3CL proteinase inhibitor(Boji Medical)

Given the high pathogenicity and rapid mutation rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is imperative to sustain efforts in drug research and development. Herein, we present the design, synthesis, and evaluation of peptidomimetic spiropyrrolidine derivatives as potent 3CL^pro inhibitors against SARS-CoV-2. Among the synthesized derivatives, several compounds exhibited high potency in inhibiting 3CL^pro, with IC₅₀ values ranging from 21 nM to 53 nM. Notably, compounds 9b and 9h displayed improved enzymatic inhibition (IC₅₀ = 25 nM and 21 nM, respectively) compared to nirmatrelvir (47 nM). Compound 9b showed enhanced stability in human and mouse liver microsomes compared to nirmatrelvir, whereas 9h exhibited similar stability to nirmatrelvir in both species. Furthermore, compound 9h displayed exceptional potency in cellular assays targeting the SARS-CoV-2 replicon within Huh7 cells, with a single-digit nanomolar activity that is 5.6 times better than that of nirmatrelvir. In a pharmacokinetic study in mice (PO, 20 mg/kg), compound 9h exhibited a prolonged plasma half-life (T_1/2 = 2.58 h) compared to nirmatrelvir (T_1/2 = 0.51 h) and demonstrated an AUC_(0-t) value (1106 h∗ng/mL) equivalent to that of nirmatrelvir (1023 h∗ng/mL). These findings indicate that compound 9h is a promising lead for developing a novel 3CL^pro inhibitor against SARS-CoV-2.

The COVID-19 pandemic, exacerbated by persistent viral mutations, underscored the urgent need for diverse inhibitors targeting multiple viral proteins. In this study, we utilized covalent DNA-encoded libraries to discover innovative triazine-based covalent inhibitors for the 3-chymotrypsin-like protease (3CL^pro, Nsp5) and the papain-like protease (PL^pro) domains of Nsp3, as well as novel non-nucleoside covalent inhibitors for the nonstructural protein 12 (Nsp12, RdRp). Optimization through molecular docking and medicinal chemistry led to the development of LU9, a nonpeptide 3CL^pro inhibitor with an IC₅₀ of 0.34 μM, and LU10, whose crystal structure showed a distinct binding mode within the 3CL^pro active site. The X-ray cocrystal structure of SARS-CoV-2 PL^pro in complex with XD5 uncovered a previously unexplored binding site adjacent to the catalytic pocket. Additionally, a non-nucleoside covalent Nsp12 inhibitor XJ5 achieved a potency of 0.12 μM following comprehensive structure-activity relationship analysis and optimization. Molecular dynamics revealed a potential binding mode. These compounds offer valuable chemical probes for target validation and represent promising candidates for the development of SARS-CoV-2 antiviral therapies.