Design, synthesis and antiproliferative activities of novel 5H-pyridazino[4,5-b]indoles

A novel series of 5H-pyridazino[4,5-b]indoles were designed and synthesized in order to find novel potent anticancer compounds. The structures were confirmed by 1H NMR and MS. Their antiproliferative activities against two cancer cell lines were tested by the MTT method in vitro. Three of compounds (1e, 1g, and 1h) exhibited potent antiproliferative activities, especially compound 1h (with IC50 values of 5.2 μmol/L and 1.9 μmol/L against Bel-7402 and HT-1080, respectively). The preliminary structure-activity relationships of 5H-pyridazino[4,5-b]indole derivatives were discussed.