Abstract
Vlasouliolides A-D (1-4), four rare sesquiterpene lactone dimers, were isolated from Vladimiria souliei. The common structural characteristic of 1-4 is the C32 skeleton comprising two sesquiterpene lactone units linked by a C11-C13' single bond with one acetyl connected to the C-13 position of one of the two sesquiterpene lactone units. The stereochemistries of 1-4 were assigned by a combination of NOESY correlations and Cu-Κα X-ray crystallographic analyses. Compounds 1-4 strongly inhibited the production of NO in LPS-stimulated RAW 264.7 cells. Furthermore, 1 and 2 inhibited the activation of NF-κB in LPS-induced 293T cells.