Synthesis, antitumor evaluation and SAR of new 1H-pyrrolo [3,2-c] quinoline-6,9-diones and 11H-indolo [3,2-c] quinoline-1,4-diones.

New 1H-pyrrolo [3,2-c] quinoline-6,9-diones, 11H-indolo [3,2-c] quinoline-1,4-diones and 7,8,9,10-tetrahydro-11H-indolo [3,2-c] quinoline-1,4-diones, either unsubstituted or methylated, have been synthesized and evaluated for antitumor activity. They were compared to previously described quinones which bear either a methoxy group or an aziridinyl substituent on the quinone nucleus in order to establish structure-activity relationships and to obtain compounds as active as aziridinylquinones, but with less toxicity. A new synthetic route was developed using dimethoxy derivatives as key compounds that reacted with ceric ammonium nitrate (CAN) to give quinones by oxidation demethylation. The biological results obtained in vitro indicated that: (i) new quinones display cytotoxicity higher than that of the methoxyquinones; (ii) unsubstituted compounds are the most active; (iii) methylation of the pyrrole NH has no influence on unsubstituted quinones, but affords inactive derivatives when the quinone nucleus is methylated; (iv) compared to the aziridinyl-quinones, some compounds are equally active or more active. Despite the cytotoxicity exerted in vitro, we could not find evidence for any antitumor activity of quinones against in vivo P388 murine leukemia.