Potential Drugs for the Treatment of COVID-19: Synthesis, Brief History and Application

Coronaviruses (CoVs) belonging to the Betacoronavirus group, an unusually large RNA genome, are characterized by club-like spikes that project from their surface. An outbreak of a novel coronavirus 2019 (nCOVID-19) showing a unique replication strategy and infection has posed a significant threat to international health and the economy around the globe. Scientists around the world are investigating few previously used clinical drugs for the treatment of COVID-19. This review provides synthesis and mode of action of recently investigated drugs like Chloroquine, Hydroxychloroquine, Ivermectin, Selamectin, Remdesivir, Baricitinib, Darunavir, Favipiravir, Lopinavir/ritonavir and Mefloquine hydrochloride that constitute an option for COVID-19 treatment.

Immunological aspects and gender bias during respiratory viral infections including novel Coronavirus disease-19 (COVID-19): A scoping review

The human immune system is not adequately equipped to eliminate new microbes and could result in serious damage on first exposure. This is primarily attributed to the exaggerated immune response (inflammatory disease), which may prove detrimental to the host, as evidenced by SARS‐CoV‐2 infection. From the experiences of Novel Coronavirus Disease‐19 to date, male patients are likely to suffer from high‐intensity inflammation and disease severity than the female population. Hormones are considered the significant pillars of sex differences responsible for the discrepancy in immune response exhibited by males and females. Females appear to be better equipped to counter invading respiratory viral pathogens, including the novel SARS‐CoV‐2, than males. It can be hypothesized that females are more shielded from disease severity, probably owing to the diverse action/influence of estrogen and other sex hormones on both cellular (thymus‐derived T lymphocytes) and humoral immunity (antibodies).

Hormones are considered as significant pillars of sex differences and influence both the innate as well as adaptive immune responses.

Sex hormones and their potential role in the immune responses has not been completely understood.

Females are more shielded from disease severity probably owing to their unique hormonal constitution.

In females, the immunological cells have been noted to restrict the spread of infections as compared to males.

Males suffer from increased severity of respiratory infections and are less prone to autoimmune disorders as compared to the female counterparts.

Estrogen and other sex hormones play a key role both in restricting the inflammatory responses and in effective clearance of pathogens including the novel Coronairus.

Stem cell therapies and benefaction of somatic cell nuclear transfer cloning in COVID-19 era

BACKGROUND

The global health emergency of COVID-19 has necessitated the development of multiple therapeutic modalities including vaccinations, antivirals, anti-inflammatory, and cytoimmunotherapies, etc. COVID-19 patients suffer from damage to various organs and vascular structures, so they present multiple health crises. Mesenchymal stem cells (MSCs) are of interest to treat acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection.

MAIN BODY

Stem cell-based therapies have been verified for prospective benefits in copious preclinical and clinical studies. MSCs confer potential benefits to develop various cell types and organoids for studying virus-human interaction, drug testing, regenerative medicine, and immunomodulatory effects in COVID-19 patients. Apart from paving the ways to augment stem cell research and therapies, somatic cell nuclear transfer (SCNT) holds unique ability for a wide range of health applications such as patient-specific or isogenic cells for regenerative medicine and breeding transgenic animals for biomedical applications. Being a potent cell genome-reprogramming tool, the SCNT has increased prominence of recombinant therapeutics and cellular medicine in the current era of COVID-19. As SCNT is used to generate patient-specific stem cells, it avoids dependence on embryos to obtain stem cells.

CONCLUSIONS

The nuclear transfer cloning, being an ideal tool to generate cloned embryos, and the embryonic stem cells will boost drug testing and cellular medicine in COVID-19.

Diverse Immunological Factors Influencing Pathogenesis in Patients with COVID-19: A Review on Viral Dissemination, Immunotherapeutic Options to Counter Cytokine Storm and Inflammatory Responses

The pathogenesis of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still not fully unraveled. Though preventive vaccines and treatment methods are out on the market, a specific cure for the disease has not been discovered. Recent investigations and research studies primarily focus on the immunopathology of the disease. A healthy immune system responds immediately after viral entry, causing immediate viral annihilation and recovery. However, an impaired immune system causes extensive systemic damage due to an unregulated immune response characterized by the hypersecretion of chemokines and cytokines. The elevated levels of cytokine or hypercytokinemia leads to acute respiratory distress syndrome (ARDS) along with multiple organ damage. Moreover, the immune response against SARS-CoV-2 has been linked with race, gender, and age; hence, this viral infection's outcome differs among the patients. Many therapeutic strategies focusing on immunomodulation have been tested out to assuage the cytokine storm in patients with severe COVID-19. A thorough understanding of the diverse signaling pathways triggered by the SARS-CoV-2 virus is essential before contemplating relief measures. This present review explains the interrelationships of hyperinflammatory response or cytokine storm with organ damage and the disease severity. Furthermore, we have thrown light on the diverse mechanisms and risk factors that influence pathogenesis and the molecular pathways that lead to severe SARS-CoV-2 infection and multiple organ damage. Recognition of altered pathways of a dysregulated immune system can be a loophole to identify potential target markers. Identifying biomarkers in the dysregulated pathway can aid in better clinical management for patients with severe COVID-19 disease. A special focus has also been given to potent inhibitors of proinflammatory cytokines, immunomodulatory and immunotherapeutic options to ameliorate cytokine storm and inflammatory responses in patients affected with COVID-19.

COVID-19 vaccination campaign in Nepal, emerging UK variant and futuristic vaccination strategies to combat the ongoing pandemic

With the emergence of the new variants of concern (VOC) of the SARS-CoV-2, the efficacy of certain vaccines against them requires further research and considerations for future scenarios of COVID-19 vaccination. The vaccines' lack of efficacy against VOC will pose at risk to the vaccinated population and is a public health threat. In this commentary, we discuss Nepal's recent experiences and expectations regarding the confirmation of VOC B.1.1.7 from the United Kingdom in the country.

Role of Inflammatory Cytokines in COVID-19 Patients: A Review on Molecular Mechanisms, Immune Functions, Immunopathology and Immunomodulatory Drugs to Counter Cytokine Storm

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a severe pandemic of the current century. The vicious tentacles of the disease have been disseminated worldwide with unknown complications and repercussions. Advanced COVID-19 syndrome is characterized by the uncontrolled and elevated release of pro-inflammatory cytokines and suppressed immunity, leading to the cytokine storm. The uncontrolled and dysregulated secretion of inflammatory and pro-inflammatory cytokines is positively associated with the severity of the viral infection and mortality rate. The secretion of various pro-inflammatory cytokines such as TNF-α, IL-1, and IL-6 leads to a hyperinflammatory response by recruiting macrophages, T and B cells in the lung alveolar cells. Moreover, it has been hypothesized that immune cells such as macrophages recruit inflammatory monocytes in the alveolar cells and allow the production of large amounts of cytokines in the alveoli, leading to a hyperinflammatory response in severely ill patients with COVID-19. This cascade of events may lead to multiple organ failure, acute respiratory distress, or pneumonia. Although the disease has a higher survival rate than other chronic diseases, the incidence of complications in the geriatric population are considerably high, with more systemic complications. This review sheds light on the pivotal roles played by various inflammatory markers in COVID-19-related complications. Different molecular pathways, such as the activation of JAK and JAK/STAT signaling are crucial in the progression of cytokine storm; hence, various mechanisms, immunological pathways, and functions of cytokines and other inflammatory markers have been discussed. A thorough understanding of cytokines' molecular pathways and their activation procedures will add more insight into understanding immunopathology and designing appropriate drugs, therapies, and control measures to counter COVID-19. Recently, anti-inflammatory drugs and several antiviral drugs have been reported as effective therapeutic drug candidates to control hypercytokinemia or cytokine storm. Hence, the present review also discussed prospective anti-inflammatory and relevant immunomodulatory drugs currently in various trial phases and their possible implications.

Mortality Rates of Coronavirus Disease 2019 (COVID-19) Caused by the Novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2)

Background The significance of the global prevalence and incidence of coronavirusdisease 2019 (COVID-19) is a measure of its severity. However, without statistical data, one cannot understand the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. This study, based on good data, enables us to know how the disease is spreading, what impact the pandemic has on the lives of people around the world, and whether the countermeasures that countries have been taking are successful for controlling and preventing the disease. Therefore, this study is undertaken to estimate the infection fatality rates (IFRs) and case-fatality rates (CFRs) in various countries and regions of the world. Methods COVID-19-related data were collected from various countries belonging to different World Bank categories based on economies (low-income, low-middle income, upper-middle income, and high-income countries) and the World Health Organization's (WHO's) regional classification of countries (the Americas, European, African, South-East Asia, Eastern Mediterranean, and Western Pacific regions). The data were collected from the WHO's dedicated website on COVID-19, and statistical methods like mean, standard deviation, p-value, and percentages were used to calculate the IFR and CFR. Results Mexico (8.94%) reported the highest IFR among all the countries. The low-income countries reported increased IFR (2.46±1.91) as compared to the other groups. The European region (7.3%) and the American region (5.3%) recorded the highest CFRs. The South-East Asian region reported the lowest CFR (1.1%). Conclusions The low-income group countries showed higher rates of IFR and lower CFRs. Lower IFRs and increased CFRs were noted among the high-income group countries and the American and European regions respectively. The varied IFRs and CFRs could be attributed to multiple factors that include climatic conditions, living environments, age, sex, comorbidities, among others.

Computational investigations of three main drugs and their comparison with synthesized compounds as potent inhibitors of SARS-CoV-2 main protease (Mpro): DFT, QSAR, molecular docking, and in silico toxicity analysis

In this study, we examined five previously synthesized compounds and checked their binding affinity towards the SARS-CoV-2 main protease (M^pro) by molecular docking study, and compared the data with three FDA approved drugs, i.e., Remdesivir, Ivermectine and Hydroxychlorochine. In addition, we have investigated the docking study against the main protease of SARS-CoV-2 (M^pro) by using Autodock 4.2 software package. The results suggested that the investigated compounds have property to bind the active position of the protein as reported in approved drugs. Hence, further experimental studies are required. The formation of intermolecular interactions, negative values of scoring functions, free binding energy and the calculated binding constants confirmed that the studied compounds have significant affinity for the specified biotarget. These studied compounds were passed the drug-likeness criteria as suggested by calculating ADME data by SwissADME server. Moreover, the ADMET properties suggested that the investigated compounds to be orally active compounds in human. Furthermore, density functional computations (DFT) were executed by applying GAUSSIAN 09 suit program. In addition, Quantitative Structure-Activity Relationship (QSAR) was studied by applying HyperChem Professional 8.0.3 program.

Recent progress in chemical approaches for the development of novel neuraminidase inhibitors

Influenza virus is the main cause of an infectious disease called influenza affecting the respiratory system including the throat, nose and lungs. Neuraminidase inhibitors are reagents used to block the enzyme called neuraminidase to prevent the influenza infection from spreading. Neuraminidase inhibitors are widely used in the treatment of influenza infection, but still there is a need to develop more potent agents for the more effective treatment of influenza. Complications of the influenza disease lead to death, and one of these complications is drug resistance; hence, there is an urgent need to develop more effective agents. This review focuses on the recent advances in chemical synthesis pathways used for the development of new neuraminidase agents along with the medicinal aspects of chemically modified molecules, including the structure-activity relationship, which provides further rational designs of more active small molecules.

Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease

A novel series of mixed-ligand complexes of the type, [M(L1)(L2)Cl]·2H2O [L1 = 2-(α-methyl salicylidene hydrazine) benzimidazole (primary ligand), L2 = 2,2′-bipyridine (bipy; secondary ligand), M = Co(ii), Ni(ii), Cu(ii) and Zn(ii)], were based on the physicoanalytical studies. The spectroscopic findings revealed tridentate nature of the Schiff base ligand (L1) and its coordination to the metal ions via azomethine nitrogen, ring nitrogen and the deprotonated phenolic oxygen atoms. Furthermore, the synthesized compounds were evaluated for antimicrobial activity against Bacillus subtilis, Escherichia coli and Salmonella typhi microorganisms. In addition, molecular docking studies were carried out against Middle East respiratory syndrome coronavirus (PDB ID: 4ZS6) and severe acute respiratory syndrome coronavirus 2 main protease (PDB ID: 6W63).

The recent challenges of highly contagious COVID-19, causing respiratory infections: Symptoms, diagnosis, transmission, possible vaccines, animal models, and immunotherapy

COVID-19 is highly contagious pathogenic viral infection initiated from Wuhan seafood wholesale market of China on December 2019 and spread rapidly around the whole world due to onward transmission. This recent outbreak of novel coronavirus (CoV) was believed to be originated from bats and causing respiratory infections such as common cold, dry cough, fever, headache, dyspnea, pneumonia, and finally Severe Acute Respiratory Syndrome (SARS) in humans. For this widespread zoonotic virus, human-to-human transmission has resulted in nearly 83 lakh cases in 213 countries and territories with 4,50,686 deaths as on 19 June 2020. This review presents a report on the origin, transmission, symptoms, diagnosis, possible vaccines, animal models, and immunotherapy for this novel virus and will provide ample references for the researchers toward the ongoing development of therapeutic agents and vaccines and also preventing the spread of this disease.

The recent challenges of highly contagious COVID-19, causing respiratory infections: Symptoms, diagnosis, transmission, possible vaccines, animal models, and immunotherapy

COVID-19 is highly contagious pathogenic viral infection initiated from Wuhan seafood wholesale market of China on December 2019 and spread rapidly around the whole world due to onward transmission. This recent outbreak of novel coronavirus (CoV) was believed to be originated from bats and causing respiratory infections such as common cold, dry cough, fever, headache, dyspnea, pneumonia, and finally Severe Acute Respiratory Syndrome (SARS) in humans. For this widespread zoonotic virus, human-to-human transmission has resulted in nearly 83 lakh cases in 213 countries and territories with 4,50,686 deaths as on 19 June 2020. This review presents a report on the origin, transmission, symptoms, diagnosis, possible vaccines, animal models, and immunotherapy for this novel virus and will provide ample references for the researchers toward the ongoing development of therapeutic agents and vaccines and also preventing the spread of this disease.

Structural and Theoretical Investigations, Hirshfeld Surface Analyses, and Cytotoxicity of a Naphthalene-Based Chiral Compound

A novel Schiff base compound derived from the condensation of 2-hydroxy-1-naphthaldehyde with (1S,2S)-(-)-1,2-diphenylethylenediamine in 2:1 M ratio was reported and investigated by elemental analyses, Fourier transform infrared and NMR spectroscopic studies, and single-crystal X-ray crystallography. Hirshfeld surface analyses were also carried out to measure the various intermolecular contacts controlling the supramolecular topology, suggesting the H···O (7.6%) contacts to be the most significant interactions, whereas the H···H (48.9%) and C···H (40.2%) interactions are less-significant. The data obtained from the energy calculations revealed the structure observed experimentally to be the most stable isomer and its energy being lower by 18.0441 kcal/mol than the less stable one. Density functional theory calculations were also carried out to analyze the natural charges, reactivity descriptors, and different intramolecular charge transfer interactions. The in vitro anticancer activity of the compound was evaluated by MTT assays against human colorectal cancer cells, HT-29 and SW620. The results showed that the compound has potential anticancer activity against these cells lines.

Sustainable and Efficient Route for the Regeneration of Carbonyl Compounds from Oximes Using Aqueous Extract of Sapindus laurifolia under Microwave Radiation

The synthesis of organic compounds using aqueous medium has become an indispensable tool for modern chemical synthesis strategies because of its ability to produce pure products with higher yield at ambient temperature. The conversion of oxime group into carbonyl group serves as a key step for several organic syntheses. This article describes the regeneration of carbonyl compounds from the oxime group present in various carbon skeletons using I₂ and aqueous extract of Sapindus laurifolia under microwave radiation. A correlation has been established between the critical micellar concentration of saponin extracted from Sapindous laurifolia and the yield percentage of regenerated different carbonyl compounds. An effortless, competent, and environmentally compassionate protocol for the regeneration of carbonyl compound with a high percent of yield in the range 45-95% could be achieved.