Miniaturized click chemistry and direct screening facilitate the discovery of triazole piperazine SARS-CoV-2 Mpro inhibitors with improved metabolic stability.

The continuous mutational nature of SARS-CoV-2 and its inter-species' similarities emphasize the urgent need to design and develop more direct-acting antiviral agents against highly infectious variants. Herein, we report on the efficient discovery of potent non-covalent non-peptide-derived Mpro inhibitors using miniaturized click chemistry and direct screening. Based on the privileged piperazine scaffold, 68 triazole-containing derivatives were assembled and screened. Notably, representative compound C1N46 (IC50 = 1.87 μM, EC50 = 6.99 μM, CC50 > 100 μM) displayed potent inhibition activity against Mpro and showed promising anti-SARS-CoV-2 properties in vitro. Additionally, C1N46 exhibited improved liver microsome stability compared to lead compound GC-14. Docking studies predicted a multi-site binding mode of the triazole-based compounds. In conclusion, our studies validate the efficacy and feasibility of click chemistry in rapidly discovering antiviral agents.