Eremophilane sesquiterpenes from the endophyte Microdiplodia sp. KS 75-1 and revision of the stereochemistries of phomadecalins C and D

Two new eremophilane sesquiterpenes, compounds 1 and 2, were isolated from the endophytic fungus Microdiplodia sp. KS 75-1, together with the known compounds phomadecalins C (3) and D (4). Their structures were determined by extensive 1D- and 2D-NMR and MS spectral analyses. The previously reported stereochemistry at C-8 of 3 and 4 were revised on the basis of NOEs experiments. Compounds 1 and 2 showed antimicrobial activity against Pseudomonas aeruginosa.