This science is beyond me. It says (I guess) that ivermectin is promising because it has high binding energy, something I've seen elsewhere (or maybe here before?).

Along the manuscript written, the ivermectin drug has been tested as anti-SARS-CoV-2 (Caly et al., 2020) and their results showed a reduction of ∼500 times the cell culture of the virus in 48 hours. The authors also highlighted the anti-viral activity of the ivermectin against a broad range of viruses in vitro (Tay et al, 2013; Wagstaff et al, 2012). Thus, our docking calculation using this drug gives a binding energy of –8.1 kcal/mol. This finding is very promising since the second best-scored ligand also an anti-parasitic agent like the Lig8301 (selamectin) and Lig8568 (doramectin) drugs, Table 1. Moreover, the main interacting residues with the S-protein are: R403, I418, Y489 and F490. In this way, our calculations indicate that the ivermectin drug may bind in the RBD region, inhibiting the coupling of the SARS-CoV-2 S-protein with the human ACE2 receptor. Recently, Fan et al. (Fan et al., 2020) showed that the selamectin (lig8301) inhibits completely the spike protein of coronavirus GX_P2V, which shares 92.2% amino acid identity with the 2019-nCoV.

Ivermectin not mentioned by name inthe conclusion.

#Conclusions Currently, we are surviving at a global health crisis caused by the SARS-CoV-2 virus, which is responsible by the COVID-19 outbreak since the end of the 2019. To date, there is not a vaccine against COVID-19 and the social isolation is the main strategy adopted to avoid the spread of this novel coronavirus. Therefore, herein we used molecular dynamics (MD) simulation and docking calculations to study the SARS-CoV-2 S-protein with the main goal to obtain possible drugs candidates for repurposing them against to COVID-19. Our approach was study the SARS-CoV-2 S-protein before it bounded with the human angiotensin-converting enzyme 2 receptor preventing the human cell infection. Overall, the S-protein does not undergo significantly structural change along the 18 ns MD simulation equilibration in water solvent. The main change occurs in the receptor-binding domain (RBD) which was converted from “up” (angle of 54.3 degrees) to “down” (angle of 43.0 degrees) conformation. In this transition, the RBD increased surface area enhanced the possibility of interactions with the solvent and also with the possible drugs. In this way, we carried out virtual screening by docking calculations using the S-protein at 18 ns of the MD simulation as receptor and 9091 approved drugs as ligands. In these calculations, 14 traditional herbal isolate and 10 approved drugs were obtained as a potent candidates to inhibit the SARS-CoV-2 S-protein with binding affinity bellow –8.1 kcal/mol. In addition, our calculations were successful to predict the binding of the ivermectin in ACE2, which this drug was used recently with high efficiency to control viral replication in vitro. Overall, the R403, R405, Y449, L455, G496 and Y505 residues are the most interacting with ligands. MD simulations of the three ligands@complexes show that the ligands remain bounded in the RBD region along the simulation. Where the binding energies obtained from MM/MBSA calculations were –38.51 (± 1.59), –40.43 (± 1.92) and 2.67 (± 1.18) kcal/mol for Lig8522, Lig8970 and Lig6843, respectively. Finally, herein we highlight some important issues to be taken into account for repurposing known drugs for the COVID-19 outbreak.

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Molecular study.

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