In silico-guided design, synthesis and in vitro evaluation of thiazolo-pyridines targeting SARS-CoV-2 Nsp13

In the search for novel antiviral agents targeting SARS-CoV-2 non-structural protein 13 (Nsp13), we applied an integrated in silico drug design workflow combining ADME profiling, molecular interaction field analysis, molecular docking and thermodynamic evaluations to identify thiazolo-pyridine derivatives as promising scaffolds. This computational strategy enabled the rational prioritization of compounds and guided the design and synthesis of a novel series of [1,3]thiazolo[5,4-b]pyridine-6-carboxamides (19 and 20) and [1,3]thiazolo[5,4-h][1,6]naphthyridines (21 and 22). Among the synthesized compounds, 19h and 19n emerged as the most potent candidates, demonstrating dual inhibitory activity with IC₅₀ values for unwinding and ATPase activities in the low micromolar range. Kinetic analyses confirmed a competitive inhibition mechanism, as these compounds successfully compete with the natural substrate ATP for the enzyme's active site. Overall, our findings highlight the effectiveness of integrated computational approaches for accelerating antiviral lead optimization and establish the thiazolo-pyridine core as viable chemotype for further Structure-Activity Relationship (SAR) studies and preclinical development.