A new cytotoxic compound from the leaves of Styrax annamensis Guillaumin.

New propene derivative 1-(3',4'-methylenedioxyphenyl)-2-(2''-hydroxy-5-(3'''-hydroxypropyl)-3''-methoxyphenyl)prop-2-en-1-one (1), along with three known triterpenoids ursolic acid (2), pomolic acid (3), and maslinic acid (4) were isolated from the leaves of Styrax annamensis species. All structures were assigned by spectroscopic analysis. Compound 1 showed potent cytotoxicity against four cancer cell lines (KB, HepG2, Lu, and MCF7) with the IC50 values of 3.19, 2.87, 2.33, and 2.44 µM, respectively.