The inhibitory strength against viral enzyme was expressed as IC50, which is the concentration of the inhibitor needed to inhibit half of the enzyme activity in the tested condition. The K i value is reflective of ligand‐binding affinity to the enzyme. The inhibitory activity for cell‐based bioassays is expressed as EC50, which is a half maximal effective concentration required to induce the biological response. The warhead group means a “reactive group” of the inhibitors that can form both covalent and noncovalent interactions with amino acids in the active site of the enzyme.