Molecular insights into the interaction of eighteen different variants of SARS-CoV-2 spike proteins with sixteen therapeutically important phytocompounds: in silico approach.

SARS-CoV-2 has mutated many times among different populations. We analyzed wild-type spike protein and 18 different variants of SARS-CoV-2 spike protein known until the beginning of 2022 (alpha, beta, B.1.429, B.1.616, B.1.620, B.1.617.3, C.1.2, delta, epsilon, eta, gamma, iota, kappa, lambda, mu, omicron, theta, and zeta) for their interaction with 16 phytocompounds and remdesivir, resulting into 425 combinations. The largest number of mutations has been reported in the omicron followed by delta variant. However, the virulence of the delta variant has been reported higher as compared to omicron. Mutations at a few locations (D215G, K417N, E484K, N501Y, D614G, and P681H) were common in most of the variants. 3 D structures of all the 18 spike proteins were created using SWISS-MODEL to test the binding affinities with caffeine theophylline, emodin, vitexin, berberine, curcumin, piperine, quercetin, artemisinin, carvacrol, capsaicin, tetrahydrocannabinol, cannabidiol, α- pinene, β- pinene and gingerol. Phytocompounds and mutant variants were prepared using AutoDock 4.2.6 software. Binding affinities of the selected phytocompounds with the different mutant spike proteins were achieved using AutoDock Vina. Out of all combinations investigated, the best binding affinities were observed with 3 variants of SAR-CoV-2 with 5 phytocompounds along with remdesivir. The range of best binding energies varied from -9.1 to -8.0 kcal/mol. Further, MD simulation was done for selected 9 phytocompound-spike mutant complexes for analyzing the stability of interactions for 100 ns. ADMET studies via ProTox-II and SwissADME displayed that phytocompounds are safe and less toxic in comparison to remdesivir.Communicated by Ramaswamy H. Sarma.