Design and synthesis of new 2-arylnaphthyridin-4-ones as potent antitumor agents targeting tumorigenic cell lines.

To develop new anticancer drug candidates from 2-arylnaphthyridin-4-one (AN), we have designed and synthesized a series of 3'-hydroxy and 6-hydroxy derivatives of AN. The results of cytotoxicity screening indicated that the replacement of the 3'-methoxy moiety on the C-ring phenyl group of AN (6a-e) with 3'-hydroxy (7a-e) made no significant effect on the inhibitory activity against HL-60, Hep3B and NCI-H460 cancer cell lines. On the other hand, replacing the 6-methoxy group on the A-ring of AN (6g-i) with a 6-hydroxy group (7g-i) resulted in reduced inhibitory activity against the above three cancer cell lines. Among the above-mentioned target compounds, 2-(3-hydroxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (7a) demonstrated the greatest potency and the best selectivity toward tumorigenic cancer cell lines. In a 7a preliminary mechanism of action study in Hep3B hepatoma cells, 7a showed the effects on microtubules followed by cell cycle arrest and sequentially led to apoptosis. In addition, a phosphate prodrug (11) of 7a exhibited significant antitumor activity when tested in a Hep3B xenograft nude mice model. Since compound 11 has demonstrated good development potential, it is recommended for further preclinical studies.