A structure-activity relationship study of 1,2,4-triazolo[1,5-a][1,3,5]triazin-5,7-dione and its 5-thioxo analogues on anti-thymidine phosphorylase and associated anti-angiogenic activities.

Thirty-three 1,2,4-triazolo[1,5-a][1,3,5]triazin-5,7-dione and its 5-thioxo analogues were designed and synthesized which contained different substituents at meta- and/or para-positions of 2-phenyl or 2-benzyl ring attached to the fused ring structure. The preliminary pharmacological evaluation demonstrated that the 5-thioxo analogues of 1,2,4-triazolo[1,5-a][1,3,5]triazine exhibited a varying degree of inhibitory activity towards thymidine phosphorylase, comparable or better than reference compound, 7-Deazaxanthine (7-DX, 2) (IC50 value = 42.63 μM).