Two New Antibacterial Sesquiterpenoids from Centipeda minima

Abstract Two new guaiane‐type sesquiterpene lactones, compounds 1 and 2 , along with three known guaianolide‐ or pseudoguaianolides, were isolated from Centipeda minima (whole plant). Their structures were identified by spectroscopic and mass‐spectrometric analyses. The configuration at C(5) of the guaiane framework of 1 was rationalized by quantum‐mechanical calculations ( Table 2 ). All compounds were found to be active against eight different microbial pathogens ( Table 3 ), with MIC values in the range of 6.25–100 μg/ml.