Flavone eupatorin is one of the constituents of Orthosiphon stamineus, a medicinal herb used in
folk medicine in South East Asia for treatment of various disorders. In our study, we investigated the antiproliferative properties of a
chloroform extract of the leaves of O. stamineus and of pure
eupatorin. The compound was able to reduce the number of viable
cancer cells to the same extent as the extract, with IC(50) values in micromolar range. Moreover, both the
eupatorin standard and the extract caused cells to arrest in the G2/M phase of the cell cycle. This clearly demonstrates that
eupatorin contributes significantly to the overall extract activity. Induction of mitotic catastrophe, accompanied by key molecular events defining apoptosis, is the mechanism of
eupatorin-induced cell death. Importantly,
eupatorin (at the doses cytotoxic to
cancer cells) did not kill normal cells; it only limited migration of HUVEC endothelial cells and their ability to create tubes. The ability of
eupatorin to nonspecifically inhibit many
protein kinases was proven and is the probable cause of its cellular effects. In summary,
eupatorin emerges as a promising agent in anticancer research.