Discovery of natural products as influenza neuraminidase inhibitors: in silico screening, in vitro validation, and molecular dynamic simulation studies

Influenza is a highly contagious respiratory illness that imposes a significant global burden. Antiviral neuraminidase inhibitors (NAIs) such as oseltamivir (OC) have been proven essential, but the emergence of resistant viral strains necessitates the development of novel therapies. This study explored the potential of natural products as alternative NAIs. We used virtual screening against the Chinese Ethnic Characteristic Drug Database, followed by Quantum Mechanics/Molecular Mechanics Generalized Born Surface Area (QM/MM-GBSA) rescoring with ligands treated as QM region. Compounds preserved from docking-based virtual screening were reranked based on QM/MM-GBSA scores, and the top 15 compounds with binding free energy lower than that of native inhibitor OC were selected for NA inhibitory assay. Among the tested compounds, compounds T6S0444 (Salvianolic acid A) demonstrated significant inhibitory activity against both wild-type and H274Y-mutated influenza NAs, suggesting their potential as novel anti-influenza agents. Specifically, compound T6S0444 exhibited greater inhibitory activity against N2-H274Y than the wild-type N2, with IC50 values of 5.3 +/- 0.4 mu M and 12.8 +/- 1.2 mu M, respectively. This distinctive selectivity for mutant viral strains is not observed in current antiviral drugs for influenza. Furthermore, these compounds demonstrated low cytotoxicity, indicating their potential as safe anti-influenza agents. In summary, we have identified a promise NA inhibitor, T6S0444, a potential therapeutic for the treatment of oseltamivir-resistant influenza.