Purity >98%. KIN59 is a purine riboside derivative that allosterically inhibits thymidine phosphorylase (TPase; IC50 s = 44 and 67 μM for purified E. coli and human enzymes, respectively). Through this action, KIN59 blocks the conversion of thymidine to thymine. KIN59 inhibits TPase-induced angiogenesis in a chicken chorioallantoic membrane assay and reduces endothelial cell migration without impacting proliferation. KIN59 also inhibits the binding of fibroblast growth factor 2 (FGF2) to FGF receptor 1, preventing the growth and neovascularization of subcutaneous tumors induced by FGF2-transformed endothelial cells injected in immunodeficient nude mice.