ABSTRACT
The COVID-19 pandemic has caused adverse health (severe respiratory, enteric and systemic infections) and environmental impacts that have threatened public health and the economy worldwide. Drug repurposing and small molecule multi-target directed herbal medicine therapeutic approaches are the most appropriate exploration strategies for SARS-CoV-2 drug discovery. This study identified potential multi-target-directed Parkia bioactive entities against SARS-CoV-2 receptors (S-protein, ACE2, TMPRSS2, RBD/ACE2, RdRp, MPro, and PLPro) using ADMET, drug-likeness, molecular docking (AutoDock, FireDock and HDOCK), molecular dynamics simulation and MM-PBSA tools. One thousand Parkia bioactive entities were screened out by virtual screening and forty-five bioactive phytomolecules were selected based on favorable binding affinity and acceptable pharmacokinetic and pharmacodynamics properties. The binding affinity values of Parkia phyto-ligands (AutoDock: -6.00--10.40 kcal/mol; FireDock: -31.00--62.02 kcal/mol; and HDOCK: -150.0--294.93 kcal/mol) were observed to be higher than the reference antiviral drugs (AutoDock: -5.90--9.10 kcal/mol; FireDock: -35.64--59.35 kcal/mol; and HDOCK: -132.82--211.87 kcal/mol), suggesting a potent modulatory action of Parkia bioactive entities against the SARS-CoV-2. Didymin, rutin, epigallocatechin gallate, epicatechin-3-0-gallate, hyperin, ursolic acid, lupeol, stigmasta-5,24(28)-diene-3-ol, ellagic acid, apigenin, stigmasterol, and campesterol strongly bound with the multiple targets of the SARS-CoV-2 receptors, inhibiting viral entry, attachment, binding, replication, transcription, maturation, packaging and spread. Furthermore, ACE2, TMPRSS2, and MPro receptors possess significant molecular dynamic properties, including stability, compactness, flexibility and total binding energy. Residues GLU-589, and LEU-95 of ACE2, GLN-350, HIS-186, and ASP-257 of TMPRSS2, and GLU-14, MET-49, and GLN-189 of MPro receptors contributed to the formation of hydrogen bonds and binding interactions, playing vital roles in inhibiting the activity of the receptors. Promising results were achieved by developing multi-targeted antiviral Parkia bioactive entities as lead and prospective candidates under a small molecule strategy against SARS-CoV-2 pathogenesis. The antiviral activity of Parkia bioactive entities needs to be further validated by pre-clinical and clinical trials.
ABSTRACT
COVID-19 pandemic is continue with thousands of new cases every day around the world, even then different vaccines have been developed and proven efficacious against SARS-CoV-2. Several know antivirals drugs have been repurposed or tested against SARS-CoV-2 but we still don’t have an effective therapeutic strategy to control this viral infection. Moreover, in the race of finding out an efficient antiviral, excess uses of antiviral drugs developed a selective pressure on the virus that results in the high frequency of mutations and the possible emergence of antiviral drug resistance against SARS-CoV-2. Omicron is a recently emerged, highly mutated variant of SARS-CoV-2, reported for high infectivity. In the present study, we performed molecular docking analysis between available potential antiviral drugs (remdesivir, nirmatrelvir, molnupiravir, EIDD-1931, GS-441524, and favipiravir) and omicron S protein including S protein/ACE2 complex. Our results suggest high infectivity of omicron, however, the known antiviral drugs were found efficacious against omicron variant. Further, to investigate the high infectivity of omicron, we performed a docking experiment between omicron S protein and neuropilin1 (NRP1). Surprisingly, results suggest high affinities with NRP1 than ACE2. Overall, results suggest that omicron favors NRP1 binding over ACE2, the possible reason behind improved infectivity of omicron variant.