Chloroquine: A Potential Drug in the COVID-19 Scenario

Repositioning antivirals against COVID-19: Synthetic pathways, mechanisms, and therapeutic insights

The pandemic of COVID-19 has ignited a global race to locate effective therapies with drug repositioning emerging as a leading strategy due to its cost-effectiveness and established safety profiles. Remdesivir, Favipiravir, Hydroxychloroquine, and Chloroquine have been the focus of rigorous clinical trials to determine their therapeutic potential against SARS-CoV-2. This article delves into the innovative synthetic strategies behind these drugs, providing a blueprint for researchers navigating the complex landscape of antiviral development. Beyond synthesis, we explore the fascinating mechanisms of action: hydroxychloroquine and chloroquine elevate lysosomal pH to impede autophagy and viral replication; favipiravir, a nucleoside analogue, induces lethal mutagenesis or RNA chain termination and remdesivir disrupts viral RNA synthesis through delayed chain termination. By merging synthetic methodologies with mechanistic insights, this article offers a comprehensive resource aimed at accelerating the development of potent COVID-19 therapies and underscores the crucial part that chemistry in addressing global health emergencies. It also underscores the vital function of chemistry in addressing global health emergencies and highlights how innovative drug design and repurposing can provide rapid responses to emerging infectious diseases. This fusion of chemistry and virology not only advances our understanding of drug action but also paves the way for the discovery of new therapeutic agents crucial in future pandemics.

Fragment-based Drug Discovery Strategy and its Application to the Design of SARS-CoV-2 Main Protease Inhibitor

Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) emerged at the end of 2019, causing a highly infectious and pathogenic disease known as 2019 coronavirus disease. This disease poses a serious threat to human health and public safety. The SARS-CoV-2 main protease (Mpro) is a highly sought-after target for developing drugs against COVID-19 due to its exceptional specificity. Its crystal structure has been extensively documented. Numerous strategies have been employed in the investigation of Mpro inhibitors. This paper is primarily concerned with Fragment-based Drug Discovery (FBDD), which has emerged as an effective approach to drug design in recent times. Here, we summarize the research on the approach of FBDD and its application in developing inhibitors for SARS-CoV-2 Mpro.

Fragment-based design of SARS-CoV-2 Mpro inhibitors

The SARS-CoV-2 virus has been identified as a causative agent for COVID-19 pandemic. About more than 6.3 million fatalities have been attributed to COVID-19 worldwide to date. Finding a viable cure for the illness is urgently needed in light of the present pandemic. The prominence of main protease in the life cycle of virus shapes the main protease as a viable target for design and development of antiviral agents to combat COVID-19. The current study presents the fragment linking strategy to design the novel Mpro inhibitors for COVID-19. A total of 293,451 fragments from diversified libraries have been screened for their binding affinity towards Mpro enzyme. The best 1600 fragment hits were subjected to fragment joining to achieve 100 new molecules using Schrödinger software. The resulting molecules were further screened for their Mpro binding affinity, ADMET, and drug-likeness features. The best 13 molecules were selected, and the first 6 compounds were investigated for their ligand-receptor complex stability through a molecular dynamics study using GROMACS software. The resulting molecules have the potential to be further evaluated for COVID-19 drug discovery.

Drugs repurposing for SARS-CoV-2: new insight of COVID-19 druggability

INTRODUCTION

The ongoing epidemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) creates a massive panic worldwide due to the absence of effective medicines. Developing a new drug or vaccine is time-consuming to pass safety and efficacy testing. Therefore, repurposing drugs have been introduced to treat COVID-19 until effective drugs are developed.

AREA COVERED

A detailed search of repurposing drugs against SARS-CoV-2 was carried out using the PubMed database, focusing on articles published 2020 years onward. A different class of drugs has been described in this article to target hosts and viruses. Based on the previous pandemic experience of SARS-CoV and MERS, several antiviral and antimalarial drugs are discussed here. This review covers the failure of some repurposed drugs that showed promising activity in the earlier CoV-pandemic but were found ineffective against SARS-CoV-2. All these discussions demand a successful drug development strategy for screening and identifying an effective drug for better management of COVID-19. The drug development strategies described here will serve a new scope of research for academicians and researchers.

EXPERT OPINION

Repurposed drugs have been used since COVID-19 to eradicate disease propagation. Drugs found effective for MERS and SARS may not be effective against SARS-CoV-2. Drug libraries and artificial intelligence are helpful tools to screen and identify different molecules targeting viruses or hosts.

Structure-based docking, pharmacokinetic evaluation, and molecular dynamics-guided evaluation of traditional formulation against SARS-CoV-2 spike protein receptor bind domain and ACE2 receptor complex

There is an urgent need for reliable cure and preventive measures in this hour of the outbreak of SARS-CoV-2. Siddha- and Ayurvedic-based classical formulations have antiviral properties and great potential therapeutic choice in this pandemic situation. In the current study, in silico-based analysis for the binding potential of phytoconstituents from the classical formulations suggested by the Ministry of Ayush (Kabasura Kudineer, Shwas Kuthar Rasa with Kantakari and pippali churna, Talisadi churna) to the interface domain of the SARS-CoV-2 receptor-binding domain and angiotensin-converting enzyme 2 was performed. Maestro software from Schrodinger and tools like Glide Docking, induced fit docking, MM-GBSA, molecular dynamics (MD) simulation, and thermal MM-GBSA was used to analyze the binding of protein PDB ID:6VW1 and the selected 133 ligands in comparison with drug molecules like favipiravir and ribavirin. QikProp-based ADMET evaluation of all the phytoconstituents found them nontoxic and with drug-like properties. Selection of top ten ligands was made based on docking score for further MM-GBSA analysis. After performing IFD of top five molecules iso-chlorogenic acid, taxiphyllin, vasicine, catechin and caffeic acid, MD simulation and thermal MM-GBSA were done. Iso-chlorogenic acid had formed more stable interaction with key residue among all phytoconstituents. Computational-based study has highlighted the potential of the many constituents of traditional medicine to interact with the SARS-CoV-2 RBD and ACE2, which might stop the viral entry into the cell. However, in vivo experiments and clinical trials are necessary for supporting this claim.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11696-021-01917-z.

Neurological Manifestation of SARS-CoV-2 Induced Inflammation and Possible Therapeutic Strategies Against COVID-19

There are regular reports of extrapulmonary infections and manifestations related to the ongoing COVID-19 pandemic. Coronaviruses are potentially neurotropic, which renders neuronal tissue vulnerable to infection, especially in elderly individuals or in those with neuro-comorbid conditions. Complaints of ageusia, anosmia, myalgia, and headache; reports of diseases such as stroke, encephalopathy, seizure, and encephalitis; and loss of consciousness in patients with COVID-19 confirm the neuropathophysiological aspect of this disease. The brain is linked to pulmonary organs, physiologically through blood circulation, and functionally through the nervous system. The interdependence of these vital organs may further aggravate the pathophysiological aspects of COVID-19. The induction of a cytokine storm in systemic circulation can trigger a neuroinflammatory cascade, which can subsequently compromise the blood-brain barrier and activate microglia- and astrocyte-borne Toll-like receptors, thereby leading to neuronal tissue damage. Hence, a holistic approach should be adopted by healthcare professionals while treating COVID-19 patients with a history of neurodegenerative disorders, neuropsychological complications, or any other neuro-compromised conditions. Imperatively, vaccines are being developed at top priority to contain the spread of the severe acute respiratory syndrome coronavirus 2, and different vaccines are at different stages of development globally. This review discusses the concerns regarding the neuronal complications of COVID-19 and the possible mechanisms of amelioration.

Global epidemiology of coronavirus disease 2019 and lessons for effective control of this and future pandemics

Barely 1 year after severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was first reported in China, the virus has infected approximately 120 million people, caused around 3 million deaths, and adversely affected the global economy. Despite stringent measures to flatten the epidemiologic curve of the pandemic, there have been spikes and waves of the infection in many countries, particularly in the American, European, and Asian continents. This review critically evaluated the global epidemiology of the novel coronavirus disease 2019 (COVID-19) to provide advice on other possible ways of managing the disease as various COVID-19 vaccines are being rolled out. To effectively control this and possible future epidemics/pandemics, there is a need to maintain a healthy balance between saving lives and livelihoods in the implementation of lockdowns. Unwarranted human exposures to animals, particularly pangolins, civet cats, bats, dromedary camels, and other wildlife known to be reservoirs and intermediate hosts of coronaviruses should be prevented. All the identified strains of SARS-CoV-2, including the highly infectious UK and South African variants, should be incorporated in COVID-19 vaccine production; to widen the protection spectrum. Some of the COVID-19 vaccines require primary inoculation, booster vaccination after 2-4 weeks and annual revaccination for adequate immunization against SARS-CoV-2. Survivors of COVID-19 may require only a single vaccine dozing and annual revaccination thereafter. Adoption of One Health approach and the development of globally coordinated active surveillance systems against emerging and reemerging zoonotic viruses are imperative.