DNA-POLYMERASE AND TOPOISOMERASE-II INHIBITORS FROM PSORALEA-CORYLIFOLIA

An ethanol extract of Psoralea corylifolia caused strong DNA polymeras e inhibition in a whole cell bioassay specific for inhibitors of DNA r eplication enzymes. Bioassay-directed purification of the active compo unds led to the isolation of the new compound corylifolin (1) and the known compound bakuchiol (2) as DNA polymerase inhibitors. On the basi s of the structures of 1 and 2, resveratrol (3) was tested and found t o be active as a DNA polymerase inhibitor in this bioassay. Neobavaiso flavone (4) was isolated as a DNA polymerase inhibitor, daidzein (5) a s a DNA polymerase and topoisomerase II inhibitor, and bakuchicin (6) as a topoisomerase II inhibitor.