New cytotoxic benzopyrans from the leaves of Mallotus apelta

Two new benzopyrans 6-[1′-oxo-3′(R)-hydroxy-butyl]-5, 7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (1) and 6-[1′-oxo-3′(R)-methoxy-butyl]-5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran (2) were isolated from the leaves ofMallotus apelta Muell.-Arg., (Euphorbiaceae). Their chemical structures were elucidated by spectroscopic analyses, especially by 1D- 2D-NMR and MS spectra. Compound1 was found to have strong cytotoxic effect against two human cancer cell lines as human hepatocellular carcinoma (Hep-2, IC50: 0.49 μg/mL) and rhabdosarcoma (RD, IC50: 0.54 μg/mL), while compound2 showed moderate activity against Hep-2 cell line (IC50, 4.22μg/mL), byin vitro assay.