Synthesis and biological evaluation of dihydrofuran-fused perhydrophenanthrenes as a new anti-influenza agent having novel structural characteristic.

Dihydrofuran-fused perhydrophenanthrenes were synthesized by means of o-quinodimethane chemistry with high generality and stereoselectivity, and found to exhibit potent anti-influenza activity. These compounds exerted an inhibitory effect on various strains of influenza virus growth, including influenza A and B, with a concentration dependent manner, and direct cytotoxicity was low. Several biological experiments suggested that these new drugs affected a virus replication process before mRNA synthesis stage. Novel rigid cage-type of structural characteristic of the compounds has not been found in hitherto anti-influenza drugs, and will provide new basis and motif for exploring promising and unprecedented anti-influenza agents.