Rationale for the use of N-acetylcysteine in both prevention and adjuvant therapy of COVID-19

N-Acetylcysteine: A Review of Clinical Usefulness (an Old Drug with New Tricks)

OBJECTIVE

To review the clinical usefulness of N-acetylcysteine (NAC) as treatment or adjunctive therapy in a number of medical conditions. Use in Tylenol overdose, cystic fibrosis, and chronic obstructive lung disease has been well documented, but there is emerging evidence many other conditions would benefit from this safe, simple, and inexpensive intervention. Quality of Evidence. PubMed, several books, and conference proceedings were searched for articles on NAC and health conditions listed above reviewing supportive evidence. This study uses a traditional integrated review format, and clinically relevant information is assessed using the American Family Physician Evidence-Based Medicine Toolkit. A table summarizing the potential mechanisms of action for N-acetylcysteine in these conditions is presented. Main Message. N-acetylcysteine may be useful as an adjuvant in treating various medical conditions, especially chronic diseases. These conditions include polycystic ovary disease, male infertility, sleep apnea, acquired immune deficiency syndrome, influenza, parkinsonism, multiple sclerosis, peripheral neuropathy, stroke outcomes, diabetic neuropathy, Crohn's disease, ulcerative colitis, schizophrenia, bipolar illness, and obsessive compulsive disorder; it can also be useful as a chelator for heavy metals and nanoparticles. There are also a number of other conditions that may show benefit; however, the evidence is not as robust.

CONCLUSION

The use of N-acetylcysteine should be considered in a number of conditions as our population ages and levels of glutathione drop. Supplementation may contribute to reducing morbidity and mortality in some chronic conditions as outlined in the article.

Antioxidants and COVID-19

Oxidative mechanisms are not only involved in chronic degenerative diseases but also in infectious diseases, among which viral respiratory diseases. Antioxidants have the capability to counteract the action of oxidants by scavenging reactive oxygen species (ROS) and by inhibiting oxidant generating enzymes. Overproduction of ROS and deprivation of antioxidant systems play a major role in COVID-19 occurrence, progression, and severity. Interconnected pathways account for the relationships between oxidative damage and inflammation resulting from an interplay between transcription factors having opposite effects. For instance, Nrf2 downregulates inflammation by inhibiting endogenous antioxidant enzymes such as NQO-1 and HO-1. On the other hand, NF-κB upregulates pro-inflammatory cytokines and chemokines, such as IL-1β, IL-6, IL-8, PGE-2, COX-2, TNF-α, MMP-3, and MMP-4. A central protective role against oxidants is played by reduced glutathione (GSH), which is depleted in SARS-CoV-2 infection. N-acetylcysteine (NAC), a precursor of GSH, is of particular interest as an anti-COVID-19 agent. GSH and NAC hamper binding of the S1 subunit of SARS-CoV-2 spike proteins to the angiotensin-converting enzyme 2 (ACE2) receptor. In addition, NAC and its derivatives possess a broad array of antioxidant and antiinflammatory mechanisms that could be exploited for COVID-19 prevention and adjuvant therapy. In particular, as demonstrated in a previous clinical trial evaluating influenza and influenza-like illnesses, the oral administration of NAC may be expected to decrease the risk of developing COVID-19. Furthermore, at the very high doses used worldwide as an antidote against paracetamol intoxication, intravenous NAC is likely to attenuate the pulmonary and systemic symptoms of COVID-19.

A Mechanistic Link Between Selenium and Coronavirus Disease 2019 (COVID-19)

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is a rapidly emerging disease caused by a highly contagious virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and this disease has affected millions of people across the world and led to hundreds of thousands of deaths worldwide. Nutrition is a key factor related to this disease, and nutritional status may determine the risk and outcomes of SARS-CoV-2 infection. Selenium is one of the major trace elements required for redox functions and has significant roles in viral infections. The purpose of this review was to examine the current evidence on the role of selenium in COVID-19. We reviewed studies on selenium and COVID-19, and other relevant studies to understand how selenium status can modify the risk of SARS-CoV-2 infection, and how selenium status might affect a person post-infection.

RECENT FINDINGS

We found that oxidative stress is a characteristic feature of COVID-19 disease, which is linked with the immunopathological disorder observed in individuals with severe COVID-19. Selenium plays a key role in strengthening immunity, reducing oxidative stress, preventing viral infections and supporting critical illness. Moreover, selenium deficiency is related to oxidative stress and hyperinflammation seen in critical illness, and selenium deficiency is found to be associated with the severity of COVID-19 disease. Selenium supplementation at an appropriate dose may act as supportive therapy in COVID-19. Future studies in large cohorts of COVID-19 are warranted to verify the benefits of selenium supplementation for reducing risk and severity of COVID-19.

Potential protective mechanisms of green tea polyphenol EGCG against COVID-19

Background

The world is in the midst of the COVID-19 pandemic. In this comprehensive review, we discuss the potential protective effects of (−)-epigallocatechin-3-gallate (EGCG), a major constituent of green tea, against COVID-19.

Scope and approach

Information from literature of clinical symptoms and molecular pathology of COVID-19 as well as relevant publications in which EGCG shows potential protective activities against COVID-19 is integrated and evaluated.

Key findings and conclusions

EGCG, via activating Nrf2, can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Through inhibition of SARS-CoV-2 main protease, EGCG may inhibit viral reproduction. EGCG via its broad antioxidant activity may protect against SARS-CoV-2 evoked mitochondrial ROS (which promote SARS-CoV-2 replication) and against ROS burst inflicted by neutrophil extracellular traps. By suppressing ER-resident GRP78 activity and expression, EGCG can potentially inhibit SARS-CoV-2 life cycle. EGCG also shows protective effects against 1) cytokine storm-associated acute lung injury/acute respiratory distress syndrome, 2) thrombosis via suppressing tissue factors and activating platelets, 3) sepsis by inactivating redox-sensitive HMGB1, and 4) lung fibrosis through augmenting Nrf2 and suppressing NF-κB. These activities remain to be further substantiated in animals and humans. The possible concerted actions of EGCG suggest the importance of further studies on the prevention and treatment of COVID-19 in humans. These results also call for epidemiological studies on potential preventive effects of green tea drinking on COVID-19.

The Molecular Basis of COVID-19 Pathogenesis, Conventional and Nanomedicine Therapy

In late 2019, a new member of the Coronaviridae family, officially designated as "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2), emerged and spread rapidly. The Coronavirus Disease-19 (COVID-19) outbreak was accompanied by a high rate of morbidity and mortality worldwide and was declared a pandemic by the World Health Organization in March 2020. Within the Coronaviridae family, SARS-CoV-2 is considered to be the third most highly pathogenic virus that infects humans, following the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV). Four major mechanisms are thought to be involved in COVID-19 pathogenesis, including the activation of the renin-angiotensin system (RAS) signaling pathway, oxidative stress and cell death, cytokine storm, and endothelial dysfunction. Following virus entry and RAS activation, acute respiratory distress syndrome develops with an oxidative/nitrosative burst. The DNA damage induced by oxidative stress activates poly ADP-ribose polymerase-1 (PARP-1), viral macrodomain of non-structural protein 3, poly (ADP-ribose) glycohydrolase (PARG), and transient receptor potential melastatin type 2 (TRPM2) channel in a sequential manner which results in cell apoptosis or necrosis. In this review, blockers of angiotensin II receptor and/or PARP, PARG, and TRPM2, including vitamin D3, trehalose, tannins, flufenamic and mefenamic acid, and losartan, have been investigated for inhibiting RAS activation and quenching oxidative burst. Moreover, the application of organic and inorganic nanoparticles, including liposomes, dendrimers, quantum dots, and iron oxides, as therapeutic agents for SARS-CoV-2 were fully reviewed. In the present review, the clinical manifestations of COVID-19 are explained by focusing on molecular mechanisms. Potential therapeutic targets, including the RAS signaling pathway, PARP, PARG, and TRPM2, are also discussed in depth.

Management of COPD patients during COVID: difficulties and experiences

Introduction: The role of COPD in COVID-19 is not yet well understood. However, there is increasing evidence showing that COPD patients with COVID-19 have a higher risk of presenting a serious infection, a greater likelihood of requiring ICU support, and a higher mortality than other groups.Areas covered: In this article, we address some critical questions on COVID-19 as they pertain to COPD. In particular, we discuss whether the usual algorithms of pharmacological and non-pharmacological management in COPD still apply.Expert opinion: Patients with COPD must continue their regular therapy, regardless of whether they are affected by COVID-19. Corticosteroids reduce mortality in COVID-19 patients in need of supportive oxygen therapy or invasive mechanical ventilation. It is essential that a COPD patient who has tested positive for SARS-CoV-2 is closely followed over time because any delay in diagnosis and initiation of appropriate therapy could negatively affect his/her prognosis. However, we still do not know if COVID-19 infection occurs and evolves differently in each of the recognized COPD phenotypes and, therefore, whether it needs a different management. There are other open questions concerning COVID-19 and COPD that need to be considered. Future studies are absolutely necessary to answer these questions.

Guidelines for Reopening a Nation in a SARS-CoV-2 Pandemic: A Path Forward

Background and Objectives: Action, not fear, is the path forward in the coronavirus infectious disease 2019 (COVID-19) pandemic. Since early 2020, the world's nations have faced conundrums over severe acute respiratory syndrome corona virus type 2 (SARS-CoV-2) infections resulting in COVID-19 resulting in national closures, and thus, a clear understandable plan that nations can implement is required to reopen. The healthcare benefits of reopening a nation more likely than not exceed the benefits of continued pandemic-related closure. Pandemic-related closures have resulted in countless delayed or avoided urgent care evaluations. Furthermore, routine care of acute and chronic illnesses, including evaluations, diagnoses, and treatments, has also been delayed. Isolation, loss of income, and fear have resulted in mental health conditions or exacerbated existing conditions. The magnitude of untoward ramifications is unknown and may ultimately represent an inestimable degree of danger and morbidity, and even death. The pandemic of SARS-CoV-2 has created an atmosphere of fear of COVID-19 that has directly and indirectly injured the world's population. Since this has resulted in increasing morbidity and mortality, creating economic chaos, and near systemic collapse of educational systems with no well described plan forward, it is the purpose of this study to provide guidelines that provide a path forward to safely open a nation. Physicians often equipped by their education, training, and experiences across disciplines are uniquely positioned to comprehend, coordinate, and teach other physicians, business owners, and municipal and government leaders from guidelines. As such, physicians may take the lead in a path forward to reopening a nation, including opening businesses, educational facilities, and religious establishments, while minimizing the risk of SARS-CoV-2 infection. Materials and Methods: Reviews of the literature among the disciplines of environmental air, sanitation, social interaction, medical testing, vaccination, protection, and disease prevention and safety allowed for the conceptualization and eventual genesis of identifiable interventions which either reduce the viral load in the environment or inactivate the virus from replication. Each of the guidelines was selected based on the principle that it involved the elimination or inactivation of the viral particle. With a reduction in viral load or inactivation of replication, the implementation of these guidelines is expected to allow for reopening a nation with an increased level of safety. Results: The guidelines identified, including air exchange (ventilation), air filtration, personal protective filtering devices (masks), hand hygiene, social distancing, screening and testing, vaccines, high-risk patient protection, medical management, and adjunctive therapies, are described and referenced. Conclusions: In that the pandemic is primarily a public health issue, the path forward is best coordinated by local, regional, and national physicians. Many physicians with a breadth of experiences are uniquely positioned to coordinate the implementation of these interdisciplinary guidelines. Using these guidelines as a planned, coordinated action, not fear, is a path forward. Nations have a decision to make: closuring versus opening.

Hypoxia may be a determinative factor in COVID-19 progression

The disease which develops following SARS-CoV-2 virus infection, known as COVID-19, in most affected countries displays mortality from 1.5% to 9.8%. When leukocytosis due to granulocytosis, thrombocytopenia, and increased level of D-dimers are detected early during the disease course, they are accurate predictors of mortality. Based on the published observations that each of the aforementioned disturbances by itself may appear as a consequence of hypoxia, a hypothesis is presented that early hypoxia consequential to sleep apnea and/or blunted respiratory response to chemical stimuli is an early determinant of COVID-19 progression to the severe and critical stage. Further, it is noted that host-directed therapies which may counteract hypoxia and its early downstream effects are initiated only upon hospitalization of COVID-19 patients, which is too late to be fully effective. An example is anticoagulation treatment with low molecular weight heparin. Repurposing drugs which could counteract some early posthypoxic events, such as fluvoxamine, amantadine and N-acetylcysteine, for post-exposure prophylaxis of SARS-CoV-2 infection and early prehospital treatment of COVID-19, is indicated.

Elucidating of oxidative distress in COVID-19 and methods of its prevention

The pandemic of SARS-CoV-2 stimulates significant efforts and approaches to understand its global spread. Although the recent introduction of the vaccine is a crucial prophylactic step, the effective treatment for SARS-CoV-2 is still undiscovered. An in-depth analysis of symptoms and clinical parameters, as well as molecular changes, is necessary to comprehend COVID-19 and propose a remedy for affected people to fight that disease.

The analysis of available clinical data and SARS-CoV-2 infection markers underlined the main pathogenic process in COVID-19 is cytokine storm and inflammation. That led us to suggest that the most important pathogenic feature of SARS-CoV-2 leading to COVID-19 is oxidative stress and cellular damage stimulated by iron, a source of Fenton reaction and its product hydroxyl radical (•OH), the most reactive ROS with t_1/2–10⁻⁹s. Therefore we suggest some scavenging agents are a reasonable choice for overcoming its toxic effect and can be regarded as a treatment for the disease on the molecular level.

The age-dependent decline of the extracellular thiol-disulfide balance and its role in SARS-CoV-2 infection

SARS-CoV-2 (COVID-19) infection can cause a severe respiratory distress syndrome. The risk of severe manifestations and mortality characteristically increase in the elderly and in the presence of non-COVID-19 comorbidity. We and others previously demonstrated that the low molecular weight (LMW) and protein thiol/disulfide ratio declines in human plasma with age and such decline is even more rapid in the case of inflammatory and premature aging diseases, which are also associated with the most severe complications of COVID-19 infection. The same decline with age of the LMW thiol/disulfide ratio observed in plasma appears to occur in the extracellular fluids of the respiratory tract and in association with many pulmonary diseases that characteristically reduce the concentrations and adaptive stress response of the lung glutathione. Early evidence in literature suggests that the thiol to disulfide balance of critical Cys residues of the COVID-19 spike protein and the ACE-2 receptor may influence the risk of infection and the severity of the disease, with a more oxidizing environment producing the worst prognosis. With this hypothesis paper we propose that the age-dependent decline of LMW thiol/disulfide ratio of the extracellular fluids, could play a role in promoting the physical (protein-protein) interaction of CoV-2 and the host cell in the airways. Therefore, this redox-dependent interaction is expected to affect the risk of severe infection in an age-dependent manner. The hypothesis can be verified in experimental models of in vitro CoV-2 infection and at the clinical level in that LMW thiols and protein thiolation can now be investigated with standardized, reliable and versatile laboratory protocols. Presenting the verification strategy of our hypothesis, we also discuss available nutritional and ancillary pharmacological strategies to intervene on the thiol/disulfide ratio of extracellular fluids of subjects at risk of infection and COVID-19 patients.

Common drugs, vitamins, nutritional supplements and COVID-19 mortality

The FDA has approved only one drug, remdesivir, for the treatment of COVID-19. The FDA has granted an emergency use authorization for the rheumatoid arthritis treatment drug, baricitinib (Olumiant), for the treatment of COVID-19 in some cases. For this reason, investigators have paid considerable attention to the association between commonly used drugs and the outcome of patients with COVID-19. Aspirin and ibuprofen have been reported to reduce the mortality rate. Omeprazole can increase mortality. In addition, some studies have demonstrated that famotidine diminishes mortality, while others have indicated that famotidine leads to a poorer prognosis. The present study used UK Biobank (UKB) data to assess the association of commonly used drugs with COVID-19 mortality. Data processing was performed on Minerva, a Linux mainframe with Centos 7.6. The UK Biobank Data Parser (ukbb_parser) was used, a python-based package that allows easy interfacing with the large UK Biobank dataset. The results revealed that aspirin and omeprazole were associated with an elevated mortality rate. Ibuprofen-related mortality was lower than laxative-related mortality. Aspirin users were also significantly older than other subjects. The association with mortality of cholesterol-lowering medications, blood pressure-lowering medications, hormone replacement and oral contraceptives in 134 female subjects revealed insignificant variability. The association of nutritional supplements in 238 subjects with mortality indicated that variability was insignificant. The lower mortality linked to the supplementation of vitamin D and vitamin B, presumably B complex, has been previously observed. On the whole, the present study demonstrates that although some of the associations described among drugs and COVID-19 are not novel, the utility of a new source, UKB, may prove to be useful in further examining these associations.

COVID-19-related cognitive dysfunction may be associated with transient disruption in the DLPFC glutamatergic pathway

Cognitive impairment has recently attracted researchers as one of the possible neuropsychiatric manifestations of COVID-19, although how the infection perpetuates impairment of cognitive functions is still obscure. We presented a 29-year-old male patient with COVID-19 who developed new-onset transient attention deficit and memory problems following a SARS-CoV-2 infection. Structural neuroimaging was normal. MR-spectroscopy (MRS) of the bilateral DLPFC revealed significant for decreased levels of N-acetylaspartate (NAA), glutamate, and glutamate/glutamine ratio. After a follow-up without any medical treatment but with suggestions of memory exercises for three months a control MRS screening of DLPFC showed improved levels of NAA, glutamate, and glutamate/glutamine ratio. This report may suggest that cognitive deficits in SARS-CoV-2 infection can result from glutamatergic dysfunction with decreased NAA and glutamate levels in bilateral DLPFC.

The Combination of Bromelain and Acetylcysteine (BromAc) Synergistically Inactivates SARS-CoV-2

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is the cause of a worldwide pandemic, currently with limited therapeutic options. The spike glycoprotein and envelope protein of SARS-CoV-2, containing disulfide bridges for stabilization, represent an attractive target as they are essential for binding to the ACE2 receptor in host cells present in the nasal mucosa. Bromelain and Acetylcysteine (BromAc) has synergistic action against glycoproteins by breakage of glycosidic linkages and disulfide bonds. We sought to determine the effect of BromAc on the spike and envelope proteins and its potential to reduce infectivity in host cells. Recombinant spike and envelope SARS-CoV-2 proteins were disrupted by BromAc. Spike and envelope protein disulfide bonds were reduced by Acetylcysteine. In in vitro whole virus culture of both wild-type and spike mutants, SARS-CoV-2 demonstrated a concentration-dependent inactivation from BromAc treatment but not from single agents. Clinical testing through nasal administration in patients with early SARS-CoV-2 infection is imminent.

Can N-3 polyunsaturated fatty acids be considered a potential adjuvant therapy for COVID-19-associated cardiovascular complications?

Coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has currently led to a global pandemic with millions of confirmed and increasing cases around the world. The novel SARS-CoV-2 not only affects the lungs causing severe acute respiratory dysfunction but also leads to significant dysfunction in multiple organs and physiological systems including the cardiovascular system. A plethora of studies have shown the viral infection triggers an exaggerated immune response, hypercoagulation and oxidative stress, which contribute significantly to poor cardiovascular outcomes observed in COVID-19 patients. To date, there are no approved vaccines or therapies for COVID-19. Accordingly, cardiovascular protective and supportive therapies are urgent and necessary to the overall prognosis of COVID-19 patients. Accumulating literature has demonstrated the beneficial effects of n-3 polyunsaturated fatty acids (n-3 PUFA) toward the cardiovascular system, which include ameliorating uncontrolled inflammatory reactions, reduced oxidative stress and mitigating coagulopathy. Moreover, it has been demonstrated the n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are precursors to a group of potent bioactive lipid mediators, generated endogenously, which mediate many of the beneficial effects attributed to their parent compounds. Considering the favorable safety profile for n-3 PUFAs and their metabolites, it is reasonable to consider n-3 PUFAs as potential adjuvant therapies for the clinical management of COVID-19 patients. In this article, we provide an overview of the pathogenesis of cardiovascular complications secondary to COVID-19 and focus on the mechanisms that may contribute to the likely benefits of n-3 PUFAs and their metabolites.

Perspectives for the Use of N-acetylcysteine as a Candidate Drug to Treat COVID-19

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndromerelated coronavirus-2 (SARS-CoV-2), has become an ongoing pandemic worldwide. However, there are no vaccines or antiviral drugs with proven clinical efficacy. Therefore, a remedial measure is urgently needed to combat the devastating COVID-19. The pharmacological activities of Nacetylcysteine (NAC) and its potential functions in inhibiting the progression of COVID-19 make it a promising therapeutic agent for the infection. In this mini-review, we discussed the therapeutic potential of NAC in COVID-19 from the perspective of its multisite pharmacological actions.

l-Cysteine Stimulates the Effect of Vitamin D on Inhibition of Oxidative Stress, IL-8, and MCP-1 Secretion in High Glucose Treated Monocytes

Objective: Vitamin D deficiency is common in the general population and diabetic patients, and supplementation with vitamin D is widely used to help lower oxidative stress and inflammation. The cytokine storm in SARS-CoV2 infection has been linked with both diabetes and Vitamin D deficiency. This study examined the hypothesis that supplementation with vitamin D, in combination with l-cysteine (LC), is better at reducing oxidative stress and thereby, more effective, at inhibiting the secretion of the pro-inflammatory cytokines, Interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in U937 monocytes exposed to high glucose concentrations. Methods: U937 monocytes were pretreated with 1,25 (OH)₂ vitamin D (VD, 10 nM) or LC (250 µM) or VD + LC for 24 h and then exposed to control or high glucose (HG, 25 mM) for another 24 h. Results: There were significantly greater reactive oxygen species (ROS) levels in monocytes treated with HG than those in controls. Combined supplementation with VD and LC showed a more significant reduction in ROS (46%) in comparison with treatment with LC (19%) or VD (26%) alone in monocytes exposed to HG. Similarly, VD supplementation, together with LC, caused a more significant inhibition in the secretion of IL-8 (36% versus 16%) and MCP-1 (46% versus 26%) in comparison with that of VD (10 nM) alone in high-glucose treated monocytes. Conclusions: These results suggest that combined supplementation with vitamin D and LC has the potential to be more effective than either VD or LC alone in lowering the risk of oxidative stress and inflammation associated with type 2 diabetes or COVID-19 infection. Further, this combined vitamin D with LC/N-acetylcysteine may be a potent alternative therapy for SARS-CoV2 infected subjects. This approach can prevent cellular damage due to cytokine storm in comorbid systemic inflammatory conditions, such as diabetes, obesity, and hypertension.

Potential Role of Antioxidant and Anti-Inflammatory Therapies to Prevent Severe SARS-Cov-2 Complications

The coronavirus disease 2019 (COVID-19) pandemic is caused by a novel severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2). Here, we review the molecular pathogenesis of SARS-CoV-2 and its relationship with oxidative stress (OS) and inflammation. Furthermore, we analyze the potential role of antioxidant and anti-inflammatory therapies to prevent severe complications. OS has a potential key role in the COVID-19 pathogenesis by triggering the NOD-like receptor family pyrin domain containing 3 inflammasome and nuclear factor-kB (NF-kB). While exposure to many pro-oxidants usually induces nuclear factor erythroid 2 p45-related factor2 (NRF2) activation and upregulation of antioxidant related elements expression, respiratory viral infections often inhibit NRF2 and/or activate NF-kB pathways, resulting in inflammation and oxidative injury. Hence, the use of radical scavengers like N-acetylcysteine and vitamin C, as well as of steroids and inflammasome inhibitors, has been proposed. The NRF2 pathway has been shown to be suppressed in severe SARS-CoV-2 patients. Pharmacological NRF2 inducers have been reported to inhibit SARS-CoV-2 replication, the inflammatory response, and transmembrane protease serine 2 activation, which for the entry of SARS-CoV-2 into the host cells through the angiotensin converting enzyme 2 receptor. Thus, NRF2 activation may represent a potential path out of the woods in COVID-19 pandemic.

Oxidative Stress Status in COVID-19 Patients Hospitalized in Intensive Care Unit for Severe Pneumonia. A Pilot Study

BACKGROUND

A key role of oxidative stress has been highlighted in the pathogenesis of COVID-19. However, little has been said about oxidative stress status (OSS) of COVID-19 patients hospitalized in intensive care unit (ICU).

MATERIAL AND METHODS

Biomarkers of the systemic OSS included antioxidants (9 assays), trace elements (3 assays), inflammation markers (4 assays) and oxidative damage to lipids (3 assays).

RESULTS

Blood samples were drawn after 9 (7-11) and 41 (39-43) days of ICU stay, respectively in 3 and 6 patients. Vitamin C, thiol proteins, reduced glutathione, γ-tocopherol, β-carotene and PAOT® score were significantly decreased compared to laboratory reference values. Selenium concentration was at the limit of the lower reference value. By contrast, the copper/zinc ratio (as a source of oxidative stress) was higher than reference values in 55% of patients while copper was significantly correlated with lipid peroxides (r = 0.95, p < 0.001). Inflammatory biomarkers (C-reactive protein and myeloperoxidase) were significantly increased when compared to normals.

CONCLUSIONS

The systemic OSS was strongly altered in critically ill COVID-19 patients as evidenced by increased lipid peroxidation but also by deficits in some antioxidants (vitamin C, glutathione, thiol proteins) and trace elements (selenium).

Repurposed Drugs, Molecular Vaccines, Immune-Modulators, and Nanotherapeutics to Treat and Prevent COVID-19 Associated with SARS-CoV-2, a Deadly Nanovector

The deadly pandemic, coronavirus disease 2019 (COVID-19), caused due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has paralyzed the world. Although significant methodological advances have been made in the field of viral detection/diagnosis with 251 in vitro diagnostic tests receiving emergency use approval by the US-FDA, little progress has been made in identifying curative or preventive therapies. This review discusses the current trends and potential future approaches for developing COVID-19 therapeutics, including repurposed drugs, vaccine candidates, immune-modulators, convalescent plasma therapy, and antiviral nanoparticles/nanovaccines/combinatorial nanotherapeutics to surmount the pandemic viral strain. Many potent therapeutic candidates emerging via drug-repurposing could significantly reduce the cost and duration of anti-COVID-19 drug development. Gene/protein-based vaccine candidates that could elicit both humoral and cell-based immunity would be on the frontlines to prevent the disease. Many emerging nanotechnology-based interventions will be critical in the fight against the deadly virus by facilitating early detection and enabling target oriented multidrug therapeutics. The therapeutic candidates discussed in this article include remdesivir, dexamethasone, hydroxychloroquine, favilavir, lopinavir/ritonavir, antibody therapeutics like gimsilumab and TJM2, anti-viral nanoparticles, and nanoparticle-based DNA and mRNA vaccines.

Significance of thiol-disulfide balance in SARS-CoV-2 infection

Studies of the molecular mechanisms regarding interaction of different viruses with receptors on the host cell surface have shown that the viral entry depends on the specific relationship between free thiol (SH) groups and disulfides on the virus surface, as well as the thiol disulfide balance on the host cell surface. The presence of oxidizing compounds or alkylating agents, which disturb the thiol-disulfide balance on the surface of the virus, can also affect its infectious potential. Disturbed thiol-disulfide balance may also influence protein-protein interactions between SARS-CoV-2 protein S and ACE2 receptors of the host cell. This review presents the basic mechanisms of maintaining intracellular and extracellular thiol disulfide balance and previous experimental and clinical evidence in favor of impaired balance in SARS-CoV-2 infection. Besides, the results of the clinical application or experimental analysis of compounds that induce changes in the thiol disulfide balance towards reduction of disulfide bridges in proteins of interest in COVID-19 infection are presented.

The interplay between inflammatory pathways and COVID-19: A critical review on pathogenesis and therapeutic options

COVID-19, caused by SARS-CoV-2, emerged as the deadliest outbreak that has now become a serious health issue to mankind. Activation of inflammatory signaling pathways and cytokine storm are crucial factors that lead to acute respiratory distress syndrome (ARDS) in COVID-19 patients. Excessive secretion of pro-inflammatory cytokines and chemokines leads to the dysregulation of the innate immune system. The cytokine storm attracts many inflammatory cells that infiltrate into the lung tissues and ultimately cause immune damage. In addition to the dysregulation of the immune system, dysfunction of the renin-angiotensin system (RAS) due to the downregulation of ACE2 is also associated with the mortality of COVID-19 patients. Both the mechanisms are directly or indirectly associated with cytokine storm that promotes vascular hyperpermeability, vascular edema leading to hypercoagulation and hence multiorgan damage. As of now, there is no specific treatment available for COVID-19, but scientists have purposed several treatment options including cytokine inhibitors, JAK inhibitors, immunomodulators, plasma therapy, etc. In this article, we have provided the detailed mechanism of occurrence of SARS-CoV-2 induced inflammatory storm and its connection with the pre-existing inflammatory conditions. Possible treatment options to cope up with the severe clinical manifestations of COVID-19 are also discussed.

N-Acetylcysteine as a treatment for sulphur mustard poisoning

In the long and intensive search for effective treatments to counteract the toxicity of the chemical warfare (CW) agent sulphur mustard (H; bis(2-chloroethyl) sulphide), the most auspicious and consistent results have been obtained with the drug N-acetylcysteine (NAC), particularly with respect to its therapeutic use against the effects of inhaled H. It is a synthetic cysteine derivative that has been used in a wide variety of clinical applications for decades and a wealth of information exists on its safety and protective properties against a broad range of toxicants and disease states. Its primary mechanism of action is as a pro-drug for the synthesis of the antioxidant glutathione (GSH), particularly in those circumstances where oxidative stress has exhausted intracellular GSH stores. It impacts a number of pathways either directly or through its GSH-related antioxidant and anti-inflammatory properties, which make it a prime candidate as a potential treatment for the wide range of deleterious cellular effects that H is acknowledged to cause in exposed individuals. This report reviews the available literature on the protection afforded by NAC against the toxicity of H in a variety of model systems, including its efficacy in treating the long-term chronic lung effects of H that have been demonstrated in Iranian veterans exposed during the Iran-Iraq War (1980-1988). Although there is overwhelming evidence supporting this drug as a potential medical countermeasure against this CW agent, there is a requirement for carefully controlled clinical trials to determine the safety, efficacy and optimal NAC dosage regimens for the treatment of inhaled H.

Immune-Modulating Drug MP1032 with SARS-CoV-2 Antiviral Activity In Vitro: A potential Multi-Target Approach for Prevention and Early Intervention Treatment of COVID-19

At least since March 2020, the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) pandemic and the multi-organ coronavirus disease 2019 (COVID-19) are keeping a firm grip on the world. Although most cases are mild, older patients and those with co-morbidities are at increased risk of developing a cytokine storm, characterized by a systemic inflammatory response leading to acute respiratory distress syndrome and organ failure. The present paper focuses on the small molecule MP1032, describes its mode of action, and gives rationale why it is a promising option for the prevention/treatment of the SARS-CoV-2-induced cytokine storm. MP1032 is a phase-pure anhydrous polymorph of 5-amino-2,3-dihydro-1,4-phthalazinedione sodium salt that exhibits good stability and bioavailability. The physiological action of MP1032 is based on a multi-target mechanism including localized, self-limiting reactive oxygen species (ROS) scavenging activities that were demonstrated in a model of lipopolysaccharide (LPS)-induced joint inflammation. Furthermore, its immune-regulatory and PARP-1-modulating properties, coupled with antiviral effects against SARS-CoV-2, have been demonstrated in various cell models. Preclinical efficacy was elucidated in LPS-induced endotoxemia, a model with heightened innate immune responses that shares many similarities to COVID-19. So far, during oral clinical development with three-month daily administrations, no serious adverse drug reactions occurred, highlighting the outstanding safety profile of MP1032.

Role of Oxidative Stress on SARS-CoV (SARS) and SARS-CoV-2 (COVID-19) Infection: A Review

Novel coronavirus disease 2019 (COVID-19) has resulted in a global pandemic and is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several studies have suggested that a precise disulfide-thiol balance is crucial for viral entry and fusion into the host cell and that oxidative stress generated from free radicals can affect this balance. Here, we reviewed the current knowledge about the role of oxidative stress on SARS-CoV and SARS-CoV-2 infections. We focused on the impact of antioxidants, like NADPH and glutathione, and redox proteins, such as thioredoxin and protein disulfide isomerase, that maintain the disulfide-thiol balance in the cell. The possible influence of these biomolecules on the binding of viral protein with the host cell angiotensin-converting enzyme II receptor protein as well as on the severity of COVID-19 infection was discussed.

Paracetamol-Induced Glutathione Consumption: Is There a Link With Severe COVID-19 Illness?

COVID-19 pandemic is posing an unprecedented sanitary threat: antiviral and host-directed medications to treat the disease are urgently needed. A great effort has been paid to find drugs and treatments for hospitalized, severely ill patients. However, medications used for the domiciliary management of early symptoms, notwithstanding their importance, have not been and are not presently regarded with the same attention and seriousness. In analogy with other airways viral infections, COVID-19 patients in the early phase require specific antivirals (still lacking) and non-etiotropic drugs to lower pain, fever, and control inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol (PAC) are widely used as non-etiotropic agents in common airways viral infections and hence are both theoretically repurposable for COVID-19. However, a warning from some research reports and National Authorities raised NSAIDs safety concerns because of the supposed induction of angiotensin-converting enzyme 2 (ACE2) levels (the receptor used by SARS-CoV2 to enter host airways cells), the increased risk of bacterial superinfections and masking of disease symptoms. As a consequence, the use of NSAIDs was, and is still, discouraged while the alternative adoption of paracetamol is still preferred. On the basis of novel data and hypothesis on the possible role of scarce glutathione (GSH) levels in the exacerbation of COVID-19 and of the GSH depleting activity of PAC, this commentary raises the question of whether PAC may be the better choice.

Rationale for the use of N-acetylcysteine in both prevention and adjuvant therapy of COVID-19

COVID‐19 may cause pneumonia, acute respiratory distress syndrome, cardiovascular alterations, and multiple organ failure, which have been ascribed to a cytokine storm, a systemic inflammatory response, and an attack by the immune system. Moreover, an oxidative stress imbalance has been demonstrated to occur in COVID‐19 patients. N‐ Acetyl‐L‐cysteine (NAC) is a precursor of reduced glutathione (GSH). Due to its tolerability, this pleiotropic drug has been proposed not only as a mucolytic agent, but also as a preventive/therapeutic agent in a variety of disorders involving GSH depletion and oxidative stress. At very high doses, NAC is also used as an antidote against paracetamol intoxication. Thiols block the angiotensin‐converting enzyme 2 thereby hampering penetration of SARS‐CoV‐2 into cells. Based on a broad range of antioxidant and anti‐inflammatory mechanisms, which are herein reviewed, the oral administration of NAC is likely to attenuate the risk of developing COVID‐19, as it was previously demonstrated for influenza and influenza‐like illnesses. Moreover, high‐dose intravenous NAC may be expected to play an adjuvant role in the treatment of severe COVID‐19 cases and in the control of its lethal complications, also including pulmonary and cardiovascular adverse events.