Abstract: OBJECTIVE: Three sesquiterpene lactones 1-O-acetylbritannilactone, isoalantolactone and britannilactone were isolated from the roots of Inula helenium and the flowers of Inula japonica. The antitumor activities of the three sesquiterpenoids in the cell lines of HeLa, HEC-1, SHIN3, HOC-21 and HAC-2 were measured, and the relationship between structure and activity and the possible mechanisms were explored. METHODS: The effect of three sesquiterpene lactones on five cell lines was measured by MTT assay in vitro. The apoptosis induced by isoalantolactone was examined by flow cytometry. RESULTS:Isoalantolactone exhibited excellent anti-proliferative activities on HeLa, SHIN3 and HOC-21 and HAC-2 cell lines, while 1-O-acetylbritannilactone and britannilactone demonstrated weak anti-proliferative activities on HeLa, SHIN3, HOAC-21 and HAC-2 cell lines even at the concentration of 100 μmol/L. The apoptotic rate in isoalantolactone group with the concentration of 12.5 μmol/L was higher than that in PBS group. CONCLUSION: MTT assay indicated that anti-proliferative activities in HeLa, SHIN3, HOAC-21 and HAC-2 cell lines were closely related to structure, 1,10-seco of eudesmane sesquiterpene lactone resulted in reduced anti-proliferative activity. The anti-tumor activity of isoalantolactone was probably achieved by inducing HeLa cell apoptosis.

Key words: haplopappus gracillis, sesquiterpenes, gynecologic neoplasms, anti-proliferative activity, apoptosis