石斛联苄类化合物抑制血管新生的机制

Bibenzyl from Dendrobium inhibits angiogenesis and its underlying mechanism

联苄类是传统中药石斛中一类含量较多的活性化合物。本研究首先考察了从石斛属药用植物中分离得到的6种联苄类化合物抑制VEGF(vascular endothelial growth factor)诱导的人脐静脉内皮细胞(humanumbilical vascular endothelial cell,HUVEC)管腔形成的实验,发现除tristin外其他联苄类化合物在10μmol.L 1时均显示出了明显的抑制活性,其中moscatilin的最低有效浓度为1μmol.L 1。进一步研究表明,moscatilin能浓度依赖性地抑制VEGF诱导的HUVEC细胞管腔的形成。免疫印迹(Western blotting)结果表明,moscatilin能抑制VEGF诱导的VEGFR2(vascular endothelial growth factor receptor 2,Flk-1/KDR)及ERK1/2(extracellularregulated protein kinases)的磷酸化激活,并能同时抑制由VEGF诱导的ERK1/2上游信号通路c-Raf和MEK1/2激酶的磷酸化。结果表明,moscatilin抑制血管新生活性的机制与阻断VEGFR2及c-Raf-MEK1/2-ERK1/2信号级联通路的激活有关。

Bibenzyl is a type of active compounds abundant in Dendrobium. In the present study, we investigated the inhibitory effects of six bibenzyls isolated from Dendrobium species on vascular endothelial growth factor （VEGF）-induced tube formation in human umbilical vascular endothelial cells （HUVECs）. All those bibenzyls inhibited VEGF-induced tube formation at 10 lamol.L-1 except tristin, and of which moscatilin was found to have the strongest activity at the same concentration. The lowest effective concentration of moscatilin was 1 tmol.L-1. Further results showed that moscatilin inhibited VEGF-induced capillary-like tube formation on HUVECs in a concentration-dependent manner. Western blotting results showed that moscatilin also inhibited VEGF-induced phosphorylation of VEGFR2 （Flk-1/KDR） and extracellular signal- regulated kinase 1/2 （ERK1/2）. Further results showed that moscatilin inhibited VEGF-induced activation of c-Raf and MEK1/2, which are both upstream signals of ERK1/2. Taken together, results presented here demonstrated that moscatilin inhibited angiogenesis via blocking the activation of VEGFR2 （Flk-1/KDR） and c-Raf-MEK1/2-ERK1/2 signals.