Triazenoindazoles and triazenopyrazolopyridines: design, synthesis, and cytotoxic activity

Several triazenoindazoles 3a-e and triazinopyrazolopyridines 6a-i were prepared through the reaction of the corresponding 3-amino-4-chloroindazole and 3-aminopyrazolopyridine diazonium salts 2 and 5 with a number of secondary amines. All compounds were evaluated for their in vitro cytotoxic activity on three cell lines, HepG2, MCF7, and HeLa. Most compounds inhibited cell growth with IC(50) less than 0.1 microM. Compound 6d was the most potent, with an IC(50) of 0.03 microM against HepG2 and 0.05 microM against MCF7 and HeLa cells.