Current targets and drug candidates for prevention and treatment of SARS-CoV-2 (COVID-19) infection

Angiotensin-converting enzyme 2 (ACE2), the host cell-binding site for SAR-CoV-2, poses two-fold drug development problems. First, the role of ACE2 itself is still a matter of investigation, and no specific drugs are available targeting ACE2. Second, as a consequence of SARS-CoV2 interaction with ACE2, there is an impairment of the renin-angiotensin system (RAS) involved in the functioning of vital organs like the heart, kidney, brain, and lungs. In developing antiviral drugs for COVID-19, ACE2, RNA-dependent RNA polymerase (RdRp), and the specific enzymes involved in the viral and cellular gene expression have been the primary targets. SARS-CoV-2 being a new virus with unusually high mortality, there has been a need to get medicines in an emergency, and the drug repurposing has been a primary strategy. Considering extensive mortality and morbidity throughout the world, we have made a maiden attempt to discover the drugs interacting with RAS and identify the lead compounds from herbal plants using molecular docking. Both host ACE2 and viral RNA-dependent RNA polymerase (RdRp) and ORF8 appear to be the primary targets for the treatment of COVID-19. While the drug repurposing of currently approved drugs seems to be one strategy for the treatment of COVID-19, purposing phytochemicals may be another essential strategy for discovering lead compounds. Using in silico molecular docking, we have identified a few phytochemicals that may provide insights into designing herbal and synthetic therapeutics to treat COVID-19.