The recent outbreak of coronavirus disease 2019 COVID 19 caused by SARS CoV 2 in December 2019 raised global health concerns. The viral 3 chymotrypsin like cysteine protease 3CL pro enzyme controls coronavirus replication and is essential for its life cycle. 3CL pro is a proven drug discovery target in the case of severe acute respiratory syndrome coronavirus SARS CoV and middle east respiratory syndrome coronavirus MERS CoV . ...