Synthesis and Biological Evaluation of Pyrazolo[3,4-<i>b</i>]pyridin-4-ones as a New Class of Topoisomerase II Inhibitors

A series of 1,3,6-triphenylpyrazolo[3,4-b]pyridin-4-one derivatives was designed, synthesized and evaluated for cytotoxic activity in A375 human melanoma and human erythroleukemia (HEL) cells. The new pyrazolopyridones displayed comparable activities to the antitumor compound etoposide. The inhibitory effect of compounds 17, 18, 27 and 32 against topoisomerase II-mediated cleavage activities was measured finding good correlation with the results obtained from MTS assay. Docking studies into bacterial topoisomerase II (DNA Gyrase), topoisomerase IIα and topoisomerase IIβ binding sites in the DNA binding interface were performed. Keywords: Pyrazolo[3, 4-b]pyridine, etoposide, topoisomerase, docking studies.