Fig. 1

Alkaloid extract of YHS suppressed VEGF-mediated HUVEC proliferation (a) The proliferation of HUVECs cultured in standard media after the treatment of various concentrations of alkaloid extract of YHS for 24 h with and without VEGF. Data are presented as mean ± SEM. ***, P < 0.001; **, P < 0.01; *, P < 0.05, paired t-test. b Time-course study of alkaloid extract of YHS on proliferation of HUVECs. HUVECs were treated with various concentrations of alkaloid extract of YHS for 12, 24 and 48 h in the presence of VEGF, after which HUVEC proliferation was detected by MTT assay. Data are presented as mean ± SEM. ***, P < 0.001; **, P < 0.01; *, P < 0.05, paired t-test. c Ki67 staining in HUVECs that had been treated with various concentrations of alkaloid extract of YHS for 24 h in the absence and presence of VEGF. Proliferation was determined by the ratio of the average number of Ki67-positive cells to total cells. Data are presented as mean ± SEM. **, P < 0.01; *, P < 0.05, paired t-test. d LDH release from HUVECs after the treatment of various concentrations of alkaloid extract of YHS for 24 h. Data are presented as mean ± SEM, paired t-test. e Representative images of HUVEC morphology after 48 h exposure to (a) 0 μg/ml; (b) 10 μg/ml; (c) 50 μg/ml; (d) 100 μg/ml of alkaloid extract of YHS in the presence of 20 ng/ml VEGF, scale bar: 250 μm