Triterpenoid constituents isolated from the bark of Abies sachalinensis.

Three new lanostane-type triterpenoids (1-3) were isolated from the bark of Abies sachalinensis along with a known compound (4). The structures of 1-4 were characterized by spectroscopic methods including NMR and MS. Compound 4 and some derivatives were tested for inhibitory effects on in vitro DNA topoisomerases I and II and found to be selective catalytic inhibitors of topoisomerase II activity with IC(50) values in the range 43-76 microM.