The global minimum structure of 2a for isoplagiochin B obtained from MC conformational search gave the good agreement with that expected from the NOE relationship, whereas for dihydroisoplagiochin B , it was suggested that 4a and 4b have exchangeable mobility in solution. The presence of two aromatic rings which can be connected through the double bond may serve to maintain the backbone conformation. Efforts are currently underway to determine the precise backbone conformation and
its relationship to biological activity of a series of bis(bibenzyls), such as Marchantins as antimitotic agents.