Regulation of hypoxia inducible factor (HIF)-1 alpha stabilization, which in turn contributes to adaptation of tumor cells to hypoxia has been highlighted as a promising therapeutic target in angiogenesis-related diseases. We have identified a new small molecule, G0811, as a potent angiogenesis inhibitor that targets HIF-1 alpha signal transduction. G0811 suppressed HIF-1 alpha stability in cancer cells and inhibited in vitro and in vivo angiogenesis, as validated by tube formation, chemoinvasion, and chorioallantoic membrane (CAM) assays. In addition, G0811 effectively decreased the expression of vascular endothelial growth factor (VEGF), which is one of target genes of HIF-1 alpha. However, G0811 did not exhibit anti-proliferative activities or toxicity in human umbilical vein endothelial cells (HUVECs) as effective doses. These results demonstrate that G0811 could be a new angiogenesis inhibitor that acts by targeting HIF-1 alpha signal transduction pathway. (C) 2013 Elsevier Inc. All rights reserved.