Pharmacological agents under investigation in the treatment of coronavirus disease 2019 and the importance of melatonin

Indole-Based Compounds as Potential Drug Candidates for SARS-CoV-2

The COVID-19 pandemic has posed a significant threat to society in recent times, endangering human health, life, and economic well-being. The disease quickly spreads due to the highly infectious SARS-CoV-2 virus, which has undergone numerous mutations. Despite intense research efforts by the scientific community since its emergence in 2019, no effective therapeutics have been discovered yet. While some repurposed drugs have been used to control the global outbreak and save lives, none have proven universally effective, particularly for severely infected patients. Although the spread of the disease is generally under control, anti-SARS-CoV-2 agents are still needed to combat current and future infections. This study reviews some of the most promising repurposed drugs containing indolyl heterocycle, which is an essential scaffold of many alkaloids with diverse bio-properties in various biological fields. The study also discusses natural and synthetic indole-containing compounds with anti-SARS-CoV-2 properties and computer-aided drug design (in silico studies) for optimizing anti-SARS-CoV-2 hits/leads.

Melatonin effect on platelets and coagulation: Implications for a prophylactic indication in COVID-19

Severe COVID-19 is associated with the dynamic changes in coagulation parameters. Coagulopathy is considered as a major extra-pulmonary risk factor for severity and mortality of COVID-19; patients with elevated levels of coagulation biomarkers have poorer in-hospital outcomes. Oxidative stress, alterations in the activity of cytochrome P450 enzymes, development of the cytokine storm and inflammation, endothelial dysfunction, angiotensin-converting enzyme 2 (ACE2) enzyme malfunction and renin–angiotensin system (RAS) imbalance are among other mechanisms suggested to be involved in the coagulopathy induced by severe acute respiratory syndrome coronavirus (SARS-CoV-2). The activity and function of coagulation factors are reported to have a circadian component. Melatonin, a multipotential neurohormone secreted by the pineal gland exclusively at night, regulates the cytokine system and the coagulation cascade in infections such as those caused by coronaviruses. Herein, we review the mechanisms and beneficial effects of melatonin against coagulopathy induced by SARS-CoV-2 infection.

Optimization of application schedule of camphecene, a novel anti-influenza compound, based on its pharmacokinetic characteristics

Due to high variability and rapid life cycle, influenza virus is able to develop drug resistance against direct-acting antivirals. Development of novel virus-in113039hibiting drugs is therefore important goal. Previously, we identified camphor derivative, camphecene, as an effective anti-influenza compound. In the present study, we optimize the regimen of its application to avoid high sub-toxic concentrations. The protective activity of camphecene was assessed on the model of lethal pneumonia of mice caused by influenza viruses. Camphecene was administered either once a day or four times a day, alone or in combination with Tamiflu. Mortality and viral titer in the lungs were studied. Pharmacokinetics of camphecene was studied in rabbits. We have demonstrated that camphecene, being used every 6 h at a dose of 7.5 mg/kg/day, results in antiviral effect that was statistically equal to the effect of 100 mg/kg/day once a day, that is, the same effect was achieved by 13 times lower daily dose of the drug. This effect was manifested in decrease of mortality and decrease of virus' titer in the lungs. The studies of pharmacokinetics of camphecene have demonstrated that it does not accumulate in blood plasma and that its m ultiple applications with dosage interval of 65 min are safe. In addition, the results of the study demonstrate also that camphecene possesses additive effect with Tamiflu, allowing to decrease the dose of the latter. The results suggest that due to safety and efficacy, camphecene can be further developed as potential anti-influenza remedy.

Ultrasensitive and highly selective "turn-on" fluorescent sensor for the detection and measurement of melatonin in juice samples

Melatonin (MLT), a hormone related to the regulation of brain functions, is directly related to sleep quality and is considered to be a possible adjuvant therapy for patients needing hospitalization for coronavirus disease 2019 pneumonia, and accurate measurement of MLT is crucial. Herein, a new, highly sensitive, and easy operation fluorescent probe was provided based on Zr metal-organic framework encapsulation into the molecularly imprinted polymer (MOF@MIP). By combining unique properties of MIP and fluorescent MOF, selectivity and operation of the applied method were significantly improved. Different characterization methods, such as XRD, FT-IR, and FE-SEM, were used to confirm the synthesis reliability. MOF@MIP was successfully used for the precise identification and ultrasensitive detection for trace amounts of MLT. The detection mechanism for the analytical system is based on the ''turn-on'' fluorescence (FL) signal in 404 nm. The findings proved that it is possible to detect trace amounts of MLT in real samples including grape, cherry, and sour cherry juice. The linear range and the limit of detection (LOD) for trace amounts of MLT were obtained as 1-100 ng/mL and 0.18 ng/mL, respectively.

In-silico screening of naturally derived phytochemicals against SARS-CoV Main protease

Coronavirus disease 2019 (COVID-19) is a rapidly growing pandemic that requires urgent therapeutic intervention. Finding potential anti COVID-19 drugs aside from approved vaccines is progressively going on. The chemically diverse natural products represent valuable sources for drug leads. In this study, we aimed to find out safe and effective COVID-19 protease inhibitors from a library of natural products which share the main nucleus/skeleton of FDA-approved drugs that were employed in COVID-19 treatment guidelines or repurposed by previous studies. Our library was subjected to virtual screening against SARS-CoV Main protease (Mpro) using Molecular Operating Environment (MOE) software. Twenty-two out of those natural candidates showed higher binding scores compared to their analogues. We repurpose these natural products including alkaloids, glucosinolates, and phenolics as potential platforms for the development of anti-SARS-CoV-2 therapeutics. This study paves the way towards discovering a lead used in the treatment of COVID-19 from natural sources and introduces phytomedicines with dual therapeutic effects against COVID-19 besides their original pharmacological effects. We recommend further in vitro evaluation of their anti-COVID-19 activity and future clinical studies.

Benefits and adverse events of melatonin use in the elderly (Review)

Melatonin is a hormone secreted by the pineal gland in accordance with the circadian rhythm when the light level decreases. Reduction of melatonin secretion with age may be associated with physiological aging in neurodegenerative diseases by affecting the suprachiasmatic nucleus or of the neuronal pathways of transmission to the pineal gland. A significant decrease in melatonin synthesis has been reported in various disorders and diseases, including cardiovascular diseases, metabolic disorders (particularly diabetes type 2), cancer and endocrine diseases. In addition to the fact, that melatonin is a sleep inducer, it also exerts cytoprotective properties as an antioxidant and free radical scavenger. The therapeutic role of melatonin has been demonstrated in sleep disorders, eye damage and cardiovascular disease. The association between melatonin and β-blockers has had a positive impact on sleep disorders in clinical trials. Previous studies have reported the anti-inflammatory effect of melatonin by adjusting levels of pro-inflammatory cytokines, including interleukin (IL)-6, IL-1β and tumor necrosis factor-α. Melatonin treatment has been demonstrated to decrease IL-6 and IL-10 expression levels and efficiently attenuate T-cell proliferation. Currently, there is an inconsistency of scientific data regarding the lowest optimal dose and safety of melatonin for long-term use. The aim of the present review was to summarize the evidence on the role of melatonin in various clinical conditions and highlight the future research in this area.

Identification of lead compounds from large natural product library targeting 3C-like protease of SARS-CoV-2 using E-pharmacophore modelling, QSAR and molecular dynamics simulation

COVID-19 is a novel disease caused by SARS-CoV-2 and has made a catastrophic impact on the global economy. As it is, there is no officially FDA approved drug to alleviate the negative impact of SARS-CoV-2 on human health. Numerous drug targets for neutralizing coronavirus infection have been identified, among them is 3-chymotrypsin-like-protease (3CL^pro), a viral protease responsible for the viral replication is chosen for this study. This study aimed at finding novel inhibitors of SARS-CoV-2 3C-like protease from the natural library using computational approaches. A total of 69,000 compounds from natural product library were screened to match a minimum of 3 features from the five sites e-pharmacophore model. Compounds with fitness score of 1.00 and above were consequently filtered by executing molecular docking studies via Glide docking algorithm. Qikprop also predicted the compounds drug-likeness and pharmacokinetic features; besides, the QSAR model built from KPLS analysis with radial as binary fingerprint was used to predict the compounds inhibition properties against SARS-CoV-2 3C-like protease. Fifty ns molecular dynamics (MD) simulation was carried out using GROMACS software to understand the dynamics of binding. Nine (9) lead compounds from the natural products library were discovered; seven among them were found to be more potent than lopinavir based on energies of binding. STOCK1N-98687 with docking score of -9.295 kcal/mol had considerable predicted bioactivity (4.427 µM) against SARS-CoV-2 3C-like protease and satisfactory drug-like features than the experimental drug lopinavir. Post-docking analysis by MM-GBSA confirmed the stability of STOCK1N-98687 bound 3CL^pro crystal structure. MD simulation of STOCKIN-98687 with 3CL^pro at 50 ns showed high stability and low fluctuation of the complex. This study revealed compound STOCK1N-98687 as potential 3CL^pro inhibitor; therefore, a wet experiment is worth exploring to confirm the therapeutic potential of STOCK1N-98687 as an antiviral agent.

The Coronavirus Disease 2019 (COVID-19): Key Emphasis on Melatonin Safety and Therapeutic Efficacy

Viral infections constitute a tectonic convulsion in the normophysiology of the hosts. The current coronavirus disease 2019 (COVID-19) pandemic is not an exception, and therefore the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, like any other invading microbe, enacts a generalized immune response once the virus contacts the body. Melatonin is a systemic dealer that does not overlook any homeostasis disturbance, which consequently brings into play its cooperative triad, antioxidant, anti-inflammatory, and immune-stimulant backbone, to stop the infective cycle of SARS-CoV-2 or any other endogenous or exogenous threat. In COVID-19, the corporal propagation of SARS-CoV-2 involves an exacerbated oxidative activity and therefore the overproduction of great amounts of reactive oxygen and nitrogen species (RONS). The endorsement of melatonin as a possible protective agent against the current pandemic is indirectly supported by its widely demonstrated beneficial role in preclinical and clinical studies of other respiratory diseases. In addition, focusing the therapeutic action on strengthening the host protection responses in critical phases of the infective cycle makes it likely that multi-tasking melatonin will provide multi-protection, maintaining its efficacy against the virus variants that are already emerging and will emerge as long as SARS-CoV-2 continues to circulate among us.

Computational study of the therapeutic potentials of a new series of imidazole derivatives against SARS-CoV-2

Owing to the urgent need for therapeutic interventions against the SARS-coronavirus 2 (SARS-CoV-2) pandemic, we employed an in silico approach to evaluate the SARS-CoV-2 inhibitory potential of newly synthesized imidazoles. The inhibitory potentials of the compounds against SARS-CoV-2 drug targets - main protease (Mpro), spike protein (Spro) and RNA-dependent RNA polymerase (RdRp) were investigated through molecular docking analysis. The binding free energy of the protein-ligand complexes were estimated, pharmacophore models were generated and the absorption, distribution, metabolism, excretion and toxicity (ADMET) properties of the compounds were determined. The compounds displayed various levels of binding affinities for the SARS-CoV-2 drug targets. Bisimidazole C2 scored highest against all the targets, with its aromatic rings including the two imidazole groups contributing to the binding. Among the phenyl-substituted 1H-imidazoles, C9 scored highest against all targets. C11 scored highest against Spro and C12 against Mpro and RdRp among the thiophene-imidazoles. The compounds interacted with HIS 41 - CYS 145 and GLU 288 – ASP 289 – GLU 290 of Mpro, ASN 501 of Spro receptor binding motif and some active site amino acids of RdRp. These novel imidazole compounds could be further developed as drug candidates against SARS-CoV-2 following lead optimization and experimental studies.

Role of Melatonin on Virus-Induced Neuropathogenesis-A Concomitant Therapeutic Strategy to Understand SARS-CoV-2 Infection

Viral infections may cause neurological disorders by directly inducing oxidative stress and interrupting immune system function, both of which contribute to neuronal death. Several reports have described the neurological manifestations in Covid-19 patients where, in severe cases of the infection, brain inflammation and encephalitis are common. Recently, extensive research-based studies have revealed and acknowledged the clinical and preventive roles of melatonin in some viral diseases. Melatonin has been shown to have antiviral properties against several viral infections which are accompanied by neurological symptoms. The beneficial properties of melatonin relate to its properties as a potent antioxidant, anti-inflammatory, and immunoregulatory molecule and its neuroprotective effects. In this review, what is known about the therapeutic role of melatonin in virus-induced neuropathogenesis is summarized and discussed.

SARS-COV-2 (COVID-19): Cellular and biochemical properties and pharmacological insights into new therapeutic developments

COVID‐19 caused by SARS‐COV‐2 first appeared in the Wuhan City of China and began to spread rapidly among people. Rapid progression of the outbreak has led to a major global public health problem of a potentially fatal disease. On January 30, 2020, WHO declared the pandemic as the sixth public health emergency of the world. Upon this, the whole country has started to take the necessary precautions. The new coronavirus uses membrane‐bound angiotensin‐converting enzyme 2 (ACE2) to enter into the cells, such as SARS‐CoV, and mostly affects the respiratory tract. Symptoms of COVID‐19 patients include fever (93%), fatigue (70%), cough (70%), anorexia (40%) and dyspnoea (34.5%). The elderly and people with underlying chronic diseases are more susceptible to infection and higher mortality. Currently, a large number of drugs and vaccines studies are ongoing. In this review, we discussed the virology, epidemiological data, the replication of the virus, and its relationship with cardiovascular diseases on COVID‐19 pandemics, treatment and vaccines. Thereby, this study aims to neatly present scientific data in light of many regarding literature that can be a clue for readers who research this disease prevention and treatment.