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 M1 (4), (+)-gomisin M2 (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 M1 (4) exhibited the most potent anti-HIV activity, with EC50 and therapeutic index (TI) values of <0.65 μM and >68, respectively.