Design, synthesis and structure-activity relationships of novel 4-phenoxyquinoline derivatives containing 1,2,4-triazolone moiety as c-Met kinase inhibitors

A series of novel 4-phenoxyquinoline derivatives containing 1,2,4-triazolone moiety were synthesized and evaluated for their in vitro cytotoxic activity against four cancer cell lines (HT-29, H460, A549 and MKN-45). Most of the compounds exhibited moderate-to-significant cytotoxicity. Compounds 33, 37, 39, 44, 46, 47, 53, 55, 61, 64 and 66 were further examined for their inhibitory activity against c-Met kinase. The most promising compound 47 (with c-Met IC50 value of 1.57 nM) showed remarkable cytotoxicity against HT-29, H460, A549 and MKN-45 cell lines with IC50 values of 0.08 μM, 0.14 μM, 0.11 μM and 0.031 μM, respectively, and thus it was 1.1- to 2.3- fold more potent than foretinib. Their preliminary structure-activity relationships (SARs) studies indicate that electron-withdrawing groups on the terminal phenyl rings are beneficial for improving the antitumor activity.