ABSTRACT
Background: The recent outbreak of the COVID-19 pandemic has raised a global health concern due to the unavailability of any vaccines or drugs. The repurposing of traditional herbs with broad-spectrum anti-viral activity can be explored to control or prevent a pandemic. Objective(s): The 3-chymotrypsin-like main protease (3CLpro), also referred to as the "Achilles' heel" of the coronaviruses (CoVs), is highly conserved among CoVs and is a potential drug target. 3CLpro is essential for the virus' life cycle. The objective of the study was to screen and identify broad--spectrum natural phytoconstituents against the conserved active site and substrate-binding site of 3CLpro of HCoVs. Method(s): Herein, we applied the computational strategy based on molecular docking to identify potential phytoconstituents for the non-covalent inhibition of the main protease 3CLpro from four different CoVs, namely, SARS-CoV-2, SARS-CoV, HCoV-HKU1, and HCoV-229E. Result(s): Our study shows that natural phytoconstituents in Triphala (a blend of Emblica officinalis fruit, Terminalia bellerica fruit, and Terminalia chebula fruit), namely chebulagic acid, chebulinic acid, and elagic acid, exhibited the highest binding affinity and lowest dissociation constants (Ki), against the conserved 3CLpro main protease of SARSCoV-2, SARS-CoV, HCoV-HKU1, and HCoV-229E. Besides, phytoconstituents of other herbs like Withania somnifera, Glycyrrhiza glabra, Hyssopus officinalis, Camellia sinensis, Prunella vulgaris, and Ocimum sanctum also showed good binding affinity and lower Ki against the active site of 3CLpro. The top-ranking phyto-constituents' binding interactions clearly showed strong and stable interactions with amino acid residues in the catalytic dyad (CYS-HIS) and substrate-binding pocket of the 3CLpro main proteases. Conclusion(s): This study provides a valuable scaffold for repurposing traditional herbs with anti--CoV activity to combat SARS-CoV-2 and other HCoVs until the discovery of new therapies.Copyright © 2021 Bentham Science Publishers.
ABSTRACT
In recent years, it has been reported that many herbal plants contain antiviral agents which combat a human disease that is caused by pathogenic viruses. The natural products which are obtained from plants as antiviral agents against viruses have gone through researches to check the efficacy and potentials of the herbal products in the prevention of viral disorders. On the basis of randomized controlled studies and in-vivo studies, and in-vitro studies, some agents are utilized all across the globe. Progressively numerous studies on therapy of antivirals have been increased. Though, efficacy remains disputable for antiviral drugs that are employed for viral disorders. The viral diseases are challenging for the health of people around the world cause significant increase in mortality and enhance crises. There are many synthetic antiviral drugs that have a large number of side effects and have narrow therapeutic window range, while in the other hand herbal formulations have minimized side effects. The advantages of herbal formulation over synthetic drugs encourage us to devise and expand new herbal moieties against the emerging viral infections. The medicinal plants contain phytochemicals that have antiviral properties. In this paper, the activity of antiviral agents from medicinal plants which have importance in Ayurveda, are discussed along with their source.
ABSTRACT
The emerging SARS-CoV-2 infection is the cause of the global COVID-19 pandemic. To date, there are limited therapeutic options available to fight this disease. Here we examined the inhibitory abilities of two broad-spectrum antiviral natural products chebulagic acid (CHLA) and punicalagin (PUG) against SARS-CoV-2 viral replication. Both CHLA and PUG reduced virus-induced plaque formation in Vero-E6 monolayer at noncytotoxic concentrations, by targeting the enzymatic activity of viral 3-chymotrypsin-like cysteine protease (3CLpro) as allosteric regulators. Our study demonstrates the potential use of CHLA and PUG as novel COVID-19 therapies.