Discovery of berberine based derivatives as anti-influenza agent through blocking of neuraminidase.

In this study, we investigated the antiviral activity of newly synthesized berberine derivatives (BD) against influenza virus infection using several strains in in vitro and in silico. The CPE reduction, pre-incubation, NA activity inhibition and molecular docking assays were used for antiviral evaluation. The anti-influenza activities of BDs were stronger than plant-derived pure commercial berberine, and some of the BDs were more potent than control drug Oseltamivir. The cytotoxicity level was observed in the range 63.16-1639µg/mL for synthesized BDs. Additionally, BDs were detected as able to block influenza viral particles. We targeted neuraminidase one of the influenza surface protein for further probing. Moreover, BDs registered competitive NA inhibition activity comparing with Oseltamivir. The active site of viral NA subunit was fully blocked by BD as the same location as Oseltamivir. The binding energies between influenza NA subunit and BD-5 were higher than Oseltamivir. More H-bonds and NA residues were occupied by BD for stronger binding ability than Oseltamivir. These results indicated that BD inhibits various strains of influenza virus by blocking of viral NA subunit.