New Cytotoxic Sesquiterpene Lactones from the Leaves of Tithonia Diversifolia and their Apoptosis Effect Evaluation in KB Cancer Cells.

From the leaves of Tithonia diversifolia, nine sesquiterpenoids (1-9), including two new ones (tagitinin J (1) and tagitinin K (2)) were isolated and structurally determined. Their chemical structures were elucidated by extensive analyses of the HRESIMS and NMR spectral data, as well as comparison with the literature. All of the isolated compounds (except compounds 7-9) significantly exhibited cytotoxic activity against four human cancer cell lines (KB, HepG2, A549 and MCF7), with IC values ranging from 0.