摘要Objective An organic layer prepared from the cortex of Morus alba (Moraceae) was studied in order to identify the active compounds for heparinase. Methods Bioassay-guided fractionation resulted in the isolation of sanggenon G Results The compound showed inhibitory activity with IC50 of 3.7 μmol/L on heparinase in vitro as well as 24 μmol/L in invasion assay using MDA-MB231 cells. Sanggenon G also had the moderate cytotoxicity at SW 620 (colon) and ACHN (kidney) cancer cell lines with IC50 of 10.96 and 13.44 μmol/L, respectively. Conclusion This is the first time that prenylated flavonoid sanggenon G is described as heparinase inhibitor. Besides, this flavonoid would be expected to be a metastasis inhibitor of cancer cells and also a valuable reagent to explore the mechanism of heparinase/heparanase-mediated metastasis.