Antiangiogenic Activity of Flavonols in Chorioallantoic Membrane (CAM) Assay

Angiogenesis is a fundamental step in the transition of tumors from a dormant state to a malignant one. Food factors capable of inhibiting angiogenesis, if found, would be useful tools to stop the progression of small cancers. In this study, we examined the antiangiogenic activities of four flavonols commonly found in foods: galangin, kaempferol, quercetin, and myricetin. The effects of these flavonols were tested in an in vivo model of angiogenesis, the chorioallantoic membrane (CAM) assay. These compounds showed strong antiangiogenic activities. Furthermore, we compared the results of the CAM assay with those of an in vitro model of angiogenesis, the tube formation assay. Flavonols with strong antiangiogenic activities in the CAM assay also showed strong inhibitory activities in the tube formation assay. We discuss the structure-activity relationship for the flavonols with regard to their antiangiogenic activities.