Cyanorona-20: The first potent anti-SARS-CoV-2 agent.

Explicit hindrance and blockade of the viral RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 is considered one of the most promising and efficient approaches for developing highly potent remedies for COVID-19. However, almost all of the reported viral RdRp inhibitors (either repurposed or new antiviral drugs) lack specific selectivity against the novel coronaviral RdRp and still at a beginning phase of advancement. Herein, I discovered and introduce a new pyrazine derivative, (E)-N-(4-cyanobenzylidene)-6-fluoro-3-hydroxypyrazine-2-carboxamide (cyanorona-20), as the first potent SARS-CoV-2 RdRp inhibitor with very high selectivity (209- and 45-fold more potent than favipiravir and remdesivir, respectively). This promising selective specific anti-COVID-19 compound is also deemed to be the first distinctive derivative of favipiravir. Cyanorona-20, the unprecedented nucleoside/nucleotide analog, was designed, synthesized, characterized, computationally studied, and biologically evaluated for its anti-COVID-19 actions (through a precise in vitro anti-COVID-19 assay). The results of the biological assay displayed that cyanorona-20 surprisingly exhibited very high and largely significant anti-COVID-19 activities (anti-SARS-CoV-2 EC = 0.45 μM), and, in addition, it could be also a very promising guide and lead compound for the design and synthesis of new anti-SARS-CoV-2 and anti-COVID-19 agents through structural modifications and further computational studies. Further appraisal for the improvement of cyanorona-20 medication is a prerequisite requirement in the coming days. In a word, the ascent of the second member (cyanorona-20 "Corona Antidote") of the novel and promising class of anti-COVID-19 pyrazine derivatives would drastically make a medical uprising in the pharmacotherapeutic treatment regimens and protocols of the recently-emerged SARS-CoV-2 infection and its accompanying COVID-19.