Abstract: BACKGROUND AND AIM: In order to investigate the anti_proliferative activity against HeLa cell line and to explore the possible mechanism of three natural compounds: 7_hydroxy_ 2_octen_5_olide (1), methyl 5,7_dihydroxy_2 (Z)_octenoate (2) and 3,7_dihydroxy_5_octanolide (3) isolated from leaves of Euscaphis japoneca Kantiz. MATERIALS AND METHODS: The anti_proliferative effects of the three compounds on HeLa cells were tested by MTT assay in vitro. The apoptosis induced by above three compounds was studied by FCM. The morphological changes of HeLa cells were examined by transmission electron microscope. RESULTS: Compounds 1 and 2 exhibited dose_dependent anti_proliferative activity on cultured HeLa cells. The concentrations of compounds 1 and 2 resulting in 50％ survival rates (IC50) for HeLa cells were 49.34 μmol/L and 24.53 μmol/L, respectively. Comparing with the control group, the apoptosis rate and the expression of P53 in HeLa cells were markedly higher for compound 1 group (P<0.01). The morphological changes of HeLa cells incubated with compound 1 showed chromatin condensation, marginal and nuclear fragmentation. CONCLUSION: 7_Hydroxy_2_octen_5_olide and methyl 5, 7_dihydroxy_2 (Z)_octenoate isolated from the leaves of Euscaphis japoneca Kanitz could inhibit the proliferation of HeLa cells in vitro. Its anti_prolifrative activity might be associated with upregulating the expression of P53 and inducing the occurrence of apoptosis.

Key words: euscaphis japoneca kanitz, esters compounds, anti_proliferative activity, apoptosis, P53