Helioxanthin (ACH126447) and its analogues exhibit significant in vitro antiviral activity against hepatitis B virus (HBV, EC50=1 uM) and flavivirus. IC50 value: 1/3/2 uM (EC50, HBV/HCV/HSV-1) [1] Target: Anti-HBV; Anti flavivirus in vitro: Helioxanthin and its analogues decreased cellular RNA levels of HBV and antigen expression as well as selective inhibition of HBV replication in a cell culture model [2]. Helioxanthin analogue 8-1 exhibited anti-DHBV activity as demonstrated by quantification of viral DNA, RNA, covalently closed circular DNA and protein synthesis. Analogue 8-1 did not affect the stability of cellular macromolecules and did not have a sustained antiviral effect after drug removal. When DHBV replication was induced, virus-harbouring cells were more susceptible to the cytotoxicity of 8-1 than non-induced cells [3].