Background: The ongoing COVID-19 pandemic has created an alarming situation due to extensive loss of human lives and economy, posing enormous threat to global health security . Till date, no antiviral drug or vaccine against SARS-CoV-2 has reached the market, although a number of clinical trials are under way . The viral 3-chymotrypsin-like cysteine protease (3CL pro), playing pivotal roles in coronavirus replication and polyprotein processing, is essential for its life cycle . In fact, 3CL pro is already a proven drug discovery target for SARS- and MERS-CoVs . This underlines the importance of 3CL protease in the design of potent drugs against COVID-19 .
Methods: We have collected one hundred twenty-seven relevant literatures to prepare the review article . PubMed, Google Scholar and other scientific search engines were used to collect the literature based on keywords, like``SARS-CoVs-3CL protease ,"`` medicinal plant and anti-SARS-CoVs-3CL protease"published during 2003-2020 . However, earlier publications related to this topic are also cited for necessary illustration and discussion . Repetitive articles and non-English studies were excluded .
Results: From the literature search, we have enlisted medicinal plants reported to inhibit coronavirus 3CL protease . Some of the plants like Isatis tinctoria L. (syn . Isatis indigotica Fort .), Torreya nucifera (L.) Siebold and Zucc., Psoralea corylifolia L., and Rheum palmatum L. have exhibited strong anti-3CL pro activity . We have also discussed about the phytochemicals with encouraging antiviral activity, such as, bavachinin, psoralidin, betulinic acid, curcumin and hinokinin, isolated from traditional medicinal plants . Conclusion: Currently, searching for a plant-derived novel drug with better therapeutic index is highly desirable due to lack of specific treatment for SARS-CoV-2 . It is expected that in-depth evaluation of medicinally important plants would reveal new molecules with significant potential to inhibit coronavirus 3CL protease for development into approved antiviral drug against COVID-19 in future.
Index: 3-chymotrypsin-like cysteine protease, SARS-CoV-2, coronavirus disease 2019, main protease, plant products, plant-derived 3CLpro inhibitors