Optimization and biological evaluation of l-DOPA derivatives as potent influenza PA N endonuclease inhibitors with multi-site binding characteristics

Emerging and potential influenza pandemics still are an enormous worldwide public health challenge. The PA endonuclease has been proved to be a promising target for anti-influenza drug design. Here, we report the discovery and optimization of potent Y-shaped PA inhibitors featuring multi-site binding characteristics with l-DOPA as a starting point. We systematically modified the hit 1 bearing two-binding characteristics based on structure-based rational design combined with multisite binding and conformational constraint strategies, generating four families of l-DOPA derivatives for SARs analysis. Among these substances, N, 3-di-substituted 1, 2, 3, 4-tetrahydroisoquinoline derivative T-31 displayed superior properties as a lead PA endonuclease inhibitor and antiviral agent. The lead T-31 inhibited PA endonuclease activity with an IC value of 0.15 μM and showed broad and submicromolar anti-influenza potency in cell-based assays. More importantly, T-31 could simultaneously target both influenza HA and the RdRp complex, thus interfering with virus entry into host cells and viral replication. This study offers a set of novel PA endonuclease inhibitors with multi-site binding characteristics starting from the l-DOPA skeleton.