Rubrisandrins A and B, lignans and related anti-HIV compounds from Schisandra rubriflora

Bioactivity-directed fractionation of an ethanolic extract of the fruits of Schisandra rubriflora led to the isolation and identification of dibenzocyclooctadiene lignans including the new lignans rubrisandrins A ( 1a + 1b) and B ( 2) and the known lignans gomisin J (3), (+/-)-gomisin M-1 (4), (+)-gomisin M-2 (5), schisanhenol (6), deoxyschisandrin, schisantherin B, schisandrin, tigloylgomisin P, gomisin O, angeloylgomisin P, and epigomisin O. Their structure and stereochemistry were determined by spectroscopic methods, including 2D-NMR techniques. Compounds 1 and 3-6 were active as anti-HIV agents. (+/-)- Gomisin M-1 (4) exhibited the most potent anti-HIV activity, with EC50 and therapeutic index (TI) values of < 0.65 mu M and > 68, respectively.