Abstract
Diazodization of pyrazolo[3,4-b] pyridine 1 afforded diazonium salt 2 that coupled with active methylene compounds such as 3a, b, 6-8, 15a, b, 16a, b, 17, and 24 in pyridine to give aryl hydrazone derivatives 4a, b, 9-11, 18a, b, 19a, b, 20, and 25, respectively. The previous synthesized compounds underwent cyclization in acetic acid to give the corresponding pyridopyrazolotriazines 5a, b, 12-14, 21a, b, 22a-c, 23, and 26, respectively. The newly synthesized compounds were characterized by elemental analysis and spectral data and screened for their antioxidant activities. The results of ABTS method showed clearly that compounds 1, 4b, 5b, 11, 20, 25, and 26 displayed promising in vitro antioxidant activities. Compounds 1 and 4a exhibited high protection against DNA damage induced by the bleomycine iron complex.