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The 3C-like protease (3CL^pro) of severe acute respiratory syndrome associated coronavirus (SARS-CoV) is vital for SARS-CoV replication and is a promising drug target. Recombinant 3CL^pro was expressed in Pichia pastoris GS115 as a 42 kDa protein that displayed a K _m of 15 ± 2 μM with Dabcyl-KTSAVLQSGFRKME-Edans as substrate. Purified 3CL^pro was used for inhibition and kinetic assays with seven flavonoid compounds. The IC₅₀ of six flavonoid compounds were 47–381 μM. Quercetin, epigallocatechin gallate and gallocatechin gallate (GCG) displayed good inhibition toward 3CL^pro with IC₅₀ values of 73, 73 and 47 μM, respectively. GCG showed a competitive inhibition pattern with K _i value of 25 ± 1.7 μM. In molecular docking experiments, GCG displayed a binding energy of −14 kcal mol⁻¹ to the active site of 3CL^pro and the galloyl …