New Friedelane Triterpenoids with Antimicrobial Activity from the Stems of Drypetes paxii

Two new friedelane-type triterpenes named 12α-hydroxyfriedelane-3,15-dione and 3β-hydroxyfriedelan-25-al, together with six known compounds were isolated from the stems of Drypetes paxii HUTCH. (Euphorbiaceae). Their structures were established on the basis of conventional 1 dimensional (1D) NMR methods, 2D shift-correlated NMR experiments and mass spectra. The five friedelane-type triterpene derivatives and one olean-12-ene triterpene saponin were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria, and they appeared to be modestly active.