Computational Analysis Reveals Monomethylated Triazolopyrimidine as a Novel Inhibitor of SARS-CoV-2 RNA-Dependent RNA Polymerase (RdRp).

The human population is still facing appalling conditions due to several outbreaks of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) virus. The absence of specific drugs, appropriate vaccines for mutants, and knowledge of potential therapeutic agents makes this situation more difficult. Several 1, 2, 4-triazolo [1, 5-a] pyrimidine (TP)-derivative compounds were comprehensively studied for antiviral activities against RNA polymerase of HIV, HCV, and influenza viruses, and showed immense pharmacological interest. Therefore, TP-derivative compounds can be repurposed against the RNA-dependent RNA polymerase (RdRp) protein of SARS-CoV-2. In this study, a meta-analysis was performed to ensure the genomic variability and stability of the SARS-CoV-2 RdRp protein. The molecular docking of natural and synthetic TP compounds to RdRp and molecular dynamic (MD) simulations were performed to analyse the dynamic behaviour of TP compounds at the active site of the RdRp protein. TP compounds were also docked against other non-structural proteins (NSP1, NSP2, NSP3, NSP5, NSP8, NSP13, and NSP15) of SARS-CoV-2. Furthermore, the inhibition potential of TP compounds was compared with Remdesivir and Favipiravir drugs as a positive control. Additionally, TP compounds were analysed for inhibitory activity against SARS-CoV RdRp protein. This study demonstrates that TP analogues (monomethylated triazolopyrimidine and essramycin) represent potential lead molecules for designing an effective inhibitor to control viral replication. Furthermore, in vitro and in vivo studies will strengthen the use of these inhibitors as suitable drug candidates against SARS-CoV-2.

COVID-19: an In Silico Analysis on Potential Therapeutic Uses of Trikadu as Immune System Boosters.

Corona virus pandemic outbreak also known as COVID-19 has created an imbalance in this world. Scientists have adopted the use of natural or alternative medicines which are consumed mostly as dietary supplements to boost the immune system as herbal remedies. India is famous for traditional medicinal formulations which includes 'Trikadu'-a combination of three acrids, namely Zingiber officinale, Piper nigrum and Piper longum which have antioxidant properties that boost our immune system hence acting as a strong preventive measure. In this study, AutoDock 4.0 was used to study interaction between the phytocompounds of Trikadu with RNA-dependent polymerase protein and enveloped protein of the SARS-CoV-2 virus. Analysis of the results showed that coumarin, coumaperine and bisdemethoxycurcumin showed strong bonding interactions with both the proteins. We can conclude that Trikadu has the potential molecules; hence, it can be incorporated in the diet to boost the immune system as a preventive measure against the virus.

Mechanism of SARS-CoV-2 polymerase stalling by remdesivir.

Remdesivir is the only FDA-approved drug for the treatment of COVID-19 patients. The active form of remdesivir acts as a nucleoside analog and inhibits the RNA-dependent RNA polymerase (RdRp) of coronaviruses including SARS-CoV-2. Remdesivir is incorporated by the RdRp into the growing RNA product and allows for addition of three more nucleotides before RNA synthesis stalls. Here we use synthetic RNA chemistry, biochemistry and cryo-electron microscopy to establish the molecular mechanism of remdesivir-induced RdRp stalling. We show that addition of the fourth nucleotide following remdesivir incorporation into the RNA product is impaired by a barrier to further RNA translocation. This translocation barrier causes retention of the RNA 3'-nucleotide in the substrate-binding site of the RdRp and interferes with entry of the next nucleoside triphosphate, thereby stalling RdRp. In the structure of the remdesivir-stalled state, the 3'-nucleotide of the RNA product is matched and located with the template base in the active center, and this may impair proofreading by the viral 3'-exonuclease. These mechanistic insights should facilitate the quest for improved antivirals that target coronavirus replication.

Existing antiviral options against SARS-CoV-2 replication in COVID-19 patients.

COVID-19 caused by SARS-CoV-2, is an international concern. This infection requires urgent efforts to develop new antiviral compounds. To date, no specific drug in controlling this disease has been identified. Developing the new treatment is usually time consuming, therefore using the repurposing broad-spectrum antiviral drugs could be an effective strategy to respond immediately. In this review, a number of broad-spectrum antivirals with potential efficacy to inhibit the virus replication via targeting the virus spike protein (S protein), RNA-dependent RNA polymerase (RdRp), 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro) that are critical in the pathogenesis and life cycle of coronavirus, have been evaluated as possible treatment options against SARS-CoV-2 in COVID-19 patients.