The synthesis of 11-substituted 6-amino-11,12-dihydrobenzo[c]phenanthridines and 11-substituted 6-aminobenzo[c]phenanthridines through an efficient method is described. The antiproliferative activity of selected compounds against a wide panel of tumor cell lines was tested in the in vitro anticancer screening and the in vivo hollow fiber assay of the National Cancer Institute. Several compounds turned out to exhibit considerable cytotoxicity for tumor cells. For the study of structure-activity relationships different substituents were introduced in the 11-position. Compounds with methoxyphenyl substituents tended to show the highest potency. Several compounds exhibited noteworthy antitumor activity with GI(50) values across all cell lines <1 microM. 6-Amino-11-(3,4,5-trimethoxyphenyl)benzo[c]phenanthridine perchlorate was the most potent agent in the NCI's in vivo hollow fiber assay. Most of the tested compounds showed a remarkable selectivity for leukemia, breast cancer, and prostate cancer.

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(E)-[2-(4-(Dimethylamino)phenyl)vinyl]benzenes bearing a nitrile or carboxyl group in the 2', 3', or 4' position were synthesized and tested for substrate activity with purified pig liver flavin-containing monooxygenase (FMO1). Although the nitrile derivatives were too insoluble to saturate the catalytic site at pH 7.4, they appeared to be substrates with K(m)'s somewhat above their maximum solubility (approximately equal to 0.1 mM) in the assay medium. Of the three carboxylic acid analogs, (E)-4-[2-(4(dimethylamino)phenyl)vinyl]benzoic acid had no detectable water solubility at pH 7.4, and measurements were restricted to (E)-3-[2-(4-(dimethylamino)phenyl)vinyl]benzoic acid (DS3CO) and (E)-2-[2-(4-(dimethylamino)phenyl)vinyl]benzoic acid (DS2CO). While DS3CO and DS2CO were substrates, they also inhibited FMO1 turnover. DS3CO was the more effective inhibitor, and at 2 mM it inhibited FMO1 and microsomal-catalyzed oxidation of methimazole (N-methyl-2-mercaptoimidazole) by 80-90%. Kinetic studies indicated that the aminostilbene carboxylates were noncompetitive with both the xenobiotic substrate, methimazole, and NADPH. However, inhibition constants calculated from double reciprocal plots of velocity vs NADPH were K(i)(comp) 130 and 150 microM for DS3CO and DS2CO, respectively, whereas the uncompetitive Ki's were 10-15 times higher, which suggests that inhibition of NADPH binding may be primarily responsible for inhibition of FMO1 by the aminostilbene carboxylates. This model is also consistent with inhibition of cyclohexanone monooxygenase, a bacterial analog of FMO. DS3CO and DS2CO were again noncompetitive with methimazole but primarily competitive with NADPH. The aminostilbene carboxylates had no detectable effects on activity of pig or rat liver NADPH-cytochrome P450 reductase, which suggests that they are not nonspecific flavoprotein antagonists.

Fused pyridine derivatives R 0450 A Two-Step Synthesis of Cytostatically Active Benzo[c]phenanthridine Derivatives. -With exception of paclitaxel, title compounds (IIIc) and (VI) exhibit higher cytostatic activities than established cytostatics like cyclophosphamide or fagaronine. -(CLEMENT*, B.; WEIDE, M.; WOLSCHENDORF, U.; KOCK, I.; Angew. Chem., Int. Ed. 44 (2005) 4, 635-638; Pharm. Inst., Christian-Albrechts-Univ.,