Abstract: ObjectiveTo study the cell inhibitory and apoptosis effect of bioactive compounds extracted from Forsythia suspensa(LQ-4) on HeLa cells in vitro,and to study the mechanism of anti-tumor activity of LQ-4.MethodsLQ-4 was extracted by means of alcohol precipitation,macroporous resin chromatography,and thin-layer chromatography.Methyl thiazolyl tetrazolium(MTT) assay was used to evaluate the growth inhibition rate of HeLa cells treated by different concentrations of LQ-4.Arcridine orange/ethidium bromide(AO/EB) fluorescent staining and transmission electron microscopy(TEM) were used to observe cell morphology.Western blot was used to detect the cell apoptosis-related protein in HeLa cells treated by LQ-4(50 μg/ml) at different times.ResultsThe anti-tumor active components(LQ-4) showed time-dose-dependent inhibitory effect on the proliferation of HeLa cells in vitro.The concentration for 50% inhibition(IC₅₀) at 12,24,and 48 hours was 93.74,33.30,and 22.65 μg/mL,respectively.Fluorescence microscope and TEM detection showed that HeLa cells presented characteristic morphological changes of apoptosis after LQ-4 treatment.The results of western blot revealed that LQ-4(50 μg/mL) could promote the activation of the zymogen of caspase-8.ConclusionLQ-4 has an inhibitory effect on HeLa cell proliferation and could induce HeLa cell apoptosis,which is probably related to the decomposition of caspase-8 protease.