ABSTRACT
The inhibitory potential of Artemisia annua, a well-known antimalarial herb, against several viruses, including the coronavirus, is increasingly gaining recognition. The plant extract has shown significant activity against both the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and the novel SARS-CoV-2 that is currently ravaging the world. It is therefore necessary to evaluate individual chemicals of the plant for inhibitory potential against SARS-CoV-2 for the purpose of designing drugs for the treatment of COVID-19. In this study, we employed computational techniques comprising molecular docking, binding free energy calculations, pharmacophore modeling, induced-fit docking, molecular dynamics simulation, and ADMET predictions to identify potential inhibitors of the SARS-CoV-2 main protease (Mpro) from 168 bioactive compounds of Artemisia annua. Rhamnocitrin, isokaempferide, kaempferol, quercimeritrin, apigenin, penduletin, isoquercitrin, astragalin, luteolin-7-glucoside, and isorhamnetin were ranked the highest, with docking scores ranging from -7.84 to -7.15 kcal/mol compared with the -6.59 kcal/mol demonstrated by the standard ligand. Rhamnocitrin, Isokaempferide, and kaempferol, like the standard ligand, interacted with important active site amino acid residues like HIS 41, CYS 145, ASN 142, and GLU 166, among others. Rhamnocitrin demonstrated good stability in the active site of the protein as there were no significant conformational changes during the simulation process. These compounds also possess acceptable druglike properties and a good safety profile. Hence, they could be considered for experimental studies and further development of drugs against COVID-19.
ABSTRACT
Objectives: The novel coronavirus disease-2019 (COVID-19) that emerged in China, is a highly transmittable and pathogenic viral infection caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2); the disease has been declared by the World Health Organization as a Public Health Emergency of International Concern. The unavailability of approved therapeutic agents or vaccines is of great concern. This study performed molecular docking and absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis of some compounds isolated from Neocarya macrophylla (Sabine) Prance ex F. White (Chrysobalanaceae) against three targets of SARS-CoV-2 proteins (3C-like protease, spike protein, and papain-like protease). Materials and Methods: Phytoconstituents isolated from N. macrophylla were screened against key targets of SARS-CoV-2 using Auto Dock Vina, while the ADMET analysis was performed using swiss ADME and pkCSM ADMET descriptors algorithm protocols. Results: The in silico computational studies revealed that the compounds (catechin, catechin-3-rhamnoside, quercetin, and epicatechin) isolated from N. macrophylla can effectively bind with high affinity and lower energy values to the three target proteins of SARS-CoV-2. ADMET analysis was used to predict important pharmacokinetic properties of the compounds, such as aqueous solubility, blood-brain barrier, plasma protein binding, CYP2D6 binding, intestinal absorption, and hepatotoxicity. Conclusion: The findings of this study have shown that N. macrophylla contains potential leads for SARS-CoV-2 inhibition and thus, should be studied further for development as therapeutic agents against COVID-19.
