bis-5-Alkylresorcinols from Panopsis rubescens that inhibit DNA polymerase beta

Bioassay-guided fractionation of Panopsis rubescens, using an assay to detect DNA polymerase beta inhibition, led to the isolation of two new bis-5-alkylresorcinols (1 and 2), in addition to one known bis-5-alkylresorcinol (3). The structures of 1-3 were established as 1,3-dihydroxy-5-[14'-(3' ',5' '-dihydroxyphenyl)-cis-4'-tetradecenyl]benzene (1), 1, 3-dihydroxy-5-[14'-(3' ',5' '-dihydroxyphenyl)-cis-7'-tetradecenyl]benzene (2), and 1, 3-dihydroxy-5-[14'-(3' ',5' '-dihydroxyphenyl)tetradecenyl]benzene (3), respectively, by spectroscopic and chemical analyses. Compounds 1-3 exhibited potent inhibition of calf thymus DNA polymerase beta, with IC50 values of 7.5, 6.5, and 5.8 microM, respectively.