Inhibitory effects of quercetin on angiogenesis in larval zebrafish and human umbilical vein endothelial cells

Angiogenesis plays an essential role in many physiological and pathological processes. Quercetin, a plant pigment and traditional Chinese medicinal herb, is an important flavonoid that has anti-cancer activity. However, the function of quercetin in blood vessel development in vivo and in vitro is still unclear. In this study, we investigated the anti-angiogenic activity of quercetin in zebrafish embryos and in human umbilical vein endothelial cells (HUVECs). Our results showed that quercetin disrupted the formation of intersegmental vessels, the dorsal aorta and the posterior cardinal vein in transgenic zebrafish embryos. In HUVECs, quercetin inhibited cell viability, the expression of vascular endothelial growth factor receptor 2 and tube formation in a dose-dependent manner. In inhibiting angiogenesis, quercetin was found to be involved in suppressing the extracellular signal-regulated kinase signaling pathway in vivo and in vitro. This study has shown that quercetin has potent anti-angiogenic activity and may be a candidate anti-cancer agent for future research.