Mechanisms and clinical evidence to support melatonin's use in severe COVID-19 patients to lower mortality

A mid‑pandemic night's dream: Melatonin, from harbinger of anti‑inflammation to mitochondrial savior in acute and long COVID‑19 (Review)

Coronavirus disease 2019 (COVID‑19), a systemic illness caused by severe acute respiratory distress syndrome 2 (SARS‑CoV‑2), has triggered a worldwide pandemic with symptoms ranging from asymptomatic to chronic, affecting practically every organ. Melatonin, an ancient antioxidant found in all living organisms, has been suggested as a safe and effective therapeutic option for the treatment of SARS‑CoV‑2 infection due to its good safety characteristics and broad‑spectrum antiviral medication properties. Melatonin is essential in various metabolic pathways and governs physiological processes, such as the sleep‑wake cycle and circadian rhythms. It exhibits oncostatic, anti‑inflammatory, antioxidant and anti‑aging properties, exhibiting promise for use in the treatment of numerous disorders, including COVID‑19. The preventive and therapeutic effects of melatonin have been widely explored in a number of conditions and have been well‑established in experimental ischemia/reperfusion investigations, particularly in coronary heart disease and stroke. Clinical research evaluating the use of melatonin in COVID‑19 has shown various improved outcomes, including reduced hospitalization durations; however, the trials are small. Melatonin can alleviate mitochondrial dysfunction in COVID‑19, improve immune cell function and provide antioxidant properties. However, its therapeutic potential remains underexplored due to funding limitations and thus further investigations are required.

Assessing the antiviral potential of melatonin: A comprehensive systematic review

This review assesses the antiviral potential of melatonin through comprehensive analysis of studies across human subjects, animal models, cell cultures, and in-silico simulations. The search strategy targeted relevant research until 22 June 2023, resulting in 20 primary studies after screening and deduplication. The findings highlight strong evidence supporting antiviral properties of melatonin. In silico studies identify melatonin as a candidate against SARS-CoV-2, reducing cytokine storm-related respiratory responses. Cell culture experiments reveal its multifaceted effects on different viruses including respiratory syncytial virus, anti-dengue virus, transmissible gastroenteritis virus, and encephalomyocarditis virus. Animal studies show melatonin reduces mortality and viral replication in various infections such as Venezuelan equine encephalomyelitis and COVID-19. Clinical trials show how it could be evaluated, but with no conclusive evidence of efficacy and safety so far from large, double-blind placebo-controlled trials. These insights showcase the potential of melatonin as a versatile antiviral agent with immunomodulatory, antioxidant, anti-inflammatory and antiviral properties. In summary, our review highlights melatonin's promising antiviral properties across diverse settings. Melatonin's immunomodulatory and antiviral potential makes it a compelling candidate for further investigation, emphasising the need for rigorous clinical trials to establish its safety and efficacy against viral infections.

Safety and efficacy of melatonin as an adjuvant therapy in COVID-19 patients: Systematic review and meta-analysis

BACKGROUND

Melatonin might be beneficial to coronavirus disease 2019 (COVID-19) patients in terms of both prevention and treatment. We investigated how melatonin affected various clinical and laboratory results in COVID-19 patients.

METHODS

PubMed, Scopus, Cochrane Library and Web of Science databases were utilized for searching eligible articles fulfilling our inclusion criteria up to December 2022. We used random effect model in case of significant heterogeneity; in other cases, a fixed model was applied. RevMan was used for meta-analysis.

RESULTS

We included 11 studies in our review. Clinical improvement rate was found to be statistically significantly higher in patients taking melatonin than in the control group (OR: 5.09; 95% CI: 2.60-9.96, p ​< ​0.001). Patients receiving melatonin showed a non-significant difference in mortality rate compared to the control group (OR: 0.37; 95% CI: 0.07-1.81, p ​= ​0.22). However, in the randomized controlled trials subgroup, melatonin-treated patients showed significantly lower mortality than did the controls (OR: 0.17; 95% CI: 0.08-0.38, p ​< ​0.001). CRP level was statistically significantly lower due to melatonin treatment (weighted mean difference [WMD] ​= ​-9.85; 95% CI: -18.54 to -1.16, p ​= ​0.03). Length of hospital stay was statistically significantly shorter in patients taking melatonin compared to controls (WMD ​= ​-4.05; 95% CI: -5.39 to -2.7, p ​< ​0.001).

CONCLUSION

Melatonin was found to have substantial effects on COVID-19 patients when used as adjuvant therapy, enhancing clinical improvement and decreasing time to recovery with a shorter length of hospital stay and a shorter duration of mechanical ventilation.

Laboratory Findings and Biomarkers in Long COVID: What Do We Know So Far? Insights into Epidemiology, Pathogenesis, Therapeutic Perspectives and Challenges

Long COVID (LC) encompasses a constellation of long-term symptoms experienced by at least 10% of people after the initial SARS-CoV-2 infection, and so far it has affected about 65 million people. The etiology of LC remains unclear; however, many pathophysiological pathways may be involved, including viral persistence; a chronic, low-grade inflammatory response; immune dysregulation and a defective immune response; the reactivation of latent viruses; autoimmunity; persistent endothelial dysfunction and coagulopathy; gut dysbiosis; hormonal and metabolic dysregulation; mitochondrial dysfunction; and autonomic nervous system dysfunction. There are no specific tests for the diagnosis of LC, and clinical features including laboratory findings and biomarkers may not specifically relate to LC. Therefore, it is of paramount importance to develop and validate biomarkers that can be employed for the prediction, diagnosis and prognosis of LC and its therapeutic response, although this effort may be hampered by challenges pertaining to the non-specific nature of the majority of clinical manifestations in the LC spectrum, small sample sizes of relevant studies and other methodological issues. Promising candidate biomarkers that are found in some patients are markers of systemic inflammation, including acute phase proteins, cytokines and chemokines; biomarkers reflecting SARS-CoV-2 persistence, the reactivation of herpesviruses and immune dysregulation; biomarkers of endotheliopathy, coagulation and fibrinolysis; microbiota alterations; diverse proteins and metabolites; hormonal and metabolic biomarkers; and cerebrospinal fluid biomarkers. At present, there are only two reviews summarizing relevant biomarkers; however, they do not cover the entire umbrella of current biomarkers, their link to etiopathogenetic mechanisms or the diagnostic work-up in a comprehensive manner. Herein, we aim to appraise and synopsize the available evidence on the typical laboratory manifestations and candidate biomarkers of LC, their classification based on pathogenetic mechanisms and the main LC symptomatology in the frame of the epidemiological and clinical aspects of the syndrome and furthermore assess limitations and challenges as well as potential implications in candidate therapeutic interventions.

Long COVID: pathophysiological factors and abnormalities of coagulation

Acute COVID-19 infection is followed by prolonged symptoms in approximately one in ten cases: known as Long COVID. The disease affects ~65 million individuals worldwide. Many pathophysiological processes appear to underlie Long COVID, including viral factors (persistence, reactivation, and bacteriophagic action of SARS CoV-2); host factors (chronic inflammation, metabolic and endocrine dysregulation, immune dysregulation, and autoimmunity); and downstream impacts (tissue damage from the initial infection, tissue hypoxia, host dysbiosis, and autonomic nervous system dysfunction). These mechanisms culminate in the long-term persistence of the disorder characterized by a thrombotic endothelialitis, endothelial inflammation, hyperactivated platelets, and fibrinaloid microclots. These abnormalities of blood vessels and coagulation affect every organ system and represent a unifying pathway for the various symptoms of Long COVID.

Antiviral effect of melatonin on Japanese encephalitis virus infection involves inhibition of neuronal apoptosis and neuroinflammation in SH-SY5Y cells

Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, causes high mortality rates in humans and it is the most clinically important and common cause of viral encephalitis in Asia. To date, there is no specific treatment for JEV infection. Melatonin, a neurotropic hormone, is reported to be effective in combating various bacterial and viral infections. However, the effects of melatonin on JEV infection have not yet been studied. The investigation tested the antiviral effects of melatonin against JEV infection and elucidated the possible molecular mechanisms of inhibition. Melatonin inhibited the viral production in JEV-infected SH-SY5Y cells in a time- and dose-dependent manner. Time-of-addition assays demonstrated a potent inhibitory effect of melatonin at the post-entry stage of viral replication. Molecular docking analysis revealed that melatonin negatively affected viral replication by interfering with physiological function and/or enzymatic activity of both JEV nonstructural 3 (NS3) and NS5 protein, suggesting a possible underlying mechanism of JEV replication inhibition. Moreover, treatment with melatonin reduced neuronal apoptosis and inhibited neuroinflammation induced by JEV infection. The present findings reveal a new property of melatonin as a potential molecule for the further development of anti-JEV agents and treatment of JEV infection.

Melatonin from Microorganisms, Algae, and Plants as Possible Alternatives to Synthetic Melatonin

Melatonin dietary supplements are widely consumed worldwide, with developed countries as the largest consumers, with an estimated annual growth rate of approximately 10% until 2027, mainly in developing countries. The wide use of melatonin against sleep disorders and particular problems, such as jet lag, has been added to other applications, such as anti-aging, anti-stress, immune system activation, anticancer, and others, which have triggered its use, normally without a prescription. The chemical industry currently covers 100% of the needs of the melatonin market. Motivated by sectors with more natural consumption habits, a few years ago, the possibility of obtaining melatonin from plants, called phytomelatonin, arose. More recently, the pharmaceutical industry has developed genetically modified microorganisms whose ability to produce biological melatonin in bioreactors has been enhanced. This paper reviews the aspects of the chemical and biological synthesis of melatonin for human consumption, mainly as dietary supplements. The pros and cons of obtaining melatonin from microorganisms and phytomelatonin from plants and algae are analyzed, as well as the advantages of natural melatonin, avoiding unwanted chemical by-products from the chemical synthesis of melatonin. Finally, the economic and quality aspects of these new products, some of which are already marketed, are analyzed.

Chronobiological Efficacy of Combined Therapy of Pelargonium Sidoides and Melatonin in Acute and Persistent Cases of COVID-19: A Hypothetical Approach

Since the outbreak of the first SARS-CoV-2 epidemic in China, pharmacists have rapidly engaged and developed strategies for pharmaceutical care and supply. According to the guidelines of the International Pharmaceutical Federation (FIP), clinical pharmacists/hospital pharmacists, as members of care teams, play one of the most important roles in the pharmaceutical care of patients with COVID-19. During this pandemic, many immuno-enhancing adjuvant agents have become critical in addition to antivirals and vaccines in order to overcome the disease more easily. The liquid extract obtained from the Pelargonium sidoides plant is used for many indications such as colds, coughs, upper respiratory tract infections, sore throat, and acute bronchitis. The extract obtained from the roots of the plant has been observed to have antiviral and immunomodulatory activity. In addition to its anti-inflammatory and antioxidant effects, melatonin plays a role in suppressing the cytokine storm that can develop during COVID-19 infection. Knowing that the severity and duration of COVID-19 symptoms vary within 24 hours and/or in different time periods indicates that COVID-19 requires a chronotherapeutic approach. Our goal in the management of acute and long COVID is to synchronize the medication regimen with the patient's biological rhythm. This chapter provides a comprehensive review of the existing and emerging literature on the chronobiological use of Pelargonium sidoides and melatonin during acute and prolonged COVID-19 episodes.

Can melatonin reduce the severity of post-COVID-19 syndrome?

This short review aimed at (i) providing an update on the health benefits associated with melatonin supplementation, while (ii) considering future potential research directions concerning melatonin supplementation use relative to Coronavirus disease of 2019 (COVID-19). A narrative review of the literature was undertaken to ascertain the effect of exogenous melatonin administration on humans. Night-time melatonin administration has a positive impact on human physiology and mental health. Indeed, melatonin (i) modulates the circadian components of the sleep-wake cycle; (ii) improves sleep efficiency and mood status; (iii) improves insulin sensitivity; and (iv) reduces inflammatory markers and oxidative stress. Melatonin has also remarkable neuroprotective and cardioprotective effects and may therefore prevent deterioration caused by COVID-19. We suggest that melatonin could be used as a potential therapy in the post-COVID-19 syndrome, and therefore call for action the research community to investigate on the potential use of exogenous melatonin to enhance the quality of life in patients with post-COVID-19 syndrome. See also Figure 1(Fig. 1).

Advances And Challenges In Using Nirmatrelvir And Its Derivatives Against Sars-Cov-2 Infection

On 22 December 2021, the United States Food and Drug Administration (FDA) approved the first M^pro inhibitor, i.e., oral antiviral nirmatrelvir (PF-07321332)/ritonavir (Paxlovid), for the treatment of early severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Nirmatrelvir inhibits SARS-CoV-2 infection, but high doses or long-term treatment may cause embryonic developmental toxicity and changes in host gene expression. The chiral structure of nirmatrelvir plays a key role in its antiviral activity. Ritonavir boosts the efficacy of nirmatrelvir by inactivating cytochrome P450 3A4 (CYP3A4) expression and occupying the plasma protein binding sites. Multidrug resistance protein 1 (MDR1) inhibitors may increase the efficacy of nirmatrelvir. However, paxlovid has many contraindications. Some patients treated with paxlovid experience a second round of coronavirus disease 2019 (COVID-19) symptoms soon after recovery. Interestingly, the antiviral activity of nirmatrelvir metabolites, such as compounds 12−18, is similar to or higher than that of nirmatrelvir. Herein, we review the advances and challenges in using nirmatrelvir and its derivatives with the aim of providing knowledge to drug developers and physicians in the fight against COVID-19.

Immunoceuticals: Harnessing Their Immunomodulatory Potential to Promote Health and Wellness

Knowledge that certain nutraceuticals can modulate the immune system is not new. These naturally occurring compounds are known as immunoceuticals, which is a novel term that refers to products and systems that naturally improve an individual's immuno-competence. Examples of immunoceuticals include vitamin D3, mushroom glycans, flavonols, quercetin, omega-3 fatty acids, carotenoids, and micronutrients (e.g., zinc and selenium), to name a few. The immune system is a complex and highly intricate system comprising molecules, cells, tissues, and organs that are regulated by many different genetic and environmental factors. There are instances, such as pathological conditions, in which a normal immune response is suboptimal or inappropriate and thus augmentation or tuning of the immune response by immunoceuticals may be desired. With infectious diseases, cancers, autoimmune disorders, inflammatory conditions, and allergies on the rise in both humans and animals, the importance of the use of immunoceuticals to prevent, treat, or augment the treatment of these conditions is becoming more evident as a natural and often economical approach to support wellness. The global nutraceuticals market, which includes immunoceuticals, is a multi-billion-dollar industry, with a market size value of USD 454.55 billion in 2021, which is expected to reach USD 991.09 billion by 2030. This review will provide an overview of the immune system, the importance of immunomodulation, and defining and testing for immunocompetence, followed by a discussion of several key immunoceuticals with clinically proven and evidence-based immunomodulatory properties.

Are Nutraceuticals Effective in COVID-19 and Post-COVID Prevention and Treatment?

The beginning of the end or the end of the beginning? After two years mastered by coronavirus disease 19 (COVID-19) pandemic, we are now witnessing a turnaround. The reduction of severe cases and deaths from COVID-19 led to increasing importance of a new disease called post-COVID syndrome. The term post-COVID is used to indicate permanency of symptoms in patients who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Immune, antiviral, antimicrobial therapies, as well as ozone therapy have been used to treat COVID-19 disease. Vaccines have then become available and administered worldwide to prevent the insurgence of the disease. However, the pandemic is not over yet at all given the emergence of new omicron variants. New therapeutic strategies are urgently needed. In this view, great interest was found in nutraceutical products, including vitamins (C, D, and E), minerals (zinc), melatonin, probiotics, flavonoids (quercetin), and curcumin. This review summarizes the role of nutraceuticals in the prevention and/or treatment of COVID-19 disease and post-COVID syndrome.

Effect of 17β-estradiol on the daily pattern of ACE2, ADAM17, TMPRSS2 and estradiol receptor transcription in the lungs and colon of male rats

Covid-19 progression shows sex-dependent features. It is hypothesized that a better Covid-19 survival rate in females can be attributed to the presence of higher 17β-estradiol (E2) levels in women than in men. Virus SARS-CoV-2 is enabled to enter the cell with the use of angiotensin converting enzyme 2 (ACE2). The expression of several renin-angiotensin system components has been shown to exert a rhythmic pattern, and a role of the circadian system in their regulation has been implicated. Therefore, the aim of the study is to elucidate possible interference between E2 signalling and the circadian system in the regulation of the expression of ACE2 mRNA and functionally related molecules. E2 was administered at a dosage of 40 μg/kg/day for 7 days to male Wistar rats, and sampling of the lungs and colon was performed during a 24-h cycle. The daily pattern of expression of molecules facilitating SARS-CoV-2 entry into the cell, clock genes and E2 receptors was analysed. As a consequence of E2 administration, a rhythm in ACE2 and TMPRSS2 mRNA expression was observed in the lungs but not in the colon. ADAM17 mRNA expression showed a pronounced rhythmic pattern in both tissues that was not influenced by E2 treatment. ESR1 mRNA expression exerted a rhythmic pattern, which was diminished by E2 treatment. The influence of E2 administration on ESR2 and GPER1 mRNA expression was greater in the lungs than in the colon as a significant rhythm in ESR2 and GPER1 mRNA expression appeared only in the lungs after E2 treatment. E2 administration also increased the amplitude of bmal1 expression in the lungs, which implicates altered functioning of peripheral oscillators in response to E2 treatment. The daily pattern of components of the SARS-CoV-2 entrance pathway and their responsiveness to E2 should be considered in the timing of pharmacological therapy for Covid-19.

Unbalanced IDO1/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia

Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome’s evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.

Human Cell Organelles in SARS-CoV-2 Infection: An Up-to-Date Overview

Since the end of 2019, the whole world has been struggling with the life-threatening pandemic amongst all age groups and geographic areas caused by Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2). The Coronavirus Disease 2019 (COVID-19) pandemic, which has led to more than 468 million cases and over 6 million deaths reported worldwide (as of 20 March 2022), is one of the greatest threats to human health in history. Meanwhile, the lack of specific and irresistible treatment modalities provoked concentrated efforts in scientists around the world. Various mechanisms of cell entry and cellular dysfunction were initially proclaimed. Especially, mitochondria and cell membrane are crucial for the course of infection. The SARS-CoV-2 invasion depends on angiotensin converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2), and cluster of differentiation 147 (CD147), expressed on host cells. Moreover, in this narrative review, we aim to discuss other cell organelles targeted by SARS-CoV-2. Lastly, we briefly summarize the studies on various drugs.

Melatonin and Related Compounds: Antioxidant and Anti-Inflammatory Actions

Melatonin, an indoleamine derived from tryptophan and produced in the pineal gland and other tissues [...].