Anti-inflammatory and anti-angiogenic effects of flavonoids isolated from Lycium barbarum fruits, a traditional Chinese medicine, on human umbilical vein endothelial cells (HUVECs) were investigated. Initially, flavonoids were extracted with 80% ethanol and separated using a Cosmosil 140 C18-OPN column, with the acidic fraction eluted with deionized water being composed of chlorogenic acid, caffeoyl quinic acid, caffeic acid and p-coumaric acid and the neutral fraction eluted with methanol composed of quercetin-diglycoside, rutin and kaempferol-O-rutinoside. Flavonoid extract was effective in inhibiting expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1) induced by TNF-α in HUVECs. The RT-PCR analysis indicated that ICAM-1 mRNA induced by TNF-α was inhibited by flavonoid extract. The flavonoid extract attenuated TNF-α-induced IκB phosphorylation as well as NF-κB, p65 and p50 translocation from cytosol to nucleus, through inhibition on TNF-α- and H(2)O(2)-induced intracellular reactive oxygen species (ROS) production. For the anti-angiogenic study, the flavonoid extract inhibited vascular endothelial growth factor (VEGF)-induced cell proliferation and migration in HUVECs, as well as angiogenesis. However, the flavonoid extract did not inhibit VEGF signaling. Surprisingly, HUVECs adhesion to the extracellular matrix was compromised and adhesion-induced signaling was retarded by the flavonoid extract.