Synthesis and biological evaluation of helioxanthin analogues.

Helioxanthin and analogues have been demonstrated to suppress gene expression of human hepatitis B virus. In the continuous attempt to optimize antiviral activity, various structural motifs were grafted on the helioxanthin scaffold. Many such analogues were synthesized and evaluated for their anti-hepatitis B virus activity. Structure-activity relationships of these helioxanthin derivatives are also discussed. Among these new compounds, 15 exhibits the highest activity against HBV (EC50=0.06 μM). This compound can suppress viral surface antigen and DNA expression. Furthermore, viral RNA is also diminished while the core promoter is deactivated upon treatment by 15. A plausible working mechanism is postulated. Our results establish helioxanthin lignans as potent anti-HBV agents with unique mode of action. Since their antiviral mechanism is distinct from current nucleoside/nucleotide drugs, helioxanthin lignans constitute a potentially new class of anti-HBV agents for combination therapy.