Discovery of imidazo[1,2-a]pyridine derivatives as potent anti-influenza agents: SPR affinity-based screening and...

Novel imidazo[1,2-a]pyridine derivatives were designed as influenza A virus RNA-dependent RNA polymerase (RdRp) inhibitors via scaffold hybridization strategy. Forty-five synthesized compounds were screened by surface plasmon resonance (SPR) and bioactivity assays, which identified three compounds exhibiting potent antiviral activity against A/PR/8/34(H1N1) and strong binding to the target: 14 (IC₅₀ = 3.00 μM; K_D = 1.79 μM), 19 (IC₅₀ = 0.95 μM; K_D = 0.82 μM), and 41 (IC₅₀ = 0.29 μM; K_D = 4.11 μM). Moreover, compound 41 revealed significant broad-spectrum effects on multiple influenza virus strains. Structure-activity relationship (SAR) analysis identified key structural features on the imidazo[1,2-a]pyridine-3-carboxamide scaffold-including specific substitution patterns, linker types, and beneficial positions-that significantly enhanced inhibitory potency, providing a clear rationale for the development of potent influenza virus PA-PB1 inhibitors. Surface plasmon resonance analysis confirmed enhanced binding to the PA_C domain, while molecular docking studies identified key interactions with LYS643 and GLN408 in PA_C protein. Further molecular dynamics simulations and dynamic cross-correlation matrix analysis demonstrated stable binding modes and correlated motions within the PA_C domain. In summary, compound 41 was identified as a promising sub-micromolar RdRp inhibitor targeting the PA_C-PB1_N interface. This study also showcases the applicability of SPR-affinity based screening approach in anti-influenza drug discovery.