Polyphyllin D, a steroidal saponin from Paris polyphylla, inhibits endothelial cell functions in vitro and angiogenesis in zebrafish embryos in vivo

Angiogenesis, the process of blood vessel formation, is critical to tumour growth. The importance of angiogenesis in tumour development has lead to the development of anti-angiogenic strategies to inhibit tumour growth. In this study, polyphyllin D (PD), an active component in Chinese herb, Paris polyphylla, was evaluated for its potential anti-angiogenic effects. The inhibitory effects of PD on three important processes involved in angiogenesis, i.e. proliferation, migration and differentiation were examined using human microvascular endothelial cell line HMEC-1 by MTT assay, scratch assay and tube formation assay, respectively. Using zebrafish embryos as an animal model of angiogenesis, the anti-angiogenic effect of PD was further verified in vivo. PD suppressed the growth of HMEC-1 cells at 0.1–0.4μM without toxic effects. At 0.3μM and 0.4μM, PD significantly inhibited endothelial cell migration and capillary tube formation. About 70% of the zebrafish embryos showed defects in intersegmental vessel formation upon treatment with PD at concentrations of 0.156μM and 0.313μM. The anti-angiogenic effects of PD have been explored in the study which implied a potential therapeutic development of PD in cancer treatment.