyl‑p-cresol, and compared their characteristic activities with those of edaravone. Our analysis indicates that edaravone is in the same group as cysteine and may function via a similar mechanism. Our results suggest that analyzing lag time and k _obs is a useful method to characterize antioxidants.

Perinatal hypoxic-ischemic damage: review of the current treatment possibilities

Neonatal hypoxic-ischemic encephalopathy is a disorder with heterogeneous manifestation due to asphyxia during perinatal period. It affects approximately 3-12 children per 1000 live births and cause death of 1 million neonates worldwide per year. Besides, motor disabilities, seizures, impaired muscle tone and epilepsy are few of the consequences of hypoxic-ischemic encephalopathy. Despite an extensive research effort regarding various treatment strategies, therapeutic hypothermia with intensive care unit supportive treatment remains the only approved method for neonates who have suffered from moderate to severe hypoxic-ischemic encephalopathy. However, these protocols are only partially effective given that many infants still suffer from severe brain damage. Thus, further research to systematically test promising neuroprotective treatments in combination with hypothermia is essential. In this review, we discussed the pathophysiology of hypoxic-ischemic encephalopathy and delved into different promising treatment modalities, such as melatonin and erythropoietin. However, preclinical studies and clinical trials are still needed to further elucidate the mechanisms of action of these modalities.

The antioxidant capacity of an imidazole alkaloids family through single-electron transfer reactions

The single-electron transfer (SET) reactions from the neutral and mono-anion species of five imidazole alkaloids (lepidines A, B, C, D, and E) against hydroperoxyl radicals have been studied using the density functional theory and the Marcus theory. The deprotonated species of three alkaloids were found to have free radical scavenging activity. The antioxidant activity was studied via single-electron transfer (SET) under physiological conditions. The SET reactions for lepidines B, D, and E were found to have rate constants ranging from 10⁵ to 10⁶ M^-1 s^-1. Therefore, they are predicted to be able to deactivate hydroperoxyl radicals and therefore the damage caused by them to polyunsaturated fatty acids. It is important to mention that the acid-base equilibrium plays an important role in their free radical scavenging activity. Graphical abstract Lepidines are predicted to be able to deactivate hydroperoxyl radicals and the damage caused by them to polyunsaturated fatty acids.

4-Cl-edaravone and (E)-2-chloro-3-[(E)-phenyldiazenyl]-2-butenoic acid are the specific reaction products of edaravone with hypochlorite

3-Methyl-1-phenyl-2-pyrazolin-5-one (edaravone) is a synthetic one-electron antioxidant used as a drug for treatment against acute phase cerebral infarction in Japan. This drug also reacts with two-electron oxidants like peroxynitrite to give predominantly 4-nitrosoedaravone but no one-electron oxidation products. It is believed that this plays a significant role in amelioration of amyotrophic lateral sclerosis. The drug was approved for treatment of amyotrophic lateral sclerosis in Japan and USA in 2015 and 2017, respectively. In this study, we examined the reaction of edaravone with another two-electron oxidant, hypochlorite anion (ClO^-). Edaravone reacted with ClO^- in 50% methanolic phosphate buffer (pH 7.4) solution containing typical two-electron reductants, such as glutathione, cysteine, methionine, and uric acid, as internal references. The concentration of edaravone decreased at a similar rate as each co-existing reference, indicating that it showed comparable reactivity toward ClO^- as those references. Furthermore, 4-Cl-edaravone and (E)-2-chloro-3-[(E)-phenyldiazenyl]-2-butenoic acid (CPB) were identified as primary and end products, respectively, and no one-electron oxidation products were detected. These results suggest that edaravone treatment can bring greater benefit against ClO^--related injury such as inflammation, and 4-Cl-edaravone and CPB can be good biomarkers for ClO^--induced oxidative stress.

4-Cl-edaravone and (E)-2-chloro-3-[(E)-phenyldiazenyl]-2-butenoic acid are the specific reaction products of edaravone with hypochlorite

3-Methyl-1-phenyl-2-pyrazolin-5-one (edaravone) is a synthetic one-electron antioxidant used as a drug for treatment against acute phase cerebral infarction in Japan. This drug also reacts with two-electron oxidants like peroxynitrite to give predominantly 4-nitrosoedaravone but no one-electron oxidation products. It is believed that this plays a significant role in amelioration of amyotrophic lateral sclerosis. The drug was approved for treatment of amyotrophic lateral sclerosis in Japan and USA in 2015 and 2017, respectively. In this study, we examined the reaction of edaravone with another two-electron oxidant, hypochlorite anion (ClO⁻). Edaravone reacted with ClO⁻ in 50% methanolic phosphate buffer (pH 7.4) solution containing typical two-electron reductants, such as glutathione, cysteine, methionine, and uric acid, as internal references. The concentration of edaravone decreased at a similar rate as each co-existing reference, indicating that it showed comparable reactivity toward ClO⁻ as those references. Furthermore, 4-Cl-edaravone and (E)-2-chloro-3-[(E)-phenyldiazenyl]-2-butenoic acid (CPB) were identified as primary and end products, respectively, and no one-electron oxidation products were detected. These results suggest that edaravone treatment can bring greater benefit against ClO⁻-related injury such as inflammation, and 4-Cl-edaravone and CPB can be good biomarkers for ClO⁻-induced oxidative stress.

Reaction targets of antioxidants in azo-initiator or lipid hydroperoxide induced lipid peroxidation

Lipid peroxidation (LPO) is reported to be involved in the pathogenesis of several oxidative diseases, and several therapeutic approaches using antioxidants have been proposed. LPO is thought to progress via a complicated series of multistep reactions suggesting that the activity of each antioxidant may be different, and depends on the reacting molecules. Hence, in this study, we evaluated the inhibitory mechanisms of several antioxidants toward arachidonic acid (AA) peroxidation induced by the azo initiator 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) or a lipid hydroperoxide, hydroperoxyoctadecadienoic acid (HpODE)/hemin. Edaravone, ferrostatin-1, TEMPO and trolox effectively inhibited the production of malondialdehyde (MDA) and several oxidised AAs generated in the AAPH-induced LPO because of their scavenging ability toward lipid peroxyl radicals. In contrast, ebselen and ferrostatin-1 showed strong antioxidative activity in the HpODE/hemin-induced peroxidation. Under this condition, ebselen and ferrostatin-1 were thought to reduce HpODE and its derived alkoxyl radicals to the corresponding lipid alcohols. In conclusion, we found that each antioxidant had different antioxidative activities that prevented the progression of LPO. We expect that these findings will contribute to the design of novel therapeutic strategies using an appropriate antioxidant targeted to each step of the development of oxidative stress diseases.

Noble Metals and Soft Bio-Inspired Nanoparticles in Retinal Diseases Treatment: A Perspective

We are witnessing an exponential increase in the use of different nanomaterials in a plethora of biomedical fields. We are all aware of how nanoparticles (NPs) have influenced and revolutionized the way we supply drugs or how to use them as therapeutic agents thanks to their tunable physico-chemical properties. However, there is still a niche of applications where NP have not yet been widely explored. This is the field of ocular delivery and NP-based therapy, which characterizes the topic of the current review. In particular, many efforts are being made to develop nanosystems capable of reaching deeper sections of the eye such as the retina. Particular attention will be given here to noble metal (gold and silver), and to polymeric nanoparticles, systems consisting of lipid bilayers such as liposomes or vesicles based on nonionic surfactant. We will report here the most relevant literature on the use of different types of NPs for an efficient delivery of drugs and bio-macromolecules to the eyes or as active therapeutic tools.

Structurally Related Edaravone Analogues: Synthesis, Antiradical, Antioxidant, and Copper-Chelating Properties

Background::

The current therapeutic options available to patients diagnosed with Amyotrophic Lateral Sclerosis (ALS) are limited and edaravone is a compound that has gained significant interest for its therapeutic potential in this condition.

Objectives: :

The current work was thus undertaken to synthesize and characterize a series of edaravone analogues.

Methods:

A total of 17 analogues were synthesized and characterized for their antioxidant properties, radical scavenging potential and copper-chelating capabilities.

Results:

Radical scavenging and copper-chelating properties were notably observed for edaravone. Analogues bearing hydrogen in position 1 and a phenyl at position 3 and a phenyl in both positions of pyrazol-5 (4H)-one displayed substantial radical scavenging, antioxidants and copper-chelating properties. High accessibility of electronegative groups combined with higher electronegativity and partial charge of the carbonyl moiety in edaravone might explain the observed difference in the activity of edaravone relative to the closely related analogues 6 and 7 bearing hydrogen at position 1 and a phenyl at position 3 (6) and a phenyl in both positions (7).

Conclusion:

Overall, this study reveals a subset of edaravone analogues with interesting properties. Further investigation of these compounds is foreseen in relevant models of oxidative stress-associated diseases in order to assess their therapeutic potential in such conditions.

Myeloperoxidase-mediated oxidation of edaravone produces an apparent non-toxic free radical metabolite and modulates hydrogen peroxide-mediated cytotoxicity in HL-60 cells

Edaravone is considered to be a potent antioxidant drug known to scavenge free radical species and prevent free radical-induced lipid peroxidation. In this study, we investigated the effect of edaravone on the myeloperoxidase (MPO) activity, an enzyme responsible for the production of an array of neutrophil-derived oxidants that can cause cellular damage. The addition of edaravone to the reaction of MPO and hydrogen peroxide (H₂O₂) significantly enhanced the reduction of MPO Compound II back to native MPO. Interestingly, the MPO-mediated production of toxic hypochlorous acid exhibited a concentration-dependent biphasic effect, with the apparent optimal edaravone concentration at 10 μM. Oxidation of edaravone by MPO was examined by various analytical methods. An MPO-catalyzed product(s) of edaravone was identified at 350 nm by kinetic analysis of UV-Vis spectroscopy. Several MPO-catalyzed metabolites of edaravone were proposed from the LC-MS analyses, including oxidized dimers from edaravone radicals. Electron spin resonance (ESR) spin trapping detected a carbon-centred radical metabolite of edaravone. NMR studies revealed that there are two exchangeable hydrogens, one of which is on the α-carbon, justifying the carbon-centred edaravone radical produced from MPO. Despite the formation of an edaravone carbon-radical metabolite, it did not appear to effectively oxidize GSH (in comparison with phenoxyl radicals). Viability (ATP) and cytotoxicity (LDH release) assays showed a concentration-dependent effect of edaravone on HL-60 cells treated with either a bolus concentration of 30 μM H₂O₂ or a flux of H₂O₂ generated by 5 mM glucose and 10 mU/mL glucose oxidase. The H₂O₂-induced toxicity was ameliorated at high edaravone concentrations (100-200 μM). In contrast, low concentrations of edaravone (1-10 μM) exacerbated the H₂O₂-induced toxicity. However, the effect of edaravone at low concentration (0-10 μM) appeared more prominent with the LDH assay only. The cellular findings correlated with the biochemical studies with respect to hypochlorous acid formation. These findings provide interesting perspectives regarding the duality of edaravone as an antioxidant drug.

Edaravone, a free radical scavenger, protects against ferroptotic cell death in vitro

Ferroptosis is characterized by an iron-dependent cell death with increased lipid peroxidation and is typically induced by either a decrease in glutathione (GSH) levels due to an insufficient supply of cysteine (Cys) or the inhibition of phospholipid hydroperoxide glutathione peroxidase (Gpx4). While lipid peroxides are the direct trigger for ferroptosis, the issue of how radical species involve in the cytocidal process remains unclear. To gain insights into this issue, we employed edaravone, a free radical scavenger that is clinically approved for the treatment of acute ischemic strokes and amyotrophic lateral sclerosis (ALS), against ferroptotic cell death caused by various situations, notably under cystine deprivation. We initially investigated the effects of edaravone on ferroptosis in mouse hepatoma Hepa 1-6 cells cultivated in cystine-free medium and found that edaravone largely suppressed ferroptosis. Ferroptosis that was induced in the cells by the use of inhibitors for xCT or Gpx4 was also suppressed by edaravone. Moreover, edaravone also suppressed ferroptosis in xCT-knockout mouse-derived embryonic fibroblasts, which usually die in normal cultivating conditions due to the depletion of intracellular Cys and GSH. Although the edaravone treatment had no effects on the intracellular levels of Cys and GSH, both of which remained low in Hepa 1-6 cells under conditions of cystine deprivation, the causative factors for ferroptosis, including ferrous iron and lipid peroxide levels, were significantly suppressed. Collectively, these results indicate that radical species produced at the initial stage of the cytocidal process under Cys-deprived conditions trigger ferroptosis and scavenging these radicals by edaravone represents a promising treatment.

Synthesis, Characterization and Antioxidant Properties of a New Lipophilic Derivative of Edaravone

As part of a program aimed to obtain antioxidants able to interact with cell membrane, edaravone (EdV, 3-methyl-1-phenyl-2-pyrazolin-5-one), a well-known free radical scavenger, has been modified by alkylation at its allylic position (4) with a C-18 hydrocarbon chain, and the increased lipophilicity has been determined towards the interaction with liposomes. The obtained derivative has been studied by means of density functional theory (DFT) methods in order to characterize its lowest energy conformers and predict its antioxidant properties with respect to the parent compound EdV. The in vitro antioxidant activity of C18-edaravone was studied by means of the α,α-diphenyl-β-picrylhydrazyl (DPPH) assay and in lipid peroxidation experiments performed on artificial lipid membranes using water-soluble as well as lipid-soluble radical initiators. Moreover, since oxidative stress is involved in numerous retinal degenerative diseases, the ability of C18-edaravone to contrast 2,2-azobis (2-amidinopropane hydrochloride) (AAPH)-induced cell death was assessed in adult retinal pigmented epithelium (ARPE-19) cells. Overall, the results demonstrated that the newly synthesized molecule has a high affinity for lipid membrane, increasing the efficacy of the unmodified edaravone under stress conditions.

Edaravone for the treatment of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a progressive fatal disorder that affects all skeletal muscles, leading to death, mostly within 2-4 years from onset. To date, the anti-glutamatergic drug riluzole is the only drug that has been approved for the treatment of this disease; however, its efficacy is modest. Oxidative stress is considered to be involved in the pathology of ALS, and in this regard, the free radical scavenger edaravone, which was originally developed for the treatment of acute ischemic stroke, has also been developed for the treatment of ALS. Areas covered: This review describes the pharmacological properties of edaravone and the progress of clinical trials conducted to evaluate the efficacy of this drug in the treatment of ALS. Expert commentary: Edaravone is the first drug to show effective inhibition of the motor function deterioration experienced by ALS patients with early-stage probable and definite types. In order to effectively prolong the quality of motor function, edaravone treatment should be initiated as soon as the diagnosis has been confirmed; however, the respiratory function should be carefully monitored when a deterioration in breathing capacity is detected.

Riluzole and edaravone: A tale of two amyotrophic lateral sclerosis drugs

Over the past decades, a multitude of experimental drugs have been shown to delay disease progression in preclinical animal models of amyotrophic lateral sclerosis (ALS) but failed to show efficacy in human clinical trials or are still waiting for approval under Phase I-III trials. Riluzole, a glutamatergic neurotransmission inhibitor, is the only drug approved by the USA Food and Drug Administration for ALS treatment with modest benefits on survival. Recently, an antioxidant drug, edaravone, developed by Mitsubishi Tanabe Pharma was found to be effective in halting ALS progression during early stages. The newly approved drug edaravone is a force multiplier for ALS treatment. This short report provides an overview of the two drugs that have been approved for ALS treatment and highlights an update on the timeline of drug development, how clinical trials were done, the outcome of these trials, primary endpoint, mechanism of actions, dosing information, administration, side effects, and storage procedures. Moreover, we also discussed the pressing issues and challenges of ALS clinical trials and drug developments as well as future outlook.

Retrospective Analysis of Argatroban in 353 Patients with Acute Noncardioembolic Stroke

BACKGROUND

Argatroban is a thrombin inhibitor agent for acute noncardioembolic ischemic stroke in Japan. We studied the prognosis in patients with acute stroke treated by argatroban in comparison with the control group with ozagrel in our hospital.

SUBJECTS AND METHODS

A total of 513 patients with acute noncardioembolic ischemic stroke were enrolled retrospectively from our hospital database. Of all patients with stroke, 353 were administered with argatroban. The other 160 control patients were administered with ozagrel. The patients were examined as to their stroke types, the neurological severity according to the National Institutes of Health Stroke Scale (NIHSS), and clinical outcomes on discharge were determined according to the modified Rankin Scale (mRS).

RESULTS

A total of 353 patients with acute noncardioembolic stroke, including 138 with lacunar infarction (LIs) and 215 with atherothrombotic infarction (ATI) showed functional recovery by argatroban, but the effectiveness of argatroban was not superior to ozagrel therapy defined by the control group. A total of 255 patients with ATI who were treated with both argatroban and ozagrel showed improvement by 1 point. We could not find any significant difference between argatroban and ozagrel in the 2 stroke subtypes, LI and ATI. We also found that combination therapy of argatroban and edaravone was not superior to argatroban monotherapy in clinical outcome.

CONCLUSIONS

Argatroban therapy was not superior to control with ozagrel therapy in acute noncardioembolic ischemic stroke, including LI and ATI, regardless of the use of edaravone.

Free radical scavenger edaravone produces robust neuroprotection in a rat model of spinal cord injury

We used a multimodal approach to evaluate the effects of edaravone in a rat model of spinal cord injury (SCI). SCI was induced by extradural compression of thoracic spinal cord. In experiment 1, 30 min prior to compression, rats received a 3 mg/kg intravenous bolus of edaravone followed by a maintenance infusion of 1 (low-dose), 3 (moderate-dose), or 10 (high-dose) mg/kg/h edaravone. Although both moderate- and high-dose edaravone regimens promoted recovery of spinal motor-evoked potentials (MEPs) at 2 h post-SCI, the effect of the moderate dose was more pronounced. In experiment 2, moderate-dose edaravone was administered 30 min prior to compression, at the start of compression, or 10 min after decompression. Although both preemptive and coincident administration resulted in significantly improved spinal MEPs at 2 h post-SCI, the effect of preemptive administration was more pronounced. A moderate dose of edaravone resulted in significant attenuation of lipid peroxidation, as evidenced by lower concentrations of the free radical malonyldialdehyde in the spinal cord 3 h post-SCI. Malonyldialdehyde levels in the high-dose edaravone group were not reduced. Both moderate- and high-dose edaravone resulted in significant functional improvements, evidenced by better Basso-Beattie-Bresnahan (BBB) scores and better performance on an inclined plane during an 8 week period post-SCI. Both moderate- and high-dose edaravone significantly attenuated neuronal loss in the spinal cord at 8 weeks post-SCI, as evidenced by quantitative immunohistochemical analysis of NeuN-positive cells. In conclusion, early administration of a moderate dose of edaravone minimized the negative consequences of SCI and facilitated functional recovery.

How is edaravone effective against acute ischemic stroke and amyotrophic lateral sclerosis?

Edaravone is a low-molecular-weight antioxidant drug targeting peroxyl radicals among many types of reactive oxygen species. Because of its amphiphilicity, it scavenges both lipid- and water-soluble peroxyl radicals by donating an electron to the radical. Thus, it inhibits the oxidation of lipids by scavenging chain-initiating water-soluble peroxyl radicals and chain-carrying lipid peroxyl radicals. In 2001, it was approved in Japan as a drug to treat acute-phase cerebral infarction, and then in 2015 it was approved for amyotrophic lateral sclerosis (ALS). In 2017, the U.S. Food and Drug Administration also approved edaravone for treatment of patients with ALS. Its mechanism of action was inferred to be scavenging of peroxynitrite. In this review, we focus on the radical-scavenging characteristics of edaravone in comparison with some other antioxidants that have been studied in clinical trials, and we summarize its pharmacological action and clinical efficacy in patients with acute cerebral infarction and ALS.

Stabilizers of edaravone aqueous solution and their action mechanisms. 1. Sodium bisulfite

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) has been used as a free radical scavenging drug for the treatment of acute ischemic stroke in Japan since 2001. Edaravone is given to patients intravenously; therefore, it is distributed in the form of an aqueous solution. However, aqueous solutions of edaravone are very unstable because it is present as edaravone anion, which is capable of transferring an electron to free radicals including oxygen, and becomes edaravone radical. We observed the formation of hydrogen peroxide and edaravone trimer when aqueous edaravone solution was kept at 60°C for 4 weeks. We proposed the mechanism of edaravone trimer formation from edaravone radicals. Lowering the pH and deoxygenation can effectively increase the stability of aqueous edaravone solution, since the former reduces edaravone anion concentration and the latter inhibits edaravone radical formation. Addition of sodium bisulfite partially stabilized aqueous edaravone solutions and partially inhibited the formation of edaravone trimer. Formation of bisulfite adduct was suggested by ¹³C NMR and HPLC studies. Therefore, the stabilizing effect of sodium bisulfite is ascribed to the formation of a bisulfite adduct of edaravone and, consequently, reduction in the concentration of edaravone anion.

Edaravone suppresses retinal ganglion cell death in a mouse model of normal tension glaucoma

Glaucoma, one of the leading causes of irreversible blindness, is characterized by progressive degeneration of optic nerves and retinal ganglion cells (RGCs). In the mammalian retina, excitatory amino-acid carrier 1 (EAAC1) is expressed in neural cells, including RGCs. Loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP) and exhibits glaucomatous pathology including glutamate neurotoxicity and oxidative stress. In the present study, we found that edaravone, a free radical scavenger that is used for treatment of acute brain infarction and amyotrophic lateral sclerosis (ALS), reduces oxidative stress and prevents RGC death and thinning of the inner retinal layer in EAAC1-deficient (KO) mice. In addition, in vivo electrophysiological analyses demonstrated that visual impairment in EAAC1 KO mice was ameliorated with edaravone treatment, clearly establishing that edaravone beneficially affects both histological and functional aspects of the glaucomatous retina. Our findings raise intriguing possibilities for the management of glaucoma by utilizing a widely prescribed drug for the treatment of acute brain infarction and ALS, edaravone, in combination with conventional treatments to lower IOP.

Molecular Mechanisms behind Free Radical Scavengers Function against Oxidative Stress

Accumulating evidence shows that oxidative stress is involved in a wide variety of human diseases: rheumatoid arthritis, Alzheimer's disease, Parkinson's disease, cancers, etc. Here, we discuss the significance of oxidative conditions in different disease, with the focus on neurodegenerative disease including Parkinson's disease, which is mainly caused by oxidative stress. Reactive oxygen and nitrogen species (ROS and RNS, respectively), collectively known as RONS, are produced by cellular enzymes such as myeloperoxidase, NADPH-oxidase (nicotinamide adenine dinucleotide phosphate-oxidase) and nitric oxide synthase (NOS). Natural antioxidant systems are categorized into enzymatic and non-enzymatic antioxidant groups. The former includes a number of enzymes such as catalase and glutathione peroxidase, while the latter contains a number of antioxidants acquired from dietary sources including vitamin C, carotenoids, flavonoids and polyphenols. There are also scavengers used for therapeutic purposes, such as 3,4-dihydroxyphenylalanine (L-DOPA) used routinely in the treatment of Parkinson's disease (not as a free radical scavenger), and 3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone) that acts as a free radical detoxifier frequently used in acute ischemic stroke. The cell surviving properties of L-DOPA and Edaravone against oxidative stress conditions rely on the alteration of a number of stress proteins such as Annexin A1, Peroxiredoxin-6 and PARK7/DJ-1 (Parkinson disease protein 7, also known as Protein deglycase DJ-1). Although they share the targets in reversing the cytotoxic effects of H₂O₂, they seem to have distinct mechanism of function. Exposure to L-DOPA may result in hypoxia condition and further induction of ORP150 (150-kDa oxygen-regulated protein) with its concomitant cytoprotective effects but Edaravone seems to protect cells via direct induction of Peroxiredoxin-2 and inhibition of apoptosis.

Development of an Evaluation Method for Hydroxyl Radical Scavenging Activities Using Sequential Injection Analysis with Chemiluminescence Detection

A method for evaluating hydroxyl radical (·OH) scavenging activities using sequential injection analysis (SIA) with chemiluminescence (CL) detection was developed. In this system, CL was produced by the reaction of luminol with ·OH generated from the Fenton reaction. The scavenging activity was expressed as a diminution rate of the CL due to the scavenging of ·OH by a sample. The SIA system allows the automation of a series of experimental procedures including Fenton's reaction, scavenging of ·OH, and luminol CL reaction. The evaluation of scavenging activities in one sample (n = 3) was completed within 3.0 min. Relative standard deviations (n = 3) of scavenging activity with 700 μM L-ascorbic acid were 2.6% (intraday) and 3.7% (interday). The SIA-CL system was applied to measure ·OH scavenging activities of several antioxidants and pharmaceuticals.