Abstract: To evaluate the antitumor efficacy of the methanol extracts from the tunic and viscera of Styela plicata, the inhibitory effect on proliferation of lung cancer A549 cells was measured by methyl thiazolyl tetrazolium assay and the effect on cell morphology and apoptosis was examined using an inverted microscope, a fluorescence-activated cell sorter and a fluorescence microscope. Besides, the chemical composition of potent antitumor fractions was analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the methanol extracts from the tunic and viscera of Styela plicata could inhibit the growth of human lung cancer A549 cells at a concentration equal to or greater than 100 μg/mL but not at lower concentrations (25–75 μg/mL). In vitro tests showed that 8 column chromatographic fractions significantly inhibiting the growth of A549 cells were separated from the methanol extracts and among these, column eluted fraction 6 from visceral methanol extract (VCEF-6) separated from the visceral methanol extract exhibited the strongest antitumor activity with a half inhibition concentration of 168.7 μg/mL at 24 h. Further observation and analysis using flow cytometry and fluorescence microscope showed that the inhibitory effect of VCEF-6 on cell proliferation was related to induction of cell apoptosis. GC-MS analysis showed that VCEF-6 contained 22 known compounds, including 6 sterols, 6 alkanes, 6 aliphatic acid esters and 4 aromatic compounds. In conclusion, VCEF-6 has an inhibitory effect on the proliferation of A549 cells and induces cell apoptosis in vitro.

Key words: Styela plicata, antitumor activity, cell apoptosis, gas chromatography-mass spectrometry