A Series of Adenosine Analogs as the First Efficacious Anti-SARS-CoV-2 Drugs against the B.1.1.529.4 Lineage: A Preclinical Repurposing Research Study

RNA: The most attractive target in recent viral diseases

As an expert in the field of drug design and discovery, I tried, in this up-to-date perspective or commentary article, to recap and shed light on the previous and latest revolutionary strategies employed in medicinal and therapeutic chemistry to target the principal viral weapon used by virulent RNA viruses (e.g., the severe acute respiratory syndrome coronavirus 2 "SARS-CoV-2") to infect humans and spread infections, the genomic RNA strands. These strategies act by taking advantage of the weakness points of this attractive bioweapon to disable or attack it (itself), accordingly stop the entire viral reproduction, and effectively end the severe microbial infections such as the coronavirus disease 2019 (COVID-19). The generation of respective slightly falsely-weaved RNA strands, either endogenously or exogenously, is the principal key for designing most of these therapeutic approaches.

Current understanding of nucleoside analogs inhibiting the SARS-CoV-2 RNA-dependent RNA polymerase

Since the outbreak of the COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA-dependent RNA polymerase (RdRp) has become a main target for antiviral therapeutics due to its essential role in viral replication and transcription. Thus, nucleoside analogs structurally resemble the natural RdRp substrate and hold great potential as inhibitors. Until now, extensive experimental investigations have been performed to explore nucleoside analogs to inhibit the RdRp, and concerted efforts have been made to elucidate the underlying molecular mechanisms further. This review begins by discussing the nucleoside analogs that have demonstrated inhibition in the experiments. Second, we examine the current understanding of the molecular mechanisms underlying the action of nucleoside analogs on the SARS-CoV-2 RdRp. Recent findings in structural biology and computational research are presented through the classification of inhibitory mechanisms. This review summarizes previous experimental findings and mechanistic investigations of nucleoside analogs inhibiting SARS-CoV-2 RdRp. It would guide the rational design of antiviral medications and research into viral transcriptional mechanisms.