Sesquiterpenoids and Flavonoids from the Aerial Parts of Tithonia diversifolia and Their Cytotoxic Activity

Abstract

Cytotoxicity-guided fractionation of the 80% EtOH extract of Tithonia diversifolia has resulted in the isolation of twelve sesquiterpenoids (1—12), including three new ones (4, 10, 12), and three known flavonoids (13—15). The structures of the new compounds were determined by analysis of their spectroscopic data. The isolated compounds showed cytotoxic activity against HL-60 leukemia cells with IC₅₀ values ranging from 0.13 to 13.0 μM, when etoposide used as a positive control gave an IC₅₀ value of 0.43 μM. The cancer growth inhibitory property of 9, the main cytotoxic compound in T. diversifolia, was examined using a disease-oriented panel composed of 39 human cancer cell lines in the Japanese Foundation for Cancer Research.