Abstract: The aim of this study was to investigate the chemical constituents of the whole plant of Euphorbia thymifolia L.and to investigated the cytotoxic activities of the isolated compounds.The constituents were isolated and purified from E.thymifolia by various column chromatography.Their structures were elucidated by NMR and HR-ESI-MS and identified as secoisolariciresinol (1),dihydrodehydrodiconiferyl alcohol (2),3-［2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-2,3-dihydro-1-benzofuran-5-yl］propyl acetate (3),3,3′-bis(3,4-dihydro-4-hydroxy-6-methoxy-2H-1-benzopyran) (4),apigenin-7-O-β-D-glucopyranside (5),butylbrevifolin carboxylate (6) and apigenin (7).Compounds 1-6 were isolated from this plant for the first time.MTT assays were performed to detect the viability of Huh7.5 and A549 cells by different concentrations of drugs (compounds 1-4 and 6).When the concentration of the drugs was 40 μMol/L,compound 6 significantly reduced the proliferation of two cells.

Key words: Euphorbia thymifolia L., chemical constituents, lignans, flavonoid