Synthesis and Cytotoxicity of 2-Methyl-1-substituted-imidazo[4,5-g]quinoline-4,9-dione and 7,8-dihydro-10H-[1,4]oxazino[3′,4′:2,3]imidazo[4,5-g]quinoline-5,12-dione Derivatives Original Research Article

2-Methyl-1-substituted-imidazo[4,5-g]quinoline-4,9-diones and 7,8-dihydro-10H-[1,4]oxazino -[3′,4′:2,3]imidazo[4,5-g]quinoline-5,12-dione (19) derivatives have been synthesized from 6,7-dichloro-5,8-quinolinedione for developing the new anticancer drugs. Our study on the cytotoxicity of imidazoquinolinedione derivatives has revealed that 7,8-dihydro-10H-[1,4]oxazino-[3′,4′:2,3]imidazo[4,5-g]quinoline-5,12-dione (19), a tetracyclic heteroquinone analogue, exhibited high cytotoxicity on human colon tumor cell (HCT 15) in vitro SRB assay. The IC50 value of this compound was 0.026 μg/mL whereas those of doxorubicin and cisplatin were 0.023 μg/mL and 1.482 μg/mL, respectively. Meanwhile compounds 5–7 and 12 in the series of 1-substituted-imidazoquinolinediones showed relatively good activity on human brain tumor cell lines (XF 498).