2 PIMARANE DITERPENOIDS FROM EPHEMERANTHA-LONCHOPHYLLA AND THEIR EVALUATION AS MODULATORS OF THE MULTIDRUG-RESISTANCE PHENOTYPE

Two new pimarane diterpenoids, lonchophylloids A(1) and B (2), were is olated from the stems of Ephemerantha lonchophylla. The structures of 1 and 2 were established predominantly through the application of exte nsive H-1-and C-13-NMR, 1D-and 2D-homonuclear and heteronuclear correl ation NMR experiments, and X-ray diffraction methods. Consistent with structure-activity predictions, both compounds were capable of sensiti zing cells that expressed the multidrug resistance phenotype to the to xicity of the anticancer drug doxorubicin.