In vitro anti-angiogenesis effects and active constituents of the saponin fraction from Gleditsia sinensis.

BACKGROUND

The anomalous fruits of Gleditsia sinensis Lam. (Leguminosae), a crude drug in China, have long been used in traditional Chinese medicine for the treatment of various diseases. The saponin fraction isolated from the fruits (SFGS) is considered as the active component for the antitumor activity of this crude drug.

OBJECTIVES

The present study was performed to investigate the anti-angiogenesis activities and active constituents of SFGS.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with SFGS in the presence or absence of basic fibroblast growth factor (bFGF) in vitro. The proliferation, migration, and tube formation were studied by MTT, Transwell, and 2D Matrigel assays, respectively. The cell cycle and apoptosis were analyzed by flow cytometry. Enzyme-linked immunosorbent assay for protein expression of vascular endothelial growth factor (VEGF) and western blot analysis for caspase-3, caspase-8, and caspase-9 as well as Fas were performed. In addition, the effects of 13 saponin compounds isolated from SFGS on the tube formation of HUVECs were screened, and the structure-activity relationships were discussed.

RESULTS

SFGS, at concentrations (1, 3, and 10 µg/mL) without significant cytotoxicity on endothelial cells, significantly inhibited the proliferation, migration, and tube formation of HUVECs induced by bFGF (10 ng/mL). It moderately arrested the cell cycle to G1 phase but greatly induced cell apoptosis and increased the expressions of caspases-3, caspase-8, and Fas but not caspase-9 in HUVECs. Moreover, SFGS did not affect the bFGF-induced autosecretion of VEGF from endothelial cells. Among the 13 saponin compounds tested, gleditsiosides B, I, J, O, and Q showed inhibition of the tube formation at a concentration of 3 µM, and only gleditsioside B exerted significant inhibition at 1 µM.

CONCLUSION

SFGS is substantially able to prevent angiogenesis by interfering with multiple steps. The findings provide a new explanation for the antitumor effects of G sinensis fruits. Gleditsiosides B, I, J, O, and Q are probably the main active constituents of SFGS.