Abstract: To compare the biological activities of diosmetin and diosmetin-7-O-β-D-glucopyranoside extracted from the peel of Trichosanthes kirilowii Maxim,we investigated their cytotoxicity on different cancer cells (MCF-7,MDA-MB-231 and A549) and human umbilical vein endothelial cells (HUVECs),and the probable mechanisms were also preliminary studied.Cell viability,morphological changes of nuclei and the expression of procaspase 3,LC3B,p62 and annexin A7 (ANXA7) were measured by sulforhodamine B (SRB) assay,acridine orange and Hoechst33258 staining and western blot respectively.Intracellular reactive oxygen species (ROS) level was determined by utilizing a fluorescent probe,2′,7′-dichlorodihydrofluorescin (DCHF).SRB assay showed that diosmetin had significant inhibition effects on the proliferation of MCF-7,MDA-MB-231 and A549 human cancer cell lines in a dose-and time- dependent manner,and induced HUVECs deprived of serum apoptosis.Western blot results showed that diosmetin induced tumor cell autophagy by increasing LC3-II level.However,diosmetin-7-O-β-D-glucopyranoside had a protective effect on HUVECs deprived of serum.Hoechst 33258 staining and acridine orange staining results showed apoptosis and nuclei fragments in HUVECs deprived of serum significantly decreased after treated with diosmetin-7-O-β-D-glucopyranoside respectively.Moreover,diosmetin-7-O-β-D-glucopyranoside significantly decreased ROS levels and inhibited caspase 3 and LC3-II level in HUVECs deprived of serum.Diosmetin and diosmetin-7-O-β-D-glucopyranoside had different biological activities.Diosmetin was a good antitumor agent whereas diosmetin-7-O-β-D-glucopyranoside might be a promising substituent to protect HUVECs.

Key words: diosmetin, diosmetin-7-O-&beta, -D-glucopyranoside, apoptosis, autophagy, reactive oxygen species