Masanori Kameoka

Hepatitis B virus (HBV) is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Current therapeutic drugs for chronic HBV infection use IFN and nucleos(t)ide analogs; however, their efficacy is limited. Thus, there is an urgent need to develop new antivirals for HBV therapy. In this study, we identified a plant‐derived polyphenolic bioflavonoid, amentoflavone, as a new anti‐HBV compound. Amentoflavone treatment dose‐dependently inhibited HBV infection in HBV‐susceptible cells with HepG2‐hNTCP‐C4 and primary human hepatocyte PXB‐cells. A mode‐of‐action study showed that amentoflavone inhibits the viral entry step, but not the viral internalization and early replication processes. Attachment of HBV particles as well as HBV preS1 peptide to HepG2‐hNTCP‐C4 cells was inhibited by amentoflavone. The transporter assay revealed that amentoflavone partly inhibits uptake of sodium taurocholate cotransporting polypeptide (NTCP)–mediated bile acid. Furthermore, effect of various amentoflavone analogs on HBs and HBe production from HBV‐infected HepG2‐hNTCP‐C4 cells was examined. Robustaflavone exhibited comparable anti‐HBV activity to that of amentoflavone and an amentoflavone‐7,4', 4‴‐trimethyl ether derivative (sciadopitysin) with moderate anti‐HBV activity. Cupressuflavone or the monomeric flavonoid apigenin did not exhibit the antiviral activity. Amentoflavone and its structurally related biflavonoids may provide a potential drug scaffold in the design of a new anti‐HBV drug inhibitor targeting NTCP.