Since its first report in December 2019 from China the COVID-19 pandemic caused by the beta-coronavirus SARS-CoV-2 has spread at an alarming pace infecting about 26 lakh, and claiming the lives of more than 1.8 lakh individuals across the globe. Although social quarantine measures have succeeded in containing the spread of the virus to some extent, the lack of a clinically approved vaccine or drug remains the biggest bottleneck in combating the pandemic. Drug repurposing can expedite the process of drug development by identifying known drugs which are effective against SARS-CoV-2. The SARS-CoV-2 main protease is a promising drug target due to its indispensable role in viral multiplication inside the host. In the present study an E-pharmacophore hypothesis was generated using the crystal structure of the viral protease in complex with an imidazole carbaximide inhibitor as the drug target. Drugs available in the superDRUG2 database were used to identify candidate drugs for repurposing. The hits were further screened using a structure based approach involving molecular docking at different precisions. The most promising drugs were subjected to binding free energy estimation using MM-GBSA. Among the 4600 drugs screened 17 drugs were identified as candidate inhibitors of the viral protease based on the glide scores obtained from molecular docking. Binding free energy calculation showed that six drugs viz, Binifibrate, Macimorelin acetate, Bamifylline, Rilmazafon, Afatinib and Ezetimibe can act as potential inhibitors of the viral protease.

<p>The total cases of novel corona virus (SARS-CoV-2) infections is more than one million and total deaths recorded is more than fifty thousand. The research for developing vaccines and drugs against SARS-CoV-2 is going on in different parts of the world. Aim of the present study was to identify potential drug candidates against SARS-CoV-2 from existing drugs using <i>in silico</i> molecular modeling and docking. The targets for the present study was the spike protein and the main protease of SARS-CoV-2. The study was able to identify some drugs that can either bind to the spike protein receptor binding domain or the main protease of SARS-CoV-2. These include some of the antiviral drugs. These drugs might have the potential to inhibit the infection and viral replication.</p>

Since its first report in December 2019 from China the COVID-19 pandemic caused by the beta-coronavirus SARS-CoV-2 has spread at an alarming pace infecting about 26 lakh, and claiming the lives of more than 1.8 lakh individuals across the globe. Although social quarantine measures have succeeded in containing the spread of the virus to some extent, the lack of a clinically approved vaccine or drug remains the biggest bottleneck in combating the pandemic. Drug repurposing can expedite the process of drug development by identifying known drugs which are effective against SARS-CoV-2. The SARS-CoV-2 main protease is a promising drug target due to its indispensable role in viral multiplication inside the host. In the present study an E-pharmacophore hypothesis was generated using the crystal structure of the viral protease in complex with an imidazole carbaximide inhibitor as the drug target. Drugs available in the superDRUG2 database were used to identify candidate drugs for repurposing. The hits were further screened using a structure based approach involving molecular docking at different precisions. The most promising drugs were subjected to binding free energy estimation using MM-GBSA. Among the 4600 drugs screened 17 drugs were identified as candidate inhibitors of the viral protease based on the glide scores obtained from molecular docking. Binding free energy calculation showed that six drugs viz, Binifibrate, Macimorelin acetate, Bamifylline, Rilmazafon, Afatinib and Ezetimibe can act as potential inhibitors of the viral protease.

The world has come to a sudden halt due to the incessant spread of a viral pneumonia dubbed COVID-19 caused by the beta-coronavirus, SARS-CoV-2. The pandemic spread of the virus has already claimed lakhs of valuable lives and has infected millions of people across the globe. The situation is further worsened by the fact that there is no approved therapeutics currently available for the treatment of the disease. The only way to handle the crisis is the rapid development of a therapeutic strategy to combat the virus. Computational biology offers resources to rapidly identify novel drug leads and to repurpose existing drugs at the expense of minimal resources and time. The main protease of SARS-CoV-2 is key to the replication and propogation of the virus in the host cells. Inhibiting the protease blocks replication and hence is an attractive therapeutic target in the virus. The crystal structures of the protein in complex with inhibitors are available in public databases. Here we describe the screening of the DrugBank database, a public repository for small molecule therapeutics, to identify approved or experimental phase drugs that can be repurposed against the main protease of SARS-CoV2. The initial screening was performed on more than 13,000 drug entries in the target database using an energy optimised pharmacophore hypothesis AARRR. A sub-set of the molecules selected based on the fitness score was further screened using molecular docking by sequentially filtering the molecules through the high throughput virtual screening, extra precision and standard precision docking modalities. The most promising hits were subjected to binding free energy estimation using the MMGBSA method. Approved drugs viz, Cobicistat, Larotrectinib and Simeprevir were identified as potential candidates for repurposing. Drugs in the discovery phase identified as inhibitors include the known cysteine protease inhibitors, Calpain inhibitor IV and an experimental cathepsin F inhibitor.