Cytotoxic sesquiterpene lactones from the aerial parts of Inula aucheriana.

Inula aucheriana DC is a member of the family Asteraceae which is known to produce cytotoxic secondary metabolites noted as sesquiterpene lactones. In the present study, sesquiterpene lactones inuchinenolide B, 6-deoxychamissonolide (stevin) and 14-acetoxy-1β,5α,7αH-4β-hydroxy-guai-9(10),11(13)-dien-12,8αolide were isolated from I. aucheriana. Inuchinenolide B and 14-acetoxy-1β,5α,7αH-4β-hydroxy-guai9(10),11(13)-dien-12,8α-olide were further evaluated by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide) assay to demonstrate cytotoxic activity with IC50 values of (56.6, 19.0), (39.0, 11.8), and (55.7, 15.3) μg/mL against HepG-2, MCF-7 and A-549 cells, respectively. The cytotoxic activity of the two evaluated sesquiterpene lactones partly explains the cytotoxic activity that was previously observed for the extracts of Inula aucheriana. The isolated compounds could be further investigated in cancer research studies.