Studies on the Cytotoxicity of Miscellaneous Compounds from Eupatorium betonicaeforme (D.C.) Baker (Asteraceae)

A detailed study on the cytotoxic effects of five known constituents isolated from the flowers and roots of Eupatorium betonicaeforme is reported, including 2,2‐dimethyl‐6‐vinylchroman‐4‐one (1), 2‐senecioyl‐4‐vinylphenol (2), 6‐acetyl‐2,2‐dimethylchroman‐4‐one (3), (4E)‐8β‐angeloyloxy‐9β,10β‐dihydroxy‐1‐oxogermacra‐4,11(13)‐dien‐12,6α‐olide (4), and 3β‐hydroxyicosan‐1,5β‐olide (5). The sesquiterpene lactone 4 exhibited the highest cytotoxicity, with IC50 values ranging from 3.9 to 9.9 μM, showing some degree of cell selectivity. The antiproliferative activity of 4 was examined towards HL‐60 cells, and found to diminish cell viability in a dose‐dependent manner. Moreover, at all concentrations tested, there was a decrease in the number of cells capable of incorporating 5‐bromo‐2′‐deoxyuridine (BrdU), indicating disruption of DNA synthesis. The morphological changes induced by 4 were compatible with apoptotic cell death. This work, thus, corroborates the anticancer potential of Eupatorium secondary metabolites.