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Paper | Regular issue | Vol 63, No. 3, 2004, pp.529-537
Published online, 16th January, 2004
DOI: 10.3987/COM-03-9948
Synthesis and Cytotoxic Evaluation of Certain Tricyclic Benzo[g]quinolin-4(1H)-one and Benzo[g]quinoline-4,9,10-trione Derivatives

Shu-Lin Hsu, Yeh-Long Chen, and Cherng-Chyi Tzeng*

*Faculty of Medicinal and Applied Chemistry, College of Life Science, Kaohsiung Medical University, Kaohsiung City, Taiwan, R.O.C.


The present report describes the synthesis and evaluation of tricyclic benzo[g]quinoline-4(1H)-one derivatives (CAB type) in which an additional aromatic ring is linearly fused on the antibacterial quinolone-3-carboxylic acid to maintain a free carboxylic acid (increase water-solubility) and a coplanar tricyclic DNA-intercalating chromophore (improve antitumor activity). 1H-Benzo[g]quinoline-4,5,10-trione, 1-methyl-1H-benzo[g]quinoline-4,5,10-trione, and ethyl 1-methylbenzo[g]quinoline-4,5,10-trione-3-carboxylate exhibited significant cytotoxicity against all 60 cancer cells with mean GI50 values of 5.92, 7.75, and 2.52 μM respectively while 1-methylbenzo[g]quinoline-4,5,10-trione-3-carboxylic acid and 5-hydroxy-10-methoxy-1-methylbenzo[g]quinolin-4(1H)-one- 3-carboxylic acid were inactive, indicated free carboxylic acid at C-3 position is unfavorable. The results have also implied the importance of carbonyl moieties at C-5 and C-10 due to the inactiveness of reduced products, ethyl 5-hydroxy-10-methoxy-1-methylbenzo[g]quinolin-4(1H)-one-3-carboxylate and ethyl 10-benzyloxy-5-hydroxybenzo[g]quinolin-4(1H)-one-3-carboxylate.