Sesquiterpene lactones with COX-2 inhibition activity from Artemisia lavandulaefolia.

Two new sesquiterpene lactones, artelavanolides A (1) and B (2), and four known sesquiterpene lactones (3 - 6) were isolated from the leaves of Artemisia lavandulaefolia. Their structures were elucidated based on the analysis of spectroscopic data (1D, 2D-NMR and HR-ESI-MS). The absolute configuration of 1 was determined by the analysis of single-crystal X-ray diffraction data. Artelavanolide A (1) is a rare sesquiterpene lactone possessing an unusual skeleton with the linkage of Me(14)-C(1) that is probably formed through a rearrangement of the guaiane-type sesquiterpenoids. Artelavanolide B (2) is a new highly unsaturated guaianolide. Compounds 1 - 6 were tested for activities on the inhibition of COX-2 enzyme in vitro. All of compounds exhibited inhibitory activity against COX-2 with IC50 values ranging from 43.29 to 287.07 m compared with the positive control, celecoxib (IC50 = 18.10 m). Among them, 3 showed the best COX-2 inhibitory activity with an IC50 value of 43.29 m.