YH-53 is a potent 3CL pro inhibitor with K i values of 6.3 nM, 34.7 nM for SARS-CoV-1 3CL pro and SARS-CoV-2 3CL pro , respectively. YH-53 strongly blocks the SARS-CoV-2 replication. YH-53 is a peptidomimetic compound with a unique benzothiazolyl ketone. YH-53 has the potential for COVID-19 research In Vitro YH-53 (1-25 μM; for 24 h) efficiently reduces copies of total RNA with increased concentrations in VeroE6/TMPRSS2 cells. YH-53 (1, 5, 10, 15, 20, 25 μM; for 48 h) with 10 μM completely blocks the viral proliferation against SARS-CoV-2 were examined by a cytopathic effect (CPE) assay in Vero cells. YH-53 (10, 100 μM; for 24 h) has no cytotoxicity with a CC 50 value of >100 μM in vero cells. YH-53 (10 μM) moderately inhibits CYP1A2, CYP2D6, and CYP2C8 (26.6%, 38.0%, 66.4%, respectively). YH-53 has no inhibition on CYP2C9 and CYP3A4. YH-53 inhibits SARS-CoV 3CL pro with an IC 50 of 0.74 μM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. RT-PCRCell Line: VeroE6/TMPRSS2 cells Concentration: 1, 5, 10, 15, 20, 25 μM Incubation Time: 24 hours Result: Efficiently reduced copies of total RNA. In Vivo YH-53 (0.1 mg/kg; iv) has a T 1/2 of 2.97 hours, an AUC 0–∞ of 19.7 ng•h/mL, a V d of 3.51 L/kg in rats . YH-53 (0.5 mg/kg; oral) has a T 1/2 of 9.64 hours, an AUC 0–∞ of 3.49 ng•h/mL, a C max of 1.08 ng/mL in rats . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Rats Dosage: 0.1 mg/kg (Pharmacokinetic Analysis) Administration: IV Result: Had a T 1/2 of 2.97 hours, an AUC 0–∞ of 19.7 ng•h/mL, a V d of 3.51 L/kg. Form:Solid IC50& Target:Ki: 6.3 nM (SARS-CoV-1 3CL pro ) and 34.7 nM (SARS-CoV-2 3CL pro )