Discovering potent inhibitors against the Mpro of the SARS-CoV-2. A Medicinal Chemistry approach. (preprint)

The global pandemic caused by a single-stranded RNA (ssRNA) virus known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still at its peak, with new cases being reported daily. Though the vaccinations are done on a massive scale, the frequent mutations in the viral gene and resilience of the future strains could be more problematic. Therefore, there is always a need for new compounds to be available for therapeutic studies. We carried out the present research to discover potential drug compounds against the SARS-CoV-2 main protease. A total of 16,000 drug-like small molecules from the ChemBridge database were virtually screened to obtain the top hits. As a result, 1032 hits were selected based on their docking scores. Next, these structures were prepared for molecular docking, and each small molecule was docked into the active site of the Mpro. Only those compounds with strong interactions with the active site residues and had the highest docking score were subjected to molecular dynamics (MD) simulation. The post-simulation analyses were carried out using the in-built GROMACS commands to gauge the stability, flexibility, and compactness. Principal component analysis (PCA) and hydrogen bonding were also calculated to observe trends and affinity of the drugs towards the target. Among the five top compounds, C1, C3, and C4 revealed strong interaction with the target’s active site and remained highly stable throughout the simulation. We believe the predicted compounds in this study could be potential inhibitors in the natural system and must be considered for further practice.

In Silico Mutagenesis Based Remodeling of SARs-CoV-1 Peptide (ATLQAIAS) to Inhibit SARs-CoV-2: Structural-dynamics and Free Energy Calculations (preprint)

Background:The prolific spread of COVID-19 caused by a novel coronavirus (SARS-CoV-2) from its epicenter in Wuhan, China, to every nook and cranny of the world after December 2019, jeopardize the prevailing health system in the world and has raised serious concerns about human safety. To date efforts are continuing to design small molecule inhibitor, vaccines and many other therapeutic options are practiced but their final therapeutic potential is still to be tested. Using the old drug or vaccine or peptides could aid this process to avoid such long experimental procedure. Results:Hence, here we have repurposed a small peptide (ATLQAIAS) from the previous study which reported the inhibitory effects of this peptide. We used in silico mutagenesis approach to design more peptides from the native wild peptide, which revealed that substitutions (T2W, T2Y, L3R and A5W) could increase the binding affinity of the peptide towards the 3CLpro. Furthermore, using MD simulation and free energy calculation confirmed its dynamics stability and stronger binding affinities. Per-residues energy decomposition analysis revealed that the specified substitution significantly increased the binding affinity at residue level. Conclusion:Our wide-ranging analyses of binding affinities disclosed that our designed peptide owns the potential to hinder the SARS-CoV-2 and will reduce the progression of SARs-CoV-2-borne pneumonia. Our analysis strongly suggests the experimental and clinical validation of these peptides to curtail the recent corona outbreak.

Decoding the structure of RNA-dependent RNA-polymerase (RdRp), understanding the ancestral relationship and dispersion pattern of 2019 Wuhan Coronavirus (preprint)

Most recently, an outbreak of severe pneumonia caused by the infection of 2019-nCoV, a novel coronavirus first identified in Wuhan, China, imposes serious threats to public health. Upon infecting host cells, coronaviruses assemble a multi-subunit RNA-synthesis complex of viral non-structural proteins (nsp) responsible for the replication and transcription of the viral genome. Therefore, the role and inhibition of nsp12 are indispensable. Since there is no crystallographic structure of RdRp is available, so, here, we present the 3-dimensional structure of the 2019-nCoV nsp12 polymerase using a computational approach. nsp12 of 2019-nCoV possesses an architecture common to all viral polymerases as well as a large N-terminal extension. This structure illuminates the assembly of the coronavirus core RNA-synthesis machinery, provides key insights into nsp12 polymerase catalysis and fidelity, and acts as a template for the design of novel antiviral therapeutics. Besides, the experimental structure could reveal the organization in a more sophisticated way. Furthermore, the ancestral state reconstruction suggests the possible evolution of nCoV in Wuhan China and its dispersal to the USA. The result of our analyses postulates the possible dispersal of nCoV from the USA and Shenzhen back to Wuhan. This disclosing of valuable knowledge regarding the 3D structure of 2019-nCoV nsp12 architecture, ancestral relation, and dispersion pattern could help to design effective therapeutic candidates against the coronaviruses and design robust preventive measurements.