In our lead finding program, a series of 1, 2, 4-triazolo [1, 5-a][1, 3, 5] triazine derivatives were synthesized, and their in vitro thymidine phosphorylase inhibitory potential was explored. Among the different derivatives, compounds having keto group (C= O) at C7 and thioketo group (C= S) at C5 positions showed varying degrees of TP inhibitory activity comparable with positive control, 7-deazaxanthine(7-DX, 2)(IC50 value= 42.63 lM). ...