Alkaloid extract of Corydalis yanhusuo inhibits angiogenesis via targeting vascular endothelial growth factor receptor signaling

Background Corydalis yanhusuo W.T. Wang (YHS) is a well-known Chinese flowering herbal plant commonly used for centuries in functional food and traditional Chinese medicine. In the present study, we have identified and characterized a novel inhibitor of vascular endothelial growth factor receptor 2 (VEGFR2) with low toxicity, alkaloid extract of YHS, which suppressed angiogenesis that plays a fundamental role in a wide spectrum of physiological functions and pathological processes. Methods Proliferative ability of human umbilical vascular endothelial cells (HUVECs) was assessed using MTT assay and Ki67 immunofluorescence staining. Migration ability of HUVECs was evaluated by wound healing and transwell assays. In vitro angiogenesis was tested by spheroid sprouting and tube formation assays. In vivo vascularization was examined using Matrigel plug and chick chorioallantoic membrane (CAM) models. Protein expression and phosphorylation levels of VEGFR2, AKT, ERK and STAT3 were determined by Western blot assay. Results We demonstrated that alkaloid extract of YHS significantly inhibited a variety of VEGF-induced angiogenesis processes including proliferation, migration, sprouting, and tube formation of HUVECs. Moreover, alkaloid extract of YHS contributed to reduced in vivo neo-vessel formation in Matrigel plugs of mice and CAM models. Further mechanistic studies revealed that alkaloid extract of YHS suppressed VEGF-induced signaling pathway as evaluated by diminished phosphorylation of VEGFR2 and subsequently attenuated its downstream regulators including phospho-ERK1/2, phospho-AKT and phospho-STAT3 levels in HUVECs. Conclusion Collectively, these preclinical findings indicate that alkaloid extract of YHS remarkably limits angiogenesis and may serve as a promising anti-angiogenic drug candidate.