Current approaches for target-specific drug discovery using natural compounds against SARS-CoV-2 infection

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) recently caused a pandemic outbreak called coronavirus disease 2019 (COVID-19). This disease has initially been reported in China and also now it is expeditiously spreading around the globe directly among individuals through coughing and sneezing. Since it is a newly emerging viral disease and obviously there is a lack of anti-SARS-CoV-2 therapeutic agents, it is urgently required to develop an effective anti-SARS-CoV-2-agent.Through recent advancements in computational biology and biological assays, several natural compounds and their derivatives have been reported to confirm their target specific antiviral potential against Middle East respiratory syndrome coronavirus (MERS-CoV) or Severe Acute Respiratory Syndrome(SARS-CoV).These targets including an important host cell receptor, i.e., angiotensin-converting enzyme ACE2 and several viral proteins e.g. spike glycoprotein (S) containing S1 and S2 domains, SARS CoV Chymotrypsin-like cysteine protease (3CL^pro), papain-like cysteine protease (PL^pro), helicases and RNA-dependent RNA polymerase (RdRp). Due to physical, chemical, and some genetic similarities of SARS CoV-2 with SARS-COV and MERS-COV, repurposing various anti-SARS-COV or anti-MERS-COV natural therapeutic agents could be helpful for the development of anti-COVID-19 herbal medicine. Here we have summarized various drug targets in SARS-COV and MERS-COV using several natural products and their derivatives, which could guide researchers to design and develop a safe and cost-effective anti-SARS-COV-2 drugs.