Pentacyclic triterpenoids from Freziera sp that inhibit DNA polymerase beta

In a survey of crude plant extracts for DNA polymerase beta inhibitors, a m ethyl ethyl ketone extract prepared from Freziera sp. exhibited potent inhi bition of DNA polymerase beta. Bioassay-guided fractionation of the extract , guided by an assay to detect DNA polymerase beta inhibition, resulted in the isolation of six active pentacyclic triterpenoids (1-6). These triterpe noids had IC50 values ranging from 7.5 to 16 mu M in the presence of bovine serum albumin (BSA) and 2.6-5.8 mu M in the absence of BSA, consistent wit h the possibility that these inhibitors may be of use in vivo. (C) 2000 Els evier Science Ltd. All rights reserved.