SARS CoV-2 Delta Variant Spike Protein: Structure, Mechanism, and Docking Interaction with Antiviral Ligands from the Plants of the Phyllanthus Genus

An abrupt outbreak of “Severe Acute Respiratory Syndrome Coronavirus 2” was first identified in Wuhan City, Hubei Province, China, in December 2019, which was later disseminated globally. Individuals afflicted with this highly transmissible virus contribute to a significant public health crisis. The lack of specific vaccinations and antiviral medications for nCoV-2019, together with the emergence of mutations in the genome of the virus, necessitates a multifaceted approach to drug design and discovery for COVID-19. A comprehensive worldwide supervision plan is essential for the accurate forecast and prevention of viral infections. The SARS-CoV-2 spike (S) protein plays a crucial role in viral binding, fusion, and entrance, hence influencing the generation and evolution of antibodies and vaccines. The receptor binding domain (RBD) of the SARS-CoV-2 spike protein exhibits a significant affinity for human angiotensin-converting enzyme 2 (ACE2) receptors. It encompasses diverse mutations in the N-terminal domain (NTD) and the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, enhancing immunological efficacy. The B.1.617.2 mutant, also known as the Delta variation, is expected to spread more rapidly than earlier versions. Thus, in this study, we have evaluated the structural characteristics of the SARS-CoV-2 spike protein and the human ACE2 protein and their interactions and examined putative SPIKE-ACE2 protein-protein inhibitors derived from the phytocompounds of Phyllanthus species. This is the crucial aspect for the advancement of economical clinical trials of individual plant components for the treatment of viral diseases.