Antimitotic activity of two macrocyclic bis(bibenzyls), isoplagiochins A and B from the Liverwort Plagiochila fruticosa

Two bis(bibenzyls), isoplagiochins A (1) and B (2) have been isolated by the guidance of inhibitory effect of tubulin polymerization from the liverwort Plagiochila fruticosa (Plagiochilaceae). Isoplagiochins A and B inhibited the polymerization of tubulin at IC₅₀ 50 and 25 μM, respectively. Furthermore structure–activity relationship based on their conformations was discussed. The presence of two aromatic rings which can be connected through two atoms bridge spacer of double bond may serve to maintain the backbone conformation.