Abstract: The object of this study was to screen the anti-tumor active fraction of petroleum ether extracts from Homalocladium platycladum in vitro. MTT assay was used to study the anti-tumor efficacy of the various fractions isolated from the petroleum ether extracts against tumor cell lines PC-3 and A549.Phase contrast microscopy was used to observe the cell morphological changes after treated with the active fractions.DAPI staining method was used to determine the apoptosis of PC-3 and A549 cells induced by the active fractions.Thin layer chromatography combined with physical and chemical properties analysis was used to detect components in the active fractions,NMR analysis was used to identify the structure of monomer.Results indicated that the C_21-24,C_25-28 of the 5 separated fractions was the anti-tumor active fractions,which significantly inhibited the growth of PC-3 and A549 with dose and time-dependent manner,C_6-8 only had inhibitory effect on the proliferation of PC-3.Phase contrast microscopy observation also showed the two fractions can significantly alter the cell morphology and confirmed the reliability of the MTT results.DAPI staining results showed that C_21-24 and C_25-28  induced cell apoptosis of PC-3 and A549.TLC results showed that there have 5 components in the 3 active fractions,C₇ isolated from C_6-8 was a monomer and identified as lupeol;C_21-24 and C_25-28  was identified as steroid and triterpenoid compounds.

Key words: Homalocladium platycladum, anti-tumor activity, MTT, apoptosis, lupeol